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Full text of "The birds of Mt. Isarog National Park, Southern Luzon, Philippines, with particular reference to altitudinal distribution"

FIELDIANA 



Zoology 

NEW SERIES, NO. 60 



The Birds of Mt. Isarog National Park, 
Southern Luzon, Philippines, 
with Particular Reference 
to Altitudinal Distribution 



Steven M. Goodman 
Pedro C. Gonzales 



September 28, 1990 
Publication 1415 



PUBLISHED BY FIELD MUSEUM OF NATURAL HISTORY 



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Croat, T. B. 1978. Flora of Barro Colorado Island. Stanford University Press, Stanford, Calif, 943 pp. 

Grubb, P. J., J. R. Lloyd, and T. D. Pennington. 1963. A comparison of montane and lowland rain forest in Ecuador. 

I. The forest structure, physiognomy, and floristics. Journal of Eu:ology, SI: 567-601. 
Langdon, E. J. M. 1979. Yage among the Siona: Cultural patterns in visions, pp. 63-80. In Browman, D. L.,and R. A. 

Schwarz, eds.. Spirits, Shamans, and Stars. Mouton Publishers, The Hague, Netherlands. 
Murra, J. 1946. The historic tribes of Ecuador, pp. 785-821. In Steward, J. H., ed.. Handbook of South American 

Indians. Vol. 2, The Andean Civilizations. Bulletin 143, Bureau of American Ethnology, Smithsonian 

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THIS PUBLICATION IS PRINTED ON ACID-FREE PAPER. 



FIELDIANA 



Zoology 

NEW SERIES, NO. 60 



The Birds of Mt. Isarog National Park, 
Southern Luzon, Philippines, 
with Particular Reference 
to Altitudinal Distribution 



Steven M. Goodman 

Museum of Zoology 
University of Michigan 
Ann Arbor. Michigan 48109 

Present Address: 

Department of Zoology 

Field Museum of Natural History 

Chicago. Illinois 60605-2496 



Pedro C. Gonzales 

Chief, Zoological Division 
National Museum of the Philippines 
Old Congress Building 
Rizal Park 
Manila, Philippines 



Accepted July 25, 1989 
Published September 28, 1990 
Publication 1415 



PUBLISHED BY FIELD MUSEUM OF NATURAL HISTORY 



© 1990 Field Museum of Natural History 

ISSN 0015-0754 

PRINTED IN THE UNITED STATES OF AMERICA 



Table of Contents 

Abstract 1 

Introduction 1 

Study Site and Methods 2 

Account of the 1988 Fieldwork 2 

Vegetational and Ecological Types of Mt. 

Isarog 2 

Collections 6 

Measurements 7 

Netting 8 

Observations 8 

Systematic Order and Nomenclature 8 

Species Accounts 8 

Discussion 30 

Altitudinal Overlap of Congeners 31 

Densities of Birds Based on Netting 31 

Altitudinal Distribution of Birds on Mt. 
Isarog and Other Philippine Moun- 
tains with Mossy Forest 33 

Changes in the Resident Avifauna of Mt. 

Isarog Between 1961 and 1988 36 

The State of Mt. Isarog National Park .... 36 

Acknowledgments 37 

Literature Cited 38 



List of Illustrations 



2. View of western side of Mt. Isarog from 
approximately 250 m 4 

3. Partially cleared lowland forest at 900 m 5 

4. Transitional lowland/montane forest at 
about 1050 m 6 

5. Mossy forest at 1 750 m 7 

6. Graph comparing number of species oc- 
curring in distinct ecological zones and at 
various elevations on four mountains in 

the Philippines 34 



List of Tables 



1 . Capture rate of Brachypteryx montana in 
mammal snap-traps 21 

2. Altitudinal distribution of resident bird 
species on Mt. Isarog 24 

3. Netting success on Mt. Isarog of resident 
birds captured between 28 February and 

30 May 1988 32 

4. The species composition of mossy forest 
avifaunas on four mountains in the Phil- 
ippines 35 

5. Differences in the number of resident 
species found on Mt. Isarog in 1961 and 
1988 37 



1 . Map of southeastern Luzon and Mt. Isa- 
rog 3 



The Birds of Mt. Isarog National Park, 
Southern Luzon, Philippines, 
with Particular Reference 
to Altitudinal Distribution 



Abstract 

Mt. Isarog National Park is located in south- 
eastern Luzon, Philippines, on the Camarines Pen- 
insula. The mountain is an old volcanic peak that 
rises to 1 966 m. The local climate is characterized 
by the lack of a pronounced dry season. Four dis- 
tinct vegetational zones occur on the mountain: 
parang grassland (from the lowlands to 900 m), 
lowland forest (from 450 to 900 m), montane for- 
est (from 900 to 1 500 m), and mossy forest (from 
1500 m to the summit). 

Information presented herein on the birds of Mt. 
Isarog is based on the collections of D. S. Rabor, 
obtained in the spring of 1961, and our own col- 
lections and observations, made in the late winter 
and spring of 1988. Our survey was conducted at 
six focal points along an elevational transect of the 
mountain. In the species accounts and discussion 
sections particular attention is given to the alti- 
tudinal distributions of the resident birds. We also 
report measurements and weights of collected birds, 
breeding data, stomach contents, some taxonomic 
information, and general natural history obser- 
vations. 

A total of 135 bird species has been recorded 
on Mt. Isarog: 1 1 6 residents and 1 9 migrants or 
winter visitors. Species number and density de- 
crease with altitude. Some of the factors that might 
result in this relationship are analyzed. Three dis- 
tinct patterns were found in the distribution of 
congeners on the mountain: complete altitudinal 
sympatry, broad elevational disjunction, and a 
small amount of overlap with apparent species 
replacement. 

The distribution of the forest birds on Mt. Isa- 
rog, based on the four vegetational zones, is com- 
pared to three other mountains on Philippine is- 



lands. In all cases the number of species on each 
mountain decreases with altitude. The elevations 
where different types of forest occurs varies be- 
tween mountains. No species of mossy forest bird 
is endemic to any one of these mountains, nor is 
there a fleet of species limited to the mossy forest 
zone. 

Since Rabor visited Mt. Isarog in 1961, much 
of the lowland forest has been cleared. By com- 
paring his survey results with our 1988 informa- 
tion it can be estimated that about 42% (27 of 64 
species) of the lowland forest (between 450 and 
900 m) birds have been locally extirpated. The 
remaining tracts of forest within and outside the 
park boundaries are still being cut, and the region 
is severely threatened with deforestation. The de- 
ployment of rangers in the area to enforce existing 
laws against illegal logging, and a local education 
program directed towards information about hab- 
itat destruction and watershed management are 
suggested as important steps in conserving the re- 
maining undisturbed forests of Mt. Isarog. 



Introduction 

Although the island of Luzon, Philippines, has 
been the site of numerous ornithological studies, 
most of the information on the birds of that island 
is contained in systematic reviews and descrip- 
tions of new taxa. Only a few studies on regional 
avifaunas of Luzon have been published; most of 
these deal with the biogeographically distinct north 
(e.g.,Ogilvie-Grant, 1894; McGregor, 1904, 1924; 
Morioka & Sakane, 1 979) and only a few deal with 
the central and southern portions of the island 
(Ogilvie-Grant, 1895; Wolfe, 1938; Gilliard, 1950). 



GOODMAN & GONZALES: BIRDS OF MT. ISAROG NATIONAL PARK 



Surprisingly, none of these studies contains quan- 
tified information on the altitudinal distribution 
of the resident montane avifauna on the island. 
Also, to our knowledge no detailed bird list is 
available for any montane Philippine national park. 
This monograph reviews the bird species known 
from Mt. Isarog National Park in southeastern Lu- 
zon, describes their altitudinal distribution and 
density, and compares these patterns with mon- 
tane avifaunas on other islands in the Philippines. 



Study Site and Methods 

The southern end of Luzon is divided into the 
large Camarines Peninsula (including the regions 
Albay, Camarines, and Sorsogon) and the smaller 
Bondoc Peninsula. The topography of southern 
Luzon is dominated by several volcanic moun- 
tains: Bulusan ( 1 560 m) in the extreme south. Ma- 
yon (2421 m) and Isarog (1966 m) in the center, 
and Labo (942 m) in the north. Mt. Isarog lies 5 
km north and 20 km east of Naga City, at 1 3°40'N, 
123°2rE. 

The climate of the Camarines Sur Province near 
Mt. Isarog is characterized by the lack of a pro- 
nounced dry season, and a period of maximum 
rainfall between November and January. The av- 
erage annual rainfall at Naga City (ca. 20 m ele- 
vation) is 280 cm and the temperature range is 
approximately from 16 to 30° C (O'Brien, 1968). 
Typhoons occur mostly in May and from Septem- 
ber to November, principally along the Pacific 
Ocean coast. 

The Bicolanos are the main cultural group pres- 
ently inhabiting southeastern Luzon (O'Brien, 
1 968). Formerly, non-Bicolano tribal peoples lived 
on Mt. Isarog and surrounding lowland areas; their 
cultural identities are ambiguous but they were 
presumably a mixture of several different heritages 
(Jagor, 1870, 1875; Miller, 1911; Lynch, 1948). 
One of these groups were semi-nomadic forest 
dwellers known as Agta. At the turn of the 20th 
century the Agta lived on the lower slopes of Mt. 
Isarog, where they subsisted as hunter-gatherers 
and as agriculturalists (Miller, 1911). The subse- 
quent fate of these people is not clear. We were 
told in spring 1988 that the last of the "mountain 
peoples" had left Mt. Isarog about 20 years before. 

Account of the 1988 Fieldwork 



Heaney, on the distribution, systematics, and bio- 
geography of Southeast Asian animals, particular- 
ly mammals (Heaney, 1 986). The 1 988 survey was 
a joint expedition between the Philippine National 
Museum (pnm), the United States National Mu- 
seum of Natural History (usnm), and Silliman 
University. 

On the morning of 27 February 1988 a recon- 
naissance group went from Naga City to the Pani- 
cuason Central Nursery, at about 450 m on the 
western slope of Mt. Isarog (13°40'N, 123°20'E). 
The nursery is located 4 km north and 1 8 km east 
of Naga City. A local guide and Goodman spent 
the next two days making a survey of the western 
slopes of Mt. Isarog. On 1 March the balance of 
the field team arrived at the nursery to commence 
the survey. 

From 3 to 3 1 March the field team (in various 
combinations), along with several local people, 
worked out of a series of five camps on the west 
and northwest slopes of the mountain: camp 1 at 
900 m, camp 2 at 1125 m. camp 3 at 1350 m, 
camp 4 at 1 550 m, and camp 5 at 1 750 m (fig. 1). 
These camps and the Panicuason Central Nursery 
served as six focal points for an elevational tran- 
sect. Two camps were often in simultaneous op- 
eration, each by crews of 5-10 individuals. Be- 
cause the primary focus of the expedition was 
mammals, most efforts were devoted to rodent 
trapping and bat netting. Gonzales and Goodman 
represent exceptions to this focus. Their energies 
were concentrated on a bird inventory, and they 
were generally in different camps. 

From 23 to 31 March Gonzales worked an area 
of secondary forest at about 400 m. Specimens 
were obtained at this site by netting and shooting. 
Because of their close proximity and similarity in 
habitat, data from this locality and the Panicuason 
Central Nursery were combined. 

From 17 April to 8 May 1988 a field team re- 
turned to Mt. Isarog for further transect work. The 
majority of eflTort was directed to trapping and 
netting mammals and collecting plants, and no 
systematic ornithological work was conducted. All 
of the camps established on the first field trip were 
reoccupied and a similar field procedure was fol- 
lowed. 



Vegetational and Ecological Types 
of Mt. Isarog 



Our 1988 field trip to Mt. Isarog was part of a 
long-term program, under the direction of L. R. 



Following the definitions of Brown (1919) and 
Whitmore (1984), four vegetational zones are rec- 



FIELDIANA: ZOOLOGY 




Fig. 1. Map of southeastern Luzon and Mount Isarog. The solid line surrounding the mountain represents the 
reforestation project boundary. The positions of the Panicuason Central Nursery and our five transect points are 
indicated on the west side of the mountain. The inset is of the southern portion of Luzon. 



GOODMAN & GONZALES: BIRDS OF MT. ISAROG NATIONAL PARK 




Fig. 2. View of the western side of Mt. Isarog from approximately 250 m. Note the grassland vegetation in the 
foreground and the cleared areas on the lower slopes of the mountain. The upper zone is shrouded in clouds. (Photo 
taken May 1988 by L. R. Heaney.) 



ognized on Mt. Isarog: parang grassland, lowland 
forest, montane forest, and mossy forest. Brown's 
classification was developed for describing the 
plants of Mt. Makiling (= Maquiling), central Lu- 
zon, whereas Whitmore's is more generalized for 
Southeast Asian tropical forests. The three types 
of forest are not discrete ecological units with clear- 
ly definable boundaries but grade into one another. 
Parang (interspersed from the lowlands, in- 
cluding the area around the Panicuason Central 
Nursery, to camp 1 at 900 m)— This zone is not 
a natural vegetation type of the area. It is the result 
of the complete or partial removal of the original 
forest (fig. 2). Areas of paraw^ often consist of large 
patches of grass, 1-3 m high (often cogon, Impera- 
ta cylindrica), and disjunct lots of secondary forest. 
In large tracts of land, particularly at the lower 
foothills of Mt. Isarog where most of the rural 
population resides, cleared areas were converted 
directly from forest to tillable land or plantations. 
Clearings oi parang are regularly burned to thwart 
secondary forest succession. Numerous small riv- 
ers and streams that originate on the upper slopes 
of Ml. Isarog course through this area. As of early 



1988, on the west and northwest slopes of the 
mountain areas, the parang extended up to 900 m. 

Lowland Forest (in small patches from 450 to 
900 m; synonym of Dipterocarp Forest sensu 
Brown [1919])— The lower western slopes of Mt. 
Isarog have been extensively cleared, but presum- 
ably this forest type formerly extended to sea level. 
As of spring 1988, most of the original lowland 
forest on the west and northwest slopes below 450 
m had been destroyed and much of it above 450 
m had been extensively modified (fig. 3). When 
Rabor visited Mt. Isarog in 1961 (see p. 36) he 
found tracts of intact lowland forest down to ap- 
proximately 450 m. 

Small patches of forest, generally less than three 
hectares, have been cleared by 'slash and bum' 
agriculturalists. These openings are known as 
kaingin, and such an agriculturalist is known as a 
kainginero. Root crops and abaca (Musa textilis) 
are the most commonly grown domestic plants in 
these clearings. In spring 1988, the highest human 
settlements on the west side of the mountain were 
at about 650 m. Kaingin was a common feature 
of the landscape up to 900 m, where it abruptly 



FIELDIANA: ZOOLOGY 




Fig. 3. Partially cleared lowland forest at 900 m. Note 12-m mist net in foreground. The view in the upper right 
comer is northwest, towards San Miguel Bay. (Photo taken late March 1988 by S. M. Goodman.) 



stopped because of a change in topography and 
habitat (see below). 

The remaining lowland forest had the charac- 
teristic three-storied structure associated with this 
ecological zone. The tallest trees were estimated 
to be 30—45 m and in undisturbed areas they closed 
off the canopy. Approximately 40% of the large 
trees had buttressed bases. In selectively logged 
areas of the forest it is these giants that are sought 
after and removed. Strangler figs were relatively 
common in both undisturbed and secondary low- 
land forest. During March 1988 several types of 
Ficus spp. trees and shrubs were in flower and fruit. 
The lower tiers of the intact lowland forest con- 
sisted mostly of young trees and lianas. Epiphytes 
were common and groimd ferns and succulent herbs 
rare. In most areas, rattan, a type of climbing spiny 
palm (Calamus) used in commercial construction, 
had been widely harvested from the forest by local 
people. 

The Panicuason Central Nursery is the local 
headquarters of the Philippine Bureau of Forest 
Development reforestation project on Mt. Isarog. 
The main focus of this program is the replanting 
of trees in large tracts of cleared lowland forest 



between about 350 and 600 m. This is primarily 
for watershed management and to a lesser extent 
for selective logging. The oldest replanted stands 
of forest on the west side of Mt. Isarog are about 
20 years old. In virtually all replanted groves only 
one or two species of trees have been introduced, 
including Philippine mahogany ( I ire.x) and non- 
native ipil-ipil (Leucaena). One edge of the nursery 
lies along the national park boundary. Other hab- 
itats near the Panicuason Central Nursery include 
relatively large tracts of secondary lowland forest 
with a few remaining large dipterocarps and dense 
volunteer undergrowth; cleared areas used as tree 
plantations; and, just outside the park, small set- 
tlements surrounded by large agricultural fields. 
Directly above the nursery the Yabo River courses 
through several deep gorges, which are covered 
with some undisturbed lowland forest. 

Montane Forest (from approximately 900 to 
1 500 m; synonym of Midmountain Forest sensu 
Brown [1919])— Directly behind camp 1 at 900 m 
the mountain rose almost vertically for about 1 50 
m. Between the bottom and the top of this steep 
slope many characteristics of the forest changed. 
Some of these differences appear diagnostic of the 



GOODMAN & GONZALES: BIRDS OF MT. ISAROG NATIONAL PARK 




Fig. 4. Transitional lowland/montane forest at about 1050 m. (Photo taken late March 1988 by S. M. Goodman.) 



shift from lowland to montane forest (Brown, 
1919). The trees were straighter, the structure of 
the forest two-storied, and the canopy more open. 
The understory at about 1050 m was denser than 
in areas below, and various types of palms, ferns, 
tree saplings, and bamboo were relatively com- 
mon. Ficus spp. were rare (fig. 4). The first dense 
growths of epiphytic ferns, pandans, and orchids 
were noted here. Although rare, pitcher plants (Ne- 
penthes), arborescent palms, and oaks (Lithocar- 
pus) were found at this elevation. Vines of rattan 
at least 40 mm in diameter were not uncommon. 

As one moved up in elevation, to about 1 500 
m, epiphytes in the subcanopy and ground plants, 
as well as a generally denser understory, became 
more widespread. Within the montane forest there 
was a noticeable change in the percentage of trees 
with structural modifications: at 1125 m about 
30% of the large trees had buttressed bases and at 
1350 m between 10% and 15% had them. We 
classify our camp 2 at 1 125 m as montane forest 
with some transitional elements of lowland forest 
and camp 3 as montane forest. 

Mossy Forest (from approximately 1 500 m to 
the summit at 1966 m; synonym of Upper Moun- 
tain Rain Forest sensu Whitmore [1984])— The 
transition zone from montane to mossy forest was 



gradual. The area around our camp 4 at 1550 m 
still had some characteristics of montane forest; 
however, there was a noticeable reduction in tree 
size and stature, vines became rare, strangler figs 
completely dropped out, and there was a distinct 
increase in moss cover on tree branches and trunks. 
At about 1650 m the transition was more dra- 
matic (fig. 5). The tallest trees were seldom over 
1 m and often were covered with luxuriant growths 
of mosses, liverworts, orchids, and ferns (often up 
to 25 cm thick). The locally high humidity and 
regular rains kept the forest saturated with mois- 
ture. No trees with buttressed bases were noted, 
although some trees had support stilts. Pandans 
were abundant, often covering the trunks of larger 
trees. In some areas the ground debris was made 
up largely of shed pandan leaves. This habitat con- 
tinued up to the summit, where strong winds caused 
the trees to become even more twisted and stunt- 
ed. Near the summit there were patches of grass- 
land, up to several hectares in size. 



Collections 

Dioscoro S. Rabor visited Mt. Isarog between 
23 March and 29 April 1 96 1 and made a collection 



FIELDIANA: ZOOLOGY 




Fig. 5. Mossy forest at 1750 m. Note luxuriant growth of ground cover and moss. (Photo taken in late March 
1988 by L. R. Heaney.) 



of birds. His work on Mt. Isarog was part of a 
broader survey of vertebrates inhabiting the 
mountains in the provinces of Camarines Sur and 
Sorsogon (Rabor, 1966). He worked the south- 
eastern slopes of Mt. Isarog and used Curry as his 
base station (fig. 1). Although we have no exact 
information on how Rabor obtained specimens, 
it is presumed he had mist nets, and on the basis 
of wounds on several specimens, he also had fire- 
arms. He acquired some birds from local hunters. 
About 750 skins in the Rabor collection from Mt. 
Isarog are deposited at the Field Museum of Nat- 
ural History (fmnh) and another 94 at the College 
of Forestry, University of Philippines at Los Ba- 
nos. A portion of the fmnh material is cataloged 
within the Conover Collection (cc). A few addi- 
tional specimens from the 1961 Rabor collection 
were sent to the Delaware Museum of Natural 
History and the University of Michigan Museum 
of Zoology. All of this Rabor material has been 
studied, but only specimens housed in the fmnh 
have been used herein. This is because the other 
collections are a subset of the material in the fmnh 
in both species represented and altitudinal infor- 
mation. Six new subspecies of birds were named 
from this collection (Rand & Rabor, 1967). Rabor 



also collected mammals at Mt. Isarog, including 
the type specimens of the endemic genus and spe- 
cies Archboldomys luzonensis (Musser, 1982) and 
the species Rhynchomys isarogensis (Musser & 
Freeman, 1981). 

