Bulletin

7 pee”. ISSN 0038-3872

SOU RHEIN exAeIEFORNIA ACADEMY OF SCIENCES

BULLETIN

Volume 94 Number 2

BCAS-A94(2) 131-178 (1995) AUGUST 1995

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Bull. Southern California Acad. Sci.
94(2), 1995, pp. 131-148
© Southern California Academy of Sciences, 1995

Distribution, Habitat, and Current Status of the San Pedro
Martir Rainbow Trout, Oncorhynchus mykiss nelsoni (Evermann)

Gorgonio Ruiz-Campos! and Edwin P. Pister?

1Facultad de Ciencias, Universidad Aut6noma de Baja California
Apdo. Postal 1653, Ensenada, Baja California, 22800, México
2Desert Fishes Council, P.O. Box 337, Bishop, California 93515, USA

Abstract. —The distribution, habitat, and current status of Oncorhynchus mykiss
nelsoni (Evermann) were evaluated in the two main drainages of the western slope
of the Sierra San Pedro Martir (Santo Domingo and San Rafael), Baja California,
Mexico. The known localities of distribution (type locality and transplant sites),
as well as other previously unsurveyed localities, were monitored during a period
of seven years (January 1987 to March 1994) to document occurrence of the trout
and to evaluate their habitat characteristics. The conservation status for this
subspecies was determined as stable in the two main drainages, which range in
altitude from 540 to 2030 m above sea level. Recommendations for future con-
servation and management of the trout and their habitats are provided.

Resumen.—La distribucion, habitat, y estatus actual de Oncorhynchus mykiss
nelsoni (Evermann) fueron evaluados en los dos sistemas hidrologicos principales
de la pendiente occidental de la Sierra San Pedro Martir (Santo Domingo y San
Rafael), Baja California, México. Las localidades conocidas de distribucion (lo-
calidad tipo y sitios de introduccion), ademas de otras previamente no investi-
gadas, fueron muestreadas durante un periodo de siete anos (Enero 1987 a Marzo
1994) para documentar la ocurrencia de la trucha y para evaluar sus caracteristicas
de habitat. Su estatus de conservacion fue determinado como estable para los dos
sistemas hidrologicos principales, a través de un rango altitudinal de 540 a 2030
msnm. Recomendaciones para la futura conservacion y manejo de esta trucha y
de sus habitat son aqui establecidas.

The San Pedro Martir rainbow trout, Oncorhynchus mykiss nelsoni (Evermann,
1908), also called Baja trout or Nelson’s trout, is endemic to the western slope of
the Sierra San Pedro Martir (SSPM), Baja California, México (Miller 1950;
MacCrimmon 1971; Smith 1984; Ruiz-Campos 1993). Its conservation status is
categorized as “‘special concern” (Williams et al. 1989) or “rare” (Secretaria de
Desarrollo Social 1994) due to its restricted distribution and low abundance. Both
statuses were based mainly on old collecting records in the type locality of Rio
Santo Domingo [=Rio San Ramon or Arroyo San Antonio de Murillos] near
Rancho San Antonio (cf., Evermann 1908; Snyder 1926; Needham 1938, 1955;
Needham and Gard 1959), and strengthened by more recent observations of
potential threats to its habitat by changes in land use practices (increased livestock
grazing, logging, etc.).

131

132 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES

The first record of this trout was based on four specimens collected by VE. Heller
in June 1902 in the Rio Santo Domingo near Rancho San Antonio (Meek 1904).
Subsequently, a second collection of nine specimens from the same locality was
made on July 30, 1905 by E. W. Nelson (Nelson 1921). These specimens were
given to Dr. B. W. Evermann, who described them as a new species, Salmo nelsoni
(Evermann 1908). In the same locality C. C. Lamb and A. E. Borell collected
approximately 150 trout on April 24-27, 1925. Snyder (1926) concluded that
Nelson’s trout closely resembled the coastal rainbow trout Salmo irideus (=On-
corhynchus mykiss irideus). The peculiar traits of Nelson’s trout such as the wild
and non-migratory nature, plus its temperature tolerance, encouraged P. R. Need-
ham and collaborators to make three collecting trips to Rancho San Antonio
between 1936 and 1938 in order to obtain a trout brood stock for hatchery culture
and for planting in California and Oregon waters (Needham 1938, 1955; Needham
and Gard 1959). During the first trip (May 17, 1936) 30 trout were caught and
preserved for study. On the second trip (May 23, 1937) 50 yearlings were captured
and transported alive to the Forest Home State Fish Hatchery near Redlands,
California. Needham’s final collecting trip was made on May 14, 1938 and yielded
325 fingerlings ranging from two to three inches in total length (TL). These fish
were sent to the U.S. Fisheries Station at Clackamas, Oregon. However, both
introductions failed. The first failure occurred in California in March 1938 when
a torrent of water, rocks, and debris wiped out the entire hatchery and its ponds.
The second happened in Oregon in 1940 when about forty trout between 254 and
356 mm TL died due to problems in the water supply to the pond where they
were held (Needham 1955).

The original natural distribution of O. m. nelsoni was a 24 km section of the
Rio Santo Domingo from above Rancho San Antonio to the base ofa high waterfall
that blocks upstream migration (Evermann 1908; Nelson 1921; Snyder 1926;
Needham 1938; Smith 1991). In addition, Needham (1938) reported the occur-
rence of this trout in the Arroyo La Zanja (not Arroyo Santa Cruz as was originally
reported), a small tributary of the Rio Santo Domingo near Rancho San Antonio.

The ancestor of this trout was probably an anadromous coastal rainbow trout
(steelhead), coming from Southern California coastal streams, which passed south-
ward through the sea from stream to stream as far as the Rio Santo Domingo
during a period when climatic conditions were favorable (Evermann 1908; Snyder
1926; Needham 1938; Hubbs 1946; Smith 1991). The trout of the Rio Santo
Domingo have presumably been isolated from contact with other trout of the
rainbow series for a long time, perhaps as much as 10,000 years (Dr. Robert R.
Miller’s letter dated on September 17, 1977, addressed to Mr. Carlos Yrureta-
goyena). In an electrophoretic study, Berg (1987) found that Nelson’s trout possess
a unique allele of creatine kinase, Ck-2 (115), which is not found in other trout
of the coastal rainbow series. In addition, Nelson’s trout has a strong genetic
affinity to the coastal rainbow trout from Southern California.

Several transplants of Nelson’s trout into other streams on the western slope
of the SSPM have been reported: La Mision (~San Pedro Martir), La Grulla, La
Zanja, El Potrero, and San Rafael (Charles E. Utt’s letter dated June 15, 1945,
addressed to Dr. Carl L. Hubbs). However, the establishment of trout in all of
these localities had not been confirmed before the current study.

This paper evaluates the current distribution and conservation status of O. m.

TROUT OF THE SIERRA SAN PEDRO MARTIR 133

nelsoni on the western slopes of SSPM. Research was conducted during 1987 to
1994 in order to obtain information for its future conservation and management.

Study Area

Geology.—The SSPM is the most elevated of several batholithic terrains that
comprise the Peninsular Ranges of southern California and Baja California. The
Picacho del Diablo is the highest peak in the SSPM (ca. 3095 m above sea level).
The range is bounded on the east by the great escarpment of the SSPM fault and
by the strike-slip Agua Blanca fault to the north (O’Connor and Chase 1989). The
summit plateau slopes to the south and west, and the tilted surfaces are broken
by one or two faults associated with approximately 1000 m of relief (Woodford
and Harris 1938). The geologic formations of the SSPM are similar to the Sierra
Nevada of the United States, with outcrop areas composed of Mesozoic batholithic
rocks having metasedimentary wall rocks, and igneous rocks primarily constituted
by tonalites and granodiorites (Gastil et al. 1975).

Hydrology. —Three main river systems drain the SSPM: Rio San Rafael to the
northwest and the rios San Telmo and Santo Domingo to the southwest (Yrur-
etagoyena-Ugalde 1992). The annual discharge of the Rio Santo Domingo during
dry years between 1950 and 1977 did not exceed 10 million m?/y, but in the
period between 1978 and 1985 it increased to 180 million m?/y (Secretaria de
Agricultura y Recursos Hidratlicos 1983). The streams of the SSPM have peren-
nial flows in their headwaters but are intermittent in their middle and lower courses
during extremely dry conditions (Tamayo and West 1964). The mouths of all
these streams are blocked from the ocean by the formation of sandbars, except
during extreme flooding events after storms (Tamayo 1962).

Riparian vegetation. — Three zones of vegetation are found along streams in the
SSPM, which are similar to those described for the coastal streams of Southern
California (Faber et al. 1989). First is the active zone, which is inundated during
winter rains and has a variable and unstable morphology. Arroyo Willow (Salix
lasiolepis), Red Willow (S. laevigata) and Fremont Cottonwood (Populus fre-
montii) are representative. Second is the border zone, that is less subject to dis-
ruption but has a reliable water supply. This zone is occupied by larger trees of
willow, cottonwood, and Western Sycamore (Platanus racemosa). Finally is the
outer zone, which is occasionally affected by flooding events and is occupied by
Coast Live Oak (Quercus agrifolia) and Western Sycamore.

Aquatic macrophytes are uncommon in the streams of the SSPM (Delgadillo-
Rodriguez 1992) but may be found in some large deep pools. Emergent plants
such as Southern Cattail (Typha domingensis) and Water Cress (Rorippa nastur-
tium-aquaticum); rooted floating plants (e.g., Floating-leaved Pondweed, Pota-
mogeton natans); free floating plants such as duckweeds (Lemna gibba and L.
trisulca); and submerged plants (Berula erecta, Ceratophyllum demersum, Ra-
nunculus aquatilus, and R. hydrocharoides) are typical.

Methods

Forty-nine collecting trips were carried out to various localities on the western
slopes of the Sierra San Pedro Martir (Fig. 1) from January 1987 to March 1994.
Special attention was given to those localities where trout had been previously
recorded or transplanted. The number of collecting trips to each locality, indicated

134 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES

(Dyvoiince
FAROUE WACIOWAL
SAW PEDRO WARTIR

ft ital

Fig. 1. Location of collecting stations in the Sierra San Pedro Martir, Baja California, México.
Exact locations and elevations of stations are given in Appendix 1.

in parentheses, was dependent on its accessibility: Arroyo San Rafael between
Rancho Mike’s Sky and Rancho Garet (27): Arroyo San Rafael at its mouth (1):
Arroyo San Telmo between San Telmo and Rancho San José (1): Arroyo El Potrero
at Rancho El] Potrero (2); Arroyo Santa Cruz at Rancho Santa Cruz (3); Arroyo
Santa Cruz at its confluence with Arroyo Valladares (2): Arroyo La Grulla at La
Grulla meadow (4); Arroyo San Antonio de Murillos at Rancho San Antonio (3);
Arroyo La Zanja at its confluence with Arroyo San Antonio (3); Arroyo Vallecitos
at Vallecitos meadow (1); and Arroyo Valladares between the Rancho [Viejo]
Valladares and the Rancho [Nuevo] Valladares (2).

Place names and geographic features varied among available maps. We used
1:50,000 topographic maps published by the Comision de Estudios del Territorio
Nacional (CETENAL) as the authority. Where a particular physical feature or
locality received other names in the literature we provide the equivalent.

Trout were collected using AC electrofishing equipment (120 V) along 200 m
stream sections. At remote localities with difficult access (e.g.. arroyos La Grulla,
La Zanja, and San Antonio de Murillos), trout were captured by hook and line
and dip nets. Trout were measured in the field (standard length [SL] in millimeters)
and weighed to the nearest gram. Some specimens were preserved in 10% formalin
buffered with sodium borate. Five scales per specimen were selected for age
determination (Ruiz-Campos 1993). Most of the trout preserved were utilized for
life history and population ecology analyses (Ruiz-Campos 1993), and other spec-
imens were deposited in the Colecci6n de Vertebrados (Seccion Peces) at the
Facultad de Ciencias. Universidad Autonoma de Baja California, Ensenada.

TROUT OF THE SIERRA SAN PEDRO MARTIR 135

To describe stream morphology and hydrology, we selected three sampling
points along each stream surveyed, including all available habitat types such as
pools, riffles, etc. These sampling points were marked as reference positions for
future measurements. The stream cross-section measurements were made along
a line perpendicular to the streambank, considering the following features: (1)
stream width, (2) velocity of water, measured with a current meter (Swoffer model
2100), and (3) stream depth (Duff and Cooper 1978; Platts et al. 1983). Both
velocity and depth were measured at 50 cm-intervals.

Discharge was calculated in m3Zs for each stream cross-section using the fol-
lowing equation (Hynes 1970): Q = [W x D xX V] (0.9), where: Q = rate of
discharge; W = average stream width; D = average stream depth; V = average
water velocity; and 0.9 is the constant for friction on sandy bottoms.

Historical data on trout length reported in total length (TL) were transformed
to SL by dividing TL by 1.145 (Carlander 1969).

Results and Discussion

Oncorhynchus mykiss nelsoni is now distributed in two main drainages: Rio
Santo Domingo (arroyos San Antonio de Murillos, La Zanja, El Potrero, La Grulla,
and La Mision) and Rio San Rafael (Arroyo San Rafael), within an altitude range
of 540 m (Rancho San Antonio) to 2030 m (La Grulla) (Fig. 1).

Rio Santo Domingo Drainage

The Rio Santo Domingo drainage has seven major tributaries (arroyos La
Grulla, El Potrero, Valladares, Santa Cruz, La Zanja, La Mision and San Antonio;
Fig. 1). The Rio Santo Domingo is called various names through its course towards
the Pacific coast. At its headwater it is known as the Arroyo San Antonio, but
after its junction with the Arroyo La Zanja it is called Arroyo San Antonio de
Murillos. Finally, it is called the Rio Santo Domingo after its confluence with
Arroyo Valladares. :

Arroyo San Antonio de Murillos.—This second order stream of the Rio Santo
Domingo is the type locality for O. m. nelsoni. The sampled section of this stream
was from its confluence with Arroyo La Zanja to in front of the Rancho San
Antonio (Fig. 2A).

Historical records: Arroyo San Antonio de Murillos was first visited by E. Heller
(June 1902) and later by E. W. Nelson (July 30, 1905), who both made collections
of trout. During Nelson’s visit in 1905, stream characteristics included a mean
width of 3.0 m, a maximum depth of 25.4 cm in the middle of the channel, and
a current of 2.68 m/s. Subsequent collections in this same locality were made by
P. R. Needham and collaborators on May 17, 1936, May 23, 1937 (Needham
1938), and May 14, 1938 (Needham 1955; Needham and Gard 1959). In May
of 1936, young-of-the-year (YOY or age-0) from 27.7-66.6 mm, were abundant.
However, specimens between 88.7 and 155.3 mm were relatively scarce. Stream

—
Fig. 2. (A) Arroyo San Antonio de Murillos ca. Rancho San Antonio. (B) Arroyo La Zanja ca.
confluence with the Arroyo San Antonio.

Fig. 3. Specimens of Oncorhynchus mykiss nelsoni. (A) From Arroyo San Antonio de Murillos
(105 mm SL). (B) From Arroyo La Grulla (181 mm SL).

136 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES

TROUT OF THE SIERRA SAN PEDRO MARTIR 307)

138 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES

TROUT OF THE SIERRA SAN PEDRO MARTIR 139

width was 3.6 to 4.5 m with a discharge of 0.113 m?/s. In May of 1937, only two
YOY were observed and individuals 110.9 to 199.6 mm were fairly common.
Discharge was 0.170 m?/s. Low densities of trout were noted in this same locality
during 1904 (Nelson 1921) and in the winter of 1936-1937 (Needham 1938).
Both authors speculated that this was caused by severe floods that strongly alter
stream morphology and eliminate most riparian vegetation. Almost a half century
later (October 28, 1983), E. P. Pister collected 19 trout 115 to 205 mm by hook
and line. At that time, the stream had large, deep pools and heavy riparian
vegetation.

