Effects of harvesting ponderosa pine on nongame bird populations

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1

1

/]rt.i mm

Effects of Harvesting Ponderosa Pine
on Nongame Bird Populations

Robert C. Szaro and Russell P. Balda

Research Paper RM-212
Rocky Mountain Forest and
Range Experiment Station
Forest Service

U.S. Department of Agriculture

Research Paper RM-212

December 1979

Effects of Harvesting Ponderosa Pine
on Nongame Bird Populations

^ Robert C. Szaro, Research Wildlife Biologist
Rocky Mountain Forest and Range Experiment Station^

and

Russell P. Balda, Professor of Biology
Northern Arizona University

Abstract

Bird species diversity and species richness in the ponderosa pine
forest were not significantly affected by forest cutting and logging
except on the clearcut plot. Bird population densities were signifi-
cantly increased on the silviculturally cut and irregular strip shelter-
wood plots and were significantly decreased on the severely thinned
and clearcut plots. Guidelines are recommended that will allow sub-
stantial logging of the ponderosa pine forest while still maintaining
bird density, diversity, and species richness.

'Central headquarters maintained at Fort Collins in cooperation with Colorado State Univer-
sity. Szaro is at the Station's Research Work Unit at Tempe in cooperation with Arizona State
University. Study was conducted under graduate program at Northern Arizona University.

Effects of Harvesting Ponderosa Pine
on Nongame Bird Populations ,

Robert C. Szaro and Russell P. Balda

Management Implications

The forest manager can remove between one-
sixth and two-thirds of the available foliage of the
ponderosa pine forest either in strips (and prob-
ably in blocks) or by thinning without detrimen-
tally affecting the breeding bird community in
terms of species richness, density, and diversity.
Increased densities on silviculturally cut and ir-
regular strip shelterwood plots are probably at
least partially due to openings (MacArthur et al.
1962; Marshall 1957, 1963). However, forest
treatments must consider that the quality of the
bird community on cut and control areas are not
equal. Species found on the control plot, such as
the hermit thrush, red-faced warbler, western fly-
catcher, and pygmy nuthatch, are replaced on the
cut areas by species such as the western wood
pewee, yellow-rumped warbler, and rock wren.

When forests are managed for tree and/or
water yield, some specific guidelines can be
followed to minimize the impact of habitat modifi-
cation on bird populations. To simply state that
foliage volume can be reduced by one-sixth to
two-thirds is of little real significance to forest
managers. Foliage volume is important to the
birds because it is related to the resource base
but is difficult and time consuming to measure.
Therefore, to maintain and/or increase (by up to
35%) ponderosa pine forest bird populations, the
following guidelines are recommended:

1. The total basal area of a given stand can be
reduced by 15% to 50%. However, large-
scale removal should be in strips or blocks.
In a uniform thinning operation, consider
removing only 30% of the total basal area.

2. Remove no more than 45% of those trees with
a d.b.h. of 9 inches or greater. Leave a
minimum of 32 trees per acre.

3. Remove no more than 75% of those trees with
a d.b.h. between 6 and 9 inches. Leave a
minimum of 17 trees per acre.

4. Remove 80% of the trees with a d.b.h. be-
tween 3 and 6 inches leaving approximately
25 trees per acre.

5. Gambel oak should not be removed at all. If
absolutely necessary, remove no more than
25% of the oaks.

6. Several overmature trees per acre should be
left to allow for adequate snag recruitment.

7. Snags should be left as nesting and roosting
sites for cavity nesters. Balda (1975) sug-
gests 2.6 snags per acre.

These guidelines are based on a comparison be-
tween the control plot and the silviculturally cut
and the irregular strip shelterwood plots.