On our 1988 trip to Mt. Isarog, between 27 
February and 31 March, birds were obtained in 
mist nets, in mammal snap-traps, or by shooting 
with air rifles; a few specimens were purchased 
from local people. During this work 373 birds were 
collected. Most of these animals were prepared as 
skeletons or fluid-preserved specimens. On the 
second 1988 trip to Mt. Isarog, between 17 April 
and 8 May, an additional 60 bird specimens were 
taken. The 1988 collections were divided between 
the PNM and usnm. Including the 1 96 1 Rabor ma- 
terial in various museums and our own 1988 col- 
lections, a total of 1 ,293 bird specimens have been 
examined from Mt. Isarog. 



Measurements 

Because little quantified information is avail- 
able in the literature on the measurements of Lu- 
zon birds, particularly from the southern portion 



GOODMAN & GONZALES: BIRDS OF MT. ISAROG NATIONAL PARK 



of the island, summary statistics have been in- 
cluded for most resident species taken on Mt. Isa- 
rog. Unless explicitly noted, measurements are of 
adults. For sample sizes (in parentheses) less than 
four, the measurements for each individual are 
listed. Measurements for larger samples are given 
as mean ± standard deviation, followed by the 
range. 

Linear measurements were taken only from dried 
skins; specimens saved in fluid or as skeletons are 
not included in these summary statistics. Mea- 
surements include (all in mm): Wing— measured 
from the bend of the flattened wing at carpal joint 
to longest primary tip. Tail— measured from the 
point of insertion of central rectrices to distal tip. 
Exposed culmen— measured from the base of the 
feathering on the forehead to maxilla tip. Bill from 
nostril— measured from anterior edge of nostril to 
maxilla tip. Bill width— measured across the edges 
of the bill rami at the level of the anterior edge of 
nostril. Weights are given in grams. For many Ra- 
bor specimens a range of altitudes was given on 
the tag; for convenience, only the median is re- 
ported here. The 1988 elevational information is 
based primarily on altimeter readings. 



Netting 

A series of mist nets was operated at each tran- 
sect site. All nets used were 2.6 m high, 36-mm 
size mesh, and 12 m long. A net left up for a 24- 
hour period is termed a "net-day." 

Nets were checked during daylight hours at least 
once every two hours, and we generally never had 
more than eight nets in operation at any one time 
per transect zone. Nets were left up throughout the 
night to catch bats and nocturnal birds. The bot- 
tom edge of the lowest net panel was generally set 
1 m above the ground. At each transect zone the 
nets were placed in a variety of habitats, e.g., on 
the rim of ridge tops, in parang, and in lanes in 
thick understory growth. 



Observations 



6; and camp 5 at 1750 m— 4. Regular notes were 
kept on the species observed or heard daily, the 
elevation, and surrounding habitat. Both Gonzales 
and Goodman carried altimeters, so precise details 
of the elevational ranges of identified birds could 
be worked out. In order to quantify this infor- 
mation the following "abundance measures" have 
been used: abundant— seen or heard numerous 
times each day per transect zone, common— seen 
or heard once each day per transect zone, uncom- 
mon—seen or heard every two or three days per 
transect zone, rare— seen or heard once or twice 
for duration of stay in any transect zone. 



Systematic Order and Nomenclature 

We have generally followed the systematic ar- 
rangement and common names used by Gonzales 
and Rees (1988); in some cases alternative names 
from Dickinson et al. (in press) have been pre- 
sented in parentheses. An asterisk (*) at the start 
of any species account indicates that at least one 
specimen taken on Mt. Isarog of the respective 
taxon has been examined. In cases when a bird 
was only observed in the area and not collected, 
the presumed subspecies has been inferred on 
known patterns of geographic variation; this is de- 
noted with the use of brackets ([ ]) surrounding the 
subspecies name. 



Species Accounts 
Family Accipitridae 

Aviceda jerdoni [magnirostris] Jerdon's Baza 

This species was observed once. An adult was 
noted on 14 March 1988atl550m soaring over 
the forest. According to duPont (1971) this sub- 
species is endemic to the islands of Mindanao, 
Palawan, and Samar, and although not previously 
recorded on Luzon, it is presumably the form oc- 
curring there. 



In addition to collecting and netting specimens, 
members of the 1988 expedition gathered obser- 
vational information on birds. The cumulative 
number of observer-days per transect zone was: 
Panicuason Central Nursery (including 400 m 
camp)— 14; camp 1 at 900 m— 14; camp 2 at 1 125 
m— 7; camp 3 at 1350 m — 9; camp 4 at 1550 m— 



*Pernis celebensis steerei Barred Honey Buzzard 

The single record of this species on Mt. Isarog 
is one Rabor collected on 19 April 1961 between 
610 and 760 m. 

Measurements— Immature female (I)— wing 
385, tail 265, exposed culmen 32.8, weight 588. 



FIELDIANA: ZOOLOGY 



*Pernis apivorus philippensis 
Buzzard 



Crested Honey 



An adult male collected on 20 April 1961 be- 
tween 450 and 610 m is the only known record 
for the mountain. duPont (1971) did not list this 
species as occurring on Luzon. Stresemann and 
Amadon (1979) include Luzon in its distribution, 
but the basis for this was not stated. 

Measurements— Male (1)— wing 414, tail 283, 
exposed culmen 39.7, weight 1,004. 



*Haliastur Indus intermedius Brahminy Kite 

The single record of this species on Mt. Isarog 
is an immature bird obtained by Rabor on 1 9 April 
1961 between 450 and 610 m. The bird was molt- 
ing the wing and tail feathers. 



*Spilornis holospilus Philippine Serpent Eagle 

We occasionally observed pairs of Philippine 
Serpent Eagles between 450 and 900 m soaring 
over partially cleared areas and remaining patches 
of forest. We did not note it at higher elevations. 
Rabor collected four adults between 200 and 
760 m. 

Measurements— Wing— male (3) 357, 363, 368, 
female (1) 369; tail-male (3) 232, 237, 241, fe- 
male (1)225; exposed culmen— male (3) 32.9, 35.3, 
35.6, female (1) 35.8; weight-male (3) 656, 688, 
858. 



*Accipiter gularis gularis Japanese Sparrowhawk 

An adult male (based on size, wing 172 and tail 
111) was taken at approximately 380 m on 24 
March 1961. This species is a winter visitor to the 
PhiHppines (duPont, 1971). 

Weight - Male (1) 123. 



*Accipiter virgatus confusus Besra 

We have three records of this species on the 
mountain. On 18 March 1988 an immature bird 
was netted in primary forest at 1550 m, on 25 
March 1988 an adult was captured in a heavily 
disturbed area at 450 m, and on 24 April 1961 an 
adult was taken at approximately 260 m. The 25 
March bird was caught while chasing a pair of 



Pachycephala philippinensis; the raptor had insect 
and beetle remains in its stomach. The gizzard of 
the immature bird was empty. 

Measurements— Wing— male (2) 1 50, 1 66, im- 
mature male (1) 159; tail— male (2) 109, 114, im- 
mature male (1) 120; exposed culmen— male (2) 
16.5, 16.6, immature male (1) 16.0; weight— male 
(2) 94, 97, immature male (1) 120. 



*Accipiter soloensis Chinese Goshawk 

There are two records for Mt. Isarog of this mi- 
grant from the Asian mainland. On 23 March 1 96 1 
an immature bird and an adult female were col- 
lected at approximately 260 m. 

Weight— Female (1) 159, immature female (1) 
160. 



*Butastur indicus Grey-faced Buzzard 

A Grey-faced Buzzard was collected by Rabor 
on 23 April 1961 at about 680 m. This is the only 
known record for Mt. Isarog of this migrant from 
the Asian mainland. 

Weight— Immature female (1)418. 



*Hieraaetus kienerii formosus 
Eagle 



Rufous-bellied 



Records of this species include an adult male 
taken on 29 March 1961 at 610 m and an im- 
mature bird the following day at about 680 m. 

Measurements— Wing— male (1) 346, imma- 
ture unsexed(l) 368; tail — male (1) 182, immature 
unsexed (1) 195; exposed culmen— male (1) 33.9, 
immature unsexed (1) 32.7; weight — male (1) 733, 
immature unsexed (1) 932. 



Family Falconidae 

*Microhierax erythrogenys erythrogenys 
pine Falconet 



Philip- 



We found this species only in the vicinity of 900 
m, where adults were netted on 9 and 10 March. 
On 1 1 March an immature bird was noted in a 
partially cleared area hawking insects from a tree 
perch about 1 5 m above the ground. Rabor col- 
lector six adults between 450 and 760 m. 

Measurements— Wing— male (5) 107.0 ± 1.26, 



GOODMAN & GONZALES: BIRDS OF MT. ISAROG NATIONAL PARK 



106-109, female (3) 109, 113, 1 16; tail-male (5) 
58.8 ± 2.93, 55-63, female (3) 64, 64, 67; exposed 
culmen-male(5) 11.9 ± 0.11, 11.7-12.1, female 
(3) 12.3, 12.5, 12.5; weight-male (5) 42.3 ± 2.27, 
38.0-44.0, female (2) 55.8, 61.5. 



Family Phasianidae 

Gallus gallus [gallus] Red Junglefowl 

Recorded only once. The distinctive call of this 
species was heard at dusk from a tract of primary 
forest above the 900 m camp. The nearest known 
human habitation with domestic chickens was 
about 400 m below in elevation and Vi km distant 
from this site. Other records of this species in 
southeastern Luzon include a female (fmnh cc 
23359) "with several young chicks" taken between 
100 and 300 m at Tugas, Matnog, Sorsogon Prov- 
ince, on 19 May 1961 and two females (fmnh cc 
23358, 23360) obtained between 760 and 910 m 
at Mt. Bulusan, Sorsogon Province, in mid-May 
1961. 



Measurements— Female (1)— wing 159, tail 86, 
exposed culmen 18.7, weight 219. 



Family Rallidae 

*Atnaurornis olivaceus olivaceus 
hen (Bush-hen) 



Plain Swamp- 



An adult male and female were taken by Rabor 
on 20 April 1961 between 450 and 610 m. These 
are the only known records for the moimtain. 



Family Scolopacidae 

*Actitis hypoleucos Common Sandpiper 

The only record for Mt. Isarog of this winter 
visitor to the Philippines is one taken on 24 April 
1961 at about 250 m. 

Weight- Female (1) 58.4. 

Family Columbidae 

* Treron pompadora axillaris Pompadour Green 
Pigeon 

The only record of this species from Mt. Isarog 
is a female collected by Rabor on 25 March 1961 
between 450 and 610 m. The bird had an enlarged 
ovary. 



*Phapitreron leucotis leucotis 
Dove 



White-eared Brown 



This species was widely distributed up the slopes 
of Mt. Isarog. It was distinctly more common be- 
tween 450 and 1125m than in the vicinity of 1 350 
m, and was not recorded above the latter zone. It 
seemed primarily confined to dipterocarp and low- 
er montane forest. At 900 m it was sympatric with 
P. amethystina. 

One female collected on 26 March 1988 at 450 
m had ovarian follicles measuring up to 5 mm; 
towards the end of the month White-eared Brown 
Doves were heard singing, and this species may 
have been about to commence breeding. All of the 
five birds obtained by Rabor in the first half of 
April 1961 were in or approaching breeding con- 
dition. Specimens we took at 450 m and 900 m 
had fig seeds in their stomachs. On several occa- 
sions this species was noted near the 1 350 m camp 
feeding on Lithocarpus acorns. 

Measurements— Wing— male (2) 135, 141, fe- 
male (4) 129.5 ± 1.50, 127-131; tail-male (2) 
83, 89, female (4) 82.0 ± 3.16, 78-86; exposed 
culmen -male (2) 14.4, 15.6, female (3) 14.4, 15.2, 
15.9; weight-male (2) 120, 1 44, female (4) 146.8 
± 27.7, 106-184. 



*Phap it reran amethystina amethystina Amethyst 
Brown Dove 

We found the Amethyst Brown Dove only in 
the vicinity of the 900 m camp, where it was un- 
common. This species appears to be restricted to 
undisturbed areas of lowland forest on Mt. Isarog. 
Rabor collected 10 specimens between 450 and 
1060 m, including several adults in breeding con- 
dition between late March and mid-April and three 
fledglings in the first half of April. 

Measurements— Wing— male (1) 151, female 
(5) 145.8 ± 3.76, 141-151; tail-male (1) 93, fe- 
male (4) 88.8 ± 5.26, 80-94; exposed culmen— 
male (1) 23.5, female (5) 22.8 ± 0.48, 21.9-23.2; 
weight-male (1) 149, female (5) 141.8 ± 8.74, 
130-155. 

*Ptilinopus occipitalis Yellow-breasted Fruit 
Dove 

We did not record this species on Mt. Isarog. 
Rabor collected 1 3 specimens in late March and 



10 



FIELDIANA: ZOOLOGY 



April 1961 between 300 and 1060 m; several were 
in or approaching breeding condition. 

Measurements— Wing— male (8) 161.9 ± 3.37, 
157-167, female (5) 156.4 ± 3.07, 153-161; tail- 
male (6) 102.0 ± 3.37, 98-107, female (5) 97.7 ± 
3.20, 94-103; exposed culmen— male (8) 16.1 ± 
0.35, 15.4-16.5, female (4) 15.58 ± 0.49, 15.0- 
16.3; weight-male (7) 244.3 ± 15.38, 224-271, 
female (5) 234.8 ± 9.28, 225-252. 



*Ptilinopns leclancheri ledancheri 
Fruit Dove 



Black-chinned 



The only known records of this species from 
Mt. Isarog are a male collected between 450 and 
610 m on 29 April 1961 and a female at 700 m 
on 3 April 1961. 



each transect zone, except at 1350 m. It appeared 
to be less common at lower altitudes, particularly 
in disturbed and replanted tracts of forest. This 
may have in part been related to relatively heavy 
hunting pressure on doves and pigeons by kain- 
gineros living on the lower slopes of the mountain. 
This species' distinctive call could occasionally be 
heard at the higher altitudes, generally at dusk and 
dawn. A specimen taken on 30 March 1988 at 450 
m had slightly enlarged ovarian follicles and an- 
other on 31 March 1961 at approximately 840 m 
had a shelled egg in the oviduct. 

Measurements— Wing— male (3) 183, 185, 186, 
female (3) 178, 180, 180; tail -male (3) 176, 177, 
188, female (3) 173, 175, 180; exposed culmen- 
male (3) 15.6, 15.9, 16.1, female (2) 14.7, 15.3; 
weight- male (3) 157, 183, 191, female (2) 191 
(with egg), 177. 



Ducula aenea [aenea] Green Imperial Pigeon 

We noted this species on several occasions at 
450 m and 1 125 m. A flock of three was observed 
at the latter altitude feeding on acorns. 



Chalcophaps indica [indica] Emerald Dove 

We have a single observation of this species in 
late March 1988 at 450 m. 



*Ducula poliocephala poliocephala 
Imperial Pigeon 



Pink-bellied 



We observed this species once in the forest at 
900 m and twice in the primary forest at 1350 m. 
Rabor collected one adult female (with an enlarged 
ovary) on 6 April 1961 at 610 m. 

Measurements— Female (1)— wing 227, tail 
147, exposed culmen 19.7, weight 622. 



*GalUcolumba luzonica luzonica 
Bleeding-heart Pigeon 



Luzon 



We observed a Luzon Bleeding-heart Pigeon at 
450 m and Rabor collected an adult female at 
approximately 700 m. 

Measurements— Female (1)— wing 143, tail 90, 
exposed culmen 16.2, weight 133. 



*Columba vitiensis griseogulahs 
Pigeon 



Metallic Wood 



We observed the Metallic Wood Pigeon once at 
900 m and twice at 1350 m, among the lower 
branches of forest trees. Two adult males were 
collected by Rabor in the first half of April 1961 
at approximately 1 140 and 1670 m, one of which 
had slightly enlarged gonads. 

Measurements— Male (2)— wing 245, 246; tail 
149, 155; exposed culmen 21.7, 22.1; weight 508. 



Family Psittacidae 

Cacatua haematuropygia 
vented) Cockatoo 



Philippine (Red- 



A group of two or three was observed at about 
1 100 m flying over the forest. The distinctive white 
plumage, parrot-like flight, and harsh cry were di- 
agnostic. One of our Bicolano guides mentioned 
that this species was occasionally observed on Mt. 
Isarog. 



*Macropygia phasianella tenuirostris 
billed (Brown) Cuckoo Dove 



Slender- 



This species was sparsely distributed along our 
transect survey of Mt. Isarog. We recorded it in 



* Bolbopsittacus lunulatus lumdatus Guaiabero 

Guaiabero were noted a few times at about 450 
m. They were seen singly or in groups of up to 
three in partially cleared forest or at the edge of 



GOODMAN & GONZALES: BIRDS OF MT. ISAROG NATIONAL PARK 



11 



fields. Rabor collected six specimens between 450 
and 760 m. The only record above this zone is 
one netted in 1988 at 900 m in a disturbed area. 
A bird taken on 9 March 1988 at 450 m had a 
slightly thickened oviduct and egg follicles mea- 
suring up to 5 mm. The stomachs of two birds 
obtained at 450 m contained fig seeds and fruits. 
Measurements — Wing— male (7) 100.3 ± 
1.01, 98-103, female (2) 103, 103; tail-male (7) 
36.1 ± 1.81, 34-40, female (1) 35; exposed cul- 
men-male(6) 18.5 ± 1.03, 17.2-20.0, female (1) 
20.1; weight-male (7) 66.6 ± 6.32, 60-80, female 
(3)61,72, 77. 



*Loriculus philippensis philippensis 
Hanging Parakeet (Colasisi) 



Philippine 



We noted this species a few times in the vicinity 
of 450 m, where it was uncommon. Rabor ob- 
tained one between 450 and 760 m on 25 April 
1961. 

Measurements— Immature male (1)— wing 97, 
tail 42, exposed culmen 15.6. 



Family Cuculidae 

*Cuculus fugax pectoralis Hodgson's Hawk 
Cuckoo 

We recorded this species twice on Mt. Isarog: 
single adults were netted at 450 m and 1 125 m. 



way & Wells, 1976) two males obtained at about 
610 m on 5 and 17 April are referable to C. s. 
horsfieldi (wing 216 and 212, respectively); a fe- 
male obtained on 7 April between 1060 and 1220 
m (wing 195) and a male on 1 5 April between 450 
and 610 m (wing 1 86) cannot be confidently iden- 
tified to subspecies. 
WEiGHT-Male (2) 73, 103; female (1) 81. 



*Cacomantis variolosus sepulcralis Brush Cuckoo 

We foimd the Brush Cuckoo to be common be- 
tween 450 and 1125 m, uncommon at 1350 m, 
and rare at 1 550 m. Rabor collected 1 1 specimens 
between about 6 1 and 1 220 m. Throughout March 
1988 this species was regularly heard vocalizing 
in the early morning hours from tree perches in 
the forest and at the edge of clearings. Specimens 
taken in late March and early April had enlarged 
gonads, including a female on 1 April 1 96 1 with 
a "ripe egg." Two immature females were ob- 
tained on 1 1 and 1 8 April 1961. Stomach contents 
of several individuals contained insect remains. 
We found no evidence for the occurrence of Ca- 
comantis merulinus on Mt. Isarog. 

Measurements— Wing— male (7) 1 15.7 ± 0.70, 
11 5-1 17, female (2) 114, 11 5; tail-male (7) 120.0 
± 5.07, 113-130, female (1) 115; exposed cul- 
men-male(7) 16.8 ± 0.49, 16.0-17.7, female (2) 
15.8, 16.9; weight-male (7) 32.0 ± 1.51, 30-34, 
female (2) 30, 33. 



*Cuculus micropterus micropterus Indian Cuckoo 

Two adults were taken by Rabor: a male on 1 4 
April 1961 at approximately 530 m and a female 
the following day at about 840 m. duPont (1971) 
considered this species a straggler in the Philip- 
pines to Mindoro and Negros. In addition to the 
Mt. Isarog specimens, other Luzon records include 
a male taken on 1 5 April 1 960 in Cagayan Prov- 
ince (fmnh 258836), and one netted in 1967 and 
two in 1970 at Dalton Pass, Nueva Vizcaya Prov- 
ince (McClure & Leelavit, 1972). 