Current status: We visited and sampled this locality again on April 26-27, 1991,
June 29-30, 1991, and June 17-18, 1992. Predominant riparian vegetation is
Arroyo Willow, Coast Live Oak, Western Sycamore, Fremont Cottonwood, and
Mule Fat (Baccharis salicifolia). Vegetative cover was scarce and discontinuous,
probably resulting from high erosion and siltation caused by flooding during the
winter of 1991-1992. Morphological and flow characteristics of the stream ex-
hibited little variation among the sampling dates. Ranges registered were as fol-
lows: discharge, 0.159 to 0.171 m?/s; width, 4.86 to 5.82 m; stream velocity,
0.337 to 0.380 m/s; and depth, 8.0 to 11.6 cm. In June 1991, eleven trout 85.9
to 152 mm (Fig. 3A) were captured during 3 hours of intensive sampling, mostly
YOY (N = 5). During June 1992, 10 YOY (46 to 60 mm) were captured, and
only one adult specimen was seen in this locality.

Arroyo La Zanja.—The site surveyed (Fig. 2B) was 200 m upstream from the
confluence with the Arroyo San Antonio.

Historical records: Arroyo La Zanja was stocked with trout from Arroyo La
Mision in 1935 and 1936 by E. C. Utt. The number of trout stocked in 1935 is
unknown. However, approximately 16 were stocked in 1936 in a pool of the
Arroyo La Zanja near “Young Ditch” (a mining ditch now abandoned).

Needham (1938) confused this creek with the Arroyo Santa Cruz, a tributary
of the Arroyo Valladares near Rancho Valladares. His collections were taken from
Arroyo La Zanja because at that time fish were scarce in Arroyo San Antonio de
Murillos due to altered morphology after a flooding event. Discharge in the Arroyo
La Zanja was ca. 0.037 m?/s (May 17, 1936) and 0.042 m?/s (May 23, 1937).

Current status: Arroyo La Zanja was sampled on June 18, 1992, at which time
the collecting site consisted of many small pools and long riffles averaging 2.5 m
in width and 25 cm in depth. Moderate riparian vegetative cover was represented
primarily by Arroyo Willow and Mule Fat. Four YOY (55 to 75 mm) were
collected along a 100 m stream transect. No adult trout were captured or seen.

Arroyo El Potrero.—This stream (Fig. 4A) represents the middle tributary of
the Arroyo Valladares with its confluence near Rancho El Potrero.

Historical records: Trout brought from the Arroyo La Mision were stocked into
Arroyo El Potrero by C. E. Utt during 1937 and 1941. There is no previous
information on habitat characteristics for this locality.

Current status: Arroyo El Potrero was visited three times in 1989, and habitat
was evaluated, on March 11, June 17, and November 26; but only twice were

—_—
Fig. 4. (A) Arroyo El Potrero ca. Rancho El Potrero. (B) Arroyo La Grulla at La Grulla meadow.

140 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES

trout collected. In March, we collected only one trout, a 3-year-old adult (166
mm). However, in June, six specimens 53.9 to 145.1 mm (age, 0 to 2) were
captured. Riparian vegetation was Arroyo Willow, Mule Fat, and Coast Live Oak.
Morphology and stream fiow varied as follows during the three different dates:
width, 1.88 to 4.11 m: depth, 7 to 23 cm; velocity, 0.16 to 0.32 m/s; and flow,
0.050 to 0.142 m?/s.

Arroyo Valladares.—The segment surveyed was from Rancho [Nuevo] Valla-
dares to Rancho [Viejo] Valladares. This stream is a tributary of the Rio Santo
Domingo, with its confluence near Rancho San Juan.

Historical records: No historical information was discovered regarding the oc-
currence or stocking of trout in this locality.

Current status: An electrofishing survey was conducted on June 19, 1992 and
again on March 11, 1994 to investigate the presence of trout in the stream. Three
100 m transects were made between the confluence of the Arroyo Santa Cruz and
the Rancho [Viejo] Valladares (abandoned mines). No trout were seen or collected
during sampling efforts. Morphology and discharge of the stream during June
1992 and March 1994, registered the following average values, respectively: width
(4.52 and 10.06 m), depth (31.6 and 10.2 cm), velocity (0.26 and 0.50 m/s), and
discharge (0.341 and 0.452 m?/s). The site surveyed exhibited only sparse cover
by riparian vegetation (Narrow-leaved Willow [Salix exigua], Mule Fat, Western
Sycamore, and Broom Baccharis [Baccharis sarothroides]). Also noted was the
absence of large and deep pools due to extensive sand accumulation. The stream’s
physical features might explain the absence of trout in this locality.

Arroyo Santa Cruz.—The site surveyed was from the Rancho Santa Cruz to
the confluence with Arroyo Valladares near Rancho [Nuevo] Valladares.

Historical records: There are no historical records concerning the occurrence
or stocking of trout in this stream. It should be noted that this arroyo was confused
with Arroyo La Zanja by Needham (1938).

Current status: Three sampling trips were made in 1989 to the stream near
Rancho Santa Cruz (March 12, June 18, and November 26). No trout were
collected or seen during electrofishing sampling along the stream. During all three
visits, the stream was very narrow and shallow (width, 2.56 to 3.15 m; depth, 4.5
to 5.8 cm). A low flow was also observed (velocity, 0.05 to 0.25 m/s; and discharge,
0.007 to 0.038 m?/s). Riparian vegetation was scattered and in low density and
was represented by Arroyo Willow and Coast Live Oak. The stream was judged
to have a low potential for trout habitat due to the absence of pools and the sparse
cover by riparian vegetation. On March 11, 1994, we made a 100 m stream
transect near the confluence with Arroyo Valladares. No trout were collected or
seen during the sampling. Average stream characteristics in that locality were:
width, 3.25 m; depth, 9.73 cm: velocity, 0.217 m/s; and discharge, 0.054 m?/s.

Arroyo La Grulla (the main stream flowing in La Grulla meadow; Fig. 4B).—
This stream is the most extreme headwater for the Rio Santo Domingo. In La
Grulla meadow there are two small ponds whose outlets discharge into a small
stream that flows to Arroyo La Grulla.

Historical records: During 1935 and 1936, C. E. Utt stocked trout from Arroyo
La Mision into the Arroyo La Grulla. The number of trout stocked in 1935 is
unknown. However, approximately 30 specimens were stocked in 1936. On June
18 and 19, 1984, we captured 32 specimens (65 to 210 mm) in the Arroyo La

TROUT OF THE SIERRA SAN PEDRO MARTIR 141

Grulla near its confluence with the small stream from the meadow. Two additional
trout (215 and 232 mm) were taken from the small stream itself.

This meadow has been used since the time of the missionaries for cattle grazing
during the spring and summer (Nelson 1921; Meling 1991). In July 1905, E. W.
Nelson visited the meadow and noted that the borders of the ponds and all of
the valley bottom had been heavily grazed and trampled.

Current status: This locality was surveyed three times in 1990 (March 23, August
_ 11, and September 30) and one time in 1992 (October 24) in areas where trout
had been previously recorded. The locality of Arroyo La Grulla near its confluence
with the small stream from the meadow was the only site with trout (Fig. 3B).
On March 1990, seven specimens were captured (111 to 181 mm; age, 1 to 3).
During the August 1990 trip, 30 specimens were collected (48.8 to 163.0 mm),
mostly age-1 fish. In September 1990, 11 trout were collected, ranging from 60.4
to 143.5 mm (age, 0 to 2). Four adult trout and several YOY were seen in October
1992. The average morphology and flow characteristics of the stream were variable
among sampling dates: width, 2.08 (March) to 8.90 m (October); depth, 17 (Sep-
tember) to 31 cm (March); velocity, 0.055 (October) to 0.170 m/s (March); and
flow, 0.071 (September) to 0.203 m?/s (August). Small pools with abundant aquatic
macrophytes such as P. natans, C. demersum, and R. nasturtium-aquaticum were
common. Bank vegetation was mainly rushes (Eleocharis sp.), which provided
little cover to the stream. Most cover was supplied by aquatic macrophytes and
in a lesser proportion by Jeffrey Pine (Pinus jeffreyi). High livestock grazing activity
was noted in the meadow, principally along riparian vegetation, with accompa-
nying ground alteration due to trampling.

Arroyo La Mision (near Mision San Pedro Martir). —This stream is also known
as the Arroyo San Pedro Martir or El Horno. It is a tributary of the Arroyo San
Antonio.

Historical records: C. E. Utt stocked the Arroyo La Mision with trout from
Arroyo San Antonio de Murillos in the summer of 1929. This stream is the first
site where Nelson’s trout were introduced. Subsequent visits by Utt between 1934
and 1938, confirmed the establishment of trout in this locality.

Unfortunately, it was not possible to visit this locality during our investigations.
However, in the last five years it has been repeatedly visited by Carlos Lazcano,
a geologist/explorer of the SSPM. He collected various specimens of trout, mainly
adults, by hook and line (Carlos Lazcano, pers. comm.).

Rio San Rafael Drainage

The Rio San Rafael basin is the second most important hydrologic system in
the Sierra San Pedro Martir. This river drains into the Pacific Ocean near Bahia
Colonet [Colnett]. Major tributaries are San Rafael, La Fresa, Vallecitos and Agua
Zarca.

Arroyo San Rafael.—The site studied is located between Rancho Garet also
known as Garate or Las Truchas (Fig. 5A) and Rancho Mike’s Sky (Fig. 5B). Most
sampling for trout was conducted at this locality due to its easy access and high
abundance of fish.

Historical status: The Arroyo San Rafael was stocked twice with trout from
Arroyo La Zanja by C. E. Utt. The first stocking was in 1938 when 16 trout were
released into the stream about a mile below the intake of the Johnston ditch (a

142 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES

Fig. 5. (A) Arroyo San Rafael at Rancho Garet. (B) Arroyo San Rafael at Rancho Mike’s Sky.

hydraulic mining venture). The second trout stocking occurred in the summer of
1939, with 14 trout being released at Rancho Garet.

Also at Arroyo San Rafael. Ruiz-Campos (1989) determined natural repopu-
lation rates in 100 m stream segments through repeated removal by electrofishing.
These results showed high rates of recolonization, mainly by YOY, reaching total
recuperation in less than 10 weeks. Ruiz-Campos and Cota-Serrano (1992) de-
scribed the seasonal diet and feeding ecology of the subspecies at this locality,
which indicated a basically insectivorous diet and a specialized feeding strategy
with regard to type and size of prey consumed.

Current status: During this investigation, 27 trout collecting trips were made
to the Arroyo San Rafael between January 1987 and January 1994 (cf., Appendix
2 for sampling dates) with the main objectives of determining population density
and structure. Observations on life history and habitat requirements have been
recently described by Ruiz-Campos (1993). The average density of trout in 200
m sections along the stream through a seven year period is shown in Fig. 6. Trout
density was relatively stable from January 1987 to August 1989 (ranging from 20
to 98 trout/200 m stream; mean = 48.8; Fig. 6A). However, between August 1989
and March 1993 trout density dropped to 0 to 14 trout/200 m stream (mean =
4.8; Fig. 6B), likely a consequence of the high mortality caused by a forest fire in
August 1989. As a result of this event. the morphology of the stream was strongly
modified due to accumulation of ash and sand, particularly in the large and deep
pools (Fig. 7A). A gradual recovery in trout density was recorded from July 1993
to January 1994 (26 and 86 trout/200 m stream, respectively; Fig. 6B). A similar
case of trout mortality resulting from delayed effects of fire by acute exposure to

TROUT OF THE SIERRA SAN PEDRO MARTIR 143

A NUMBER OF TROUT/200 M STREAM IR NUMBER OF TROUT/200 M STREAM
JANUARY 1987 TO DECEMBER 1989 JANUARY 1991 TO JANUARY 1994

TROUT DENSITY/200 M STREAM TROUT DENSITY/200 M STREAM

a

a
oa
a

>
a

DN
g Quaunuuaannann)

26

20> 14

UULURERRUBERER!)

KNRUVVUUEURRULETALT

g10
2| ) So
2 LLL LPL ES 0 eee gh
JEMAMJJASOND JEMAMJ JASONDUFMAMJ JASOND JFMAMJJASOND JFMAMJJASOND JFMAMJJASOND J
MONTH (1987 to 1989) MONTHS (1991 to 1994)

SAMPLING WITH ELECTROFISHING (120 V ac)

Fig. 6. Trout density per 200 m stream section in the Arroyo San Rafael, Sierra San Pedro Martir,
Baja California, México, from January 1987 to January 1994.

suspended sediment was observed in two streams of northwestern Wyoming
(Bozek and Young 1994).

The length of the trout collected ranged form 34.2 to 240 mm (age, 0 to 4).
Specimens <124 mm were the most abundant.

The stream at the locality of Rancho Mike’s Sky is characterized by many large,
deep (up to 2.0 m) pools alternating with riffle habitat. Dense riparian cover is
provided mainly by Arroyo Willow, Fremont Cottonwood, and Western Syca-
more. From October 1988 to December 1989, the average stream depth and
discharge was variable, registering the highest values in winter (43.9 cm deep and
a discharge of 2.204 m?/s) and the lowest in summer (28.2 cm deep and a discharge
of 0.639 m?/s). In January 1993, the highest rainfall in the last 30 years was
registered in the mediterranean region of Baja California, causing heavy flooding
and strongly modifying stream morphologies (Fig. 7B). Trout density in the Arroyo
San Rafael during that month was low (4 trout/200 m stream), increasing after
one year to as high as 86 trout/200 m stream (Fig. 6B).

On March 12-13, 1994, the lower part of the Arroyo San Rafael was visually
surveyed in an area 500 m upstream from its mouth to verify the possible oc-
currence of trout. None were observed in this segment. Unsuitable habitat con-
ditions were noted, such as high siltation in the stream channel, average depth
less than 30 cm, and lack of arboreal riparian vegetation.

Arroyo Vallecitos.—This stream is a tributary of the Arroyo San Rafael and
reflects the usual highly fluctuating runoff patterns resulting from major discharges
during the winter rainy season.

No records of occurrence or trout introduction at this locality were discovered
in the literature.

On March 20, 1992, we surveyed a 100 m segment of the Arroyo Vallecitos.
No trout were collected or seen. The average morphology and flow of the stream
in the segment surveyed was as follows: 3.81 m wide, 12.0 cm deep, and a flow
rate of 0.259 m?/s.

Another stream surveyed in the SSPM was the Arroyo San Telmo in three
different localities: Rancho Meling [=San José], Ejido Sinaloa, and San Telmo.

No historical information was found concerning the presence or stocking of
trout in this stream.

SOUTHERN CALIFORNIA ACADEMY OF SCIENCES

144

TROUT OF THE SIERRA SAN PEDRO MARTIR 145

During the investigation of these sites no trout were seen, possibly due to poor
habitat quality (e.g., low and variable flow, sparse cover, and heavy deposition
of sand). Local residents reported that they have never seen or heard of trout in
the stream.

Recommendations on Conservation and Management

The current conservation status of the San Pedro Martir rainbow trout may be
_ judged as stable. However, it should be noted that this is a consequence of the
remoteness and inaccessibility of their distribution sites and not a result of the
application of a conservation or management plan. These sites should be consid-
ered fragile ecosystems that may be endangered by anthropogenic activities. There-
fore, it is fundamental that both in the short and long term, an integral ecosystem
conservation and management plan should be established.