Introduction

Avian ecologists have long been interested in
relating breeding bird populations to the vegeta-
tion of an area (Beecher 1942, Johnston and Odum
1956, Bond 1957). As the structure of a habitat
becomes more complex, the number of different
bird species increases (Karr 1968, MacArthur
and MacArthur 1961, MacArthur et al. 1966,
Recher 1969). The population density of black-
burnian warblers^ and myrtle warblers appears
to be closely correlated with foliage volume
(MacArthur 1958). Moreover, foliage volume may

'Common and scientific names of all birds and trees
referred to in this paper are listed in the appendix.

be an important factor limiting the densities of
parula warblers and nuthatches (Balda 1969,
Morse 1967). Data by Balda (1969) strongly sug-
gest that removing tall ponderosa pines (40 to 70
feet) may have a negative effect on the density of
Grace's warblers; whereas the removal of the
understory may reduce the populations of the
gray-headed junco and the chipping sparrow.

Bird population densities in a particular habitat
are believed to be regulated by many factors. Any
alteration of that habitat may affect the suitability
of the habitat for a given species' niche require-
ments. This study examined effects of timber
management practices on bird populations and
ways these practices can be used to manage non-
game bird populations.

1

study Areas

Five study plots were chosen in relatively homo-
geneous stands of ponderosa pine v^ith a buffer
around the periphery of at least 330 feet. Study
plots contained about the same proportions of dif-
ferent size classes of trees and density of Gambel
oak. All study areas were set up as 35-acre plots
except for the study area on the clearcut water-
shed, which encompassed 100 acres.

The five study areas are in the Coconino Na-
tional Forest, Coconino County, Arizona. All the
areas are located within a 13-mile radius on the
Beaver Creek Watershed. The areas included a
clearcut, a severely thinned, an irregular strip
shelterwood, a silviculturally cut (individual tree
selection], and a control plot. All study sites were
cut before the study began except for the silvicul-
turally cut area, which was cut during the spring
of 1974.

The ponderosa pine vegetation type, which was
found on all study areas before treatment, is
found primarily in areas of brolliar, siesta, and
sponsellar soils (Williams and Anderson 1967).

Control Plot

The control is located on watershed 13 approx-
imately 41 miles southeast of Flagstaff at an ele-
vation of 7,200 feet. The study area is on a south-
west-facing slope of about 17°, in the west-central
portion of the 368-acre watershed.

Watershed 13 was left untreated as the control
area. Ponderosa pine was the dominant tree spe-
cies with an importance value ^of 253 (table 1].
There were approximately 262 trees per acre
with a canopy volume of 276,800 cubic feet per
acre and a total basal area of 116.3 square feet
per acre. Of the trees of the plot, 78% had a d.b.h.
of 9 inches or smaller (table 2). In fact, the control
plot had 3.7 times as many trees with a d.b.h. be-
tween 3 and 6 inches than any other study plot
(table 2).

Silviculturally Cut Plot

The silviculturally cut plot is located on water-
shed 8, approximately 39 miles southeast of Flag-
staff at an elevation of 7,400 feet. The study area
is on a west-facing slope of about 13°, in the
southwest corner of the 1,800-acre watershed.

The prescription called for stands made up of
trees smaller than 10 inches d.b.h. to be thinned
to a growing stock level of 60 square feet per acre

of basal area.^ Stands consisting of trees 12 inches
d.b.h. and larger were thinned to an actual 70
square feet per acre of basal area. Trees were cut
to upgrade the stand rather than to obtain uniform
spacing. In most cases, Gambel oak were left intact.

The treatment was completed in early spring
1974; ponderosa pine was the major dominant
tree species with an importance value of 263.4
(table 1]. There were approximately 96 trees per
acre with a canopy volume of 243,500 cubic feet
per acre. This amounted to a reduction of 28.9%
in the available foliage. The total basal area for
all tree species was 101.5 square feet per acre.

Irregular Strip Shelterwood Plot

The irregular strip shelterwood cut plot is
located on watershed 14, approximately 42 miles
southeast of Flagstaff, at an elevation of 7,050
feet. The study area is on a south-facing slope of
about 9°, in the southeast corner of the 546-acre
watershed.