*Cuculus saturatus horsfieldi Oriental Cuckoo 

Four specimens of this migrant from the Asian 
mainland were taken by Rabor on Mt. Isarog in 
1961. On the basis of wing measurements (Med- 



*Chrysococcyx xanthorhynchus amethystinus 
Violet Cuckoo 

The only record of this species for Mt. Isarog is 
an adult female taken on 4 April 1961 at 760 m 
containing a "ripe egg." 

Measurements— Female (1)— wing 105, tail 65, 
exposed culmen 15.7, weight 21.2. 



*Surniculus lugubris chalybaeus Drongo Cuckoo 

We recorded this species once on Mt. Isarog. A 
single bird was observed and heard calling at sun- 
rise on 2 March 1988 at 450 m. Rabor collected 
three adult specimens in 1961 between 610 and 
680 m. 

Measurements— Wing— male (2) 128, 133, fe- 
male (1) 124; tail-male (2) 105, 99, female (1) 



12 



FIELDIANA: ZOOLOGY 



103; exposed culmen— male (2) 19.3, 19.9, female 
(1) 19.6; weight-male (2) 33, 35, female (1) 36. 



*Eudynamys scolopacea mindanensis 
Koel 



Common 



There are three records from the area. One was 
heard calling near the 1550 m camp during the 
night of 12-13 March and one was observed at 
1125 m on 21 March 1988. Rabor collected a 
female with an enlarged ovary on 26 April 1 96 1 
at approximately 380 m. 

Measurements— Female (1)— wing 203, tail 
186, exposed culmen 30.6, weight 223. 



*Phaenicophaeus superciliosus superciliosus Red- 
crested Malkoha 

We found this species only in the vicinity of 450 
m where it was uncommon and locally sympatric 
with Phaenicophaeus cumingi. Rabor collected 2 1 
Red-crested Malkohas between approximately 300 
and 760 m; these included fledglings and nestlings 
in the first half of April and adult females in breed- 
ing condition in the second half of April. A female 
taken on 24 March was just molting from subadult 
to adult plumage. 

Measurements— Wing— male (6) 161.2 ± 5.05, 
155-1 70, female (10) 158.3 ± 2.65, 153-163; tail- 
male (6) 21 1.8 ± 2.91, 208-215, female (10) 212.4 
± 11.44, 191-224;exposedculmen— male(5) 34.5 
± 0.95, 33. 1-35.6, female (10) 33.8 ± 0.99, 32.3- 
35.1; weight-male (5) 121.6 ± 4.27, 118-130, 
female (8) 123.4 ± 10.31, 105-138. 



155-177,female(13) 162.9 ±4.27, 155-171;tail- 
male (9) 2 15.7 ±6.36, 205-227, female (13) 2 12.8 
± 8.31, 195-227; exposed culmen— male (9) 36.0 
± 1.54, 34.3-39.8, female (13) 34.8 ± 1.29,32.9- 
36.6; weight-male (9) 179.8 ± 13.03, 160-204, 
female (13) 169.2 ± 21.7, 121-207. 



*Centropus viridis viridis Philippine Coucal 

We found this species only in the vicinity of 450 
m, where it was uncommon. Rabor collected seven 
specimens between late March and late April 1 96 1 
between approximately 300 and 700 m, including 
several adults (in or approaching breeding con- 
dition) and two nestlings. An adult male collected 
on 28 March 1988 had enlarged testes. The stom- 
achs of two specimens contained insects. 

Measurements— Wing— male (4) 153.5 ± 4.39, 
150-161, female (3) 170, 172, 176; tail-male (4) 
222.3 ± 9.60, 212-238, female (3) 227, 228, 253; 
exposed culmen— male (4) 27.2 ± 0.56, 26.4-27.9, 
female (2) 27.8, 30.0; weight-male (3) 124, 126, 
140, female (3) 152, 153, 157. 



*Centropus unirufus Rufous Coucal 

There are two records of this species. In early 
April 1961 Rabor collected an adult female and 
an adult male between 550 and 760 m. The male 
had enlarged testes. 

Measurements— Wing-male (1) 161, female 
(1) 164; tail— male (1)222, female (1)2 10; exposed 
culmen — male (1) 34.9, female (1) 38.3; weight- 
male (1) 146, female (1)215. 



* Phaenicophaeus cumingi 
koha 



Scale-feathered Mal- 



We noted this species with some regularity and 
heard it vocalizing in patches of undisturbed forest 
and replanted areas from 450 to 900 m. One bird 
was caught in a mammal snap-trap placed on the 
ground. Rabor collected 23 specimens between 300 
and 760 m. 

A female taken on 8 March 1988 had enlarged 
ovarian follicles. The stomach of one bird ob- 
tained at about 650 m contained seven caterpil- 
lars, measuring up to 100 mm. Another one from 
900 m had numerous insect parts and two cater- 
pillars, the largest about 1 10 mm in length. 

Measurements— Wing— male (9) 163.2 ± 6.92, 



Family Strigidae 

*Otus longicornis Luzon Scops Owl 

This species was found from 450 m to the upper 
reaches of the mountain. It was noted calling dur- 
ing the night a few times at the 1125 m camp. 
Near the 1 350 and 1 550 m camps it was generally 
heard every night. One bird was captured in a 
mammal snap-trap placed on the ground. Adult 
specimens collected in the second half of March 
1988 were in various reproductive states, from 
having small to greatly enlarged gonads. The stom- 
achs from several birds contained insects, includ- 
ing Coleoptera and Orthoptera. We follow Mar- 



GOODMAN & GONZALES: BIRDS OF MT. ISAROG NATIONAL PARK 



13 



shall (1978) in considering this bird specifically 
distinct from Otm scops. 

Measurements— Wing— male (4) 144.8 ± 2.49, 
141-147, female (1) 148; tail-male (4) 67.3 ± 
1.79, 65-70, female (1)69; exposed culmen— male 
(3) 16.5, 17.2, 17.8, female (1) 16.7; weight -male 
(8) 72.3 ± 3.53, 69-78, female (1) 95. 

*Otus megalotis Philippine Scops Owl 

The Philippine Scops Owl was found to be wide- 
ly distributed on the slopes of Mt. Isarog. It was 
regulariy heard calling at night at 450 and 900 m, 
was rare from 1 125 to 1550 m, and appeared to 
be absent at 1750 m. Several males taken in the 
first half of March 1988 were in or approaching 
breeding condition. We follow Marshall (1978) in 
considering this owl specifically distinct from Otus 
bakkamoena. The Mt. Isarog specimens all have 
heavy tarsi, feathered down to the proximal por- 
tion of the toes. 

Measurements— Male (3) wing— 168, 173, 173; 
tail-75, 78, 81; exposed culmen-22.0, 22.5, 23.9; 
weight- 159, 165, 182. 



Rabor collected a male Philippine Frogmouth 
at approximately 530 m. duPont (1971) noted that 
this species' distribution on Luzon was restricted 
to the northern portion of the island, where the 
endemic form B. s. microrhynchus occurred. The 
Mt. Isarog specimen matches birds from northern 
Luzon in plumage coloration and size. A female 
taken at Mt. Bulusan, San Roque, Sorsogon Prov- 
ince, southeastern Luzon (fmnh 265627), is the 
palest in plumage coloration of any Philippine B. 
Septimus in the fmnh collection and has a short 
wing (128 mm). 

Measurements— Male (1)— wing 137, weight 
69. 



Family Caprimulgidae 

*Eurostopodus macrotis macrotis Great Eared 
Nightjar 

This species was regularly seen at dusk near 450 
m taking to the air and foraging for insects. The 
stomach of the single specimen was empty except 
for a few beetle parts. 



*Ninox philippensis philippensis Philippine 
(Boobook) Hawk Owl 

This species was common at 450 m and 900 m; 
birds were regularly heard calling or captured in 
mist nets at night. It was uncommon at 1 125 m 
and not recorded above this altitude. Several birds 
collected in March 1988 were in or approaching 
breeding condition. Insects, mostly beetles, were 
found in the stomachs of specimens. 

Measurements — Wing— male (10) 171.6 ± 
5.30, 163-179; tail-male (10) 79.6 ± 4.48, 72- 
86; exposed culmen-male (7) 19.0 ± 0.98, 17.4- 
19.9; weight-male (11) 115.7 ± 8.1, 110-135, 
female (1) 141. 

*Ninox scutulata randl Brown (Boobook) Hawk 
Owl 

The only records we have for Mt. Isarog are two 
adult females taken by Rabor in April 1961 be- 
tween 450 and 610 m. 

Measurements— Female (2)— wing 217, 221; 
tail 117, 117; weight 195, 205. 

Family Podargidae 

* Batrachostomus septimus microrhynchus Phil- 
ippine Frogmouth 



Family Apodidae 

Collocalia cf. vanikorensis Island Swiftlet 

Flocks of aerial-foraging swiftlets were observed 
on Mt. Isarog from 450 m to the summit. On the 
basis of size and plumage coloration some of the 
swiftlets were tentatively identified as C. vaniko- 
rensis (sensu Dickinson, 1989); however, no spec- 
imens of this species have been collected on Mt. 
Isarog. Swiftlets comparable to C. vanikorensis were 
distinctly less common at 1550 m and 1750 m 
than at lower altitudes. Above 1550 m they were 
generally noted towards the latter portion of the 
afternoon, particularly on cloudy and rainy days, 
and on occasion in mixed flocks with at least Col- 
localia esculenta. 



*Collocalia esculenta marginata Glossy (White- 
bellied) Swiftlet 

Flocks of Glossy Swiftlets were commonly not- 
ed flying above the slopes of the mountain. At 
lower elevations they regularly flew among Island 
Swiftlets, but above 1550 m the two species ap- 
peared segregated. The rump feathers of the single 



14 



FIELDIANA: ZOOLOGY 



Mt. Isarog specimen are distinctly edged with white, 
characteristic of C e. marginata (duPont, 1971). 
Measurements— Male (1)— wing 103, tail 43, 
weight 7.0. 



Family Trogonidae 

*Harpactes ardens luzoniensis 
Trogon 



Philippine 



A single bird was noted in early March 1988 at 
900 m near the transition zone between diptero- 
carp and lower montane forest. In 1961, Rabor 
collected 1 1 specimens between about 450 and 
1060 m. These include females on 30 March and 
20 April with enlarged ovaries, and a male on 29 
March molting from subadult to adult plumage. 

Measurements— Wing— male (2) 134, 140, fe- 
male (8) 140.4 ± 3.67, 134-145: tail-male (2) 
150, 161. female (8) 155.9 ± 6.94, 150-169; ex- 
posed culmen- male (2) 18.2, 19.0, female (6) 19.5 
± 0.67, 18.6-20.7; weight-male (2) 80, 87, fe- 
male (8) 85.8 ± 4.44, 80-92. 



Family Alcedinidae 

*Alcedo cyanopectus cyanopectus 
Kingfisher 



Dwarf River 



We recorded this species once; a female was 
collected on 26 March 1988 along a river at about 
450 m. The specimen's stomach contained insect 
remains. 

Measurements— Female (1)— wing 62, tail 24, 
exposed culmen 35.1, weight 21.5. 



*Ceyx melanurus melanurus 
(Jungle) Kingfisher 



Philippine Forest 



The only record for the area is a female (with 
an enlarged ovary) taken by Rabor on 5 April 1961 
at about 610 m. 

Measurements— Female (1)— wing 57, tail 18, 
exposed culmen 32.7, weight 22. 



*Halcyon chloris chloris Collared Kingfisher 

A female collected by Rabor on 2 1 April 1 96 1 
between 450 and 610 m is the only known record 
for the mountain. 



*Halcyon smyrnensis gularis 
Kingfisher 



White-throated 



We observed the White-throated Kingfisher 
several times at 450 m, generally near streams or 
rivers. Rabor took an adult female, with an en- 
larged ovary, on 3 April 1961 between 300 and 
450 m. 



*Halcyon lindsayi lindsayi 
fisher 



Spotted Wood King- 



The Spotted Wood Kingfisher was encountered 
every day in the 450 to 900 m zone and on two 
days at 1350 m. At 900 m this species' character- 
istic rattle-like call was heard each morning before 
sunrise and on several occasions birds were cap- 
tured in mist nets during the predawn hours. Ra- 
bor collected nine specimens between 450 and 6 1 
m. A female taken on 25 March 1 988 had a shelled 
egg in the oviduct and other ova measuring 35 x 
26 and 16 x 16 mm, and another bird obtained 
on 20 April 1961 had an enlarged ovary. The 
stomach contents of collected birds consisted of 
insects, including larvae and beetles. 

Measurements — Wing— male (10) 113.3 ± 
4.47, 108-124, female (5) 1 12.4 ± 2.06, 109-1 15; 
tail - male (10) 84. 7 ± 1.90, 82-88, female (5) 85.0 
± 2.61, 81-89; exposed culmen-male (8) 40.78 
± 1.85,37.5^4.3, female (5) 41.56 ± 1.35,40.0- 
43.7; weight-male (10) 83.7 ± 6.76, 72-96; fe- 
male (3) 95, 96, 117. 



Family Coraciidae 

*Eurystomus orientalis cyanocollis Dollarbird 

The only record of the Dollarbird on Mt. Isarog 
is a male collected by Rabor on 4 April 1961 at 
about 610 m. 

Measurements— Male (1)— wing 185, tail lOI, 
exposed culmen 27.5, weight 129. 

Family Bucerotidae 

*Penelopides panini manilloe Tarictic Hombill 

This species was uncommon at 450 and 900 m. 
It was often observed in pairs, moving along stream 
channels, river beds, or at the edge of the forest. 
One was collected from a tree standing in grass- 



GOODMAN & GONZALES: BIRDS OF MT. ISAROG NATIONAL PARK 



15 



land. Ten specimens were taken by Rabor in 1961 
between 300 and 760 m. Several individuals ob- 
tained in late March 1988 and early April 1961 
were in breeding condition, including a female on 
6 April with a "ripe egg." Birds collected at 450 
m had Ficus fruit and seeds in their stomachs. 

Measurements— Wing— male (11) 235.5 ± 
4.79, 224-241, female (2) 224, 229; tail-male (1 1) 
193.3 ± 5.78, 181-202, female (2) 184, 186; ex- 
posed culmen-male (1 1) 92.7 ± 3.64,88.1-99.5, 
female (2) 78.9, 80.9; weight-male (9) 450.2 ± 
26.6, 400-479, female (2) 470, 475. 



*Buceros hydrocorax hydrocorax Rufous Horn- 
bill 

An adult male obtained by Rabor on 20 April 
1961 between 610 and 760 m is the only known 
record of this species on Mt. Isarog. 

Measurements— Male (1)— wing 420, tail 314, 
weight 1,824. 



Family Capitonidae 

*Megalaima haemacephala haemacephala 
Crimson-breasted (Coppersmith) Barbet 

This species was uncommon at 450 m in dis- 
turbed areas and secondary forest. We did not 
record it above this zone. Rabor collected two 
specimens, one of which had slightly enlarged tes- 
tes, on 8 and 9 April 1 96 1 between 300 and 610 m. 



Family Picidae 

*MuUeripicus funebris funebris 
pecker 



Sooty Wood- 



We found the Sooty Woodpecker to be uncom- 
mon in the vicinity of 450 m. In 1961 Rabor re- 
corded it between 300 and 600 m and collected 
four birds, including a female on 23 March with 
an enlarged ovary. 

Measurements— Wing— male (3) 160, 160, 164, 
female (1) 152; tail-male (3) 125, 131, 137, fe- 
male(l) 125; exposed culmen—male(3)35. 5, 36.7, 
37.4, female (1) 36.5; weight-male (3) 164, 164, 
170, female (1) 161. 



We recorded this species once on Mt. Isarog. 
An adult was observed at 450 m in a section of 
relatively undisturbed forest near the Yabo Falls. 
Two adults were collected by Rabor on 1 8 April 
1961 between 450 and 610 m. 

Measurements— Wing— male (1) 205, female 
( 1 ) 208; tail— male (1)151, female (1)1 50; exposed 
culmen-male (1) 51.5, female (1) 50.2; weight- 
male (1) 250, female (1) 243. 



*Dendrocopos maculatus validirostris Philippine 
Pygmy Woodpecker 

This species was observed each day we were 
camped at 450, 900, and 1 125 m, in both primary 
and secondary forests. It was uncommon at 1350 
m and not recorded above this altitude. A male 
taken by Rabor between 910 and 1060 m on 29 
March 1 96 1 had enlarged testes. 

Measurements— Wing— male (2) 84, 88, fe- 
male (2) 82, 86; tail-male (2) 37, 37, female (2) 
36, 40; exposed culmen-male (2) 17.9, 18.3, fe- 
male (2) 18.4, 19.0; weight-male (2) 24, 25, fe- 
male (1) 25. 



*Chrysocolaptes lucidus haematribon 
(Flameback) Goldenback 



Greater 



We found this species to be uncommon in both 
primary and secondary forest at 900 and 1 125 m, 
and rare at 450 m. On 23 March 1988, three adults 
were observed calling and moving about the forest 
just above our 1125m camp. The following morn- 
ing one was found nearby excavating a hole in a 
dead tree about 15 m above the ground. Rabor 
collected 16 Greater Goldenbacks in 1961 be- 
tween 210 and 1060 m, including a male on 1 
April with enlarged testes. 

Measurements— Wing— male (8) 144.0 ± 3.16, 
139-150, female (8) 142.3 ±4.63, 135-148; tail- 
male (8) 82.9 ± 3.79, 76-89, female (8) 79.6 ± 
3.64, 75-86; exposed culmen-male (8) 39.03 ± 
1.88, 36.4-^2.4, female (8) 34.8 ± 1.44, 32.6- 
36.4; weight-male (8) 130.9 ± 8.01, 123-145, 
female (7) 126.4 + 9.60, 110-143. 



Family Pittidae 



*Dryocopus javensis confusus 
Woodpecker 



White-bellied *Pitla erythrogaster erythrogaster Red-breasted 
Pitta 



16 



FIELDIANA: ZOOLOGY 



The only record of this species for Mt. Isarog is 
an aduh female collected by Rabor on 5 April 1961 
at about 610 m. 

Measurements— Female (1)— wing 100, tail 33, 
exposed culmen 20.5, weight 66. 



Pitta kochi Koch's (Whiskered) Pitta 

Koch's Pitta was observed once on Mt. Isarog. 
On 19 March 1988 a single bird was watched for 
about three minutes foraging on the ground at a 
distance of up to 5 m. The salient plumage char- 
acteristics of the Koch's Pitta were clearly dis- 
cemable. According to duPont (1971),this species 
is restricted to northern Luzon; however, single 
birds were captured in 1 967 at Dalton Pass, Nueva 
Vizcaya Province, and in 1964 at Balian, Laguna 
Province (McClure & Leelavit, 1972). 



Family Campephagidae 

*Coracina striata striata Bar-bellied Cuckoo- 
shrike 

Three specimens of the Bar-bellied Cuckoo- 
shrike were collected by Rabor in 1961 between 
450 and 610m. One of the birds was an immature. 



*Coracina coerulescens coerulescens 
Cuckoo-shrike 



Black 



*Lalage nigra chilensis Pied Triller 

We found the Pied Triller to be uncommon at 
450, 900, and 1 550 m. It is not clear if this species' 
altitudinal distribution on Mt. Isarog is continu- 
ous. In all cases it was observed in clearings, both 
natural and man-made. Rabor collected three adult 
specimens— two at 150 m and one between 450 
and 610 m. 

Measurements— Male— wing (2) 93, 94; tail (3) 
all in molt; exposed culmen (3) 13.8, 14.2, 14.4; 
weight (2) 26.5, 27.6. 



*Pericrocotus divaricatus divaricatus Ashy Min- 
ivet 

The only known records on Mt. Isarog for this 
migrant from the Asian mainland are a pair of 
adult males taken by Rabor on 3 April 1961 at 
610 m. 



* Pericrocotus flammeus novus Scarlet Minivet 

Specimens from Mt. Isarog include an adult male 
with enlarged testes taken on 24 March 1 96 1 be- 
tween 300 and 450 m and another adult male with 
slightly enlarged testes obtained on 1 April 1 96 1 
between 610 and 760 m. 

Measltrements— Male (2)— wing 78, 85; tail 80, 
86; exposed culmen 12.3, 12.4; weight 16.5, 18.0. 



Seventeen Black Cuckoo-shrikes were taken by 
Rabor in 1961 between 300 and 760 m. These 
included adults in late March and early April with 
enlarged gonads. The 1988 expedition did not re- 
cord either Coracina species. 