Some recommendations for future conservation and management of this sub-
species, derived from the present study as well as from those recently described
by Ruiz-Campos (1993), are as follows: (1) Because the type locality (Rancho San
Antonio) in the Rio Santo Domingo [=Arroyo San Antonio de Murillos] is situated
outside the limits of the Parque Nacional de la Sierra San Pedro Martir, it should
be preserved as an area of protection for the endemic germplasm of this rainbow
trout subspecies; (2) Strictly prohibit the introduction of exotic and non-native
fishes or any other life form to the streams of the SSPM, which might harmfully
interact with the endemic trout. The introduction of exotic and non-native fishes,
mainly of congeneric or conspecific taxa, has caused numerous negative effects
on native trout populations of the southwestern United States, such as competitive
exclusion, hybridization, loss of genetic diversity, and decline of the native pop-
ulations (Rinne and Minckley 1985; Rinne 1988a; Berg and Gall 1988; Leary
1991; Behnke 1992; Dowling and Childs 1992); (3) Regulated sport fishing of this
trout may be practiced in those sites where it has traditionally occurred (e.g., San
Rafael and La Grulla arroyos). It is suggested that the trout catch be limited to
160 mm SL (183 mm TL) or larger. This will permit individuals less than that
size to reach sexual maturity with consequent spawning (Ruiz-Campos 1993); (4)
Prohibit the taking of trout during its spawning period, which occurs between
January and March (Ruiz-Campos 1993); and (5) Develop a habitat management
plan that includes the conservation of both aquatic and riparian ecosystems.
Regulations should be implemented to prevent alteration of these habitats by
cattle grazing and other anthropogenic uses such as dam construction, logging and
water diversion (Rinne 1988b; Marcus et al. 1990a, b; Contor and Platts 1991).

The future of Oncorhynchus mykiss nelsoni and its habitats will depend on
careful planning and application of a holistic conservation and management pro-
gram for the watersheds of the Sierra San Pedro Martir. Such steps will ensure
the continuity of this endemic subspecies which is a biological inheritance and
an integral part of our own natural history.

—_—

Fig. 7. Modification of the morphology of the Arroyo San Rafael. (A) Siltation by ashes and sand
after a forest fire in August 1989. (B) Erosion of stream channel and elimination of riparian vegetation
cover by heavy flooding events in January 1993.

146 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES

Acknowledgments

Many individuals provided invaluable field assistance during the ichthyological
and limnological samplings in the study area. Our thanks go to C. Yruretagoyena,
L. Macias, G. Rubio, V. Roman, J. Gomez, P. Cota, M. Villalobos, I. Montes,
A. Bastidas, D. Leon, M. Valles, A. Gerardo, L. Quintana, J. Alaniz, R. Pérez,
J. Delgadillo, M. Rodriguez, J. Castellon, F. Camarena, C. Marquez, O. Tapia,
C. Ochoa, E. Lopez, J. Escamilla, J. Torres, D. Armenta, J. Ramirez, C. Gardunio,
A. Valdés, W. Zuniga, and V. Salceda. Also, thanks to Jon P. Rebman and three
anonymous reviewers for revisionary and constructive comments. This study was
supported by the Consejo Nacional de Ciencia y Tecnologia (grants: PCECCNA-
050389, P22OCCOR-892393, and 0340-N9107), the Direcci6n General de In-
vestigacion y Superacion Académica de la Secretaria de Educacion Publica (grants:
C-88-01-081 and C-89-01-185), and the Direccion General de Estudios de Pos-
grado, Universidad Autonoma de Baja California (project 0148).

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148 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES

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Accepted for publication 26 December 1994

Appendix 1. Collecting stations in the Sierra San Pedro Martir. Baja California, México.

Primary
Station Elevation Sub- vegeta-
number Name and coordinates (m) strate tion*
1 Rio San Rafael (lower part) <5 S CSS
30°58'10"N, 116°16'15°W
2 Arroyo San Rafael at Rancho Mike’s Sky 1219 S-G CHA
31°06'35°N, 115°38'C5"°W
3 Arroyo San Rafael at Rancho Garet 1350 S-G CHA
31°04'25°N, 115°36'05°W
- Arroyo Vallecitos at Vallecitos meadow 2430 S-G CON
31°01'20"N, 115°28'15°W
5 Arroyo San Telmo at San Telmo town 120 S CSS
30°58'25°N, 116°05'30°W
6 Arroyo San Telmo at Ejido Sinaloa 130 S CSS
30°57'15°N, 115°59'40°W
7 Arroyo San Telmo [=San José] at Rancho San José 640 S CSS
30°57'30°N, 115°44°30"W
8 Arroyo El Potrero at Rancho El Potrero 950 S-G CHA
30°55'00°N, 115°38'45°W
9 Arroyo Santa Cruz at Rancho Santa Cruz 860 S-G CHA
30°52'30"N, 115°37'50"W
10 Arroyo Santa Cruz (lower part) 690 G CHA
30°51'40°N, 115°42'15°W
11 Arroyo Valladares at Rancho [Viejo] Valladares 700 S CHA
30°52'157N, 115°41'35"W
12 Arroyo Valladares at Rancho [Nuevo] Valladares 690 S CHA
30°51'40°N, 115°42'15°W
13 Arroyo La Zanja ca. confluence with A. San Antonio 565 S-G CSS
30°49'10°N, 115°37'35"W
14 Arroyo San Antonio de Murillos at R. San Antonio 540 S-G CSS
30°49'05°N, 115°37'50°W
15 Arroyo San Antonio ca. confluence with A. La Zanja 565 S-G CSS
30°49'05’"N, 115°37'30"W
16 Arroyo La Grulla at La Grulla meadow 2030 S-G CON

30°53'30°N, 115°29'00"W
* Adjacent to riparian vegetation. Key to vegetation: CON = Coniferous forest, CSS = Coastal sage

scrub, CHA = Chaparral.
Key to substrate: S = Sand, G = Gravel, S-G = Sand-gravel.

Appendix 2

Sampling dates in Arroyo San Rafael, Sierra San Pedro Martir, Baja California, México. 1987:
January 27, March 22, June 9, September 17-18 and December 5-6. 1988: February 11-12, March
26-27, May 7-8, June 29, August 20. October 5, November 5 and December 11. 1989: January 21-
22, February 19. May 20, August 20 and December 10. 1991: October 3 and December 8. 1992:
January 25 and March 18. 1993: January 31, March 6, April 25, and July 29. 1994: January 19.

Bull. Southern California Acad. Sci.
94(2), 1995, pp. 149-168
© Southern California Academy of Sciences, 1995

Large-Scale Migrations of the Painted Lady Butterfly,
Vanessa cardui (Lepidoptera: Nymphalidae), in
Inyo County, California, during 1991

Derham Giuliani! and Oakley Shields?

1P.O. Box 265, Big Pine, California 93513
26506 Jerseydale Road, Mariposa, California 95338

Abstract. — Detailed observations on significantly large migrations of Vanessa car-
dui during 1991 in Inyo County, California, are presented, with special emphasis
on their complex behavioral activities. The build up and mass exodus at a pop-
ulation center near Bishop are chronicled and provide insights into why some
butterflies migrate. A directional shift from northward to southward migration
occurred during the summer. The migration phenomenon in this species appears
to be dependent upon larval stress subsequently influencing adult juvenile hor-
mone levels. This behavior likely evolved during the Upper Miocene as an ad-
aptation to avoid seasonally unfavorable arid conditions.

Vanessa cardui (Linnaeus), a regular seasonal migrant, experienced a dramatic
population explosion between 1991 and 1993 in western North America, based
upon our field observations, reports from various observers, the Lepidopterists’
Society Season Summaries, and the Xerces Society’s Fourth of July Butterfly
Counts. Between 1987 and 1990, its migration activities had been minimal during
widespread drought conditions. There was no prior indication that 1991 was
destined to become a population explosion year other than its rather high abun-
dance in Santa Cruz County, Arizona, during mid-August of 1990. Years of major
V. cardui outbreaks in western North America appear to result from comparatively
high winter rainfall in its northern Mexico source area, which in turn are correlated
with, or closely follow, years of Pacific warm water intrusions brought on by El
Nino and Namias-Sumner effects (Myres 1985). The longest recorded El Nino
was present from early 1991 through late 1993 (various Science News and news-
paper articles), the same period that produced an unprecedented three successive
large migrations.

Background Information

In southern California, a very sparse migration of worn V. cardui proceeded
northwesterly through Hemet and San Bernardino in mid-February 1991 and
went WNW at Chuckwalla Valley in Riverside County in mid-March. In late
March numerous individuals were migrating to the NW on the west side of the
Salton Sea, with abundant adults basking, nectaring (especially on Hyptis emoryi
Torr. (Lamiaceae), up to 15-20 per bush), and taking brief, random, non-direc-
tional flights near the ground in Anza-Borrego Desert State Park (J. P. Donahue
in litt.). In the Apple Valley—Lucerne Valley area in early April they were common,

149

150 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES

migrating WNW. Small larvae were in huge numbers on Pectocarya recurvata
Jtn. and Cryptantha (Boraginaceae) in the Clipper Mountains of San Bernardino
County, and large numbers of adults were reported from the south-central Mojave
Desert in Riverside County, in mid-April. Many adults nectated on Rhus trilobata
Nutt. ex T. & G. (Anacardiaceae) at Idyllwild, and a heavy migration flew north-
westerly in San Gabriel Canyon and between Cajon Pass and Randsburg in late
April. Also in late April, adults were common in the Greenhorn Mountains and
near Idyllwild, while larvae were abundant on Cryptantha and Salvia columbariae
Benth. (Lamiaceae) near Hemet. In early May in the San Jacinto Mountains, they
were common and migrating to the NW, with very large numbers migrating
northward at California City in Kern County and large numbers near Tehachapi
Pass.

Migration records in Arizona during 1991 included a NW flight of V. cardui
in Tucson in late March; in addition, large numbers were seen crossing the highway
west of Phoenix in early April. In the spring, it was very common in central
Arizona, with large numbers of adults and larvae observed in the Phoenix area
over an extended period from mid-March to mid-May, whereas in most years
when there is favorable development of desert vegetation, the primary period of
activity there is mid-March to early April (K. Roever in litt.). A very wet March
plus a cool April helped maintain foodplants much later than normal, such as
annual lupine (Lupinus, Fabaceae), various borages, and introduced Malva (Mal-
vaceae). Near Higley in Maricopa County on 24 March, 120-160 individuals/5
min/15 m migrated generally NE, then shifted abruptly to the SW between 12:30
and 1:00 PM (K. Roever in litt.). The reason for the shift in direction was not
apparent, but definitely did not correlate with a reversal in wind direction. It
migrated northward in early May at Prescott and Chino Valley, Yavapai County,
and at Sun City, Maricopa County and migrated west at 300-400/5 min/15 m in
Chino Valley on 2-3 April.

In southern Nevada, they first appeared in immense numbers in late April and
continued into June. A massive northward migration was observed from Tonopah
to Warm Springs in early May. Incredible numbers were widespread in northern
Nevada in June and early July, decreasing somewhat later (still large numbers)
in July into late August.

In Utah, very large numbers were observed in the Salt Lake City area on 4
May, many migrating northward.

In Colorado, migrating painted ladies were widespread, flying northeasterly in
early May. It was the commonest butterfly at Florissant between late June and
mid-July but did not migrate. Very large numbers were also reported in New
Mexico.

A migration went northeasterly in South Dakota in early April, and there was
an abundant spring migration in North Dakota.

Tens of thousands were observed along the Snake River in Baker County,
Oregon, in late May, and in the Boise, Canyon, and Franklin Counties, Idaho.
The migration was widespread in Oregon.

Migrations reached British Columbia, Alberta, Saskatchewan, and Manitoba
in early to mid-May, with the strongest surge in Alberta and Manitoba. Adults
were reported in mid-July in Ontario, Quebec, and Labrador. The butterfly was
widespread and common during the summer in northeastern United States, as

MIGRATIONS OF VANESSA CARDUI IN INYO COUNTY 151

well as being present in the Great Plains and Midwest. There was only sporadic
representation in the Southeast, however.

The 1991 flight directions for spring migrations of V. cardui converge back to
probable source areas in northwestern Mexico, with secondary centers in northern
Baja California, the southern Mojave Desert, and the extreme northeastern So-
noran Desert. Heavy rains fell in southern Sonora and Sinaloa (approximately 20
in) during December of 1990 and January 1991, probably contributing to their
population build ups. In Sinaloa the torrential rains led to flash flood devastation,
while at the same time causing dams to burst, rivers to overflow their banks, and
extensive crop damage.

J. R. Mori and R. E. Wells (in litt.) report that in April 1991 in Baja California,
the desert areas north of a line 80 km S of Catavina were very green and lush from
heavy March rains, and that south of this line to Loreto (26° North latitude),
heavy winter rains had produced a high stand of annuals that was rapidly drying
out. They noted extremely sparse V. cardui migrants (flying generally northward)
all the way down the Baja California peninsula to as far south as Santa Rosalia
and San Lucas Bay in mid to late April, but not further south to Puerto Escondido.
On 26 April large numbers were seen migrating northward (about 15-20 per
minute crossing the highway within sight) 80 km S of Catavina, with a huge
migration flying NNW (hundreds crossing the highway within sight at any given
moment) from about 40 km N of Catavina (heaviest) to San Vicente (thinning
out).

In prior years, several source areas for migratory butterflies have been identified
for Mexico. In early April of 1949, at a promontory on the shore of Santa Maria
Bay, Baja California Sur, thousands of V. cardui were emerging from pupae (Ab-
bott 1951). Many flew south a short distance to the desert cliff edge, then flew
back north to the emergence area. Although no migration was observed, they did
migrate in California at about the same time that year. In mid-March of 1968, a
V. cardui migration center was identified by E. S. Ross (in litt.) in Sonora, Mexico,
between Hermosillo and Santa Ana. In that year, unusually early and abundant
rains occurred in the region, involving a great build up of overcrowded, wandering
larvae following host defoliation. The resultant adults simply took off NW in a
huge migration, as per numerous records from intermediate points, that ultimately
traversed the length of California from mid-March to mid-April, reaching south-
ernmost northern California on 30 March and Medford, Oregon, in early April.

In some years, active populations of V. cardui are known to spend the winter
in the Sierra Madre Oriental and the Chihuahuan Desert, with NE spring migra-
tions across Texas (C. J. Durden in litt.). The species also occasionally overwinters
in southwestern Arizona in December, commonly necataring on Hyptis emoryi
in the desert southwest of Ajo (K. Roever in litt.).

Methods and Materials

Direction of flight was obtained by stepping into the path ofa passing V. cardui
and pointing a compass at the retreating butterfly. The number of butterflies
involved in a migration was estimated by counting the individuals that crossed
a measured line, set at right angles to the direction of flight, during an interval of
time. Conversion to number/5 min/15 m provided a standard for comparison,
and compass directions were converted to geographic directions in all instances.

152 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES

All migration directions are expressed as the direction(s) that migrants were flying.
Pacific Standard Time was used for dates preceding 7 April and following 27
October, and Pacific Daylight Time was used between those dates. Instars at each
site were estimated by measuring the lengths of a sampling of larvae and comparing
these against standard instar lengths given by Hammad and Raafat (1972).