The objective of the treatment was to increase
water yield while at the same time providing good
timber production and pleasing esthetics (Brown
et al. 1974]. Clearcut strips were designed pri-
marily to increase streamflow. The alternative
"leave" strips were thinned to improve production.

The pattern was one of alternate cut and leave
strips. The cut and leave strips averaged 60 and
120 feet in width, respectively. Irregular-shaped
spacers of uncut trees, 50 to 70 feet long, at inter-
vals of about 400 feet, were left in the cut strips to
break up the visual continuity. Most of the Gambel
oak were left in the cut strips; where there was
enough oak to break up the continuity of the strips
it was not necessary to use spacers. Width of the
clearcut area within any strip varied as much as
50% (i.e., 120 ± 60 feet] to provide an estheti-
cally pleasing, irregular pattern of elongated
openings.

The treatment was completed in spring 1970.
Ponderosa pine was the dominant tree species
with an importance value of 228.2 (table 1]. There
were approximately 74 trees per acre with a
canopy volume of 92,700 cubic feet per acre and a
total basal area of 54 square feet per acre.

Severely Thinned Plot

The severely thinned plot is located on water-
shed 17, approximately 27 miles south of Flagstaff
at an elevation of 6,860 feet. The study area is on

^Personal communication with Fred Larson, Researcli
Forester, USDA Forest Service, Flagstaff, Ariz.

2

Table 1.— Composition of trees on all forested study areas

Species Relative

Relative

Relative

Importance

Absolute

Total foliage

density

dominance frequency

value

density

volume

[perceni)

(percent)

(percent)

(inoex)

{Trees per acre)

{11 /acrej

Control

1 luci uod ^Jiiic; s/U. 1

OO. f

/ /.U

o'XA. Qnn
^o^,yuu

<■> nr\ \r\r\ 1 o Q A

OdllliJcl UdK 0.*f

8.3

19.3

OD.U

OB 7nn
^o, / UU

Alligator juniper 1.5

6.0

3.7

11.2

4

13,200

^ i t\/i 1 1 1 f 1 1 1 1\/ ^iit
oi 1 vlou 1 lu 1 cii 1 y oui

rUllUcrUba piilc y 1 .0

7Q A

OO

ono i^nn

VJIctlllUcI UdtS O.U

7.5

20.6

OO.D

Q
O

4 1 ,uuu

Irregular strip shelterwood

1 UllUCIUOCt pilIC f s7. 1

o2.0

67.1

oy

CO nnn

15.7

31.5

ft7 R

1 /I
1 4

'3n inn

Alligator juniper 0.5

2.3

1.4

4.2

1

400

Severely thinned

Ponderosa 86.8

91.9

74.3

253.0

24

48,500

Gannbel oak 13.2

8.1

25.7

47.0

4

8,600

Table 2.— Tree size distribution on all forested study areas (trees per acre)

Over

Area

3-6 inches
d.b.h.

Percent
control

6-9 inches
d.b.h.

Percent
control

9 inches
d.b.h.

Percent
control

Absolute
density

Percent
control

Control

135.5

68.1

58.4

262

Silvlculturally
cut

Irregular strip
shelterwood
Severely

36.7

27.1

15.5

22.8

43.8

75.0

96

36.6

24.9
6.2

18.4
4.6

17.2
9.0

25.3
13.2

31.9
12.8

54.6
21.9

74
28

28.2
10.7

thinned

a southwest-facing slope of about 8°, in the south-
west corner of the 121-acre watershed.

Treatment was intended to provide a reason-
able opportunity for increased water yield while
leaving a lightly stocked timber stand that could
be subjected to even-aged management (Brown et
al. 1974). Slash was piled in strategically arranged
windrows. Windrows were piled as high and nar-
row as possible to maximize snow trapping and
retention. Windrows were arranged with 30-foot
breaks at intervals of 200 feet or less to reduce
possible fire spread.

Treatment was completed in spring 1969. Pon-
derosa pine was the dominant tree species with
an importance value of 253 (table 1). There were
approximately 28 trees per acre with a canopy
volume of 57,100 cubic feet per acre and a total
basal area of 22.2 square feet per acre.