Measurements— Wing— male (9) 136.2 ± 4.89, 
128-143, female(6) 130.8 ±6.87, 127-146; tail- 
male(lO) 111.5 ± 3.23, 105-117, female (7) 106.3 
± 2.91, 103-1 11; exposed culmen-male (9) 22.2 
± 0.75, 21.3-23.6, female (7) 21.4 ± 0.47, 20.5- 
22.0; weight-male (8) 65.5 ± 3.04, 6 1-70, female 
(7) 60.3 ± 4.62, 53-69. 



*Lalage melanolenca melanoleuca 
White TriUer 



Black and 



An adult female with an enlarged ovary and an 
immature bird were collected by Rabor on 23 
March 1961 between 450 and 610 m. 



Family Paridae 

*Parus elegans elegans Elegant Tit 

Single birds or groups of up to three were seen 
daily in areas between 450 and 900 m. They were 
often observed in tracts of undisturbed forest, and 
occasionally in areas with secondary and replanted 
forest. This species was uncommon at 1 1 25 m and 
not recorded higher on the mountain. Fifteen spec- 
imens were collected by Rabor in 1961, 12 of these 
were taken below 900 m and 3 at about 1 140 m. 
The majority of the Rabor birds had enlarged go- 
nads. One fledgling was found at about 6 1 m on 
6 April 1961. The stomachs of collected birds in- 
variably contained parts of small insects. 

A Pants elegans was noted on 4 March 1988 at 
900 m in a mixed species foraging flock with Sitta 
frontalis and Rhabdornis mystacalis. The Rhab- 
dornis moved at the front of the flock lifting up 



GOODMAN & GONZALES: BIRDS OF MT. ISAROG NATIONAL PARK 



17 



bark and leaves, probing into crevices, and up- 
rooting small epiphytes; the tit and nuthatch fol- 
lowed and gleaned small insects from spots visited 
by the Rhabdornis. 

Measurements— Wing— male (12) 65.5 ± 1.19, 
64-68, female (6) 65.7 ± 2.29, 63-70; tail-male 
(12) 38.0 ± 1.15, 36^0, female (6) 37.3 ± 0.75, 
36-38; exposed culmen— male (12) 10.1 ± 0.28, 
9.8-10.6, female (5) 9.3 ± 0.65, 8.2-9.9; weight- 
male (12) 13.5 ± 1.31, 10.5-15.9, female (7) 12.2 
± 1.07, 11.4-13.4. 



Family Sittidae 

*Sitta frontalis isarog Velvet-fronted Nuthatch 

The Velvet-fronted Nuthatch was common in 
the vicinity of 900 m, and uncommon at 450 m 
and 1350 m. There are 13 specimens in the Rabor 
collection taken in 1961 between 450 and 1220 
m. We found single birds or groups of up to four 
foraging together, occasionally in mixed species 
flocks, in both primary and secondary forest. Be- 
tween 4 and 7 March 1988 we observed a pair 
gathering moss for nesting material and carrying 
it to a hole excavated in a dead snag about 7 m 
off" the ground. Insects were the only food item 
found in the stomachs of specimens. The type lo- 
cality of S. f. isarog is Mt. Isarog (Rand & Rabor, 
1967). 

On 17 March 1988 a mixed species foraging 
flock of single Sitta frontalis, Rhipidura cyaniceps, 
and Pachycephala plateni was observed at 1350 
m. The nuthatch moved through the forest picking 
at and tearing open bark and small epiphytes, after 
which the flycatchers would sally forth and glean 
insects. (See under Parus elegans for another in- 
cident of 5;''a involved in a mixed species foraging 
flock.) 

Measurements— Wing— male (6) 77.0 ± 1.15, 
76-79, female (8) 76.6 ± 1.58, 76-80; tail-male 
(6) 39.3 ± 0.94, 38^1, female (8) 39.6 ± 1.80, 
37-43; exposed culmen— male (6) 15.0 ± 0.65, 
14.3-16.3, female (8) 14.4 ± 0.70, 13.5-15.4; 
weight-male (6) 16.8 ± 0.56, 16.0-17.4, female 
(8) 16.3 ± 0.73, 15.5-17.9. 



Family Rhabdornitliidae 



We found the Stripe-headed Rhabdornis only 
in the zone between 450 and 900 m, where it was 
uncommon in primary and secondary forest. In 
1961 Rabor collected 13 specimens between 300 
and 910 m; 2 taken in late March had enlarged 
gonads. On 29 February 1988 a Stripe-headed 
Rhabdornis was observed entering an excavated 
hole in a tree, about 5 m above the ground, with 
food in its bill. 

This species was noted on two occasions in mixed 
species foraging flocks. On 4 March 1988, one was 
observed moving through the forest at 900 m rip- 
ping up debris on trees, followed by three Phyl- 
loscopus cebuensis. (See under Parus elegans for a 
description of another mixed species foraging flock 
incident.) 

Measurements— Wing— male (9) 84. 1 ± 1.20, 
82-86, female (4) 82.5 ± 1.66, 81-85; tail-male 
(9) 47.4 ± 1.64, 44-50, female (4) 45.5 ± 0.50, 
45^6; exposed culmen— male (9) 21.3 ± 0.98, 
20.0-23.2, female (4) 20.5 ± 0.28, 20.0-20.7; 
weight-male (8) 27.8 ± 2.07, 23.5-30.9, female 
(4) 29.6 ± 0.71, 28.5-30.3. 



Family Timaliidae 

*Napothera rabori sorsogonensis Luzon (Ra- 
bor's) Wren Babbler 

This species was obtained twice on Mt. Isarog. 
One was captured in a mammal snap-trap placed 
on the ground in primary forest at 900 m and 
another at an unknown elevation. These speci- 
mens were compared to the type of A^. r. sorso- 
gonensis taken in the Sorsogon Province, southern 
Luzon, and they match the plumage characters 
that distinguish this form (Rand & Rabor, 1967; 
duPont, 1971). A third individual was noted above 
the 900 m camp foraging on the ground. The bird 
was watched for a few minutes as it flipped over 
leaf and wood debris while slowly walking across 
the forest floor. Although the bird was never ac- 
tually observed swallowing food, it appeared to be 
eating invertebrates picked up from the ground. 

Measurements— Wing— male (1) 91, unsexed 
(1) 85; tail— male (1)71, unsexed (1) in molt; bill 
from nostril— male (1) 14.2; exposed culmen— 
male (1) 21.1; weight— male (1) 65, unsexed (1) 
57. 



*Rhabdornis mystacalis mystacalis Stripe- 
headed Rhabdornis 



*Stachyris capitalis affinis Rusty-crowned Tree 
Babbler 



18 



FIELDIANA: ZOOLOGY 



Five specimens were taken by Rabor on Mt. 
Isarog in 1 96 1 — four between 300 and 6 1 m and 
one at about 1 140 m. Birds taken on 25 March 
and 1 9 April 1 96 1 had enlarged gonads. 

Measurements— Wing— male (4) 70.5 ± 2.06, 
67-72, female (1) 70; tail-male (4) 59.8 ± 2.27, 
56-62, female (1) 60; exposed culmen— male (3) 
14.5, 14.8, 15.4, female (1) 15.4; weight -male (4) 
14.9 ± 0.90, 13.4-15.8, female (1) 15.6. 



*Stachyris whiteheadi sorsogonensis Whitehead's 
(Chestnut-faced) Tree Babbler 

This species is one of the most common and 
widely distributed birds on the slopes of Mt. Isa- 
rog. Its abundance increased between 900 m and 
the summit. Single individuals or flocks of up to 
1 5 birds were regularly heard calling and moving 
about in the forest above 1550 m. At the upper 
altitudes the netting success of this species was the 
highest of any bird (see p. 31). In the vicinity of 
900 m it was uncommon and virtually all of the 
records from this elevation are of netted individ- 
uals. 

On the basis of gonad size, the majority of spec- 
imens we obtained in March 1988 were not in 
reproductive condition, although a few, mostly 
males, had slightly enlarged gonads; perhaps this 
species was about to commence breeding. We ob- 
served some apparent courtship begging and feed- 
ing displays by adults. A substantial number of 
the birds obtained by Rabor in April 1961 had 
enlarged gonads, which would give credence to a 
late spring/summer breeding season. On several 
occasions this species was observed drinking water 
held in pitcher plants (Nepenthes sp.). 

Measurements— Wing— male (61) 69.6 ± 1.54, 
65-74, female (68) 67.7 ± 1.40, 63-71; tail-male 
(60) 55.7 ± 1.24, 53-60, female (66) 54.6 ± 1.31, 
50-58; exposed culmen— male (58) 15.21 ± 0.55, 
14.0-16.1, female (65) 14.65 ± 0.58, 13.0-15.9; 
weight-male (32) 22.8 ± 1.96, 18.0-26.7, female 
(35)21.0 ± 2.10, 17.0-26.2. 



Family Pycnonotidae 

*Pycnonotus urostictus urostictus Wattled Bul- 
bul 

The Wattled Bulbul was apparently confined to 
areas near and below 900 m. Single birds were 



collected on 10 March 1988 at 900 m and 1 1 April 
1961 at 450 m. 

Measurements— Male (2)— wing81, 83; tail 70, 
74; exposed culmen 13.2, 13.6; weight 24, 27. 



*Pycnonotus goiavier goiavier Yellow-vented 
Bulbul 

We found this species to be common in areas 
with secondary growth at and below 450 m. Twen- 
ty-two specimens were taken in 1961 by Rabor, 
20 from below 380 m, and single birds from about 
530 and 700 m. On the basis of gonad size, spec- 
imens taken in late March and April were ap- 
proaching breeding condition. Immature birds were 
collected on 24 March and 24 April 1961. We 
regularly noted small groups of Yellow-vented 
Bulbuls in fig trees feeding on ripening fruits, a 
food that on the basis of gizzard analysis (N = 12) 
made up the predominant portion of their diet. 
One stomach also contained insect parts. 

Measurements— Wing— male (10) 85.1 ± 1.76, 
83-88, female (13) 82.7 ± 3.14, 80-87; tail-male 
(10)78.0 ± 2.28, 75-81, female (13) 76.5 ± 1.94, 
74-80; exposed culmen— male (9) 15.1 ± 0.45, 
14.4-15.7, female (12) 14.8 ± 0.50, 14.0-15.4; 
weight-male (7) 29.3 ± 1.28, 27-31, female (1 1) 
29.3 ± 1.21, 27-31. 



*Hypsipetes philippinus philippinus Philippine 
Bulbul 

The Philippine Bulbul was one of the most com- 
mon birds on Mt. Isarog in areas up to 900 m; 
neither Rabor nor our group found it any higher. 
Birds were generally observed in secondary forest 
or heavily disturbed areas. Specimens taken in both 
March 1961 and 1988 and April 1961 had en- 
larged gonads. A nestling was obtained on 24 March 
and a fledgling on 9 April 1961. 

Near 450 m, groups of up to five birds were 
noted in Ficus trees feeding on ripening fruits, and 
fig seeds were common in most examined stom- 
achs. This species' diet is largely frugivorous, al- 
though insects were found in gizzards of several 
birds. 

Measurements— Wing— male (17) 99.9 ± 2.04, 
95-102, female (18) 95.0 ± 2.94, 89-100; tail- 
male (16) 86.0 ± 2.12, 82-90, female (18) 81.8 ± 
2.85, 77-87; exposed culmen— male (17) 20.7 ± 
0.78, 19.0-22.2, female (17) 19.6 ± 2.68, 19.4- 



GOODMAN & GONZALES: BIRDS OF MT. ISAROG NATIONAL PARK 



19 



21.8; weight-male (19) 38.3 ± 2.66, 35-43, fe- 
male (19) 36.9 ± 3.75, 31^8. 



Family Irenidae 

*Irena cyanogaster cyanogaster Philippine Fairy 
Bluebird 

The distinctive call of the Phihppine Fairy Blue- 
bird was heard daily, often as part of the dawn 
chorus, in the vicinity of our 900 and 1125 m 
camps. At 450 m and 1350 m (the highest point 
it was noted) this species was uncommon. Rabor 
collected 17 specimens on Mt. Isarog, all of which 
were from below 1060 m. Birds taken from late 
March through April were in or approaching 
breeding condition. The stomach of one specimen 
was empty and another contained a few insect 
parts. 

Measurements— Wing— male (8) 136.8 ± 3.46, 
131-142, female (9) 133.9 ± 3.38, 128-138; tail- 
male (8) 104.6 ± 1.32, 103-107, female (9) 101.3 
± 2.26, 98-104; exposed culmen— male (7) 25.8 
± 1.09, 24.0-26.7, female (9) 26.2 ± 0.83, 24.6- 
27.0; weight-male (9) 79.6 ± 3.72, 75-87, female 
(9) 77.4 ±6.16, 71-90. 



Family Turdidae 

*Brachypteryx montana andersoni White-browed 
Short wing 

The White-browed Shortwing was a character- 
istic bird of areas with undisturbed forest. It was 
uncommon at 900 m, common from 1125 to 1350 
m, and abundant from 1 550 m to the summit. We 
did not record this species below 900 m. Rabor 
obtained 1 5 specimens on the mountain, all above 
1000 m, with the exception of a single female col- 
lected at 610 m. 

This species was regularly captured in snap-traps 
placed on the ground for small mammals. The trap 
success rate of Brachypteryx was highest on the 
upper portion of the mountain (table 1), which 
concurs with our estimates of altitudinal abun- 
dance based on sight records. 

This species was regularly heard singing on our 
March 1988 trip during the predawn and dawn 
chorus. Males would vocalize from the forest floor 
or perches up to 1 m off" the ground. Most adults 
taken in March 1961 and 1988 and April 1961 
had enlarged gonads. Immatures were obtained on 



1 7 and 2 1 April 1961. Food remains in the stom- 
achs of collected birds consisted of small insect 
parts and occasionally land snails. The type lo- 
cality of B. m. andersoni is Mt. Isarog (Rand & 
Rabor, 1967). 

Measurements— Wing— male (1 1) 66.9 ± 1.31, 
65-70, female (12) 65.8 ± 2.27, 62-70; tail-male 
(1 1) 44.5 ± 0.89, 43-46, female (1 1) 43.5 ± 2.53, 
38^8; exposed culmen-male (1 1) 12.9 ± 0.66, 
11.7-14.0, female (11) 13.1 ± 0.51, 12.7-14.0; 
weight- male (15) 16.9 ± 1.89, 13.0-20.0, female 
(17) 18.5 ± 1.29, 16.0-21.0. 



*Copsychus luzoniensis luzoniensis 
browed Shama 



White- 



Rabor collected two adult male White-browed 
Shama in mid-April 1961 between 450 and 610 
m, one of which had slightly enlarged testes. 

Measurements— Male (2)— wing 77, 80; tail 75, 
76; exposed culmen 14.6, 15.5; weight 22.8, 25.3. 



*Monticola solitahus philippensis 
thrush 



Blue Rock- 



Adult male specimens of the Blue Rockthrush 
collected on Mt. Isarog include one with enlarged 
gonads taken on 29 March 1961 between 1060 
and 1125m and another on 1 April 1 96 1 between 
610 and 760 m. This species is a migrant to the 
Philippines from the Asian mainland. 



*Zoothera andromedae Sunda Thrush 

This species was recorded only once on Mt. Isa- 
rog. A male was netted on 14 March 1988 at 1500 
m; it had enlarged gonads. 

Measurements— Male (1)— wing 125, tail 66, 
exposed culmen 23.5, weight 81. 



*Zoothera dauma aurea Scaly Thrush 

The Scaly Thrush, a winter visitor to Luzon 
from the Asian mainland, was recorded on a few 
occasions at 450 m. Without exception it was not- 
ed foraging on the ground, generally in undis- 
turbed areas of forest. One bird was taken in a 
mammal snap-trap placed on the forest floor. 



20 



FIELDIANA: ZOOLOGY 



* Turdus poliocephalus mayonensis Island Thrush 

The Island Thrush is one of the more widely 
distributed forest birds on Mt. Isarog. We found 
this species to be common at elevations at and 
above II 25 m. It was generally seen singly or in 
pairs. It was one of the common songsters of the 
predawn and early morning chorus. 

The plumage coloration of Mt. Isarog birds is 
similar to specimens of T. p. mayonensis taken in 
the Albay Province of southern Luzon. This spe- 
cies was regularly seen foraging on the forest floor, 
and several birds were captured in mammal snap- 
traps. The gonads of several specimens collected 
in March 1988 and April 1961 were enlarged. 

Measurements — Wing— male (10) 124.3 ± 
2.24, 121-128, female (3) 117, 121, 127; tail- 
male (10) 93.3 ± 2.15, 90-97, female (3) 88, 91, 
96; exposed culmen-male (9) 19.8 ± 0.91, 18.5- 
21.0, female (3) 19.1, 19.3, 20.4; weight-male (6) 
70.5 ± 4.72, 64-77, female (3) 69, 77, 78. 



Table 1 . Capture rate of Brachypteryx montana in 
mammal snap-traps. 



Transect 


Total 






point 


Brachypteryx 


Total 


% Trap 


(m) 


taken 


trap-nights 


success 


900 


1 


777 


0.13% 


1125 


2 


455 


0.44% 


1350 


3 


945 


0.32% 


1550 


8 


848 


0.94% 


1750 


13 


759 


1.71% 



*Megalurus palustris forbesi Striated Grassbird 

This species was common in cleared and cul- 
tivated areas with grass thickets at and below 450 
m. Rabor collected an adult female on 23 March 
1961 between 150 and 300 m. 



"Megalurus timoriensis [tweeddalei] Tawny 
Grassbird 



'Turdus chrysolaus chrysolaus 
Thrush 



Brown-headed 



Two Brown-headed Thrushes were netted on 9 
March 1988 at 450 m. We did not otherwise ob- 
serve this species on Mt. Isarog. It appears to be 
a rare winter visitor to the lower elevations. 

WEiGHT-Unsexed (2) 57, 59. 



We found the Tawny Grassbird to be uncom- 
mon at about 450 m, where it was locally sym- 
patric with M. palustris. Rabor did not collect this 
species on Mt. Isarog, but he obtained two at Mt. 
Bulusan, Sorsogon Province, southeastern Luzon, 
on 1 May 1961 between 610 and 760 m. 



*Cisticola exilis semirufa 
headed) Cisticola 



Bright-capped (Golden- 



*Turdus obscurus Eye-browed Thrush 

There are two records of this mainland Asian 
migrant on Mt. Isarog. On 7 March 1988 an adult 
was netted at 900 m and on 29 March 1961 an- 
other was taken between 910 and 1060 m. 

WEIGHTS-Male (2) 65, 85. 



Family Sylviidae 

*Ceriia diphone canturians Japanese Bush War- 
bler 

An adult female Japanese Bush Warbler taken 
on 7 April 1961 between 450 and 610 m is the 
only known record of this mainland Asian migrant 
from Mt. Isarog. 



There is a single record of this species on Mt. 
Isarog. An adult male with enlarged testes was 
taken by Rabor on 3 1 March 196 1 at about 790 m. 



"Phylloscopus trivirgatus nigrorum 
Leaf Warbler 



Mountain 



The Mountain Leaf Warbler was common on 
Mt. Isarog between 1350 m and the summit. From 
900 to 1 125 m it was uncommon, and we did not 
record it lower. The exceptions are birds taken by 
Rabor on 2 April between 610 and 760 m and on 
12 April 1961 between 760 and 910 m. It was 
generally observed singly or in groups of up to four 
individuals, which tended to forage in the upper 
portion of the canopy. Several birds taken in March 
1988 and April 1961 had enlarged gonads. This 
bird was noted in a mixed species foraging flock 
(see under Rhipidura cyaniceps). There was essen- 



GOODMAN & GONZALES: BIRDS OF MT. ISAROG NATIONAL PARK 



21 



tially no altitudinal overlap on the mountain be- 
tween this species and P. cebuensis (table 2). 

Measurements— Wing— male (14) 55.8 ± 1.32, 
53-58, female (11) 53.5 ± 1.67, 52-57; tail-male 
(14)38.8 ± 1.08, 37^1, female (11) 37.1 ± 1.24, 
35-38; exposed culmen— male (13) 9.6 ± 0.34, 
9.0-10.5, female (9) 9.2 ± 0.48, 8.3-10.2; weight- 
male (7) 7.3 ± 0.97, 6.0-9.4, female (6) 7.5 ± 
1.08,6.0-8.9. 



observed moving through a patch of secondary 
forest at about 870 m. According to Watson et al. 
(1986) this form is the only one known from Luzon 
and is restricted to the northern portion of the 
island. A Mountain Tailorbird was captured in 
1967 at Balian, Laguna Province, central Luzon 
(McClure & Leelavit, 1972) and a male and female 
of this species were collected on 22 March 1926 
at Lucban, Tayabas, central Luzon (Baud, 1978). 