Typical migrators fly in rapid, non-stop, straight lines. When disturbed from
rest, they all drift in the same direction, while non-migrators circle or re-land or
move off in many directions. There appear to be several types of migration
cessation. Either they settle down for the night but will readily drift in a preferred
direction when disturbed, or, late in the season they show a declining tendency
to migrate and spend more time nectaring on flowers, with little inclination to fly
in a straight line when disturbed.

Inyo County Spring Migrations

The senior author closely monitored V. cardui activities in Inyo County during
1991 (see Figure 1). They were first observed on 23 February at Willow Creek,
Saline Valley, 2300 ft (two, worn). They were first noticed at Big Pine, Owens
Valley, 4000 ft, during 12 March-3 April in small numbers, nectaring at apricot
blossoms or circling and alighting on the ground, but did not show a tendency to
migrate. These were mostly small to medium-sized individuals with pale or faded
coloration and powdery-white ventral surfaces, though some were larger with
fairly bright colors. Possibly these had overwintered, since overwintering adults
have been observed in Saline Valley from mid-December through February in
1977-1978, though a northern Mexico source cannot be discounted. During 24
February—11 March at Big Pine, none was seen at these blossoms, when the
weather was often cool, cloudy, and breezy with few clear, sunny days. In early
March, after a winter drought, it rained 3.8 in at Big Pine over a 2—3 day period
and Bishop received 2.9 in of rain in March which later produced a sizable crop
of Amsinckia in the Owens Valley. On 29-30 March, near Ridgecrest, numerous
V. cardui were flying in all directions or circling about but were not migrating.
Occasional migrants were seen at or near Big Pine during 3—23 April. On 18-19
April in Eureka Valley, occasional V. cardui were migrating in various directions
(mainly NW and SW), circling about or landing during overcast weather.

The first appreciable wave of migrants entered the Owens Valley on 24 April
and continued at about the same densities in Owens and Deep Spring Valleys to
2 May (4-19/5 min/15 m, with a surge of 48/5 min/15 m at midday flying NW-—
WNW on 24 April at Bishop). On 4—6 May the densities dramatically increased
in the Owens Valley. On 4 May at 6400-7100 ft near Lone Pine, there were 184—
230/5 min/15 m, flying N-NNE. On 5 May comparable numbers migrated across
the northern Inyo Mountains (no counts made). On 6 May at 7500-9000 ft in
the southern White Mountains, there were 98—211/5 min/15 m flying NNW-—
NNE, with lesser numbers below 7000 ft (22—82/5 min/15 m). In Fish Lake Vailey
in early May, on a fair day without much wind, a large migration went approx-
imately N (S. Sawka pers. comm.). From 7-22 May, numbers of migrants con-
siderably declined in the Big Pine and Bishop regions to 4—30/5 min/15 m. At
Eureka Valley in mid-May, V. cardui first instar larvae were numerous on Baileya
(Asteraceae) leaves. Migrating adults flew NNW there on 16 May at 3/5 min/15

MIGRATIONS OF VANESSA CARDUI IN INYO COUNTY 153

ae: re
Mey ns. Gos

AZ

Fig. 1. Map of Inyo County and surrounding regions (modified from Johnson and Cicero 1986,
Fig. 1).

m. On 17 May, they flew NNE at 6/5 min/15 m and also nectared on flowers of
Baileya, Dalea (Fabaceae), Encelia (Asteraceae), and Larrea (Zygophyllaceae).
On 23 May at Santa Rita Flat, 6400-7200 ft, Inyo Mountains, migration again
increased (38-116/5 min/15 m), flying N-NNW, although it was sparse in the
Owens Valley (1-8/5 min/15 m), flying mostly NNE. In Eureka Valley on 25
May, many V. cardui were seen on flowers along with an occasional migrant, and
occasional ones migrated in the Inyo Mountains. On 26 May at 9000-9200 ft in
the White Mountains, the rate was 4-10/5 min/15 m, flying N-NNW. On 28-31
May, migration was extremely sparse in the Owens Valley, but on 2 June near
Bishop, it suddenly increased to 8—36/5 min/15 m, flying primarily NNW. The
latter flew from the direction of southern Owens Valley. Concurrently, near Barrel
Springs (Mazourka Canyon, Inyo Mountains), there were numerous migrants at
5:15 PM under windy, cloudy conditions, many up to 50 ft high. The rate at 5:30
PM was 51-101/5 min/15 m, flying NW-NNW, when very large numbers were
also on the many flowers of Dalea and Encelia. When disturbed by car along the

154 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES

road at 6:30 PM, they rose up as a cloud and flew approximately N or NW in
immense numbers (about 3427/5 min/15 m, a computed rate from one 13/7 sec/8
ft measurement), then resettled on the ground, on Artemisia (Asteraceae) and
other shrubs, and on pinyon pines (even up around the 6—9 m high tops of the
larger trees). By that time they had apparently settled for the night even though
it was still daylight. On 3 June at Badger Flat, 9000 ft, Inyo Mountains, the rate
was 20-43/5 min/15 m (7:30-8:05 AM), mainly NNW, yet almost ceased after
8:20 AM (2-4/5 min/15 m). At noon near Mazourka Canyon, many nectaring on
Dalea and Encelia flew NW-—NNW when disturbed. On 4 June at 4000-6000 ft
in the White Mountains, many were migrating E-ESE, occasionally up to 8000
ft, with large numbers that showed no inclination to migrate at 5000 ft on flowers
of Dalea and Encelia. From 12-21 June, migration was sparse in the Owens
Valley and nearly ceased after that. On 22 June at Cedar Flat, 7300 ft, near
Westgard Pass, rates increased (9-71/5 min/15 m), flying NNW-NNE during
unstable weather. These flew 0.2—1 m above ground level. In the afternoon, there
was a greater tendency for them to alight on flowers, bushes, trees, and on the
ground. Many interactions were observed all day, such as one on the ground would
fly up to a passing individual or two flying different directions would interact
when they passed near one another.

Bishop Migration

Ovipositions during the 4-6 May migration most likely produced a 5-11 June
mass exodus at the Bishop site since Egyptian V. cardui in early May averages
36 days from egg to adult emergence (Hammad and Raafat 1972), and the peak
in migration from the south and the peak in local emergence corresponded with
this time-schedule. Since the larvae at the Bishop site were the size of first instars
by 13 May, the eggs would have been laid about 7—9 days earlier (in an egg-laying
frenzy) using their minimum data, which would be 4-6 May. The few small larvae
observed earlier at the Bishop site on 24 and 28 April were likely from one of
the earlier flights. The length of time between egg deposition and adult eclosion
would have been about 36 days, 1.e., 4-6 May to 8-10 June. Also, both the 4-6
May and 5-11 June flights migrated at comparably high densities. The 5-11 June
exodus reached maximum densities on 7-10 June. It is not known if the stock
Hammad and Raafat used were migrant or non-migrant, but they report that V.
cardui has eight genrations a year under laboratory conditions and that females
Oviposit between 420-686 eggs each (average = 507) in captivity. (On 4 May at
Jerseydale, Mariposa County, a few females were seen to briefly oviposit in a
frenzied manner on a composite, a legume, Lupinus, and Rumex (Polygonaceae)
before resuming their migratory flight. Migrants sometimes paused briefly to
nervously nectar at meadow flowers before resuming migration.)

The first adult V. cardui from the Bishop site began to migrate on 5 June. From
6-10 June, maximum counts of departing migrants consistently occurred between
7:30-8:00 AM, 1 hr after sunrise, with far fewer numbers between 7:00—7:30
AM and after 8:30 AM (4—-56/5 min/15 m). Maximum numbers between 7:30—
8:00 AM for five minutes over 15 m were: 7 June (128), 9 June (337), 10 June
(220). From 10:30—1:30, rates were considerably reduced to 2-4/5 min/15 m. On
10 June the area was also monitored in the afternoon between 4:00-7:00 PM.
The number of emigrants per 5 minute intervals over 15 m during this time was

155

MIGRATIONS OF VANESSA CARDUI IN INYO COUNTY

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156 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES

23, 53, 18, 4, and 9, respectively. On 11 June, migration suddenly decreased just
before 8:00 AM. The 1991 daily Bishop temperatures through June are given in
Table 1.

Bishop Immatures

A 2% sq mi area just west of Bishop was periodically surveyed between 24
April—11 June, where V. cardui larvae fed on Amsinckia tessellata Gray (Bora-
ginaceae), the predominant foodplant in the Owens Valley. On 24 April the
Amsinckia plants were 3-8 cm high with evidence of only one small larva. On
28 April they were 3-15 cm high, most less than 5 cm, with some coming into
bloom, and one plant was found with webbing and another with a first instar
larva. By 13 May larval numbers in the study are had dramatically increased to
an estimated 15-45 million. The Amsinckia plants were luxuriant, 10—35 cm high,
and in full bloom. Larvae were mostly first instars (a few second instars) and
preferred to feed on the flower heads. On 19 May larvae were mostly second and
third instars. On 28 May the larvae were fourth and fifth instars (mostly last
instar), and in the morning many of them crawled over the ground in various
directions but each along a straight line, primarily westward away from the sun.
Amsinckia leaves on most plants had turned brown and brittle from desiccation.
Some Amsinckia 50 cm high had green leaves remaining and contained up to
over 100 larvae per plant. Cryptantha plants 5 cm high had up to 30 larvae per
plant (mostly last instars). Some larvae were in large isolated shrubs (e.g., Arte-
misia) preparing to pupate (one pupa found), while dense groups of shrubs had
none. Cooler than normal weather had benefited the larvae by preventing the
plants from rapidly drying out. In some areas, the larvae had stripped the Am-
sinckia leaves and were eating the flower heads. On 30 May there were many
pupae and many larvae about to pupate on an isolated Atriplex (Chenopodiaceae)
shrub. On 5 June Amsinckia had mostly dried out and only 13 last instars were
located on six plants. Many Amsinckia stems had had their outer layers eaten
away. No larvae (except one) were crawling on the ground, and 32 pupae were
located on five Amsinckia plants. One freshly emerged adult dried its wings at
the base of a small shrub at 10:40 AM, and another one took its initial flight at
12:10 AM. By 7 June there were only a few last instars in the bushes, the vast
majority now as pupae. Most pupae were in the foliage of shrubs and not on the
denuded Amsinckia, and only two last instar larvae were crawling on the ground.
Seven newly emerged adults were located between 9:20-9:30 AM. Three of these
were observed for an hour and did not fly, instead perching with folded wings
pointing toward or away from the sun for minimum light exposure. When dis-
turbed, they flew only 1-3 m, with none showing a tendency to fly in a straight
line. No flowers were evident in the fields of dried Amsinckia.

Larval behavior was monitored at the Bishop site during 28-31 May. Larvae
were motionless, mostly on Amsinckia, all night. At 5:00-5:30 AM, larvae re-
mained motionless on the Amsinckia. About 10 minutes after the 6:01 sunrise,
some larvae began to move their heads about sluggishly. At 6:27 larvae began to
move about a little on the plants. By 7:18 larvae were more active, fed, and a few
began dropping off the plants and crawling on the ground in straight lines (all
directions represented). By 8:08-8:30 most larvae were crawling on the ground,

MIGRATIONS OF VANESSA CARDUI IN INYO COUNTY 157

with only a few remaining on the Amsinckia. Numbers on the ground reached a
peak about 9:00—10:00 AM, then steadily declined until there were none by noon
when they were back on the plants, and almost none were seen in the afternoon
and at dusk on the ground. Between 10:05-10:30 AM on 28 May, numbers of
larvae crawling on the ground in a 5 ft x 5 ft plot were 19, 14, 16, 7, and 4 in
successive five minute intervals. With heat build up, larvae tended to climb back
onto the Amsinckia to get off the hot ground and then remain there the rest of
the day and overnight. Larvae on the ground moved faster as the heat increased.
Those not finding shelter experienced heat stress, i.e., scrambling madly, often
falling over on their sides, and becoming disoriented and dehydrated. Although
larvae crawled on the ground in all directions, many tended to move westward
away from the sun in the early morning and then between south and east at 10:35—
11:00 AM. The larvae seemed to migrate due to the Amsinckia drying up. All
sizes of larvae except first instars engaged in larval migration. On 4 June along
Westgard Road east of Big Pine at 6000 ft, many Amsinckia plants had various-
sized larvae on them but no larvae crawled on the ground at 9:00 AM. Here the
Amsinckia was still in fairly good condition, i.e., mostly not dried out yet.

Distances travelled by 11 third to fifth instar larvae during five minute intervals
were 1.5—6 m (average = 3.2 m). One larva covered 123 m in 1% hrs, varying
24% in direction, though it displayed signs of heat stress. Larvae crawled more
slowly over the ground in cooler weather on 31 May (1.4—2.8 m, four larvae,
average 1.9 m, in five minutes).

Sometimes unidirectional larvae briefly investigated the Amsinckia plants they
passed. Larvae that were physically turned in, or prodded to take, the opposite
direction quickly returned to their original direction of travel. Larvae would slow
their pace appreciably upon encountering shade. They deviated off their course
toward nearby shady objects, such as a car or the observer, as ground temperatures
rose. Taller objects attracted them more, and from further distance, than did
smaller objects, especially with the medium-sized larvae. They would turn a
complete circle if the observer walked around them and would follow him for
0.3-3.0 m, resuming their former directions if he then stepped back 2—4 m or
crouched. If he crouched down, one larva heading toward him would immediately
turn back to its original direction, but then turned back toward him if he stood
up. When another object 0.2-0.6 m high was placed or moved around beside the
observer when a larva was approaching him, it often confused them, one passing
in between, but others seemed to select one object and head for it, ignoring the
other. When approached closely from behind, however, larvae maintained their
original directions. Other larval experiments at this site are reported elsewhere
(Giuliani and Shields 1993).

A last instar larva that was preparing a web enclosure in an Artemisia was
collected at the Bishop site on 5 June and kept indoors at room temperatures. It
hung up to pupate on the lid of a container that afternoon, formed a pupa in the
early afternoon of 6 June, and emerged as an adult in the early morning of 13
June (ca. 6% days as a pupa).

V. cardui \arvae were found in the White Mountains during July and August
on Sphaeralcea (Malvaceae) (6700-8800 ft), Cirsium (Asteraceae) (9800—10,100
ft), and Arnica (Asteraceae) (10,000-11,500 ft). Their rate of growth was slower
with increasing altitude.

158 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES

OWENS RIVER

es |
4

81 S\HOP
t]

Fig. 2. Bishop emergence site, showing migration flight paths taken during mass exodus of newly-
emerged Vanessa cardui adults. Cross-hatching = area of high-density hostplant (Amsinckia), black
arrows = June 5-10, 1991 observations, light arrows = May 16-19, 1986 observations, GN = geo-
graphic north, MN = magnetic north.

Bishop Adults

At the Amsinckia site west of Bishop on 28-31 May, only one to three migrating
adults were observed each day. During 5-11 June the vast majority of the pupae
emerged and the adults migrated, with a maximum of 224—342/5 min/15 m on
9-10 June. These migrations radiated in almost all directions (except east) from
the population center (see Figure 2), primarily during 7:00—10:00 AM, sometimes
with a few continuing until 1:00 PM (5 June). Unlike “‘normal’’ migrators, these
usually flew slowly, were easily distracted by other V. cardui flying nearby and
flowers, and ceased migrating when the heat of the day built up, although lighter
migration flights occurred in the late afternoon. The numbers considerably de-
clined on 11 June during the hottest temperatures of the year (to then), when
most migrators had already departed and few new ones were emerging to replace
them.