Clearcut Study Plot

The clearcut plot is located on watershed 12,
approximately 43 miles southeast of Flagstaff at

an elevation of 7,040 feet. The study area is on a
southwest-facing slope of about 10°, in the south-
east corner of the 200-acre watershed.

The treatment was designed to test the effects
of clearcutting all the woody vegetation on the
watershed and windrowing the resultant slash
(Brown et al. 1974). All wood products that could
be sold were removed from the watershed. The
remaining slash and debris were machine wind-
rowed in such a way as to trap and retain snow,
reduce evapotranspiration losses, and increase
the drainage efficiency of the watershed. In areas
of heavy slash, the windrows were at least 5 feet
high and were spaced about 100 feet apart. In
areas of lighter slash, the windrows were spaced
further apart to achieve the minimum height.
Windrows were placed in either an east-west or
northeast-southwest direction.

The treatment was completed in spring 1967.
Since that time, there has been considerable
shrubby growth by Gambel oak next to the slash
windrows.

3

Methods and Materials

Tree measurements were made on all plots ex-
cept the clearcut site. The plotless point-quarter
method (Cottam and Curtis 1956) was used to sam-
ple trees with a d.b.h. of 3 inches or larger. A grid
composed of 104 points (416 trees) was sampled
on each plot. These data were then analyzed
using the standard formulas of Cottam and Curtis
(1956) to obtain the following: absolute density,
relative dominance, relative frequency, relative
density, and importance value. The following ad-
ditional data were also recorded for the trees
sampled at each point: total tree height, height
from the ground to the lowest live limb, and outer
crown diameter at the lowest live limb. Tree
crowns were classified as conical, cylindrical, or
hemispherical. Tree crown data were then ana-
lyzed and expressed in terms of foliage (or crown)
volume.

Breeding bird counts were made during the
1974 and 1975 breeding seasons using the spot-
map method described by Kendeigh (1944). Ten
censuses were taken each year on each study site.
Population densities were averaged for the 2-year
period to eliminate effects of climatic fluctua-
tions.

Species diversity (H') (Shannon and Weaver
1948) was calculated on the mean densities for all
plots by the following formula:

H' = -IF. In (Pi )

where F- is the proportion of a given bird species
present. Evenness (E) was calculated by the fol-
lowing:

E = H'/ln S

where S is the number of species present (rich-
ness).

Bird Community Composition

The effects of habitat alteration on species
composition and densities have been examined in
areas where the habitat was altered by logging
(Hagar 1960; Kilgore 1971; Lack 1933, 1939; Lack
and Lack 1951), burning (Blackford 1955, Bock
and Lynch 1970, Marshall 1957) and other means
(Karr 1968, Yeager 1955). The effects of the vari-
ous treatments on the breeding bird communities
of the clearcut, severely thinned, irregular strip
shelterwood, and silviculturally cut plots were
pronounced (table 3). The openings made by cut-
ting led to an increase of those species which
appear to require a more open habitat (rock wren,
robin, western wood pewee, and yellow-rumped
warbler) and a decrease or elimination of those

species which appear to require dense foliage
(western flycatcher, red-faced warbler, hermit
thrush, black-headed grosbeak, and pygmy nut-
hatch). Cutting the irregular strip shelterwood
and silviculturally cut sites increased population
density and slightly changed species composition
when compared to the control site.

These results tend to contradict the idea that
the greatest bird species diversity and population
densities are in the climax forest (Johnston and
Odum 1956, Karr 1968, Kendeigh 1948, Shugart
and James 1973). Studies have shown that popula-
tion densities were highest in intermediate stands
(Bond 1957, Kendeigh 1946). Karr (1968) noted a
decline in species richness and density in the last
forest stage in Illinois. The impact of fire on vege-
tation and, in turn, on breeding bird populations
was studied in chaparral (Lawrence 1966), in
pine-oak woodland (Marshall 1963), and in pon-
derosa pine (Lowe et al. 1978). The more open
habitat produced by burning in both vegetative
types led to an increase in numbers of species and
density with some changes in species composition.
A significant increase in bird species richness
and abundance followed logging in the Douglas-fir
region of northwestern California (Hagar 1960)
and in a giant sequoia forest of northern Califor-
nia (Kilgore 1971). Similarly, the cutting and/or
logging of the habitat in the ponderosa pine forest
increased bird population densities and altered
species composition.