* Phylloscopus cebuensis sorsogonensis Dubois' 
(Lemon-throated) Leaf Warbler 

We found this species uncommon at 450 m and 
rare at 900 m. Rabor obtained 1 1 specimens: 3 
between 300 and 450 m, 5 between 450 and 610 
m, 1 between 610 and 760 m, and 2 between 910 
and 1060 m. Virtually all of the specimens taken 
in late March and April had enlarged gonads. Our 
general impression was that this species forages at 
a lower vertical level in the forest than P. trivir- 
gatus. 

P. cebuensis was noted on two occasions in mixed 
species foraging flocks. (See the accounts of Rhab- 
dornis mystacalis and Prionochilus olivaceus.) 

Measurements— Wing— male (9) 58.0 ± 1.89, 
55-61, female (3) 52, 53, 54; tail-male (9) 45.2 
± 1.31, 43^7, female (2) 38, 43; exposed cul- 
men-male(9) 11.1 ± 0.26, 10.5-1 1.2, female (2) 
10.6, 10.6; weight-male (9) 9.00 ± 0.39, 8.4-9.6, 
female (3) 7.9, 8.8, 10.5. 



*Orthotomus derbianus Grey-backed Tailorbird 

We found the Grey-backed Tailorbird only in 
the vicinity of 450 m, where it was uncommon in 
grassy areas in and around secondary patches of 
forest. Rabor collected eight specimens between 
approximately 2 1 and 760 m, including a nestling 
on 25 March 1961. The stomachs of two birds 
contained small insects. 

Measurements— Wing— male (5) 53.0 ± 0.89, 
52-54, female (5) 50.6 ± 2.87, 46-54; tail-male 
(3) 47, 52, 54, female (4) 45.8 ± 4.44, 40-51; 
exposed culmen— male (5) 15.8 ± 0.43, 15.2-16.3, 
female (5) 15.12 ± 0.89, 14.3-16.7; weight-male 
(5) 10.9 ± 1.32, 9.0-12.4, female (5) 10.5 ± 0.55, 
10.0-11.5. 



Family Muscicapidae 

*Ficedula hyperythra luzoniensis Snowy-browed 
Flycatcher 



* Phylloscopus borealis cf borealis Arctic War- 
bler 

Five specimens of the Arctic Warbler, a winter 
visitor to the Philippines from Asia, were taken 
on Mt. Isarog. All the material was collected be- 
tween early March and mid-April 1 988 in lowland 
areas between 300 and 610 m. The plumage char- 
acters used to distinguish among the potential 
forms wintering on Luzon are not easily discem- 
able and these specimens are tentatively assigned 
to nominate borealis. 

WEiGHT-Male (2) 8.5, 9.2; female (2) 8.5, 8.8. 



We found this species to be uncommon at 1125 
and 1 350 m and rare at 1 550 m. One was captured 
at 1350 m in a mammal snap-trap placed on the 
ground. Rabor obtained males at 1060 m and be- 
tween 760 and 910m; one taken on 1 1 April 1 96 1 
had enlarged testes. 

Measurements— Wing— male (3) 61, 62, 62; 
tail— male (3) 43, 43, 46; exposed culmen— male 
(3) 9.5, 11.1, 11.1; weight-male (3) 8.5, 10.0, 
10.5, female (2) 9.5, 9.6. 



*Ficedula westermanni westermanni Little Pied 
Flycatcher 



Onhotomus cucullatus [philippinus] Mountain 
Tailorbird 

There is only one record of this species from the 
area. On 28 February 1988 a group of four was 



The Little Pied Flycatcher was distinctly more 
common between 1550 and 1 750 m than between 
1 1 25 and 1 350 m. The only record of it below this 
latter zone is one collected by Rabor in 1961 at 
about 1050 m. Single individuals were noted for- 



22 



FIELDIANA: ZOOLOGY 



aging in the upper portion of the forest canopy. 
On the basis of gonad size, only one of the spec- 
imens collected was in or approaching breeding 
condition; the exception was a female taken on 30 
March 1 96 1 with an enlarged ovary. The stomachs 
of two birds contained small insects. 

Measurements— Wing— male (6) 60.0 ± 1.15, 
59-62, female (4) 58.0 ± 1.87, 56-61; tail-male 
(7) 41.1 ± 0.99, 40-43, female (4) 40.0 ± 0.71, 
39^1;exposedculmen-male(7)9.7 ± 0.60,9.0- 
10.4, female (4) 10.0 ± 0.52, 9.1-10.3; weight- 
male (4) 8.1 ± 0.56, 7.5-9.0, female (2) 8.0, 9.7. 



erable variation was found in the bill length and 
width of this species, which does not appear re- 
lated to sexual dimorphism. 

Measurements— Wing— male (8) 77.3 ± 2.49, 
71-79, female (4) 77.5 ± 1.12, 76-79; tail-male 
(8) 63.3 ± 1.92, 59-66, female (4) 60.5 ± 0.50, 
60-61; exposed culmen— male (7) 10.8 ± 0.39, 
10.0-11.3, female (4) 10.4 ± 0.46, 9.8-10.9; bill 
from nostril-male (8) 7.6 ± 0.37, 6.9-8.2, female 
(4) 7.4 ± 0.32, 6.9-7.7; bill width-male (6) 5.1 
± 0.38, 4.5-5.8, female (4) 5.2 ± 0.22, 4.9-5.5; 
weight-male (6) 17.4 ± 2.05, 14.0-18.7, female 
(2) 18.9, 24.5. 



*Cyornis herioti camarinensis Blue-breasted Fly- 
catcher 



Family Monarchidae 



Rabor collected a single Blue-breasted Flycatch- 
er on Mt. Isarog between 300 and 450 m; this 
specimen is the type of C. h. camarinensis (Rand 
& Rabor, 1967). The bird was an adult male with 
enlarged testes. He also obtained two individuals 
of this form at Mt. Bulusan, Sorsogon Province, 
southeastern Luzon, in early May 1961 between 
450 and 990 m. 

Measurements— Male— wing (2) 76, 76; tail (2) 
57, 56; exposed culmen (2) 15.0, 14.2; bill from 
nostril (2) 1 1 .4, 1 1 .2; bill width (2) 5.8, 5.8; weight 
(1)21.4. 



Muscicapa griseisticta Grey-streaked Flycatcher 

We observed a single Grey-streaked IHycatcher 
on 4 March 1988 at 900 m in a thicket surrounded 
by a partially cleared area of forest. Rabor col- 
lected five females in the second half of April 1 96 1 
between 450 and 910 m. 

Weight- Female (3) 14.4, 15.6, 15.7. 



*Hypothymis azurea azurea Black-naped Mon- 
arch 

The only records from Mt. Isarog are an adult 
female taken on 30 March 1 96 1 between 300 and 
450 m and another female (with an enlarged ovary) 
taken on 24 April 1961 between 210 and 300 m. 

Measurements— Female— wing (2) 69, 70; tail 
(2) 65, 70; exposed culmen (2) 12.4, 13.2; weight 
(1)11.8. 



Hypothymis helenae [helenae] Short-crested 
Monarch 

The Short-crested Monarch was rare and only 
found in the vicinity of 900 m. A single male was 
heard calling and observed two or three times in 
the forest canopy near our camp. 



*Rhipidura cyaniceps cyaniceps Blue-headed 
Fantail 



* Muscicapa {Eumyias) panayensis nigrimentalis 
Philippine Verditer (Island Flycatcher) 

We found this species to be uncommon across 
a relatively broad zone on Mt. Isarog, from 900 
to 1550 m. Rabor collected 10 specimens: 2 at 
about 760 m, 1 between 760 and 9 1 m, 4 between 
1060 and 1220 m, and 3 at 1670 m. Several birds 
taken in late March 1 96 1 and 1 988 and April 1961 
had enlarged gonads. Singing Philippine Verditer 
were noted on several occasions near our 900 m 
camp, and two were observed feeding in a fig tree 
on insects attracted to the ripening fruit. Consid- 



The Blue-headed Fantail was one of the most 
common and widely distributed birds and was re- 
corded between 450 and 1 550 m. It was found in 
a variety of habitats ranging from heavily dis- 
turbed secondary forest to virgin primary forest. 
This species was regularly heard singing during our 
March 1988 stay on the mountain. The gonads of 
individuals collected in March 1 96 1 and 1988 and 
April 1961 were enlarged. Food remains in the 
stomachs of several birds consisted exclusively of 
insect remains. 

This fantail was noted on two occasions in mixed 
species foraging flocks. On 19 March 1988, one 



GOODMAN & GONZALES: BIRDS OF MT. ISAROG NATIONAL PARK 



23 



Table 2. Altitudinal distribution of resident bird species on Mt. Isarog.' 









Elevation 








450 m 












Species 


or below 


900 m 


1125 m 


1350 m 


1550 m 


1750 m 


Aviceda jerdoni 














R 





Pernis celebensis- 


— 


* 


— 


— 


— 


— 


Pernis apivorus' 


• 


— 


— 


— 


— 


— 


Haliastur indus' 


« 


— 


— 


— 


— 


— 


Spilornis holospilus 


U 


U 


— 


— 


— 


— 


Accipiter virgalus 


R 


— 


— 


— 


R 


— 


Hieraaetus kieneri" 


• 


— 


— 


— 


— 


— 


Microhierax erythrogenys 


41 


u 


— 


— 


— 


— 


Gatlus gallus 


->■ 


R 


— 


— 


— 


— 


Amaurornis olivaceus^ 


* 


— 


— 


— 


— 


— 


Treron pompadora' 


* 


— 


— 


— 


— 


— 


Phapitreron leucolis 


C 


C 


C 


U/R 


— 


— 


Phapitreron amethystina 


« 


u 


— 


— 


— 


— 


Plilinopus occipitalis^ 


• 


* 


— 


— 


— 


— 


Ptilinopus leclancheri'' 


• 


* 


— 


— 


— 


— 


Ducula aenea 


u 


_ 


u 


— 


— 


— 


Ducula poliocephala' 


* 


— 


— 


R 


— 


— 


Columba vitiensis' 


— 


R 


* 


R 


• 


— 


Macropygia phasianella 


R 


« 


u 


— 


U 


U 


Chalcophaps indica 


R 


— 


— 


— 


— 


— 


Gallicolumba luzonica'' 


R 


♦ 


— 


— 


— 


— 


Cacatua haematuropygia 


— 


— 


R 


— 


— 


— 


Bolbopsittacus lunulalus 


U 


R 


— 


— 


— 


— 


Loriculus philippensis^ 


u 


* 


— 


— 


— 


— 


Cuculus fuga.x 


R 


— 


R 


— 


— 


— 


Cacomantis variolosus 


C 


C 


C 


U 


R 


— 


Chrysococcyx xanthorhynchus- 


— 


* 


_ 


— 


— 


— 


Surniculus lugubris^ 


R 


— 


— 


.— 


— 


— 


Eudynamys scolopacea 


* 


— 


R 


— 


R 


— 


Phaenicophaeus superciliosus- 


U 


* 


— 


— 


— 


— 


Phaenicophaeus cumingi 


U 


u 


— 


— 


— 


— 


Centropus viridis^ 


u 


* 


— 


— 


— 


— 


Centropus unirufus" 


• 


* 


— 


— 


— 


— 


Otus longicornis 


R 


— 


U/R 


u 


U 


u 


Otus megalotis 


U 


u 


R 


R 


R 


— 


Ninox philippensis 


- c 


c 


U 


— 


— 


— 


Ninox scutulata^ 


• 


— 


— 


— 


— 


— 


Batrachostomus Septimus 


* 


— 


— 


— 


— 


— 


Eurostopodus macrotis 


c 


— 


— 


— 


— 


— 


[Collocalia vanikorensis] 


c 


c 


c 


C 


U 


u 


Collocalia esculenta 


c 


c 


c 


c 


c 


c 


Harpactes ardens^ 


* 


R 


— 


— 


— 


— 


Ceyx cyanopectus 


R 


— 


— 


— 


— 


— 


Ceyx melanurus^ 


« 


— 


— 


— 


— 


— 


Halcyon chloris' 


* 


— 


— 


— 


— 


— 


Halcyon smyrnensis 


u 


— 


— , 


— 


— 


— 


Halcyon lindsayi 


c 


c 


— 


R 


— 


— 


Eurystomus orientalist 


• 


— 


— 


— 


— 


— 


Penelopides panini 


u 


u 


— 


— 


— 


— 


Buceros hydrocorax- 


» 


— 


— 


— 


— 


— 


Megalaima haemacephala^ 


u 


— 


— 


— 


— 


— 


Mulleripicus funebris 


u 


— 


— 


— 


— 


— 


Dryocopus javensis 


R 


— 


— 


— 


— 


— 


Dendrocopos maculatus 


C 


c 


c 


u 


— 


— 


Chrysocolaptes lucidus 


R 


u 


u 


— 


— 


— 


Pitta erythrogaster^ 


• 


— 


— 


— 


— 


— 


Pitta kochi 


— 


— 


— 


R 


— 


— 


Coracina striata^ 


* 


_ 


— 


— 


— 


— 


Coracina coerulescens" 


* 


- 


— 


— 


— 


— 



' Records obtained from 1961 Rabor collection from Mt. Isarog = *. Records from 1988 expedition to the area: 
L = abundant, C = common, U = uncommon, R = rare. See Materials and Methods for definitions of terms. 
' Specimen(s) taken up to 760 m. 
' Specimen(s) taken at or up to 610 m. 



24 



HELDIANA: ZOOLOGY 



Table 2. Continued 











Elevation 








450 m 












Species 


or below 


900 m 


1125 


m 1350 m 


1550 m 


1750 m 


Lalage melanoleuca^ 


« 


— 


— 


— 


— 


— 


Lalage nigra 


U 


U 


— 


— 


U 


— 


Pericrocot us fla m meus^ 


* 


* 


— 


— ■ 


— 


— ~ 


Dicrurus balicassius 


c 


u 


— 


— 


— 


— 


Oriolus chinensis- 


u 


* 


— 


— 


— 


— 


Corvus macrorhynchos 


c 


— 


— 


— 


— 


— 


Parus elegans 


c 


c 


U 


— 


— 


— 


Sitla frontalis 


u 


c 


« 


U 


— 


— 


Rhahdornis mystacalis 


u 


u 


— 


— 


— 


— 


Napothera rabori 


— 


R 


— 


— 


— 


— 


Stachyris capitalis' 


* 


— 


« 


— 


— 


— 


Stachyris whiteheadi 


— 


u 


c 


c 


A 


A 


Pycnonotus urostictus 


— 


u 


— 


— 


— 


— 


Pycnonolus goiavier^ 


c 


* 


— 


— 


— 


— 


Hypsipeles philippinus 


A 


A 


— 


— 


— 


— 


Irena cyanogasler 


U 


C 


c 


R 


— 


— 


Brachypteryx montana' 


* 


u 


c 


C 


A 


A 


Copsychus luzoniensis^ 


* 


— 


— 


— 


— 


~~ 


Zoothera andromedae 


— 


— 


— 


— 


R 


— 


Turdus poliocephalus 


— 


— 


c 


c 


C 


C 


Megalurus paluslris 


c 


— 


— 


— 


— 


— 


Megalurus timoriensis 


u 


— 


— 


— 


— 


— 


Cisticola e.xilis* 


— 


* 


— 


— 


— 


— 


Phylloscopus trivirgatus 


— 


u 


u 


c 


c 


c 


Phylloscopus cebuensis 


u 


R 


— 


— 


— 


— 


Orthotomus cucuUatus 


— 


R 


— 


— 


— 


— 


Ortholomus derbianus^ 


u 


* 


— 


— 


— 


— 


Rhipidura cyaniceps 


c 


C 


c 


c 


c 


— 


Ficedula hyperythra^ 


— 


* 


u 


u 


R 


— 


Ficedula westermanni 


— 


— 


u 


u 


C 


c 


Cyornis herioti 


* 


— 


— 


— 


— 


— 


Muscicapa panayensis 


— 


u 


u 


u 


u 


— 


Hypothymis azurea 


* 


— 


— 


— 


— 


— 


Hypothymis helenae 


— 


R 


— 


— 


— 


— 


Pachycephala plaieni 


— 


C 


c 


A 


c 


— 


Pachycephala philippinensis^ 


u 


u 


• 


— 


— 


— 


Anihus novaeseelandiae 


* 


— 


— 


— 


— 


— 


Arlamus leucorhynchus 


* 


R 


— 


— 


— 


— 


Aplonis panayensis' 


* 


— 


— 


— 


— 


— 


Sarcops calvus 


c 


R 


— 


— 


— 


— 


Anthreptes malacensis' 


* 


— 


— 


— 


— 


— 


Nectarinia sperata^ 


* 


— 


— 


— 


— 


— 


Nectarinia jugularis 


• 


— 


— 


— 


— 


— 


Aelhopyga flagrans 


* 


* 


— 


— 


— 


— 


Aethopyga pulcherrima^ 


— 


* 


u 


c 


u 


— 


Arachnothera clarae 


R 


— 


— 


— 


— 


— 


Prionochilus olivaceus 


u 


R 


— 


— 


— 


— 


Dicaeum bicolor 


* 


C 


* 


u 


— 


— 


Dicaeum auslrale 


c 


— 


— 


— 


— 


— 


Dicaeum irigonostigma'' 


* 


« 


— 


— 


— 


— 


Dicaeum hypoleucum 


c 


R 


— 


— 


— 


— 


Dicaeum pygmaeum 


R 


— 


— 


— 


— 


— 


Zosterops nigrorum 


C 


U 


— 


— 


— 


— 


Passer montanus 


C 


— 


— 


— 


— 


— 


Erythrura hyperythra 


— 


R 


— 


— 


— 


— 


Lonchura leucogastra^ 


R 


— 


— 


— 


— 


— 


Lonchura malacca' 


* 


— 


— 


— 


— 


— 


Total number of species 


95 


64 


31 


24 


22 


9 



■* Specimen(s) taken between 610 and 680 m. 

' Specimen(s) taken up to 1060 m. 

' Specimen(s) taken up to 700 m. 

' Specimen(s) taken up to 1670 m. 

* Specimen taken at 790 m. 

' Specimen(s) taken between 1060 and 1220 m. 



GOODMAN & GONZALES: BIRDS OF MT. ISAROG NATIONAL PARK 



25 



was observed moving through the forest at 1350 
m. probing under and flipping over leaves. It was 
followed within 20 m by one Phylloscopus irivir- 
gatus and one Pachycephala plateni. (See under 
Sitta frontalis for another mixed species foraging 
flock incident.) 

Measurements— Wing— male (9) 78.9 ± 2.81, 
75-84, female (6) 76.0 ± 2.58, 71-79; tail-male 
(9) 83.0 ± 2.79, 78-88, female (6) 79.2 ± 2.48, 
74-81; exposed culmen-male (8) 11.2 ± 1.08, 
10.0-12.6, female (6) 11.0 ± 0.62, 10.0-11.8; 
weight— male (12) 13.6 ± 1.21, 12.0-15.6, female 
(8) 13.5 ± 0.47, 13.0-14.1. 



Family Pachycephalidae 

*Pachycephala plateni crissalis Philippine Whis- 
tler 

We found the Philippine Whistler to be com- 
mon or abundant between 900 and 1550 m. In 
1961 Rabor collected 18 specimens on the moun- 
tain, 1 1 of which were taken at 1670 m. This spe- 
cies was observed in both secondary and primary 
forest, and at the edge of cleared areas. There ap- 
pears to be a small zone of altitudinal overlap on 
the mountain between this species and P. philip- 
pinensis (table 2). 

The breeding season of the Philippine Whistler 
seems to be variable from year to year. The gonads 
of most adults collected in March 1 988 were small, 
and this species was not breeding. Several im- 
mature birds and recent fledglings were observed 
and netted. This is in contrast to 1961 when the 
majority of birds collected by Rabor between late 
March and late April had enlarged gonads. 

This whistler was noted on two occasions as a 
member of mixed species foraging flocks. (See un- 
der Rhipidura cyaniceps and Sitta frontalis.) 

Measurements— Wing— male (16) 82.1 ± 1.36, 
80-85, female (13) 80.4 ± 1.08, 78-82; tail-male 
(16)65.6 ± 1.97, 63-70, female (13) 65.2 ± 1.70, 
63-68; exposed culmen— male (16) 14.7 ± 0.51, 
13.9-15.8, female (12) 13.6 ± 2.91, 12.5-15.4; 
weight-male (10) 21.2 ± 6.0, 19.0-25.2, female 
(13)22.1 ± 1.84, 17.5-24.5. 