In the late morning and during the afternoon, newly emerged adults congregated
at flowers and in shrubs of Chrysothamnus (Asteraceae), Atriplex, and on the twigs
of dead shrubs. Very small shrubs had almost none. These freshly emerged adults
apparently waited until the following morning before migrating due to high midday
and afternoon temperatures. Several freshly emerged (limp) adults displayed a
strong tendency to climb up on vegetation. One of these nervously snapped its
wings open and closed at each movement made by a nearby ant on two occasions.
A passing car on 7 June at 11:30 AM caused huge numbers of freshly emerged
individuals to rise into the air from the roadbanks before resettling, in an area

MIGRATIONS OF VANESSA CARDUI IN INYO COUNTY 159

with fields of dried Amsinckia and no flowers. On 9 June at 7:38 AM, adults
migrated to the NE—NNE at 342/5 min/15 m, and a passing car created a huge
wave of them that flew in this direction. At 11:15 AM, huge numbers rose into
the air from bushes when the car pulled up, quickly resettling in the bushes. At
1:15 PM each bush passed close to with the car on both sides of the road produced
a cloud of V. cardui that quickly resettled on bushes. At 1:15 PM, over 1000 V.
cardui were on shrubs such as Atriplex and Chrysothamnus in a 5000 sq ft area
(ca. five million per sq mi), about 20-100 per shrub, mostly clustered on the
shady side with folded wings pointed toward or away from the sun for minimum
light exposure. These flew only short distances by circling about when disturbed,
without a straight line flight, before quickly resettling on bushes. Some were on
the ground in the shade beneath bushes. Occasionally one or two would leave a
bush and drift NNE for a bit before landing, although almost no migrators were
observed (2/5 min/15 m, going NNE). They remained in these bushes overnight,
and at 11 PM when temperatures were still in the 70’s flew, apparently short
distances, when touched. Clouds of them also rose from bushes just east of Big
Pine that afternoon. At 4 PM the yard at Big Pine was filled with V. cardui (40
on Encelia flowers, 3—4 times that number on shrubs, trees, and the ground). By
8 PM these were in the trees and larger shrubs, with occasional individuals still
flying about and relanding. At other emergence areas in the Owens Valley at
various unrecorded dates during the first half of June, butterflies also clustered
on the shady side of shrubs or on flowers by midday and remained there until
the next morning. When disturbed, these would rise up in large numbers. On 10
June at 6 AM they were perched in shrubs at the Bishop site and when touched
would sluggishly open and close their wings, and there were not the great numbers
seen here on shrubs at 1:15 PM on 9 June. On 11 June at 6:08 AM at the Bishop
site, the passing car caused many to fly up from bushes that were in sun but not
from bushes that were in shade.

Just after sunrise between 6:00-7:00 AM adults that had roosted in shrubs and
bushes frequently had their wings open toward the sun to warm up (“‘basking,”’
see Clench 1966), began to circle about and land on the ground, and made fiights
in a fixed direction before landing again. By 6:40 AM on 10 June there were more
on the ground than in the bushes, with increasing numbers taking short flights
heading north, and between 6:43-6:55 AM some suddenly flew north until lost
from view.

Between 7:15-7:45 AM on 6-7 June, pairs rather frequently formed when
individuals on the ground would rise up to interact with those flying over them,
both then continuing on in the same direction and speed. Possibly this could be
how migration “waves” originate. Some of the migrants would swerve off their
straight flight here and there as they proceeded. Many were flying rather weakly
or with little determination, although some were flying in straight lines fairly
strongly. The 10 June migration was unusual in that as low numbers of migrants
proceeded north, some went south between 4:00-6:45 PM while many others
remained on flowers and bushes. After 10 June there were considerably fewer
migrators in the Owens Valley.

Most migrators flew 0.3—2 m above the ground, though one was seen 9 m high.
On 9 June occasional V. cardui were circling and drifting up to 60 m high but
were not headed in a fixed direction. Many nectared at flowers when these were

160 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES

available, such as Dalea, Lycium (Solanaceae), and several others, spear be-
tween 7:00-9:00 AM and around 4:00 PM.

Several mass emergences of V. cardui have been observed by K. Roever (in
litt.), mainly in the central Maricopa (Phoenix) area of Arizona, since 1973. Adults
would emerge from the chrysalis, dry their wings, and then launch directly into
directional flight without expressing mating or feeding behavior in the immediate
vicinity of emergence. On April 14, 1973, at a mass emergence site with lupines
defoliated along Highway 95, 2-6 mi N of I-40 in Mohave County, Arizona, they
fully expanded their wings by 7:30 AM (MST) with a heavy flight starting by 8
AM. From 8:30 to 8:35 AM they flew NNW at 900/5 min/15 m, with density
about the same over a 15 mile drive north toward Oatman.

Adults at Flowers

In Inyo County during the first half of June, there were great abundances of
adults nectaring at flowers in the vicinity of Big Pine and in the White and Inyo
Mountains at low to moderate elevations (up to 6000 ft), especially on Encelia,
Dalea, and Ailanthus (Simarubaceae). These reached a peak on 2—12 June, then
gradually decreased in the Owens Valley during the second half of June until only
occasional singletons were observed at Big Pine during latest June and July,
perhaps due to summer heat. At their peak, large to very large numbers would
visit flowers. Nectaring occurred especially between 8:00—10:00 AM and in the
last afternoon until about 8:00 PM, though sometimes this period extended to
early afternoon (19 June) or even all day (13 June). Except in Mazourka Canyon
on 3 June at noon, where a large migration had been in progress on 2 June, these
showed no tendency to migrate when disturbed, preferring instead to circle about
before returning to the flowers. On 16 June at Big Pine, a migration going west
showed no tendency to alight on flowers, and nectaring adults did not interact
with the migrators except to briefly circle about from flowers. The nectaring V.
cardui appeared to come from all over Owens Valley, as they were emerging
everywhere Amsinckia was growing on the valley floor. Large numbers on flowers
were also noted on 17-21 June at 5200-7500 ft above the floor of Owens Valley
on either side. W. D. Patterson (in litt.) reports that during 2-5 June, V. cardui
adults were very common in the desert north of Bishop, with numbers flying
northward in the Benton Hot Springs/Benton area of Mono County. Elsewhere
they varied from abundant to scarce and appeared to be sedentary and absorbed
in nectaring. They were abundant and nectaring into the lower part of Westgard
Pass and at 5000-6000 ft in the Inyo Mountains. At Santa Rita Flat, 6500 ft,
Inyo Mountains, great swarms were nectaring at yellow composites. Above West-
gard Pass and on the west side of Owens Valley at SO00—5500 ft, they were present
but only in fair to low numbers.

Amsinckia

In 1991, Amsinckia was the dominant annual plant in the Owens Valley and
formed vast fields. No rain fell from September 1990 through February 1991,
unique for Owens Valley, while sufficient rains in March caused the Amsinckia
to germinate. It tended to grow in open areas and not where there was extensive
shrub growth. Though it was found up to over 7000 ft in elevation, it was not
common above the valley floor (4000 ft). Amsinckia was dense in places on the

MIGRATIONS OF VANESSA CARDUI IN INYO COUNTY 161

west side of the valley from Bishop to Big Pine and was scarce on the east side
(although dense in one 2 sq mi area east of Big Pine where two 5 ft x 5 ft plots
had 94 and 140 larvae on 21 May), and extended on down to Lone Pine. It also
extended into much of Round Valley and sparingly north of the Owens River.
Virtually everywhere Amsinckia was found, V. cardui larval impact was evident
(up to 100 larvae per plant on 28 May). Our estimate of 100 million larvae is
very conservative and does not take into account their use of foodplants other
than Amsinckia.

The emergence site monitored in 1991 is located in the Owens Valley 5-10 km
west of downtown Bishop, 4300-4500 ft in elevation. The main area is 2 x 3
km, with a 2 x 2 km westward extension. The plant was very limited west, north,
and east of this area. In 1986, Amsinckia was confined primarily to this emergence
site. No Amsinckia was found in Owens Valley in 1987-1990 due to drought,
and the open ground at the Bishop site remained barren. In 1986 and 1991, the
Bishop site had essentially the same area and density of Amsinckia, although in
1986 the Amsinckia boundary there encompassed slightly less territory and it
germinated in December instead of March. The site was open ground dominated
by Amsinckia, with Artemisia, Chrysothamnus, and Atriplex in scattered clumps.
In the past, the area had been altered by agriculture and overgrazing.

Angiosperms Utilized

The following is a list of V. cardui larval hostplants from Inyo County in 1991.
Larvae were consistently found feeding on these. Most of the plant identifications
were made by Mary DeDecker.

Asteraceae

Baileya pleniradiata Harv. & Gray
Lactuca serriola L.

Cirsium drummondii T. & G.
Tetradymia axillaria A. Nels.

Arnica parryi sonnei (Greene) Maguire

Boraginaceae

Amsinckia tessellata—the main, preferred hostplant
Pectocarya heterocarpa (Jtn.) Jtn.

Cryptantha barbigera (Gray) Greene

C. confertiflora (Greene) Pays.

C. micrantha (Torr.) Jtn.

C. pterocarya (Torr.) Greene

C. recurvata Cov.

C. utahensis (Gray) Greene

Fabaceae

Lupinus excubitus Jones

Malvaceae

Malva neglecta Wallr.

162 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES

Sphaeralcea ambigua ambigua Gray
S. a. rosacea (M. & J.) Kearn. 4,

Preffered adult nectar sources in Inyo County in 1991 were the following:

Asteraceae

Baileya pleniradiata

Chrysothamnus nauseosus (Pall.) Britton

Encelia virginensis actonii (Elmer) Keck—especially
Brassicaceae

Stanleya elata Jones

Fabaceae

Dalea fremontii Torr.—especially

Rosaceae
Prunus armeniaca L.—cultivated
P. andersonii Gray —especially
Simarubaceae

Ailanthus altissima (Mill.)—introduced Tree of Heaven

Solanaceae

Lycium sp.

Tamaricaceae

Tamarix sp.

Zygophyllaceae

Larrea divaricata Cav.

Predators and Parasites

Some predation on V. cardui was observed in Inyo County in 1991, although
few natural enemies seemed to be present. These included a large Calosoma sp.
(Carabidae) eating larvae, a large asilid fly twice capturing adults, an unidentified
wasp carrying a last instar larva back to its ground hole, black harvester ants
attacking and carrying off one larva, crows eating many larvae, and a flock of
starlings probably hunting pupae. Also, English sparrows ate the bodies on car
grills. A tachinid larva was parasitic in a few V. cardui pupae, and a small wasp
larva was rather frequently parasitic on small V. cardui larvae above 7000 ft in
the White Mountains in late summer.

Shift in Direction and Return Flight

V. cardui disappeared from lower elevations by the end of June. Migratory
flights continued above 9000 ft in the White Mountains into early September at
low rates (up to 1/5 min/15 m). No such flights were seen in the Sierra Nevada
above Owens Valley at that time. Their migration directions abruptly shifted from

MIGRATIONS OF VANESSA CARDUI IN INYO COUNTY 163

Fig. 3. Circle diagram of sudden change in individual flight directions from northwesterly to
southerly of Vanessa cardui migrators in the White Mountains above 9000 ft. Black dots = June 12-
30, 1991, light dots = July 10-30, 1991, arrows = average (median) flight direction for each period.
All directions are geographic. Each dot represents one measured migrator.

northwesterly to southerly sometime between 1-9 July (see Figure 3). Migrators
flew in all directions (no preferred direction observed) on 4 July at 9200-10,300
ft in the White Mountains.

One of us (D. G.) observed predominantly SW flights in eastern Oregon in early
August and at Cour d’Alene, Idaho, during the latter half of August.

At Jerseydale in late August, occasional V. cardui migrated SW. From 31 August
to 15 October they were common to very common there (fresh to worn), nectaring
at Cirsium, with occasional ones migrating SW-SSE. In late October to early
November, their numbers steadily decreased, with the last worn individual of the
season observed there on 15 November.

On 17 September in Eureka Valley, there were some fourth and fifth instar
larvae left and many empty webbings with fifth instar frass on Sphaeralcea am-
bigua following recent rains, with occasional adults migrating mostly SW—-WSW
at 1/5 min/15 m. At 5000 ft in the Dry Mountains on the same day, worn V.

164 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES

cardui adults were numerous on Encelia flowers, with mostly fresh ones higher
in elevation on Chrysothamnus flowers.

P. Cherubini (in litt.) noted a large SSW movement of V. cardui in early
September, beginning about 1 September, in Placerville, the Sacramento Valley,
and the area around Petaluma and Sebastopol, with thousands nectaring on yard
Buddleja (Buddlejaceae) on 14-15 September at Placerville.

On 19 October occasional migrators went ESE-E on Mt. Tamalpais and S-ESE
at Alpine Lake in Marin County. On 20 October they migrated SE-E at 14/5
min/15 m on the Point Reyes Peninsula. The Baja California peninsula appeared
devoid of V. cardui in October except for several around Catavina on 14~15
October (J. R. Mori pers. comm.). Many adults nectared on Petalonyx (Loasaceae)
in the Kelso Dunes of San Bernardino County on 29 September, and fresh to
worn adults were common on Lepidospartum (Asteraceae) in San Jacinto Valley
of Riverside County on 16 October.

In September to mid-October in Owens Valley. occasional V. cardui were seen
migrating mostly S-SW, as residents, or nectaring on Chrysothamnus nauseosus.
During early November, only single V. cardui were resident at Big Pine (last seen
there on 9 November), and only two were sighted in November in the White
Mountains (on 13 November at 7200 ft and 25 November at 8500 ft). The last
V. cardui to appear that season were observed in Saline Valley on 27 November
(13 between 1100-1700 ft) and 27-31 December (three between 2300-2400 ft).
At Hemet in Riverside County. worn adults nectared at yard Lantana (Verben-
aceae) on 24 November (five or six) and were last observed there on 26 December
(one, worn).

Migration Dynamics

Betweea 28 April and 9 June, we made observations of V. cardui migrations
in the Owens Valley region and at Jerseydale (3500 ft, Mariposa County) on a
daily basis. The largest migrations occurred on days that were clear and sunny
(warm to hot), with calm, breezy, or gusty wind conditions. None migrated during
cold temperatures. though sometimes individuals were seen that were not mi-
grating. None was observed migrating on drizzly or rainy days. In the Owens
Valley region on 9-10 May under cold, cloudy, and windy conditions, many V.
cardui were observed on the ground, probably for warmth (see Clench 1966), and
these did not migrate. The same behavior was observed while driving down the
Lead Canyon road to the Saline Valley road on 3 May when conditions were
mostly cloudy with a light wind and cooler than normal, and at Jerseydale on 2
May in cool, overcast weather. Temperature seemed to be the main factor in
limiting flights.

Migrants sometimes flew in strong gusty winds on cool days. In Owens Valley
there were two migration periods. The first occurred from mid-April to mid-May
and consisted of immigrants from the south. The second was by local emergers
during the first half of June. During the 28 April to 9 June period, migrations
were observed for 86% of the days in Owens Valley and 79% at Jerseydale. On
51% of the days in Owens Valley and 42% at Jerseydale, migrations were greater
than 1/5 min/15 m. The low numbers in the Owens Valley during the latter half
of May appeared to be due to the migration from the south ending rather than
weather-caused.