Bird pairs on all the treated plots except the
clearcut site were more highly packed (the aver-
age amount of foliage volume per average pair of
birds was smaller) than bird pairs on the control
plot. Pair packing on the severely thinned plot
was 67,800 cubic feet per pair, whereas on the
irregular strip shelterwood plot there was 64,200
cubic feet of foliage per pair. In contrast, on the
control site, there was 251,400 cubic feet of foli-
age per pair, and on the silviculturally cut site,
there was 140,300 cubic feet of foliage per pair.
On the severely thinned plot, bird pair packing
was higher than on the control site because of the
great reduction in foliage which was not accom-
panied by a proportional decrease in population
density. In fact, on the irregular strip shelterwood
plot, not only was the amount of available foliage
reduced by two-thirds, but the densities increased
as well, resulting in much higher pair packing.
Birds on both these heavily treated watersheds
might come into greater potential competition
with each other.

Bird pairs on both the severely thinned and the
irregular strip shelterwood plots were equally
packed, suggesting that approximately 65,000
cubic feet of foliage is the minimum required by a
given pair. If the bird community on the control

4

Table 3.— Breeding bird composition of the study areas (2 year average pairs per 40 ha)

Species

Control

Silviculturally
cut

Irregular
strip

Severely
thinned

Clearcu

IVlUUIIlCllil L^IMOIaCIUCC \\^LJ }

^ 3

4.5

0.8

ryyiiiy iiuuiciiom \\ju j

1fi

6.0

1.9

nuuoc wicii )

3.0

.^olitarv virpo ^FN^

3.0

6.0

9.0

6.0

YpI low-ri 1 m npd warhlpr ^FN^

1.5

12.0

3.0

1.5

Grace's warbler (FN)

9.0

19.1

14.3

6.8

....

Red-faced warbler (GN)

3.0

\A/pc + prn tananpr /FM\
VVcoLcill Ldilctyt;! ^ilN^

1 S

1 .o

3 0

Hpnatip t^in^^npr /PM\
nc|JaUL« Ldiidyd y n 1 N ^

1.5

64 5

44.3

17.0

Rnhin

3 0

5.3

3.8

0.5

Ri if ni iq-qiHpH tnvAvhpP /PM^

6.9

6 0

9.0

4.5

Mourning dove (FN)

3.0

1.5

5.3

....

Rock wren (GN)

7.2

4.5

5.0

Wormit thriiQh ^f^M^

1 Q

0 4

r^ra\/ hpaHoH iiinpo /r^M\
va 1 dy "1 icdUfcJu juiiuu ^oin^

18 8

1 1 .3

6.4

1.8

1 1 i Iri npn^ itv

22.2

29.7

32.8

24.5

14.2

W ck m mprorc a n H t pa rp TQ

f^nmmnn flipkpr /f^D^

3.0

3.0

3.4

3.0

0.8

ndiry wutjupcurxci \\^u}

\Jm\J

4.5

2.3

Acorn woodpecker (CD)

3.0

....

White-breasted nuthatch (CD)

6.8

11.3

10.5

7.5

Qfpllpr'q ipv /FN\

oidici o Jdy ^niN/

7.5

4.5

5.3

5.3

Rl^^pk-hpadpH nrn<^hpflk ^FN^

3.3

3.0

1.5

Cni\\\r\ npn ^ i tv

23.6

24.8

25.2

21.1

0.8

\A/pctprn flvp^itrhpr ^C^D^

4.9

4.2

\A/ potprn \A/ond np\iUPP /FM^

2.3

9.0

3.0

— .