*Pachycephala philippinensis philippinensis 
Yellow-bellied Whistler 

In the spring of 1988 the Yellow-bellied Whis- 
tler was uncommon at 450 m and 900 m; it was 



not recorded above this zone. Rabor obtained 1 4 
specimens on the mountain in 1961, all of which 
were taken below 760 m; the only exceptions were 
nestlings obtained on 6 and 22 April between 1 060 
and 1220 m. Several birds collected in late March 
and April had enlarged gonads and appeared to 
be in breeding condition. One specimen had beetle 
remains in its stomach. 

Measurements— Wing— male (6) 86.2 ± 3.02, 
83-90, female (8) 82.6 ± 1.87, 79-85; tail-male 

(6) 65.7 ± 0.75, 65-67, female (8) 62.5 ± 2.12, 
58-66; exposed culmen — male (6) 15.6 ± 0.35, 
15.0-16.1, female (8) 15.0 ± 0.84, 13.7-16.1; 
weight-male (5) 23.7 ± 2.60, 21.0-27.3, female 

(7) 24.3 ± 1.95, 21.0-26.9. 



Family Motacillidae 

*Motacillaflava simillima Yellow Wagtail 

Two specimens were collected by Rabor on 24 
April 1961 between 210 and 300 m. This species 
is a winter visitor to Luzon from mainland Asia. 

*Motacilla cinerea robusta Grey Wagtail 

We found this species, a migrant to the Phil- 
ippines from the Asian mainland, to be common 
at 450 m near the Panicuason Central Nursery in 
the vicinity of cleared areas and irrigated planting 
beds. Rabor collected five females below 450 m; 
his latest spring record was 24 April 1961. 

WEiGHT-Female (5) 16.9 ± 2.26, 13.5-20.2. 



*Anthus novaeseelandiae lugubris Richard's 
(Common) Pipit 

The Rabor collection contains five birds taken 
at Mt. Isarog on 23 and 24 April 1961, all below 
300 m. 



*Anthus gustavi gustavi Petchora Pipit 

A pair of Petchora Pipits was obtained on 1 
April 1961 between 610 and 760 m. This species 
is a winter visitor to the Philippines from the Asian 
mainland. 

WEiGHT-Male (1) 23.1, female (1) 17.7. 



26 



FIELDIANA: ZOOLOGY 



*Anthus hodgsoni hodgsoni Olive Tree Pipit 

The single record of this mainland Asian mi- 
grant on Mt. Isarog was a female taken on 28 
March 1961 between 910 and 1220 m. 



Family Laniidae 

*Lanius cristatus lucionensis Brown Shrike 

We found the Brown Shrike, a winter visitor to 
the Philippines from the Asian mainland, to be 
uncommon at 450 and 900 m. One was taken by 
Rabor on 21 April 1961 at about 1 140 m. They 
were generally observed perched in trees at the 
edge of parang or heavily disturbed areas. The 
stomachs of two birds contained insect remains. 

WEiGHT-Male (8) 34.2 ± 4.20, 28.5^1.5, fe- 
male (6) 32.3 ±3.31, 26.9-36.3. 



and a juvenile male on 25 April. The stomachs of 
two birds contained small fruits and fig seeds. 

Measurements— Wing— male (5) 130.6 ± 3.32, 
124-133, female (3) 131, 134, 136; tail -male (5) 
112.2 ± 2.71, 108-1 15, female (3) 108, 109, 115; 
exposed culmen-male (5) 27.2 ± 0.68, 26.2-28.3, 
female (3) 26.7, 26.7, 29.0; weight- male (5) 143.8 
± 6.24, 133-150, female (2) 149, 160. 



Family Nectariniidae 

*Anthreptes malacensis birgitae 
Sunbird 



Brown-throated 



The single record of this species on Mt. Isarog 
is a female taken by Rabor on 26 April 1 96 1 be- 
tween 450 and 610 m. 

Measurements— Female (1)— wing 61, tail 35, 
exposed culmen 18.5, weight 11.9. 



Family Sturnidae 

*Aplonis panayensis panayensis Philippine 
Glossy Starling 

The single record of this species on Mt. Isarog 
is one obtained by Rabor on 29 March 1961 at 
610 m. 

Measurements— Female— wing 106, tail 68, 
exposed culmen 17.0, weight 48.6. 



*Sturnus philippensis Chestnut-cheeked Starling 

The only record of the Chestnut-cheeked Star- 
ling, a winter visitor to Luzon from Japan, is a 
female taken on 4 April 1961 between 300 and 
450 m. 

Weight -Female (1) 28.8. 



*Nectarinia sperata sperata 
Sunbird 



Purple-throated 



Two adult males were found by Rabor in late 
March 1961 between 300 and 610 m. One had 
enlarged gonads. 

Measurements— Male (2)— wing 53, 56; tail 31, 
31; exposed culmen 14.0, 15.7; weight 6.4, 8.2. 



*Nectarinia jugularis jugularis Olive-backed 
Sunbird 

Three male Olive-backed Sunbirds were ob- 
tained by Rabor on 25 March 1961 between 150 
and 300 m. These are the only known records of 
this species for Mt. Isarog. 

Measurements— Male— wing (3) 58, 59, 60; tail 

(2) 38, 39; exposed culmen (2) 18.3, 18.6; weight 

(3) 8.0, 9.9, 9.9. 



*Sarcops calvus cahus Coleto 

We found this species to be common in heavily 
disturbed areas between 450 and 600 m, and it 
was observed once at 900 m. It could often be seen 
perched in dead trees in cleared fields or parang. 
A pair collected in late March 1988 at 450 m had 
slightly enlarged gonads and appeared to be ap- 
proaching breeding condition. Rabor obtained 
seven specimens in 1961, all below 760 m, in- 
cluding a male with enlarged testes on 19 April 



*Aethopyga Jlagrans Jlagrans Flaming Sunbird 

In 1961 Rabor obtained seven individuals of 
this species on Mt. Isarog between 300 and 910 
m. A male obtained on 1 1 April 1 96 1 had enlarged 
testes. 

Measurements— Wing— male (3) 50, 51, 52, fe- 
male (4) 47.5 ± 1.12, 46-^9; tail-male (3) 28, 
28, 31, female (4) 25.3 ± 1.30, 24-27; exposed 
culmen-male (2) 17.9, 18.2, female (4) 16.3 ± 



GOODMAN & GONZALES: BIRDS OF MT. ISAROG NATIONAL PARK. 



27 



0.39, 15.9-16.9; weight-male (3) 6.4, 6.5, 7.0, 
female (3) 6.5, 6.5, 7.3. 



female (2) 8.0, 8.6; weight-male (3) 10.0, 10.0, 
10.0, female (2) 8.5, 9.0. 



*Aethopyga pulcherrima jefferyi Mountain 
(Metallic-winged) Sunbird 

We noted the Mountain Sunbird in the zone 
between 1 125 and 1550 m. It was most common 
at 1350 m, where males were regularly observed 
singing and displaying, often from canopy perches. 
Rabor obtained five specimens from elevations 
between 610 and 1670 m, including a male on 18 
April 1 96 1 with enlarged gonads. This species was 
often found feeding on the contents of a red trum- 
pet flower, a plant most abundant near 1350 m. 

Measurements— Wing— male (2) 51, 52, fe- 
male (3) 47, 48, 48; tail-male (2) 28, 29, female 
(3) 24, 26, 26; exposed culmen— male (2) 21.5, 
21.5, female (3) 16.3, 17.9, 18.5; weight-male (1) 
6.2, female (2) 5.0, 6.3. 



Arachnothera clarae [luzonensis] Naked-faced 
Spiderhunter 

This species was noted once in the area. On 29 
February 1988, one was observed at the edge of a 
relatively undisturbed patch of forest at 450 m. 



Family Dicaeidae 

"Prionochilus olivaceus parsonsi Olive-backed 
Flowerpecker 

This species occurs on the lower slopes of Mt. 
Isarog. It was found to be uncommon at 450 m in 
both secondary and primary forest and was ob- 
served once at 900 m. Males taken on 25 March 
1988 and 19 April 1961 were in or approaching 
breeding condition. Several individuals were not- 
ed at 450 m in a fig tree picking off and eating 
flower buds; they were followed by two Phyllos- 
copus cebuensis gleaning insects from the dis- 
turbed vegetation. The stomach of one Olive- 
backed Flowerpecker contained both insect and 
plant remains. Mt. Isarog specimens are similar 
in size and plumage coloration to material of P. 
o. parsonsi taken in northern Luzon. 

Measurements— Wing— male (3) 57, 59, 60, fe- 
male (2) 50, 52; tail-male (3) 26, 27, 28, female 
(2) 23, 24; exposed culmen-male (3) 8.5, 8.5, 9.5, 



*Dicaeum bicolor inexpectatum Bicolored Flow- 
erpecker 

In 1988 the Bicolored Flowerpecker was com- 
mon at 900 m and uncommon at 1 350 m. We did 
not record it anywhere else on the mountain. In- 
dividuals were seldom noted in the forest, and 
most observations were of groups feeding in fruit- 
ing trees. Thus, there was the impression that they 
move some distance in search of food. Rabor ob- 
tained 13 specimens in 1961 from altitudes be- 
tween 450 and 1220 m. 

The breeding season of this species seems vari- 
able from year to year. In March 1 988 a few adults 
had slightly enlarged gonads and the organs seemed 
to be regressing; we also noted fledglings being fed 
by adults. Most birds taken by Rabor in April 1961 
were in breeding condition, including a female on 
8 April with a "ripe egg." He also obtained seven 
fledglings in the last third of April. 

This bird seems largely frugivorous. During ear- 
ly March 1 988 a fig tree in a clearing at 900 m was 
in fruit. Up to 20 Bicolored Flowerpeckers were 
observed in the tree at any one time feeding on 
ripening figs. The lack of other frugivores in the 
area seemed odd; this species was the only fruit- 
eating bird noted in the tree over the course of six 
days. 

Measurements— Wing— male (5) 53.2 ± 1.17, 
52-55, female (3) 53, 53, 54; tail-male (5) 23.4 
± 1.02, 22-25, female (3) 23, 23, 24; exposed 
culmen-male (5) 8.0 ± 0.42, 7.2-8.4, female (2) 
7.6, 8.5; weight-male (7) 9.3 ± 0.43, 8.7-10.0, 
female (2) 8.8, 10.0. 



*Dicaeum australe australe Philippine (Red- 
striped) Flowerpecker 

This species was common at 450 m. It was not 
recorded at any higher elevation. A female taken 
on 25 March 1988 had enlarged ovarian follicles 
and probably would have laid eggs within a few 
weeks. A male obtained on 26 March 1961 had 
enlarged testes. One bird had small insects in its 
stomach. 

Measurements— Wing— male (2) 55, 57, fe- 
male (1) 53; tail-male (2) 27, 28, female (I) 25; 
exposed culmen-male (2) 10.0, 10.3, female (1) 
9.7; weight— male (2) 7.3, 8.0. 



28 



FIELDIANA: ZOOLOGY 



*Dicaeum trigonostigma xanthopygium 
bellied Flowerpecker 



Orange- 



Rabor obtained three adult males, all with en- 
larged testes, on 24 March and 6 and 16 April 
1961 between 300 and 700 m. 

Measurements— Wing— male (3) 53, 53, 54; 
tail— male (3) 24, 24, 25; exposed culmen— male 
(3) 9.8, 9.9, 10.0; weight-male (3) 6.4, 6.7, 7.6. 



*Dicaeum hypoleucum obscurum 
(Buzzing) nowerpecker 



White-belhed 



The White-bellied Flowerpecker was common 
in the vicinity of 450 m and rare near 900 m. It 
seemed most common in areas of disturbed forest. 
Many individuals taken in late March 1961 and 
1988 and late April 1961 were in or approaching 
breeding condition. Some variation was found in 
the foods consumed— stomachs contained small 
buds and/or insects. 

Measurements— Wing— male (8) 52.5 ± 1.66, 
51-56, female (4) 52.0 ±0.71, 51-53; tail-male 
(8) 21.8 ± 0.97, 20-23, female (4) 21.5 ± 0.87, 
21-23; exposed culmen— male (8) 11.1 ± 0.35, 
10.6-11.6, female (4) 10.9 ± 0.29, 10.6-11.3; 
weight-male (8) 7.6 ± 0.60, 7.0-8.4, female (3) 
7.0, 8.7, 9.0. 



*Dicaeum pygmaeum pygmaeum Pygmy Flow- 
erpecker 

The single specimen from the mountain, an adult 
male in breeding condition, was netted on 30 March 
1988 at 450 m. 

Measurements— Male (1)— wing 46, tail 20, 
exposed culmen 8.7, weight 4.0. 



Family Zosteropidae 

*Zosterops nigrorum luzonica Yellow White-eye 

This species was found on the lower slopes of 
Mt. Isarog. At 450 m it was common and flocks 
of up to 20 were often seen feeding on swarms of 
small insects. Single birds or pairs were occasion- 
ally noted at 900 m where it was uncommon; we 
have no records above this altitude. Two birds 
taken in late March 1961 had enlarged testes. One 
taken in 1988 had small insects in its stomach. 

Measurements— Wing— male (4) 52.8 ± 1.30, 



51-54, female (2) 48, 51; tail-male (4) 35.0 ± 
0.0, 35-35, female (2) 32, 35; exposed culmen— 
male (4) 10.5 ± 0.18, 10.2-10.7, female (2) 9.7, 
10.2; weight-male (3) 8.0, 8.0, 9.2, female (2) 7.0, 
8.7. 



Family Ploceidae 

* Passer montanns saturatus Eurasian Tree Spar- 
row 

This introduced species was abundant in areas 
below 350 m, surrounding the mountain. Rabor 
collected several adults in breeding condition, 
fledglings, and immatures between late March and 
late April 1961. The Mt. Isarog material was com- 
pared to a series of P. m. saturatus from Japan 
and P. m. malaccensis from Malaca. The crown, 
wings, back, and rump color of Mt. Isarog birds 
are distinctly pale and similar to saturatus. 



Family Estrildidae 

*Erythrura hyperythra brunneiventris Tawny- 
breasted Parrotfinch 

On 9 March 1988 an adult female, not in breed- 
ing condition, was netted at 900 m in a partially 
logged area. Its stomach was empty. The specimen 
fits the description of E. h. brunneiventris given 
by duPont (1971). A comparison of the bird with 
specimens taken elsewhere in the Philippines 
showed no plumage differences. 

Measurements— Female (1)— wing 59, tail 32, 
exposed culmen 9.5, weight 12. 



*Lonchura leucogastra everetti 
Munia 



White-bellied 



Records of the White-bellied Munia on Mt. Isa- 
rog include one netted at 450 m on 5 March 1 988 
in a partially cleared area and one taken between 
610 and 760 m on 2 April 1961. The latter bird 
had enlarged gonads. Presumably this species and 
the next are common in lowland agricultural areas. 



*Lonchura malacca jagori Chestnut Munia 

Rabor found this species in the zone between 
450 and 6 1 m. A male collected on 1 6 April 1 96 1 
had enlarged testes. 



GOODMAN & GONZALES: BIRDS OF MT. ISAROG NATIONAL PARK 



29 



Measurements— Wing— male (2) 54, 57, fe- 
male (3) 54, 55, 55; tail-male (2) 35, 36, female 
(3) 33, 34, 36; exposed culmen — male (2) 11.1, 
11.2, female (3) 10.2, 11.3, 1 1.6; weight-male (2) 
11.7, 11.7, female (2) 10.1, 11.4. 



Family Oriolidae 

*Oriolus ckinensis chinensis Black-naped Oriole 

We found the Black-naped Oriole to be uncom- 
mon and restricted to the area near 450 m. There 
are 19 specimens of this bird in the Rabor collec- 
tion, all of which were taken below 530 m, with 
the exception of an adult male and female from 
between 610 and 760 m. At least half of the birds 
taken by Rabor were in or approaching breeding 
condition. His collection also includes one fledg- 
ling from 100 m and three from about 530 m, all 
obtained in the second half of April 1961. 

Measurements— Wing— male (9) 156.4 ± 4.79, 
151-163, female (4) 157.5 ± 2.87, 153-160; tail- 
male (9) 101.7 ± 2.11, 98-105, female (4) 104.0 
± 1.87, 102-107; exposed culmen-male (8) 35.2 
± 1.07, 33.6-36.5, female (3) 35.6 ± 0.78, 34.7- 
36.6; weight-male (7) 94.0 ± 1.77, 92-97, female 
(3)98, 101, 101. 



Family Dicruridae ~ 

*Dicrurus balicassius balicassius Balicassiao 

The Balicassiao is a characteristic bird of the 
lower elevations of Mt. Isarog. They were common 
at 450 m and regularly seen singly or in groups of 
up to five. This species was noted a few times at 
the edge of the forest near the 900 m camp, but 
not at any higher elevation. Rabor obtained 32 
specimens of the Balicassiao on Mt. Isarog, none 
of which were taken above 760 m. About half of 
the specimens collected in late March 1961 and 
1988 and April 1961 were in breeding condition. 
The stomach contents of these birds consisted of 
arthropods, including mantids, beetles, and spi- 
ders. 

Measurements— Wing— male (20) 142.3 ± 
2.62, 138-147, female (16) 142.6 ± 2.71, 138- 
147; tail-male (20) 112.9 ± 3.89, 106-120, fe- 
male (16) 114.6 ± 3.37, 109-122; bill from nos- 
tril-male (20) 20.5 ± 0.74, 18.9-2 1.6, female (16) 
19.6 + 4.98, 18.4-22.0; weight-male (16) 71.6 



3.67, 63.3-78.8, female (14) 73.0 ± 4.28, 65- 



80. 



Family Artamidae 

*Artamus leucorhynchus leucorhynchus White- 
breasted Wood Swallow 

We observed a single bird at about 800 m flying 
over a clearing surrounded by secondary forest. In 
1961 Rabor obtained eight specimens, including 
four fledglings on 25 April, all from areas below 
450 m. 

Measurements— Wing— male (3) 132, 136, 136, 
female (1) 133; tail-male (2) 59, 60, female (1) 
57; exposed culmen-male (3) 17.7, 19.2, 20.0, 
female (1) 19.0; weight-male (1) 41.6, female (1) 
42.9. 



Family Corvidae 

*Coryus macrorhynchos philippinus Large-billed 
Crow 

This species was common at and below 450 m. 
We generally noted it near cultivated lands and 
rarely in forested areas. Rabor collected a nestling 
between 240 and 300 m on 22 April 1961. 



Discussion 

On the basis of the combined information from 
the 1961 and 1988 expeditions, a total of 1 16 res- 
ident bird species have been recorded on Mt. Isa- 
rog. Of these, 95 species were recorded at or below 
450 ± 50 m, 64 at 900 ± 50 m, 31 at 1 125 ± 50 
m. 24 at 1350 ± 50 m, 22 at 1550 ± 50 m, and 
9 at 1750 ± 50 m. An additional 19 species of 
migrants and winter visitors were also document- 
ed. When the pattern of altitudinal distribution of 
the resident birds was examined, several interest- 
ing points and patterns emerged. 

It needs to be stated that our work on Mt. Isarog 
was not exhaustive and that aspects of the local 
avifauna still remain unknown, particularly sea- 
sonal movements and the distribution of rare and 
secretive birds. The comparison of the Mt. Isarog 
information with data sets from various moun- 
tains in the Philippines gathered by other research- 



30 



FIELDIANA: ZOOLOGY 



ers in a nonstandard manner presents further 
problems. However, because there has not been 
any pubhshed review of the altitudinal distribu- 
tion of Philippine birds, we feel that even given 
these potential problems the comparisons made 
in the discussion section allow general trends to 
be pointed out. 



Altitudinal Overlap of Congeners 

Of the 87 genera of resident birds on Mt. Isarog, 
25 locally contain more than one species (range 
from two to five). The elevational distribution 
of these birds was analyzed by dividing the moun- 
tain into the following zones: ( 1 ) parang and low- 
land forest, approximately 200 to 900 m; (2) mon- 
tane forest, 1 125 to 1350 m; and (3) mossy forest, 
1 550 to 1 750 m. Among these 25 congeneric groups 
three distinct patterns were found: complete alti- 
tudinal sympatry, broad elevational disjunction, 
or a small amount of overlap with apparent species 
replacement. 

Twelve of 25 (48%) congeneric groups occur in 
parang and lowland forest and have completely 
overlapping altitudinal ranges; these are Pernis, 
Ptilinopus, Phaenicophaeus, Centropus. Ceyx. 
Coracina. Pycnonotus. Megalurus, Orthotomus, 
Hypothymis, Nectarinia. and Lonchura. We have 
no information on finer level habitat preferences 
of the members of any of these groups and it is 
possible that some ecological segregation exists. 