MIGRATIONS OF VANESSA CARDUI IN INYO COUNTY 165

The dates when rates exceeded 1/5 min/15 m at Jerseydale corresponded to
dates that they were above or well above 1/5 min/15 m in the Owens Valley
during 28 April—9 June. On those dates where we had same day data for both
places, the Owens Valley rates averaged 2'2—-12 times greater than the Jerseydale
rates (6 May = 3x, 7 May = 9x, 12 May = 2'2x, 15 May = 3x, 2 June = 12x),
if the 4 May Lone Pine date (43'2 x) is excluded. The highest rates during the 43-
day period occurred in both places on 6 May (22-211/5 min/15 m in Owens
Valley, 34-44/5 min/15 m at Jerseydale). On eight days, rates exceeded or greatly
_ exceeded 1/5 min/15 m in the Owens Valley but not at Jerseydale even though
the weather was favorable on those days at Jerseydale.

The predominant direction of the migrators at both Big Pine and Jerseydale in
May was N to NNW. They migrated in all directions at Big Pine in June. Big
Pine is located 87 air mi ESE of Jerseydale, on the opposite side of the Sierra
Nevada. Thus the source of the Jerseydale migrants could not have been Owens
Valley and instead was in the direction of the southern San Joaquin Valley to
Baja California. In Inyo County, migration directions averaged NNW in May and
early June and S in July.

We computed flight speeds on a few migrators. On 6 May near Jerseydale in
mid-morning during warm, calm weather, 10 were clocked at 15-20 mph by
driving a car at their speed and reading the speedometer. On 4 May near Lone
Pine in the late morning in clear, cool conditions with decreasing winds that
occasionally gusted, 22 were clocked at 12—26 mph (mean = 16 mph, median =
15 mph) by using a stopwatch to time them over measured distances. On 30 April
at noon on a ridge SW of Bishop during clear, cool weather with a strong wind
blowing crosswise to their flight, three were timed at 10, 12, and 16 mph.

At Jerseydale the migrations usually began about 9:30 AM and lasted until
about 5:00 PM in May and early June. In the Owens Valley region, however,
migrations began about 7:00 AM and lasted until about 6:10 PM in May and
early June. The Bishop exodus flight on 5-11 June began about 6:30-6:50 AM
and lasted until about 6:50 PM, with an early afternoon hiatus.

In the Owens Valley and at Jerseydale on 4—6 May, the flight was characterized
by some large fresh individuals with many medium to small-sized ones. At Jer-
seydale, however, this flight actually began on 3 May with a 5 May lull. The
numbers were reduced in both places before and after these dates. V. cardui ceased
migrating at Jerseydale in mid-June with the onset of hot weather.

Several attempts were made to determine migration directions at 500 to 1000
ft elevational intervals on the same day. On 4 May along Horseshoe Meadow
road SW of Lone Pine, V. cardui migrated N-NE and N-NNE between 5100-
9100 ft in the afternoon under cool, clear, calm to breezy conditions, shifting to
NW (and E) at 9400 ft and E at 9600 ft. Wind directions were variable. They
avoided an area that was in shadow at 7100 ft at 5:30 PM, with migration ending
at 6:05 PM that day. On 6 May in the White Mountains, they migrated N-NNE
between 5000-9000 ft in mid-morning, then went N-NNW between 7000-8500
ft from 11 AM to 1 PM, and NW-—WNW at 6000 ft at 1:30 PM. Winds were light
to strong and gusty, and varied in direction. At Vista in the White Mountains,
9200 ft, 10:15 AM, a stream of migrators was funnelled up a steep canyon by
strong, gusty winds from the WSW, at 425/5 min/15 m going N-NE.

166 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES

Discussion

Migration of Vanessa cardui, a non-diapausing species, allows it to red:Stribute
a significant part of its populations to more seasonally favorable environments
over a large area. It appears incapable of surviving both summer and winter at
any one place (Larsen 1976), e.g., the hot summer in Egypt or the cold winter in
Canada. Spring migrations of V. cardui are likely due to high densities of starving,
stressed larvae migrating on the ground in search of suitable foodplants, which
in the adult stage becomes expressed as changes in behavior (e.g., gregariousness,
heightened activity, and migration), reproduction, and hormonal levels following
emergence. Perhaps only those larvae that engage in crawling behavior will migrate
as adults. It has been experimentally determined that last instar lepidopteran
larvae reared in crowded conditions are more resistant to starvation than are those
reared in isolation (Iwao 1962). Large numbers of V. cardui larvae per plant hasten
the deterioration of their foodplants, coupled with a more rapid desiccation of
annuals like Amsinckia compared to perennials. Larvae crawled in straight lines
away from hostplants because they were no longer suitable food sources, not
because of excessive larval density. When various taxa of lepidopterous larvae
were reared in crowded conditions, they developed more rapidly, had a higher
fat content, developed polyphagous feeding habits, increased feeding activity, were
more active, nervous, aggressive, and cannibalistic, and pupated more simulta-
neously than did solitary larvae (Long 1953; Iwao 1962). At the Bishop site,
crowded V. cardui larvae similarly displayed elevated activity, nervousness, some
cannibalism, and pupated relatively simultaneously. Migrant V. cardui, at eclo-
sion, have a very large fat-body reserve and undeveloped reproductive organs (cf.
Williams 1925; Herman and Dallmann 1981). No matings whatsoever were ob-
served at the Bishop emergence site or the June nectaring aggregations. In Aus-
tralian Vanessa kershawi McCoy, a close relative of V. cardui, laboratory exper-
iments suggest that short daylengths greatly affect the sex ratio in favor of females,
thus potentially enchancing the colonizing ability of early spring migrants (James
1987).

A key factor in Lepidoptera migration is juvenile hormone (JH). JH in insects
is known to regulate feeding, growth, development, metamorphosis, reproduction,
diapause, and behavior (Bowers 1991). Wild-caught, fall-migrating V. cardui adults
had low levels of JH in their haemolymph, preventing reproductive maturation
(adult reproductive diapause), with significant reproductive maturation occurring
when JH was injected (Herman and Dallmann 1981). In lepidopterous larvae
reared under crowded conditions, haemolymph titers of JH are reduced and result
in a more rapid generation time compared with isolated larvae (Yagi 1976). In
some insects, it is known that JH levels decline during starvation and are elevated
by nutrition (Benz 1972; Novak 1975; Rankin 1978). A few plants are known to
contain antijuvenile hormones (AJH) which lower the insect’s JH levels (Bowers
1991). However, some species of Boraginaceae examined for AJH’s proved neg-
ative (W. S. Bowers in litt.), and AJH’s probably have little influence on migratory
V. cardui since it utilizes such a wide variety of larval hostplants. The corpus
allatum (CA), which produces JH, is posteriorally connected to the brain and
embryonically arises “‘as ectodermal invaginations in the area between the man-
dibular and maxillary pleurites” (Novak 1975, p. 127). Nervousness is known to
inhibit CA activity in phytophagous insects (Novak 1975). JH is synthesized in

MIGRATIONS OF VANESSA CARDUI IN INYO COUNTY 167

the endoplasmic reticulum and is absorbed and dissolved by lipid droplets that
are released into the haemolymph via gradual extrusion through the surface of
the CA (Slama et al. 1974, p. 27; Novak 1975, p. 127). Adipokinetic hormone
in V. cardui metabolizes fat-body lipid reserves by releasing haemolymph-cir-
culating diglyceride lipids, thus providing the fuel necessary for its migration flights
(cf. Herman and Dallmann 1981, Herman 1993).

The delay in reproductive maturation means that migrating adults are able to
widely disperse, thus escaping adverse climates and deteriorating foodplants in
the emergence area, before mating and oviposition can begin (McDonald and
Cole 1991). Nectaring at flowers along the migration route is the most likely cause
of elevating JH levels in V. cardui which induces eventual reproductive matu-
ration. This behavior was directly observed in the central Mojave Desert in mid-
April of 1973, when many V. cardui adults both migrated and nectared in the
afternoon and avidly nectared in the early morning on wildflowers carpeting the
desert (Shields 1974). Also, Shapiro (1980) has found that return migrations of
northern California V. cardui, which frequently nectar, contain females with large
fat-bodies and reproductive immaturity early in the fall, with females reaching
reproductive maturity later in the fall. It has been experimentally determined that
amino acids obtained from nectar-feeding are utilized in gamete formation by
adult butterflies, with nectar sugars increasing total egg production (Murphy et
al. 1983). Also, nectar sugars replenish the flight fuel after lipid reserves are
depleted (DeVries and Dudley 1990).

The migration phenomenon in V. cardui most likely evolved as a means of
escaping seasonally unfavorable arid conditions, which reached a Neogene max-
imum during late Upper Miocene times in western North America (see Axelrod
1980, pp. 101-103). This would by phylogenetically possible since a close ancestor
of V. cardui already existed by lower Middle Miocene times, in the North Caucasus
(Nekrutenko 1965).

Acknowledgments

In addition to those already mentioned in the text, we thank the following
individuals for contributing some records: George T. Austin, Richard Bailowitz,
James P. Brock, Donald Constans, John F. Emmel, Thomas C. Emmel, Doris
Fredendall, Meredith Foster, Steven Foster, the late John S. Garth, Cris Guppy,
David Howell, Beverly Kohfield, Robert Larson, C. Riley Nelson, R. P. Nelson,
Richard H. Smith, Jr., and Frank Stewart. Useful comments on the manuscript
were provided by Richard A. Arnold, Thomas E. Dimock, Julian P. Donahue,
John F. Emmel, Glenn A. Gorelick, Daniel A. Guthrie, and Edward S. Ross.

Literature Cited

Abbott, C. H. 1951. A quantitative study of the migration of the Painted Lady Butterfly, Vanessa
cardui L. Ecology, 32:155-171.

Axelrod, D. I. 1980. Contributions to the Neogene paleobotany of central California. Univ. Calif.
Publ. Geol. Sci., 121:1—212, 21 pls.

Benz, G. 1972. Juvenile hormone breaks ovarian diapause in two Nymphalidae butterflies. Exper-
ientia, 28:1507.

Bowers, W.S. 1991. Insect hormones and antihormones in plants. Pp. 431-456 in Herbivores: their
interactions with secondary plant metabolites, 2E, v. 1: The chemical participants. Academic
Press.

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Clench, H. K. 1966. Behavioral thermoregulation in butterflies. Ecology, 47:1021—1034.

DeVnies, P. J., and R. Dudley. 1990. Morphometrics, airspeed, thermoregulation, and lipid reserves
of migrating Urania fulgens (Uraniidae) moths in natural free flight. Physiol. Zool., 63:235-
251.

Giuliani, D., and O. Shields. 1993. Experiments with migrating Vanessa cardui. News Lepid. Soc.,
1993:80-82.

Hammad, S. M., and A. M. Raafat. 1972. The biology of the Painted Lady Butterfly, Vanessa
(Pyrameis) cardui L. Bull. Soc. Ent. Egypte, 56:15-20.

Herman, W. S. 1993. The endocrinology of the Monarch Butterfly. Pp. 143-146 in Biology and

Conservation of the Monarch Butterfly. (S. B. Malcolm and M. P. Zalucki, eds.), Natural History

Museum of Los Angeles County, Sci. Ser. 38:419 pp.

, and S. H. Dallmann. 1981. Endocrine biology of the Painted Lady Butterfly Vanessa cardui.
J. Insect Physiol., 27:163-168.

Iwao, S. 1962. Studies on the phase variation and related phenomena in some lepidopterous insects.
Memoirs of the College of Agriculture, Kyoto Univ., 84:1—80, 3 pls.

James, D.G. 1987. Effects of temperature and photoperiod on the development of Vanessa kershawi
McCoy and Junonia villida Godart. J. Aust. Ent. Soc., 26:289-292.

Johnson, N. K., and C. Cicero. 1986. Richness and distribution of montane avifaunas in the White-
Inyo region, California. Univ. Calif. White Mtn. Res. Sta. Symp., 1:137-159.

Larsen, T. B. 1976. The importance of migration to the butterfly faunas of Lebanon, East Jordan,
and Egypt. Notul. Ent., 56:73—83.

Long, D. B. 1953. Effects of population density on larvae of Lepidoptera. Trans. R. Ent. Soc. Lond.,
104:543-585, 6 pls.

McDonald, G., and P. G. Cole. 1991. Factors influencing oocyte development in Mythimna convecta
(Lepidoptera: Noctuidae) and their possible impact on migration in eastern Australia. Bull.
Ent. Res., 81:175-184.

Murphy, D. D., A. E. Launer, and P. R. Ehrlich. 1983. The role of adult feeding in egg production
and population dynamics of the Checkerspot Butterfly Euphydryas editha. Oecologia, 56:257-
263.

Myres, M. T. 1985. A southward return migration of Painted Lady Butterflies, Vanessa cardui, over
southern Alberta in the fall of 1983, and biometeorological aspects of their outbreaks into North
America and Europe. Can. Field-Nat., 99:147-155.

Nekrutenko, Y. P. 1965. Tertiary nymphalid butterflies and some phylogenetic aspects of systematic
lepidopterology. J. Res. Lepid., 4:149-158.

Novak, V. J. A. 1975. Insect hormones. Chapman & Hall, London, 600 pp.

Rankin, M. A. 1978. Hormonal control of insect migratory behavior. Pp. 5-32 in Evolution of insect
migration and diapause. (H. Dingle, ed.), Springer-Verlag, New York, 284 pp.

Shapiro, A.M. 1980. Evidence for a return migration of Vanessa cardui in northern California. Pan-
Pac. Ent., 56:319-322.

Shields, O. 1974. Toward a theory of butterfly migration. J. Res. Lepid., 13:217—238.

Slama, K., M. Romanuk, and F. Sorm. 1974. Insect hormones and bioanalogues. Springer-Verlag,
New York & Wien, 477 pp.

Williams, C. B. 1925. The migrations of the Painted Lady Butterfly. Nature, 115:535-—537.

Yagi, S. 1976. The role of juvenile hormone in diapause and phase variation in some lepidopterous
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& London, 572 pp.

Accepted for publication 6 May 1994.

Bull. Southern California Acad. Sci.
94(2), 1995, pp. 169-171
© Southern California Academy of Sciences, 1995

Research Notes

Salinity Tolerance of Cletocamptus deitersi (Richard 1897) and its
Presence in the Salton Sea

Deborah M. Dexter

Department of Biology, San Diego State University,
San Diego, California 92182

The Salton Sea supports a limited diversity of aquatic invertebrates, and until
recently only one copepod species, the cyclopoid Apocyclops dengizicus, had been
reported from it (Dexter 1993). The presence of harpacticoid copepods has not
been reported in the scientific literature, but at least two species have been found
within the Salton Sea. In 1983 I. E. Bayly and S. H. Hurlbert collected a harpac-
ticoid in shallow water (salinity 36-38 g/L) at the north end of the Salton Sea.
This species was identified as Nitocra dubia by R. Hammond (in litt. to S. H.
Hurlbert).

In 1990 I began salinity tolerance studies on Apocyclops dengizicus. Plankton
tows collected in Oct. 1990 from Red Hill Marina, Salton Sea (salinity 43 g/L)
in water approximately 1 m deep were used to establish cultures at various sa-
linities (Dexter 1993). Within 60 days, in cultures maintained at 73 g/L a har-
pacticoid copepod became very abundant, while A. dengizicus became scarce.
This harpacticoid was not present in cultures from the same source maintained
at lower salinities. I hypothesize that at 73 g/L a few individuals avoided predation
by Apocyclops dengizicus, and increased in density as the numbers of A. dengizicus
declined through time at this high salinity.