Ody o pilUtJUt; ^1 IN^

1.5

V lUf t; l-y 1 1 1 bWdllUW \\^U)

8 3

3.0

Western bluebird (CD)

4.5

7.9

13.5

5.8

....

Mountain bluebird (FN)

0.5

Rroad-tailpH hii m m innhirH /FM^
DiUdU idiiC'Vj iiuiiiiniiiyuiiu ^niN^

4.1

12.0

9.8

OUI 1 1 1 1 lU 1 1 1 1 1 y 1 1 U Id W r\

1 S

3.0

3.0

(^iiilH r^pnQitx/

ouiiu ut^iioiiy

?fi 7

28.3

42.0

21.6

0.5

Nesting guilds

1.3

L/dvliy dilU UcpicbolUn vV-'l-'/

i^^n 1

OU. 1

48 4

24.3

roiiage nesiers ^riN)

O ( .o

fi7 1

74 4

46.0

12.4

orouna nesiers ^oiNj

90 7

91 5

13.9

1.8

Total density

110.1

147.3

144.3

84.2

15.5

Diversity (H')

2.83

2.80

2.94

2.81

1.35

Evenness

0.93

0.91

0.94

0.96

0.69

Richness

21

22

23

19

7

plot was as highly packed as that on the severely
thinned plot, it should support approximately 425
pairs per 100 acres. Since foliage volume does not
appear to be the limiting factor, then factors such
as territoriality, food supply, and lack of openings
or other habitat configurations may limit bird
populations.

The foraging and nesting guilds v^ere variously
affected by forest cutting and logging (table 3].
The pickers and gleaners and the ground feeders
increased in population density on the silvicul-

turally cut and irregular strip shelterwood plots.
The aerial feeders increased by 57% on the ir-
regular strip shelterv^ood plot in response to the
open strip areas, whereas the hammerers and
tearers remained relatively stable on all the
forested watersheds. All the foraging guilds,
except for the ground feeders, were virtually
eliminated from the clearcut plot. The cavity and
depression nesters and ground nesters greatly
decreased in population density on the severely
thinned plot, whereas the foliage nesters greatly

5

increased in population density on the silvicul-
turally cut and irregular strip shelterwood plots.
Interestingly, the majority of the ground feeders
on the clearcut plot were also foliage nesters.
These birds used the Gambel oak saplings that
were growing throughout the area for nesting
substrate. The cavity nesters which also use
cavities for roosting comprised between 60% and
94% of the wintering bird community (Szaro
1976).

Eleven species (solitary vireo, pygmy nuthatch,
Grace's warbler, white-breasted nuthatch, com-
mon flicker, hairy woodpecker, steller's jay, gray-
headed junco, chipping sparrow, broad-tailed
hummingbird, and western bluebird] were pres-
ent on all the forested plots during the study. The
common nighthawk was observed on all areas in
1975 but was not found on the silviculturally cut
plot in 1974. Several species increased their den-
sity in their typical habitat (the foliage) on the
treated plots. Of the species found on all the for-
ested plots, eight (all but the common flicker,
hairy woodpecker, and pygmy nuthatch) had their
highest population densities on treated plots indi-
cating density increases in response to openness.
In contrast, population densities of five species
(red-faced warbler, pygmy nuthatch, western fly-
catcher, violet-green swallow, and black-headed
grosbeak) were significantly reduced with heavy
alteration of the habitat. The rock wren, robin,
and western wood pewee bred only on treated
plots, whereas the acorn woodpecker was found
exclusively on the severely thinned plot. These
species probably required the increased openness
of the habitat. The common flicker, hairy wood-
pecker, and steller's jay maintained relatively
stable densities on both the control and treated
plots.

Bird species diversity and species richness in
the ponderosa pine forest were not significantly
affected (based on an importance criterion of at
least a 15% difference) by treatment except on
the clearcut plot. Bird population densities were
significantly increased by forest cutting on the
silviculturally cut and irregular strip shelterwood
plots and were significantly decreased on the
severely thinned and clearcut plots. For a more
detailed description of treatment and climatic ef-
fects see Szaro (1976).