In 8 of 25 (32%) cases at least one species of a 
congeneric group was confined to parang and low- 
land forest and at least one other member occurred 
sympatrically and also in montane forest. For ex- 
ample, Phapitreron leucotis was found from pa- 
rang to montane forest (up to 1350 m) and P. 
amethystina only in parang and lowland forest. 
Other congeneric groups showing a similar pattern 
were Ninox, Halcyon, Lalage, Phylloscopus, Ae- 
thopyga, and Dicaeiim. Within a few of these groups 
more than one species fits the pattern. Halcyon 
chloris and H. smyrnensis were restricted to areas 
at or below 450 m, while H. lindsayii occurred in 
the same areas as well as up to 1 350 m. In lowland 
areas five species of Dicaeum were sympatric, but 
the range of only one, D. bicolor, extended up to 
montane forest. The altitudinal distributions of 
the Ducula and Pitta species groups were not suf- 
ficiently well documented to clarify their range on 
the mountain. 

In the third distinctive pattern found, congeners 



had broad distributions up the mountain and often 
replaced one another within a narrow altitudinal 
zone. Three of the 25 (12%) congeneric groups fit 
this category. For example, Otus megalotis was 
uncommon in parang and lowland forest, while 
O. longicornis was rare in these areas and uncom- 
mon in montane and mossy forest. The congeneric 
groups of Ficedula and Pachycephala showed a 
similar replacement pattern. 

There is no single recognizable pattern in the 
altitudinal ranges of congeneric groups on Mt. Isa- 
rog; considerable variation was found within and 
between genera. This is presumably related to the 
ways different types of birds, whether closely re- 
lated or not, respond to varying aspects of the 
environment. Perhaps even more importantly, 
subtle differences in the use of resources by con- 
geners are difficult to quantify. Thus, our ability 
to understand the role of competition (Terborgh, 
1971) in molding these bird distributions is se- 
verely hampered, but the apparent commonness 
of elevational replacement of congeners was not 
present on Mt. Isarog. A similar pattern has been 
found in mainland Southeast Asian forests (Med- 
way, 1972). 



Densities of Birds Based on Netting 

We used mist nets to assess densities of ground 
dwelling and lower understory birds within the six 
transect zones (Karr, 1981). Of the total 378 net- 
days accrued between 3 and 31 March 1988, 97 
were at 450 m, 54 were at 900 m, 56 were at 1125 
m, 79 were at 1350 m, 66 were at 1550 m, and 
26 were at 1750 m (table 3). The number of birds 
captured and the success rate per transect zone (= 
total captured/total number of net-days) were 76 
and 0.78, 44 and 0.81, 24 and 0.43, 51 and 0.65, 
97 and 1.47, and 28 and 1.08, respectively. It is 
important to note that the number of net-days per 
transect zone was relatively low, particularly at the 
1750 m camp, and the conclusions drawn from 
this information should be considered tentative. 

There does not appear to be any clear linear 
relationship between bird density and altitude. The 
highest density was found in the mossy forest zone, 
where Stachyris whiteheadi was particularly com- 
mon. This species accounted for 74 of 97 birds 
netted at the 1550 m camp and 23 of 28 netted at 
the 1750 m camp. The lowest bird density was 
found in the midsection of the montane forest at 
1125 m and 1350 m. Moderate densities were 



GOODMAN & GONZALES: BIRDS OF MT. ISAROG NATIONAL PARK 



31 



Table 3. Netting success on Mt. Isarog of resident birds captured between 28 February and 30 May 1988.' 









Elevation (Total net-days) 








450 m 


900 m 


1125 m 


1350 m 


1550 m 


1750 m 


Species 


(97) 


(54) 


(56) 


(79) 


(66) 


(26) 


Accipiter virgalus 


1/0.01 











1/0.02 





Accipiter sp. 


1/0.01 


— 


— 


— 


— 


— 


Microhierax erythrogenys 


— 


2/0.04 


— 


— 


— 


— 


Phapitreron leucotis 


— 


1/0.02 


— 


— 


— 


— 


Bolbopsittacus lunulatus 


— . 


1/0.02 


— 


— 


— 


— 


Cuculus fugax 


— 


— 


1/0.02 


— 


— 


— 


Cacomantis variolosus 


— 


1/0.02 


— 


1/0.01 


— 


— 


Olus longicornis 


I/O.Ol 


— 


4/0.07 


2/0.03 


2/0.03 


1/0.04 


Olus megalotis 


2/0.02 


2/0.03 


— 


— 


1/0.02 


— 


Nino.x philippensis 


5/0.05 


3/0.06 


— 


— 


— 


_ 


Collocalia esculenta 


— 


1/0.02 


— 


_ 


— 


— 


Halcyon lindsayi 


7/0.07 


— 


— 


— 


— 


— 


Dendrocopos maculatus 


1/0.01 


— 


— 


— 


— 


— 


Dicrurus balicassius 


8/0.08 


— 


— 


— 


— 


— 


Parus elegans 


5/0.05 


5/0.09 


— 


— 


— 


— 


Sitta frontalis 


— 


2/0.03 


— 


— 


— 


— 


Stachyris whiteheadi 


— 


6/0.11 


3/0.05 


30/0.38 


74/1.12 


23/0.88 


Pycnonolus urostictus 


— 


1/0.02 


— 


— 


— 


— 


Hypsipetes philippinus 


17/0.18 


7/0.13 


— 


— 


— 


— 


Irena cyanogaster 


— 


1/0.02 


— 


— 


— 


— 


Brachypteryx montana 


— 


— 


1/0.02 


5/0.06 


4/0.06 


1/0.04 


Zoothera andromedae 


— 


— 


_ 


— 


1/0.02 


— 


Turdus poliocephalus 


— 


— 


1/0.02 


2/0.03 


7/0.11 


1/0.04 


Phylloscopus trivirgatus 


— 


— 


1/0.02 


1/0.01 


1/0.02 


1/0.04 


Phylloscopus cebuensis 


1/0.01 


— 


— 


— 


— 


— 


Orthotomus derbianus 


2/0.02 


— 


— 


— 


— 


— 


Rhipidura cyaniceps 


6/0.06 


4/0.07 


3/0.05 


2/0.03 


1/0.02 


— 


Ficedula hyperythra 


— 


— 


2/0.04 


1/0.01 


1/0.02 


— 


Ficedula westermanni 


_ 


_ 


1/0.02 


_ 


_ 


1/0.04 


Cyornis herioli 


1/0.01 


— 


— 


— 


— 


— 


Muscicapa panayensis 


— 


1/0.02 


1/0.02 


— 


— 


— 


Pachycephala plateni 


— 


1/0.02 


6/0. 1 1 


7/0.09 


4/0.06 


— 


Pachycephala philippinensis 


2/0.02 


— 


— 


— 


— 


— 


Phonochilus olivaceus 


4/0.04 


— 


— 


— 


— 


— 


Dicaeum bicolor 


— 


3/0.05 


— 


_ 


— 


— 


Dicaeum australe 


1/0.01 


_ 


_ 


_ 


_ 


_ 


Dicaeum hypoleucum 


10/0.10 


1/0.02 


— 


— 


— 


— 


Erythrura hyperythra 


— 


1/0.02 


— 


— 


— 


— 


Lonchura leucogastra 


1/0.01 


— 


— 


— 


— 


— 


Total success rate 


76/0.78 


44/0.81 


24/0.43 


51/0.65 


97/1.47 


28/1.08 


Total success rate excluding 














Stachyris whiteheadi 


76/0.78 


38/0.70 


21/0.38 


21/0.27 


23/0.35 


5/0.19 


Total number of species 


19 


19 


11 


9 


11 


6 



Entry given as total number captured per transect zone/netting success rate. 



found in the lowland forest at 450 m and lower 
montane forest at 900 m. 

There was considerable variation in the range 
and density of various groups on the mountain. 
Owls were the most evenly distributed family. 
Combining the data on the two Otus and one Ni- 
nox (the main food of which is large invertebrates) 
the rate of netting success was 0.07 at 450 m, 0.09 
at 900 m, 0.07 at 1 125 m, 0.04 at 1350 m, 0.05 



at 1550 m, and 0.04 at 1750 m. The flycatcher 
guild (including Rhipidura and Pachycephala) ap- 
peared to be more common at middle elevations 
than at lower or upper zones. This is compared to 
warblers, another group of insectivores, which were 
sparsely distributed across the mountain. Flow- 
erpeckers were netted with some frequency at 450 
m (0. 1 5 netting success) and at 900 m (0.07 netting 
success), but not at any higher elevation. 



32 



FIELDIANA: ZOOLOGY 



Altitudinal Distribution of Birds on Mt. Isarog 
and Other Philippine Mountains 
with Mossy Forest 

From our 1988 observations and the combined 
1961 and 1 988 collections, it is clear that the num- 
ber of resident bird species on Mt. Isarog declines 
with increasing altitude. We recorded 95 species 
at or below 450 m, 64 at 900 m, 31 at 1 125 m, 
24 at 1350 m, 22 at 1550 m, and 9 at 1750 m 
(correlation of log-transformed data, P = 0.0 1 , r 
= 0.92, N = 6) (table 2). Similar patterns have 
been described for montane avifaunas elsewhere 
in the Philippines (see below) and in tropical areas 
on other continents (Chapman, 1917; Terborgh, 
1971. 1977; Diamond & LeCroy, 1979). Philip- 
pine fruit bats show a parallel pattern of decreasing 
density and species diversity with increasing al- 
titude (Heaney et al., 1989). This pattern presum- 
ably is related to decreasing habitat complexity 
and usable primary productivity with altitude 
(Mac Arthur et al., 1966; Orians, 1969; Kikkawa 
& Williams, 1971). 

For comparison with the pattern found on Mt. 
Isarog, information on the altitudinal distribution 
of birds on Mt. Malindang(2420 m), western Min- 
danao, was tabulated from Rand and Rabor (1960); 
Mt. Halcon (2580 m), Mindoro, from Ripley and 
Rabor ( 1 9 5 8) and Morioka and Sison ( 1 98 7); and 
Canlaon Volcano (2500 m), Negros, from Ripley 
and Rabor (1956). The taxa collected near Mt. 
Halcon at Alcate, Makatok, and Lake Naujan 
(Ripley & Rabor, 1958) have not been used in the 
tabulation of species occurring on the mountain. 
In order to put the ecology of these mountains in 
context, particularly with respect to the habitats 
on Mt. Isarog, the various altitudinal zones on 
each will be briefly described. 

On Mt. Malindang, 5 1 resident bird species were 
collected between 600 and 1065 m, 49 between 
1065 and 1370 m, 38 between 1370 and 1670 m, 
22 between 1670 and 1975 m, and 18 between 
1975 and 2420 m (correlation of log-transformed 
data, P = 0.03, r = 0.91, N = 5) (fig. 6). Rand and 
Rabor ( 1 960) classified the habitats on the moun- 
tain as: (1) cultivation, grassland, or second-grovrth 
from sea level to 750 m (a small amount of original 
lowland forest was interspersed in this zone up to 
1065 m); (2) transitional lowland and montane 
forest from 1065 to 1520 m; (3) montane forest 
from 1520 to 1975 m; and (4) mossy forest from 
1975 to 2420 m. 

Fifty-three bird species have been documented 
(mostly specimens, a few observations) on Mt. 



Halcon between sea level and 750 m, 29 between 

750 and 1065 m, 31 between 1065 and 1370 m, 
26 between 1370 and 1670 m, 17 between 1670 
and 1975 m, and 7 between 1975 and 2580 m 
(correlation of log-transformed data, P = 0.03, r 
= 0.86, N = 6) (fig. 6). The vegetation on the 
mountain was classified by Ripley and Rabor 
(1958) as: (1) lowland forest from sea level to 460 
m (apparently when they visited the area in 1954 
this section of forest had not been extensively 
cleared); (2) transitional lowland and montane for- 
est from 460 to 760 m; (3) montane forest from 
760 to 1370 m; and (4) disjunct and interspersed 
climbing bamboo and mossy forest from 1220 to 
2280 m. The summit of Mt. Halcon is covered 
with clumps of short grasses and herbs, a few 
shrubs, and no trees (Morioka & Sison, 1987). 

On Canlaon Volcano, 68 resident birds were 
collected between 760 and 1370 m, 14 between 
1370 and 1975 m, and 11 between 1975 and 2490 
m (correlation of log-transformed data, P = 0.18, 
r = 0.96, N = 3) (fig. 6). The habitats were classified 
by Ripley and Rabor (1956) as: (1) transitional 
lowland and montane forest between 760 and 1 370 
m; some cultivation and second growth was found 
in this zone up to 1065 m; (2) montane forest 
between 1370 and 1975 m; and (3) mossy forest 
between 1975 and 2500 m. The summit was most- 
ly bare rock with some clumps of grasses. 

In all cases the number of resident species on 
each of these four mountains drops off with in- 
creasing altitude (fig. 6). However, the rate of de- 
crease, particularly at lower altitudes, and fluctu- 
ations in the number of species as a function of 
elevation, vary among mountains. A greater num- 
ber of resident species occurs on the lower slopes 
of Mt. Isarog than on any of the other three moun- 
tains; this is at least in part an artifact, because 
the lowest transect point on any of the four peaks 
is on Mt. Isarog at 450 m. Further, Mt. Isarog is 
the only mountain of the four on which obser- 
vational information was used in the species tab- 
ulations. There are few localities in the Luzon is- 
land group where the lowland resident avifauna is 
well known, at least in a parallel way to Mt. Isarog. 
Probably the best comparison that can be made 
is to Catanduanes Island, which lies 85 km from 
Mt. Isarog (directly off southeastern Luzon) and 
rises in elevation to just under 900 m. The number 
of resident species occurring in the lowland forest 
or parang on Catanduanes is 108 (Manuel, 1937; 
Gonzales, 1983; Goodman & Gonzales, 1989), 
compared to 1 1 1 at or below 900 m on Mt. Isarog 
(table 2). These figures are presumably typical of 



GOODMAN & GONZALES: BIRDS OF MT. ISAROG NATIONAL PARK 



33 



112 



96 



o 80 

u 

m 

■*. 64 



XI 

E 48 

z 



o 



32 



16 - 





Isarog. Mossy Forest ^ 


Mt. 


. 


Luzonx Montane Forest ^P 
\ Trans. Montane / Lowland Forest <CI^ 






\ Lowland Forest CZ5 
\ 
\ 




\ 
\ 

\^ O-^ ^'' Canlaon. Negros 


- 


V \ 




Mt. Halcon, \ 
Mindoros„ \ 




. 


°p-\-A 




\ \ '^^ ^ Mt. Malindang, 
\ '•. ^ Mindanao 








\ \ ■•■. \ 




^ -^kw^ '-. ^^ 




"^-A-'^i-. \ 


- 


\--~Z\ 








"^ ^'"^ 







400 



800 



1200 



1600 



2000 



2400 



Elevation (m) 

Fig. 6. Graph comparing the number of species occurring in distinct ecological zones and at various elevations 
on four mountains in the Philippines. Data for Mt. Canlaon, Negros, are from Ripley and Rabor ( 1 956); Mt. Halcon, 
Mindoro, from Ripley and Rabor (1958) and Morioka and Sison (1987); and Mt. Malindang, Mindanao, from Rand 
and Rabor (1960). 



the number of resident birds found in comparable 
types of lowland habitat throughout this portion 
of the Philippines. The number occurring in the 
lowland forest of Mt. Malindang, Mindanao, seems 
low, and this may be an artifact of incomplete 
information. 

At middle to high elevations the number of res- 
ident birds on the four mountains is similar. Al- 
though the actual altitude of mossy forest varies 
on these mountains, each appears to hold a rela- 
tively similar number of resident birds in this zone 
(altitude of mossy forest in parentheses): Mt. Isa- 
rog (1 550-1 966 m)- 7 species, Mt. Halcon (1975- 
2580 m)- 7 species, Canlaon Volcano (1975-2230 
m)— 10 species, and Mt. Malindang (1975-2420 
m)— 18 species (table 4). 

Given these patterns, two questions may be 
asked: ( 1 ) Is there a distinct set of species or genera 
that tend to occur in the mossy forest of these 
mountains? and (2) Is there a high degree of en- 
demism among the resident birds of this distinct 
ecological zone? When the number of species oc- 
curring in the mossy forest zone of Mt. Isarog was 
compared to those found in the mossy forest zones 



of the other three mountains several interesting 
patterns emerged: 3 of 7 species (43%) also occur 
on Mt. Halcon, 5 of 10 (50%) also occur on Can- 
laon Volcano, and 1 of 1 8 (6%) also occurs on Mt. 
Malindang (table 4). Thus, there is considerable 
variation between mountains and no distinct set 
of species forms the mossy forest resident avifau- 
na. Moreover, there is considerable variation in 
the habitat preference of certain species between 
the four mountains. 

The only species that occurs in the mossy forest 
of all four mountains is Phylloscopus trivirgatus. 
Turdus poliocephalus and Brachypteryx montana 
are found in this zone on three of the four moun- 
tains, the exception being Mt. Malindang. Of the 
30 species listed in Table 4, 19 are found on at 
least two of the four mountains, but not necessarily 
in the same ecological zones. For example, Bra- 
chypteryx montana on Mt. Malindang was re- 
stricted to transitional lowland/montane forest and 
montane forest, but on Mt. Isarog it was found 
from lowland forest to mossy forest. Parus elegans 
on Canlaon Volcano and Mt. Halcon is a mossy 
forest bird, but on Mt. Isarog it is common at low 



34 



HELDIANA: ZOOLOGY 



Table 4. The species composition of mossy forest avifaunas on four mountains in the Phihppines.' 





Mt. Malindang, 


Canlaon Volcano. 


Mt. Halcon. 


Mt. Isarog, 




Mindanao 


Negros 


Mindoro 


Luzon 


Species 


(1975-2420 m) 


(1975-2230 m) 


(1975-2580 in) 


(1550-1966 m) 


Gallus galliis 


X 


+ 


+ 


+ 


Phapitreron amethystina 


X 


+ 


+ 


+ 


Macropygia phasianella 


+ 


X 


+ 


X 


Cuculus fugax 


X 


+ 


+ 


+ 


Otus longkornis 








X 


Chrysocolaples lucidus 


X 


+ 




+ 


Coracina ostenta 




X 






Coracina tncgregori 


X 








Parus elegans 


+ 


X 


X 


+ 


Stachyhs whiteheadi 








X 


Brachypteryx montana 


+ 


X 


X 


X 


Zoolhera andromedae 


X 




+ 


+ 


Turdus poliocephalus 


+ 


X 


X 


X 


Bradypterus caudatus 


X 








Phyl/oscopus Invirgatus 


X 


X 


X 


X 


Rhipidura nigroannamomea 


X 








Ficedula hyperythra 


X 


X 


+ 


+ 


Ficedula westennanni 


+ 


X 




X 


Muscicapa panayensis 


X 


+ 


+ 


+ 


Pachycephala philippensis 


X 






+ 


Pachycephala plateni 




X 


+ 


+ 


Lanius validirostris 


+ 




X 




Dicaeum mgntore 


X 








Aethopyga boltoni 


X 








Aethopyga pulcherrima 


+ 






+ 


Zosterops monlanus 


X 


X 


X 




Zosterops nigronim 




+ 


X 


+ 


Lophozosterops goodfellowi 


X 








Hypocryptadius cinnamomeus 


X 








Pyrrhula leucogenys 


X 









Total/mountain 

Number shared with Mt. Isarog 
Number species shared with Mt. Isarog 
but occurring at lower elevations 



18 
1 



10 

5 



' This table does not include altitudinally roaming species such as swifts, x = present in mossy forest, + = present 
on respective mountain but not in mossy forest. A blank indicates that the species is unknown from that mountain. 



and uncommon at lower middle elevations. This 
pattern is opposite that found in other high-moun- 
tain tropical avifaunas, such as the Andes (Haffer, 
1987), areas of peninsular Malaysia (Medway & 
Wells, 1976), New Guinea (Beehler, 1981), and 
widely disjunct mountain ranges in Africa (Mo- 
reau, 1966; Dowsett, 1986), where many bird spe- 
cies have altitudinally limited, yet geographically 
extensive ranges. 