This new harpacticoid was identified by R. H. Hammond as Cletocamptus
bicolor, a species which has been synonymized by Yeatman (1963) with C. deitersi.
Fleeger (personal communication) confirmed that the Salton Sea Cletocamptus is
C. deitersi. C. deitersi is widely distributed throughout the world (Chandler and
Fleeger 1987, Dussart and Defaye 1990, Fleeger 1980, Lang 1948, Yeatman 1963).
It is reported from North America (Louisiana, Massachusetts, Texas), Central
America (Guatemala, Nicaragua), the Caribbean (Bermuda, Cuba, Haiti), South
America (Argentina, Ecuador, Uruguay), Hawaii, China, Australia, Ethiopia, and
Israel. Habitats for this species include brackish coastal ponds, mangroves, es-
tuaries, salt marshes, inland bays, saline lakes, freshwater lakes, and freshwater
rivers. C. deitersi is characterized as an errant deposit feeder which grazes algae
and detritus attached to sediment particles (Chandler and Fleeger 1987).

Water collected at the Salton Sea was evaporated outdoors until a salinity of
136 g/L was obtained. This water was filtered through a 35 wm mesh net and
diluted with de-ionized water to obtain the desired salinities. Cultures of 0.5 g/L
salinity were produced by combining Salton Sea water, de-ionized water, and
filtered pond water (as source of phytoplankton). Salinity was determined with a
Reichert-Jung refractometer, and final salinity determined using correction factors
for Salton Sea ionic compositions.

Harpacticoid copepods collected during Oct. 1990 were separated from cyclo-

169

170 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES

poids by maintenance at salinities between 68-73 g/L which killed the cyclopoids.
Approximately 100 ml of concentrated harpacticoid culture was introduced into
aerated plastic containers with 1.9 L of Salton Sea water adjusted to various
salinities. Copepods were introduced without acclimation, and often without rep-
lication.

A series of culture experiments were run. A total of 18 salinities were used
ranging from 0.5 to 119 g/L. Culture salinity and number of replications (in
parentheses) were: 0.5 (4), 1 (2), 6 (1), 13 (1), 17 (1), 34 (1), 45 (1), 62 (1), 68 (1),
74 (1), 80 (1), 85 (4), 90 (1), 96(2), 102 (4), 107 (4), 113 (1) and 119 (2) g/L.

Salinities were monitored every 15 days and adjusted by addition of de-ionized
water. Phytoplankton was present at all salinities and its growth was encouraged
with approximately 0.2 grams biweekly of fish food pellets (Pet Co., Koi’s Choice).
At 30, 60, 90, and 120 days, each culture was gently filtered through a 35 wm
mesh net, examined under a dissecting microscope for abundance and presence
of life history stages, and returned to its respective container.

C. deitersi cultures at salinities from 0.5 to 80 g/L supported relatively high
densities of individuals of all life history stages (nauplii, copepodites, males,
females, and gravid females) throughout the duration of the 120 day experiment
(Table 1). C. deitersi cultured at salinities between 85 to 96 g/L steadily declined
in density, but some individuals were alive at the end of 120 days. Mating was
observed at salinities from 0.5 to 107 g/L, but apparently was unsuccessful at
salinities greater than 85 g/L. Copulating pairs remained attached for at least
several hours. Reproduction was continuous during the 3 year period this species
was maintained in laboratory cultures at salinities between 20 to 60 g/L.

Harpacticoids are considered an important food source for early stages of ben-
thic fish and are often used in aquaculture systems to provide food for hatchery
fish. The ease with which C. deitersi is cultured in the laboratory, at various
salinities, without the presence of sediment, suggests it as a good candidate for
this purpose.

The cosmopolitan distribution of this species suggests its ability to tolerate a
wide variety of habitats, temperatures, and salinities. But such a distribution could
also indicate that a number of morphologically indistinguishable sibling species
are present. This study showed that the Salton Sea population of C. deitersi is
very tolerant of a wide range of salinities in culture, from basically fresh water to
high salinities. This favorable attribute may be of particular importance to this
species, given that the salinity of the Salton Sea may reach 90 g/L by the year
2010 (Black 1983) if mandated water conservation programs are followed. The
presence of this species within the Salton Sea is possibly a result of deliberate
introduction of the seagrass Diplanthera wighti from Texas by California Fish
and Game in 1957, although flora and fauna were also introduced from the Gulf
of California and from the California coast (Linsley and Carpelan 1961).

A. dengizicus is the dominant copepod within the Salton Sea and normally there
would be little interaction between this planktonic species and the benthic C.
deitersi; the sediment habitat of the latter would limit or prevent predation. A.
dengizicus is an effective predator of naupliar stages of Artemia in culture con-
ditions (Hammer and Hurlbert 1992), and on C. deitersi in laboratory cultures
without sediment. However, the upper limit of salinity tolerance differs in these
species. Reproduction in A. dengizicus becomes limited at salinities exceeding 57

SALINITY TOLERANCE OF CLETOCAMPTUS DEITERSI 171

Table 1. Salinity tolerance of Cletocamptus deitersi.

Abundance! at

Life history Salinity SSS Een tS Sete TEP IS CEES SRE ETE
stage g/liter 30 days 60days 90days 120 days
Gravid females _ 0.5, 1, 6, 13, 17, 34, 45, 62, 68, 74,80 +++ +++ spabt pape
85, 90 +++ ++ + ste
96, 102, 107 + 0 0 0
113, 119 0 0 0 0
_ Nauplii 0.5, 1, 6, 13, 17, 34, 45, 62, 68, 74,80 +++ +++ +++ Poet
85, 90 aPar + abe 0
96, 102, 107 + 0 0 0
113, 119 0 0 0 0
Copepodids 0.5, 1, 6, 13, 17, 34, 45, 62, 68, 74,80 +++ Sea stalls pdb
85, 90 ++ ++ + +
96 ++ + + +
102, 107 + + + 0
113 + 0 0 0
119 0 0 0 0

1 Abundance categories are denoted as follows: 0, not seen; +, 1—5/liter; ++, 6—2O/liter; +++,
>20/liter.

g/L (Dexter 1993), while C. deitersi appears unaffected in salinities up to 80 g/L.
I predict that C. deitersi will become more abundant in the shallow water plankton
and benthos as salinities increase at the Salton Sea.

Literature Cited

Black, G. F. 1983. Prognosis for water conservation and the development of energy resources at the
Salton Sea: destruction or preservation of this unique ecosystem? Pp. 363-382 in Aquatic
Resources Management of the Colorado River Ecosystem. (V. D. Adamas and V. A. Lamarra,
eds.), Ann Arbor Science, 697 pp. 5

Chandler, G. T., and J. W. Fleeger. 1987. Facilitative and inhibitory interactions among estuarine
meiobenthic harpacticoid copepods. Ecology, 68:1906-1919.

Dexter, D. M. 1993. Salinity tolerance of the copepod Apocyclops dengizicus (Lepeschkin, 1900), a
key food chain organism in the Salton Sea, California. Hydrobiologia, 267:203—209.

Dussart, B., and D. Defaye. 1990. Repertoire mondial des crustacés copepods des eaux int€rieures.
Crustaceana. Supplement 16, III. Harpacticoides, 384 pp.

Fleeger, J. W. 1980. Morphological variation in Cletocamptus (Copepoda: Harpacticoida), with
description of a new species from Louisiana salt marshes. Trans. Amer. Microscop. Soc., 99:
25-31.

Hammer, U. T., and S. H. Hurlbert. 1992. Is the absence of Artemia determined by the presence
of predators or by lower salinity in some saline waters? Pp. 91-102 in Aquatic ecosystems in
semi-arid regions: implications for resource management. (R. D. Roberts and M. L. Bothwell,
eds.), N.H.R.I. Symposium Series 7, Environment Canada, Saskatoon.

Lang, C. 1948. Monographie der Harpacticiden. Nordiska Bokhandeln, Stockholm, Sweden. 2 vol-
umes, 1682 pp.

Linsley, R. H., and L. H. Carpelan. 1961. Invertebrate fauna, the ecology of the Salton Sea, California,
in relation to the sportfishery. Calif. Fish and Game Fish Bull., 113:43—-47.

Yeatman, H.C. 1963. Some redescriptions and new records of littoral copepods for the Woods Hole,
Massachusetts region. Trans. Amer. Microscop. Soc., 82:197—209.

Accepted for publication 10 August 1994.

Bull. Southern California Acad. Sci.
94(2). 1995, pp. 172-175
© Southern California Academy of Sciences. 1995

Z
First Record of Madracis sp. cf. M. pharensis (Heller, 1868)
on Continental Eastern Pacific Shores

Héctor Reyes Bonilla.* Eleuterio Martinez Olguin,
and Gabriela Anaya Reyna

Universidad Auténoma de Baja California Sur,
Departamento de Biologia Marina,
Laboratorio de Ecologia del Bentos, Apartado Postal 19-B,
CP 23080. La Paz, B.C.S., México
*Centro de Investigaci6n Cientifica y de
Educaci6n Superior de Ensenada,
Departamento de Ecologia, Apartado Postal 2732,
Ensenada, B.C., México

The scleractinian coral Madracis Milne Edwards and Haime, 1848 is worldwide
in distribution and has a geologic range of Upper Cretaceous to Recent (Colgan
1990). In the eastern Pacific Ocean it has been recorded for the Eocene of Wash-
ington (U.S.A.) and Chiapas (México) (Durham 1942: Frost and Langenheim
1974), but otherwise is known only from the Recent.

There are two nominal species of Madracis reported in the eastern Pacific.
Madracis asperula Milne Edwards and Haime, 1850, was found at Islas Galapagos,
Ecuador (0°N) (Durham and Barnard 1952). The second species, originally iden-
tified as Madracis sp., was collected at Galapagos and Isla Gorgona, Colombia
(5°N) (Durham and Barnard 1952). Later. these specimens and several others
found at Islas Galapagos and Rocas Alijos, México (24°N), were identified as M.
pharensis (Heller 1868) by Wells (1983) or as Madracis sp. cf. M. pharensis (Cairns
1991: Wilson in press). M. pharensis was originally known from the eastern
Atlantic and Mediterranean Sea, but had also been reported in Bahamas, Jamaica,
Netherland Antilles, Panama. Belize, Colombia and Brasil (Laborel 1967 fide
Zibrowius 1980; Porter 1972: Wells 1973; Laborel 1974; Erhardt and Werding
1975: Reed 1985: Jackson et al. 1985: Kobluk and Lisenko 1987; van Moorsel
1988). Some of these records had been taken as dubious by Zibrowius (1980)
because the true degree of morphological variability of American coralla is un-
known.

This paper presents the first record of Madracis sp. cf. M. pharensis on the
western continental shores of America. The specimens were collected in October,
1991 at the Cabo Pulmo reef, east coast of Baja California Sur, México (23.5°N,
109.5°W). This is the northernmost reef in the eastern Pacific and has been de-
scribed elsewhere (Squires 1959: Brusca and Thomson 1975; Reyes Bonilla 1993).
The coral fauna of the reef consists of 10 species of hermatypic corals and one
ahermatype, Tubastraea coccinea Lesson, 1829 (Reyes Bonilla 1993). Voucher
specimens are deposited in the Museo de Historia Natural de la Universidad
Automoma de Baja California Sur (MHN-UABCS) (La Paz, B.C.S., México) and
in the Invertebrate Paleontology Section, Natural History Museum of Los Angeles
County (Los Angeles, CA, U.S.A.).

The coralla of Madracis sp. cf. M. pharensis were collected at a depth of 16 m

172

MADRACIS IN THE EASTERN PACIFIC 173

from crevices in a stone wall located in the outer central section of the reef, locally
known as “Los Cantiles.”’ The larger coralla were growing under a large (> 40 cm
largest diameter) colony of Pavona gigantea Verrill, 1869. Other small coralla
were seen, but not collected, on the reef substrate (granite) at 3 m depth, in the
south section of the reef. Elsewhere in the eastern Pacific (Galapagos, Gorgona,
Rocas Alijos), this form was found at depths from 24 to 343 m, whereas in the
Atlantic, some finds were as shallow as 2 m (Durham and Barnard 1952; Zibrowius
1980; Wells 1983; Cairns 1991; Wilson in press).

Wells (1983) and Cairns (1991) agree that in the Pacific, the southern distri-
butional limit of M. pharensis or Madracis sp. cf. M. pharensis is Isla Gorgona,
Colombia, based on a specimen figured by Durham and Barnard (1952) but they
have overlooked another record of the species from off the coast of Chile (25°44’S,
85°25'W) at Nazca Ridge. Several corolla were found, apparently live, on a fossil
(Pleistocene?) Porites dredged from a reported depth of 210 to 227 m (Durham
1980). The coral was identified as Stylophora sp. (?) (Allison et al. 1967), and
reidentified as Madracis sp. cf. M. pharensis by John W. Wells in 1974 (Durham
1980, p. 69). Later studies have shown that the actual depth of the guyot where
the corals were dredged is 167 m and it was dated at surface level from 29.2 to
7.2 m.y. ago (Newman and Foster 1983).

The collection deposited at the MHN-UABCS consists of 27 corolla, most of
them with 3 to 10 corallites. The largest one (23 mm in diameter) has 90 corallites,
and probably was younger than a year old, since the extension rate of M. pharensis
is 0.7 to 13.3 mm/month in the Caribbean (van Moorstel 1988). All of the colonies
are plocoid and encrusting, growing as a calcareous lamina on carbonated surfaces.
The calices are 2.06 mm in diameter (N = 15; SE = 0.11), polygonal and have
10 septa in the first cycle, which are exsert in most of the corallites. The secondary
septa are absent or reduced to a few irregular spines on the calicular wall, but in
one corallum they are well developed and conspicuous. When they occur, the
secondary septa are exsert and costae are present. Most of the calices have a
central, styliform columella, fused near the basal plate with a series of spines or
paliform lobes, which are separated by a notch from the septa. The intercalicular
coenosteum is 0.2 mm long in average and has a spinose surface.

Looking at the main skeletal characters (styliform columella, paliform lobes,
septa exsert, polygonal calices), the specimens from Cabo Pulmo are similar to
the ones described in the literature, and so may be considered M. pharensis or
its eastern Pacific form. Notwithstanding, Wilson (in press) noticed a recurrent
difference in the secondary septa among Atlantic and Pacific specimens of the
nominal species. Most of the corallites figured by Zibrowius (1980) and collected
in the Atlantic Ocean and the Mediterranean Sea, do have distinct secondary
septa even if the corallum is small. The ones from Galapagos (figured in Wells
1983 and Cairns 1991), Rocas Alijos (Wilson in press) and Cabo Pulmo have
only traces of secondary septa.

The paucity of skeletal elements in this genera has forced taxonomists to look
for very general differences to separate species. For example, the species M. kirbyi
Veron and Pichon, 1976 was differentiated from M. pharensis because of the
absence of secondary septa of the former species (Veron and Pichon 1976; Veron
1986). Similarly, Wells (1973) and Zlatarski and Martinez Estalella (1982) sep-
arated species of Madracis on the basis of the secondary septa and the growth

174 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES

form of the corallum. Considering that the first character is different arnong M.
pharensis and the Madracis specimens from the eastern Pacific, we believe that
there is enough evidence to support Wilson and even to suggest that the eastern
Pacific Madracis is a different species.

To conclude, the current distributional range of Madracis sp. cf. M. pharensis
in the eastern Pacific is from Rocas Alijos (24°N) and Cabo Pulmo (23°N) to
Nasca Ridge (25°S). A direct examination of the specimens collected at Pulmo
and Alijos, together with comparisons of the figured specimens from Islas Ga-
lapagos and Isla Gorgona, allow us to suggest that the skeletal differences among
M. pharensis and Madracis sp. cf. M. pharensis are important and consistent
enough that they may represent two different species.