Literature Cited

Balda, Russell P. 1969. Foliage use by birds of the
oak-juniper woodland and ponderosa pine
forest in southeastern Arizona. Condor
71:399-412.

Balda, Russell P. 1975. The relationship of second-
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Beecher, William J. 1942. Nesting birds and the
vegetative substrate. Chicago Ornithol. Soc,
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Blackford, John L. 1955. Woodpecker concentra-
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Bock, Carl E., and James F. Lynch. 1970. Breeding
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Bond, Richard R. 1957. Ecological distribution of
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Brown, Harry E., Malchus B. Baker, Jr., James J.
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Hagar, Donald C. 1960. The interrelation of log-
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Karr, James R. 1968. Habitat and avian diversity
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Kendeigh, S. Charles 1944. Measurement of bird
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6

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7

Appendix

Bird Common and Scientific Names

Common name Scientific name

Mourning dove

Zenaida macroura

Cnmrnnn niffhthawk

ChordeiJes minor

Rrnpid-triilprl hiimminffhird

f 1 t wClLX LCIXXO^^ XX LXXXXXXXXXXg LJXX

.SpJnsnhnrns nlnfvrprcAifi

C^X Cl O IL/X L C/X LX O XyXdl'V OwX V^LXlJ

r^nrnmnn fliplcpr

vjL/lllilil-'ll XXX^-jJN.C' A

CnlriTitp'^ nurnfiis rnfpr

\_/X cx !_/ L O CI. t-i. X CX 1/ CX L7 Cv CX 1 Cr X

Acorn woodDGckGr

MeJanerpes /ormicivorous

Hairy woodpecker

Picoides villosus

Say's phoebe

Sayornis saya

Western flycatcher

Empidonax difficilis

Western wood newee

Contopus sordiduJus

Vi nl pt-prppn ^wpi 11 nw

VXVJXOl gXOO XX iD V V cx Lxyj V V

Tnrhvrinptn thnlri'i'iinn

X Ci. C/X LV C/XXIO L Ci I/XL CXX CI O OXX L \JL

Steller's jay

Cyanocitta stelleri

VToiintain chickadee

X V X \j Lxxx I. n XXX XXX wxv cx d. O W

Pnrijs pombeii

X cx X CA. £^ CXX X L l_/ C/ XX

Whitp-hreasted nuthatch

VV XXXLO UX O cx LJ L O VJ. XX U. LXXU I. VjXX

fiittn rnrnlinpnsis

l./Xl'LCX C/CXX C/XXX L Cf X L L7X

Pvffmv nnthatch

X y QXXXy XX LX LXXf_X LwXX

.Siftn nvQwciPci

C^X L L CX Xy y £1 XXL CX Cy CX

FTousp wren

X X\-f XJLiJKj VV X C/XX

Trnp/ndvtp*? npdnn

X X C/ £1 X C CX y L Cr O CX Cf CX C/X L

Rock wren

SaJpinctes obsoietus

American robin

Turdus migratorius

Hermit thrush

Catharus guttatus

Western bluebird

Sialia mexicana

Mountain bluebird

Sialia currucoides

Solitary vireo

Vireo soJitarius

Yellow-rumped warbler

Dendroica coronata auduboni

Grace's warbler

DendroicQ graciae

Red-faced warbler

Cardellina rubri/rons

Western tanager

Piranga ludoviciana

Hepatic tanager

Piranga flava

Black-headed grosbeak

Pheucticus melanocephalus

Gray-headed junco

Junco caniceps

Rufous-sided towhee

Pipilo erythrophthalmus

Chipping sparrow

Spizella passerina

Tree Common and Scientific Names

Common name

Scientific name

Ponderosa pine

Pinus ponderosa

Alligator juniper

Juniperus deppeana

Gambel oak

Quercus gambellii

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