What about species restricted or endemic to 
mossy forest? Eleven of the 30 (37%) species found 
in mossy forest on the four mountains (table 4) 
occur on only one of the four mountains. Two of 
these species are restricted to Luzon: Otus longi- 
cornis is found at all elevations of Mt. Isarog and 
at other localities, and Stachyris whiteheadi occurs 
at lower elevations on Mt. Isarog and on numerous 



other mountains (duPont, 1971). The latter species 
shows a considerable amount of geographical vari- 
ation on Luzon, which may be related to differ- 
entiation on nonconnected mountain chains 
(Goodman & Gonzales, unpubl.). Coracina osten- 
ta was the only 1 of the 1 1 species that was re- 
stricted to Canlaon Volcano. However, this bird 
is also known from the islands of Panay and Gui- 
maras (duPont, 197 1); these two islands were con- 
nected to Negros in the late Pleistocene (Heaney, 
1986). No bird species was restricted to the mossy 
forest on Mt. Halcon. The situation on Mt. Malin- 
dang is distinctly different; of the 1 1 species in the 
sample that are restricted to a single mountain, 8 
were found only on Mt. Malindang. Of these, six 
are Mindanao endemics: Coracina mcgregori. 
Rhipidura nigrocinnamomea, Dicaeum nigrilore, 



GOODMAN & GONZALES: BIRDS OF MT. ISAROG NATIONAL PARK 



35 



Aethopyga boltoni, Lophozosterops goodfellowi, and 
Hyprocryptadius cinnamomous. Three of the six 
{Rhipidura. Aethopyga, and Lophozosterops) show 
geographical variation among several Mindanao 
mountains, while the other three are distributed 
across the island but have no recognized subspe- 
cies (duPont, 1971). Thus, although restricted to 
the island, none of these six birds is endemic to a 
single mountain. The remaining two of the eight 
Mindanao mossy forest birds are Bradypterus cau- 
datus, which has three distinct geographical forms 
occurring on Mt. Malindang and Mt. Ape (Min- 
danao) and northern Luzon, and Pyrrhula leuco- 
gonys. which has two distinct subspecies, one on 
Mindanao and the other in northern Luzon. 

There is no known bird species exclusively en- 
demic to the mossy forest of any of these four 
mountains. Many of the taxa listed in Table 4 
show great variability among mountains in their 
preferred habitat and altitudinal range. Thus, it 
appears that a substantial number of mossy forest 
birds found on these peaks are drawn from a pool 
of species adapted to a range of habitats rather 
than from an endemic and/or geographically re- 
stricted set of mossy forest taxa. The exception is 
Mt. Malindang, or more precisely Mindanao, an 
island that shows a higher degree of endemism; 
however, these endemics are not restricted to the 
mossy forest zone of any single peak. All six Min- 
danao mossy forest endemics discussed are mem- 
bers of different bird families and clearly are not 
the result of a single invasion and subsequent ra- 
diation. 



Changes in the Resident Avifauna of 
Mt. Isarog Between 1961 and 1988 

Although we have no quantifiable data on the 
amount of time that members of the 1961 expe- 
dition to Mt. Isarog spent at each elevational zone, 
it is clear from their collections that the complete 
altitudinal range of the mountain was surveyed. 
Information associated with the preferred eco- 
types of many of the birds collected and inscrip- 
tions (particularly elevation) on the specimen la- 
bels allow some inference to be made about the 
condition of the Mt. Isarog lowland forest in 1961. 

When Rabor conducted the 1961 survey, the 
area of Mt. Isarog below 450 m was probably to 
a large extent already cleared of the original forest 
and composed of large tracts of agricultural lands 
and parang (essentially as we found it in 1988). 
Below 450 m, he collected a long series of species 



associated with parang SiX\d modified areas and few 
specimens of birds characteristic of typically un- 
disturbed woodland. In 196 1 the forest from about 
450 to 900 m was presumably largely intact except 
for relatively small clearings made by shifting sub- 
sistence agriculturalists. Since 1961 this zone has 
been subjected to extensive logging and partial 
clear-cutting. The evidence for this is based on 
differences between the species collected in 1961 
and 1988 (see below). In 1988 we found no tracts 
of undisturbed lowland forest between 450 and 
900 m larger than a few hectares. The forest above 
900 m remains relatively intact, and the only clear 
disturbance is the extensive cutting of rattan. 

A combined total of 1 1 6 resident birds was found 
on the mountain by the 1961 and 1988 surveys. 
Of these, 95 occurred at or below 450 m, 64 be- 
tween 450 and 900 m, and 30 above 900 m. When 
these data are analyzed as the number of species 
found in a given zone by one survey and not the 
other, a startling pattern emerges. With one ex- 
ception, differences between the 1961 and 1988 
surveys in the number of species collected in any 
of these altitudinal zones varied from about 6 to 
1 3% (table 5). This degree of variation is presumed 
to be largely sampling variation in the total num- 
ber of species recorded per zone by each survey 
(relative to the other) and/or some aspect of spe- 
cies turnover. The only exception was the area 
between 450 and 900 m, where the 1961 survey 
found 27 species (42% of the total known from 
this zone) not recorded by the 1988 workers. This 
dramatic change is in exactly the habitat that has 
undergone the greatest ecological degradation in 
the past few decades. Thirty-four species (29%) 
collected on Mt. Isarog in 1961 were not found in 
1988, and are presumed to be locally extirpated. 
Of these 34 species, 21 (62%) were recorded by 
Rabor only at or below 610 m and 28 (82%) only 
at or below 760 m. Further, of these 34 species, 
10 (29%) are relatively large (> 100 g), 4 (12%) are 
predators, and 5 (15%) are considered particularly 
good for eating. Local human-caused extinction 
of birds resulting from the clearing of forest and 
to a limited extent by hunting, has most severely 
impacted large, raptorial, and good-tasting birds. 
It is clear that when the forest is destroyed species 
are locally extirpated, and that hunting can have 
a significant impact. 

The State of Mt. Isarog National Park 

Mt. Isarog National Park was established 20 
July 1938 by governmental proclamation no. 293. 



36 



FIELDIANA: ZOOLOGY 



Table 5. Differences in the number of resident species found on Mt. Isarog in 1961 and 1988. 



At or 

below 450 m 

(95)' 



Between 
450 and 900 m 

(64) 



Above 900 
(30) 



Total 
(116) 



Collected in 1961 but not in 1988 
Collected in 1 988 but not in 1 96 1 



7 (7.4%) 
6 (6.3%) 



27 (42.2%) 
4 (6.3%) 



2 (6.7%) 
4(13.3%) 



34 (29.3%) 
9 (7.8%) 



Number in parentheses is the total number of species recorded for the column heading. 



It comprises an area of about 10,110 hectares (Parks 
and Wildlife Office, 1968). The park has been not- 
ed as a health resort with spectacular canyons, 
gorges, ravines, and waterfalls, and as a game ref- 
uge. 

We have no specific information on the area 
from its establishment as a national park to the 
early 1960s. As discussed on p. 36, when Rabor 
visited the park in spring 1961 some undisturbed 
tracts of lowland forest still remained in the zone 
between 450 and 900 m. During the past few dec- 
ades there have been continuous logging activities 
in the area. In 1977 the Bicol area (Region 5), 
composed of the Catanduanes, Camarines Norte, 
Camarines Sur, Albay, Masbate, and Sorsogon 
provinces, had an estimated 144,085 hectares of 
virgin forest; by 1988 this had been reduced to 
16,885 hectares. Thus, on the average of 12,720 
hectares of virgin forest were lost each year during 
this period (Principe, 1988). Although the 1977 
figure may have been exaggerated, the extent of 
logging in the area has been ecologically devas- 
tating. In August 1983 the government posed a 
complete logging ban in the region, apparently to 
no avail. At present, only about 1 ,000 hectares are 
being reforested annually with important timber 
trees. Even some of the reforested areas are being 
invaded by kaingineros and laid to waste. 

During our spring 1988 field season, the drone 
of chain saws could be heard from before sunrise 
to after sunset in forested areas within the national 
park boundaries. With alarming frequency we 
could feel the ground tremble as the remaining 
large dipterocarps came crashing down. These il- 
legal, large-scale cutting operations were not con- 
ducted independently by slash and bum agricul- 
turalists, but rather by well-financed commercial 
operators. 

In 1975 it was estimated that 250 settlers lived 
within the Mt. Isarog National Park (lUCN Trop- 
ical Forest Programme, 1988). During our 1988 
visit it was clear that this number had increased. 
There were several settlements just outside the 
park boundaries. Because of the steep topography 



and the few large dipterocarp trees, the area above 
900 m appears to be relatively safe from forest 
clearing. Rattan is regularly gathered from the zone; 
however, this activity presumably has a negligible 
effect on the local forest. Our impression was that 
the majority of forest clearing within the park 
boundaries below 900 m had been initiated by 
large-scale operations for lumber and not slash and 
bum agriculturalists for crop lands. Once the pri- 
mary forest had been removed, the kaingineros 
further cleared, maintained, and planted the area. 
Thus, the greatest current threat to the Mt. Isarog 
National Park is the illegal commercial logging 
operations. 

The remaining tracts of undisturbed forest in 
the Mt. Isarog National Park are in immediate 
need of protection. This could be accomplished 
by the deployment of rangers in the area to enforce 
existing laws against illegal logging, strict legal 
prosecution against offenders, and the establish- 
ment of a local education program directed toward 
information about habitat destmction and water- 
shed management. We are aware that these sug- 
gestions would only provide short-term relief; the 
real solution for the Philippines and many other 
places in the world will only come after extensive 
social reforms to alter present economic systems 
that are based on the exploitation of natural and 
human resources. 



Acknowledgments 

Other participants in the 1988 Mt. Isarog sur- 
vey included Arcinio Batal, Renato Femandez, 
Lawrence Heaney, Fernando Jumalon, Myrissa 
Lepiten, Maylene Laranjo, Jacinto Ramos, Eric 
Rickart, Douglas Samson, David Schmidt, Leo- 
ning Tag-at, and Ruth Utzurrum. Many local peo- 
ple living in the Mt. Isarog area provided assist- 
ance. Officials of the Philippine Bureau of Forestry 
Development allowed us access to the facilities at 
the Panicuason Central Nursery. Messrs. Narvaja 



GOODMAN & GONZALES: BIRDS OF MT. ISAROG NATIONAL PARK 



37 



and Basmayor and officials of the Bicol University, 
College of Fisheries, Tabaco, Albay, provided 
transportation and helped in numerous ways. The 
ornithological work could not have been accom- 
plished without the gracious help of all of these 
people; to all we extend our warmest thanks. A 
grant from the Thomas J. Dee Fund, Field Mu- 
seum of Natural History, Chicago, allowed SMG 
to study the 1 96 1 Rabor collection from Mt. Is- 
arog. Gene Hess, Delaware Museum of Natural 
History; Julio Leuterio, College of Forestry, Uni- 
versity of Philippines at Los Baiios; and David 
Willard, Field Museum of Natural History, kindly 
allowed us access to material in their care. We 
acknowledge financial support from the Philippine 
National Museum, the Smithsonian Institution, 
and the U.S. National Science Foundation (BSR- 
85 14223 to L. R. Heaney). Mr. Brit Griswald kindly 
drafted Figures 1 and 6. For comments on an ear- 
lier draft of this paper we are grateful to Drs. L. 
R. Heaney, R. S. Kennedy, E. A. Rickart, R. W. 
Storer, and an anonymous reviewer. 



Literature Cited 

Baud, F. J. 1978. Oiseaux des Philippines de la col- 
lection W. Parsons II. Luzon, Mindoro at Palawan. 
Revue Suisse de Zoologie, 85: 55-97, 

Beehler, B. 1 98 1. Ecological structuring of forest bird 
communities in New Guinea, pp. 837-861. In Gres- 
sitt, J. L., ed., Biogeography and Ecology of New Guin- 
ea. W. Junk Publishers, The Hague. 

Brown, W. H. 1919. Vegetation of Philippine Moun- 
tains. Bureau of Printing, Manila, 434 pp. 

Chapman, F. M. 1917. The distribution of bird-life in 
Colombia; a contribution to a biological survey of 
South America. Bulletin of the American Museum of 
Natural History, 36: 1-729. 

Diamond, J. M., AND M. LeCroy. 1979. Birds of Kar- 
kar and Bagabag islands, New Guinea. Bulletin of the 
American Museum of Natural History, 164: 467-53 1 . 

Dickinson, E. C. 1989. A review oflarger Philippine 
swiftlets of the genus Collocalia. Forktail, 4: 19-53. 

Dickinson, E. C, R. S. Kennedy, and K. C. Parkes. 
In press. Checklist of Philippine Birds. British Or- 
nithologists' Union, London. 

Dowsett, R. J. 1986. Origins of the high-ahitude avi- 
faunas of tropical Africa, pp. 557-585. /« Vuilleumier, 
F., and M. Monasterio, eds.. High Altitude Tropical 
Biogeography. Oxford University Press, New York. 

DuPoNT, J. E. 1971. Philippine Birds. Delaware Mu- 
seum of Natural History, Greenville, 480 pp. 

GiLLiARD, E. T. 1950. Notes on a collection of birds 
from Bataan, Luzon, Philippine Islands. Bulletin of 
the American Museum of Natural History, 94: 457- 
504. 



Gonzales, P. C. 1983. Birds of Catanduanes. Zoolog- 
ical Papers, National Museum Manila. No. 2, 125 pp. 
Gonzales, P. C and C. P. Rees. 1988. Birds of the 
Philippines. Haribon Foundation for the Conserva- 
tion of Natural Resources, Manila, 184 pp. 
Goodman. S. M., and P. C Gonzales. 1989. Notes 
on Philippine ^^rds. 12. Seven species new to Catan- 
duanes Island. Bulletin of the British Ornithologists' 
Club, 109: 48-50. 
Haffer, J. 1987. Biogeography of neotropical birds, 
pp. 105-150. In Whitmore, T. C. and G. T. Prance, 
eds., Biogeography and Quaternary History in Trop- 
ical America. Clarendon Press, Oxford. 
Heaney, L. R. 1986. Biogeography of mammals in SE 
Asia: Estimates of rates of colonization, extinction and 
speciation. Biological Journal of the Linnean Society, 
28: 127-165. 
Heaney, L. R., P. D. Heideman, E. A. Rickart, R. B. 
Utzurrum, and J. S. H. Klompen. 1989. Eleva- 
tional zonation of mammals in the central Philippines. 
Journal of Tropical Ecology, 5: 259-280. 
lUCN Tropical Forest Programme. 1988. Philip- 
pines: Conservation of biological diversity and forest 
ecosystems. Doc. no. 1044J. International Union for 
the Conservation of Nature and Natural Resources, 
Cambridge, 21 pp. 
Jagor, [F.]. 1870. On the natives of Naga, in Luzon, 
Philippine Islands. Journal of the Ethnological Society 
of London, n.s., 2: 170-175. 

. 1875. Travels in the Philippines. Chapman and 

Hall, London, 370 pp. 
Karr, J.R. 1981. Surveying birds with mist nets. Stud- 
ies in Avian Biology, 6: 62-67. 
KiKKAWA, J, AND W. T. Williams. 1971. Altitudinal 
distribution of land birds in New Guinea. Search, 2: 
64-65. 
Lynch, F. X. 1948. Some notes on a brief field survey 
of the hill people of Mt. Iriga, Camarines Sur, Phil- 
ippines. Pnmitive Man, 21: 65-73. 
MacArthur, R. H., H. Recher, and M. Cody. 1966. 
On the relation between habitat selection and species 
diversity. American Naturalist, 100: 319-332. 
Manuel, C G. 1937. Avifauna of Catanduanes. Phil- 
ippine Journal of Science, 63: 185-189. 
Marshall, J. T., Jr. 1978. Systematics of smaller Asian 
night birds based on voice. Ornithological Mono- 
graphs, No. 25, 58 pp. 
McClure, H. E., and P. Leelavit. 1972. Birds banded 
in Asia during the MAPS program, by locality, from 
1963 through 1971. U.S. Army Research and Devel- 
opment Group, San Francisco, 478 pp. 
McGregor, R. C 1904. Birds from Benguet Province, 
Luzon, and from the islands of Lubang, Mindoro, Cuyo, 
and Cagayancillo. Bulletin of the Philippine Museum, 
3: 3-16. 

. 1924. Birds of Ilocos Norte Province, Luzon. 

Philippine Journal of Science, 25: 111-121. 
Meow ay, L. 1972. The Gunong Benom Expedition 
1967. 6. The distribution and altitudinal zonation of 
birds and mammals on Gunong Benom. Bulletin of 
the British Museum (Natural History), Zoology, 23: 
105-154. 



38 



FIELDIANA: ZOOLOGY 



Medway, L., and D. R. Wells. 1 976. The birds of the 
Malay Peninsula. Vol. V: Conclusion, and Survey of 
Every Species. H. F. & G. Witherby, London, 448 pp. 

Miller, M. L. 1911. The non-christian people of Am- 
bos Camarines. Philippine Journal of Science, 6: 321- 
326. 

MoREAU, R. E. 1966. The Bird Faunas of Africa and 
Its Islands. Academic Press, New York. 424 pp. 

MoRiOKA, H., AND T. Sakane. 1979. Breeding avifau- 
nas of Mt. Puguis, northern Luzon and Baracatan, 
Mindanao. Philippines (Part I). Bulletin of the Na- 
tional Science Museum, Japan, Series A (Zoology), 5: 
65-74. 

Morioka, H., and R. V. SisoN. 1987. Birds of the 
highlands of Mt. Halcon, Mindoro, Philippines. Jap- 
anese Journal of Ornithology, 35: 109-124. 

MussER, G. G. 1982. Results of the Archbold Expe- 
ditions. No. 110. Crunomys and the small-bodied shrew 
rats native to the Philippine Islands and Sulawesi (Ce- 
lebes). Bulletin of the American Museum of Natural 
History. 174: 1-95. 

MussER, G. G., AND P. W. Freeman. 1981. A new 
species of Rhynchomys (Muridae) from the Philip- 
pines. Journal of Mammalogy, 62: 154—159. 

O'Brien, J. J. 1968. The historical and cultural heritage 
of the Bicol people. Ateneo de Naga, Naga City, 38 1 
pp. 

Ogilvie-Grant, W. R. 1894. On the birds of the Phil- 
ippine Islands. — Pari I. Mount Arajat, central Luzon. 
Ibis, 6th Series, 6: 406^1 1. 

. 1895. On the birds of the Philippine Islands.— 

Pari IV, The province of Albay, south-east Luzon, and 
the adjacent island of Catanduanes. Ibis, 7th Series, 
1: 249-267. 

Orians, G. H. 1969. The number of bird species in 
some tropical forests. Ecology, 50: 783-801. 

Parks AND Wildlife Office. 1968. Status of conser- 
vation in the Philippines. lUCN Publications, n.s., 10: 
468^80. 



Principe, G. 1988. Forestry situation in the Bicol Re- 
gion. Speech given at Regional Forest Law Enforce- 
ment Conference, Legaspi City, 12 February 1988. 

Rabor, D. S. 1966. A repori on the zoological expe- 
ditions in the Philippines for the period 1961-1966. 
Silliman Journal, 13: 605-616. 

Rand, A. L., and D. S. Rabor. 1960. Birds of the 
Philippine Islands: Siquijor, Mount Malindang, Bo- 
hol, and Samar. Fieldiana: Zoology, 35: 225^41. 

. 1967. New birds from Luzon, Philippine Is- 
lands. Fieldiana; Zoology, 51: 85-89. 

Ripley, S. D., and D. S. Rabor. 1956. Birds from 
Canlaon Volcano in the highlands of Negros Island in 
the Philippines. Condor, 58: 283-291. 

. 1958. Notes on a collection of birds from Min- 
doro Island, Philippines. Bulletin Peabody Museum 
of Natural History, 13: 1-83. 

Stresemann, E., and D. Amadon. 1979. Order Fal- 
coniformes, pp. 271-425. In Mayr, E,, and G. W. 
Cottrell, eds.. Check-list of Birds of the Worid, vol. 1, 
2nd ed. Museum of Comparative Zoology, Cam- 
bridge, Massachusetts. 

Terborgh, J. 1971. Distribution and environmental 
gradients: Theory and a preliminary interpretation of 
distributional patterns in the avifauna of the Cordillera 
Vilcabamba, Peru. Ecology, 52: 23-40. 

. 1977. Bird species diversity on an Andean ele- 

vational gradient. Ecology, 58: 1007-1 1 19. 

Watson, G. E., M. A. Traylor, Jr., and E. Mayr. 
1986. Family Sylviidae, pp. 3-292. In Mayr, E., and 
G. W. Cottrell, eds., Check-list of Birds of the World, 
vol. XL Museum of Comparative Zoology, Cam- 
bridge, Massachusetts. 

Whitmore, T. C. 1984. Tropical Rain Forests of the 
Far East, 2nd ed. Clarendon Press, Oxford, 352 pp. 

Wolfe, L. R. 1938. Birds of central Luzon. Auk, 55: 
198-224. 



GOODMAN & GONZALES: BIRDS OF MT. ISAROG NATIONAL PARK 



39 




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