Acknowledgments

The specimens of Madracis were collected with the assistance of Sr. Ricardo
Castro, resident of Cabo Pulmo. Logistic support was provided by Oscar Arizpe
Covarrubias (Departamento de Biologia Marina, UABCS) and Luis E. Calderon
Aguilera (Departamento de Ecologia, CICESE). Edward C. Wilson (Curator, In-
vertebrate Paleontology Section, Natural History Museum of Los Angeles County)
allowed us to compare the specimens from Pulmo with the ones collected at Rocas
Alijos and discuss a draft of the paper and most of the ideas here sustained. Many
thanks to J. Wyatt Durham and an anonymous reviewer for important additions,
suggestions and comments to the paper. The report was originally included in a
thesis presented by the first author, in partial fulfillment of a Master in Science
degree. He was supported by a scholarship (No. 61593), granted by Consejo
Nacional de Ciencia y Tecnologia de México (CONACYT).

Literature Cited

Allison, E. C., J. W. Durham, and L. W. Mintz. 1967. New southeast Pacific echinoids. Occ. Pap.
Calif. Acad. Sci., 62, 23 pp.

Brusca, R. C.,and D. A. Thomson. 1975. Pulmo reef: the only “coral reef” in the Gulf of California.
Ciencias Marinas, 1:37—53.

Cairns, S.D. 1982. Stony corals (Cnidaria: Hydrozoa, Scleractinia) of Carrie Bow cay, Belize. Smiths.

Contr. Mar. Sci., 12:271-302.

. 1991. A revision of the ahermatypic Scleractinia of the Galapagos and Cocos islands. Smiths.

Contr. Zool., 504, 32 pp.

Colgan, M. W. 1990. El Nino and the history of eastern Pacific reef building. Pp. 183—232 in Global
ecological consequences of the 1982-83 El Nino-Southern Oscillation. (P. W. Glynn, ed.),
Elsevier Oceanographic Series, Amsterdam.

Durham, J. W. 1942. Eocene and Oligocene coral faunas of Washington. Jour. Paleont., 16:84—-104.

1980. A new fossil pocillopora (coral) from Guadalupe Island, México. Pp. 63-70 in The

California Islands. Proceedings of a Multidisciplinary Symposium (R. L. Bowman, ed.), Santa

Barbara Museum of Natural History.

, and J. L. Barnard. 1952. Stony corals of the eastern Pacific collected by the Velero III and
Velero IV. Allan Hancock Pac. Exped., 16, 110 pp.

Erhardt, H., and B. Werding. 1975. Los corales (Anthozoa e Hydrozoa) de la Bahia de Santa Marta,
Colombia. Museo del Mar. Fac. de Cienc. del Mar. Fundacion Univ. de Bogota Jorge Tadeo
Lozano, Bol., 7:3—50.

Frost, S. H., and R. L. Langenheim, Jr. 1974. Cenozoic reef biofacies. Tertiary larger Foraminifera
and scleractinian corals from Chiapas, México. North Ill. Univ. Press, 388 pp.

Jackson, J. B. C., J. E. Winston, and A. G. Coates. 1985. Niche breadth, geographic range and
extinction of Caribbean reef-associated cheilostome Bryozoa and Scleractinia. Proc. 5th Int.
Coral Reef Cong., Tahiti, 4:151-158.

MADRACIS IN THE EASTERN PACIFIC 175

Kobluk, D. R., and M. A. Lysenko. 1987. Southern Caribbean cryptic scleractinian corals from
Bonaire, N.A. Palaios, 2:205-218.

Laborel, J. 1974. West african reef corals: an hypothesis on their origin. Proc. 2nd Int. Coral Reef
Symp., Brisbane, 1:425-443.

Newman, W. A., and B. A. Foster. 1983. The Rapanuian faunal district (Easter and Sala y Gémez):
in search of ancient archipelagos. Bull. Mar. Sci., 33:633-644.

Porter, J. W. 1972. Ecology and species diversity of coral reefs on opposite sides of the Isthmus of
Panama. Bull. Biol. Soc. Wash., 2:89-116.

Reed, J. K. 1985. Deepest distribution of Atlantic hermatypic corals discovered in the Bahamas.
Proc. 5th Int. Coral Reef Cong., Tahiti, 6:249-254.

Reyes Bonilla, H. 1993. Estructura de la comunidad, influencia de la depredacion y biologia pob-
lacional de corales hermatipicos del arrecife de Cabo Pulmo. M. in Sc., Thesis. Centro de
Investigacion Cientifica y Educacion Superior de Ensenada, 169 pp.

Squires, D. A. 1959. Corals and coral reefs of the Gulf of California. Bull. Am. Mus. Nat. Hist.,
118:371-431.

van Moorsel, G.W.N.M. 1988. Early maximum growth of stony corals (Scleractinia) after settlement
on artificial substrata on a Caribbean reef. Mar. Ecol. Prog. Ser., 50:127-135.

Veron, J. E.N. 1986. Corals of Australia and the Indo Pacific. Agnus and Robertson, 644 pp.

, and M. Pichon. 1976. Scleractinia of eastern Australia. Part 1. Families Thamnasteriidae,

Astrocoeniidae, Pocilloporidae. Aust. Inst. Mar. Sci. Monog. Ser. 1, 56 pp.

Wells, J. W. 1973. New and old scleractinian corals from Jamaica. Bull. Mar. Sci., 23:16—58.

1983. Annotated list of the scleractinian corals of the Galapagos. Pp. 211-291 in Corals and
coral reefs of the Galapagos Islands. (P. W. Glynn and G. M. Wellington, eds.), Univ. of

California Press.

Wilson, E. C. In press. Stony corals from Rocas Alijos. in Rocas Alijos: scientific results from the
Cordell Expeditions. (R. W. Schmieder, ed.).

Zibrowius, H. 1980. Les Scléractiniaires de la Méditerranée et de |’Atlantique Nord-Oriental. Mém.
Inst. Océan. Monaco, 11, 284 pp.

Ziatarski, V. N., and N. Martinez Estalella. 1982. Les Scléractiniaires de Cuba. Acad. Bulg. de Scienc,
472 pp.

Accepted for publication 24 February 1994.

Bull. Southern California Acad. Sci.
94(2), 1995, pp. 176-178
© Southern California Academy of Sciences, 1995

7a

Distribution and Host for Four Symbiotic Crustaceans of the
Mexican Pacific (Stomatopoda and Decapoda)

Ernesto Campos

Facultad de Ciencias, Universidad Autonoma de Baja California,
Apartado Postal 2300, Ensendada,
Baja California 28000, México

E. F. Félix-Pico and F. Garcia-Dominguez

CICIMAR-IPN, Apartado Postal 592, La Paz,
Baja California Sur, México

Collecting efforts during 1990-1994 in the Mexican Pacific resulted in the
discovery of new hosts and/or range extensions for four species of symbiotic
crustaceans. The specimens have been deposited in the Invertebrate Collection
of the Facultad de Ciencias, Universidad Autonoma de Baja California. Abbre-
viations are: BC, Baja California; BCS, Baja California Sur; GC, Gulf of California.

Order Stomatopoda
Family Nannosquillidae
Alachosquilla digueti (Coutiére 1905)

Previous distribution. —From Guaymas, Sonora, and Cabo San Miguel, BC (GC)
to Isla Taboga, Panama (Hendrickx and Salgado-Barragan 1991).

Material examined. —1 male, beach at Rancho Punta Estrella, km 13 San Felipe-
Puertecitos road, San Felipe, BC (lat 30°55’N, long 114°45’W); tidal pool, free-
living.

Proposed common name. —Pacific dwarf squilla.

Remarks. — Because it features two dark spots on the telson, the Atlantic species
A. floridensis Manning, is considered distinct from A. digueti, a single spot species
(Schotte and Manning 1993). Our specimen agrees with this, but specimens of
digueti from the Gulf of California studied by Hendrickx and Salgado-Barragan
(1991, fig. 39D, pl. 30E) also possess two spots on the telson. Additional study
is necessary to decide whether these two species are synonyms or not, as suggested
by Manning (1963, 1974). Alachosquilla digueti has been recorded as a commensal
in the burrow of Balanoglossus, along with a polynoid worm, Lepidasthenia digueti
Gravier (Coutiére 1905; Schmitt 1940).

Order Decapoda
Family Alpheidae
Leptalpheus mexicanus Rios and Carvacho 1983
Previous distribution and host.—Known only from the type locality, Estuary of
the Mulegé River, BCS (GC); in burrows of the mud shrimp Upogebia dawsoni
Williams (Rios and Carvacho 1983).
Material examined. —1 male, 3 females, Mangrove at El Conchalito, Ensenada
La Paz, in front of Centro Interdisciplinario de Ciencias Marinas-—Instituto Pol-

176

SYMBIOTIC CRUSTACEANS OF THE MEXICAN PACIFIC 177

itécnico Nacional, La Paz Bay, La Paz, BCS (lat 24°10’N, long 110°25’W), 4 June
1992; in burrows of U. dawsoni.

Proposed common name. — Mexican pistol shrimp.

Remarks. —Rios (1992) and Wicksten and Hendrickx (1992), based on a per-
sonal communication, recorded L. mexicanus from the Colombian Pacific. Be-
cause this species is taxonomically poorly known we recommend that material
be re-examined to confirm this range extension. Leptalpheus mexicanus was col-
lected in burrows of Upogebia dawsoni constructed in a sandy-mud bottom. Other
burrowing species collected in El Conchalito were the goneplacid crab Malacoplax
californiensis (Lockington) and the fiddler crab Uca latimanus (Rathbun) but L.
mexicanus was not found associated with these species.

Family Pinnotheridae
Juxtafabia mulinarum (Rathbun 1918)

Distribution and previous hosts. —Santa Clara, Sonora, (GC), México to Costa
Rica, in the bivalves Chione californiensis (Broderip), C. fluctifraga (Sowerby),
C. tumens (Verril), Polymesoda inflata (Phillipi), Protothaca grata (Say) and Ta-
gelus affinis (C.B.Adams) (Campos 1993).

Material examined and new host.—1 female (hard stage), La Paz Bay, in front
of Hotel Grand Baja, La Paz, BCS (lat 24°10'N, long 110°25’W), July—August
1991; in the clam Laevicardium elatum (Sowerby).

Common name.—Clam Crab (Campos 1993).

Remarks. —The clam also hosted a juvenile of the Pacific Pen shrimp Pontonia
pinnae Lockington (see below). The general morphology of the female in hard
stage is almost identical to the male in hard stage described by Campos (1993),
including the fusion of the abdominal somites 4-5. Presence of gonopods and a
wider abdominal somite 3 allows recognition of male.

Family Palaeomonidae
Pontonia pinnae Lockington 1878

Distribution and previous host.—Upper GC to Colombia and west coast of BC
to Bahia Tortugas, BCS; in the Pen Shells Pinna rugosa (Sowerby) and Atrina
tuberculosa (Sowerby) (Campos-Gonzalez 1988; Campos et al. 1992; Lemaitre
and Alvarez-Leon 1992).

Material examined and new hosts.—1 juvenile, Bahia de la Paz, in front of
Hotel Grand Baja, La Paz, BCS, August 1989; in the clam Laevicardium elatum. —
5 juveniles, Espiritu Santo Island, BCS (lat 25°30’N, long 1 10°21'W), 19 September
1991; in the clam Megapitaria aurantica (Sowerby).

Proposed common name. —Pacific Pen shrimp.

Remarks.—As this represents a first record of P. pinnae in species of clams
(Cardiidae and Veneridae), it should be noted that all shrimps were juveniles and
that these clams could serve only as occasional hosts.

Acknowledgments

This work has been supported by the projects “‘Sistematica de Crustaceos Sim-
biontes de Baja California” of the Facultad de Ciencias, U.A.B.C. and “Estudio
de poblaciones de bivalvos en Bahia de La Paz, Bahia Magdalena y Bahia Con-
cepcion, BCS” of the CICIMAR-IPN, and by agreement CONACyT-UABC

178 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES

431100-5-3587N. E. F. Félix-Pico y F. Garcia-Dominguez are fellows of the
““ComisiOn de Operacion y Fomento de Actividades Académicas” of the Instituto
Politécnico Nacional, E. Campos is a fellow of the ‘Programa de Estimulo al
personal Académico 94/95,” of the Universidad Autonoma de Baja California.
Thanks to anonymous reviewers for their constructive comments on the manu-
script.

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(Crustacea: Brachyura: Pinnotheridae). Proc. Biol. Soc. Wash., 106(1):92-101.

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crustaceans of the Mexican Pacific (Decapoda and Isopoda). Proc. Biol. Soc. Wash., 105(4):

753-759.

Campos-Gonzalez, E. 1988. New molluscan host for two shrimp and two crabs on the coast of Baja
California, with some remarks on distribution. Veliger, 30:384—386.

Coutiére, H. 1905. Note sur Lysiosquilla digueti n. sp. commensale d’un polynoidien et d’un bal-
anoglosse de Basse Californie. Bull. Soc. Philomathique Paris, 9(7):174—179 [pp. 1-6 separate].

Hendrickx, M. E., and J. Salgado-Barragan. 1991. Los estomatopodos (Crustacea: Hoplocarida) del
Pacifico Mexicano. Inst. Cienc. Mar y Limnol., Univ. Nal. Auton. México, Publ. Esp., 10:1-
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Lemaitre, R., and R. Alvarez-Leon. 1992. Crustaceos decapodos del Pacifico Colombiano: lista de
especies y consideraciones zoogeograficas. An. Inst. Invest. Mar. Punta Betin, 21:33—76.
Manning, R. B. 1963. Preliminary revision of the genera Pseudosquilla and Lysiosquilla with de-
scription of six new genera (Crustacea: Stomatopoda). Bull. Mar. Sci. Gulf and Caribbean, 13:

308-328.

1974. Stomatopods collected by Th. Mortensen in the Eastern Pacific region (Crustacea,
Stomatopoda). Steenstrupia, 3:101-109.
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y de Bahia Concepcion, Baja California Sur, México (Crustacea: Caridea). Proc. San Diego Soc.
Nat. Hist., 14:1-13
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icanus, new species (Crustacea, Decapoda, Alpheidae). Jour. Crust. Biol., 3:306—313.
Schotte, M., and R. B. Manning. 1993. Stomatopod Crustacea from Tobago, West Indies. Proc.

Biol. Soc. Wash., 106(3):566-581.

Schmitt, W. L. 1940. The stomatopods of the west coast of America based on the collection made
by the Allan Hancock Expedition, 1933-38. Allan Hancock Pac. Exped., 5(4):129-255.
Wicksten, M. K., and M. E. Hendrickx. 1992. Checklist of penaeoid and caridean shrimps (Decapoda:
Penaeoidea, Caridea) from the Eastern tropical Pacific. Proc. San Diego Soc. Nat. Hist.,

9:1-11.

Accepted for publication 22 August 1994.

i

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7
CONTENTS

Distribution, Habitat, and Current Status of the San Pedro Martir Rainbow
Trout, Oncorhynchus mykiss nelsoni (Evermann). By Gorgonio Ruiz-
Campos and EdwintPPister 2.4.2) ee 131

Large-Scale Migrations of the Painted Lady Butterfly, Vanessa cardui (Lep-
idoptera: Nymphalidae), in Inyo County, California, during 1991. By
Derham: Giuhianivand Oakley, Shields 2a 149

Research Notes

Salinity Tolerance of Cletocamptus deitersi (Richard 1897) and its Presence
imethe Salton: Sea. By DeborahyMeWexte ree eee 169

First Record of Madracis sp. cf. M. pharensis (Heller, 1868) on Continental
Eastern Pacific Shores. By Héctor Reyes Bonilla, Eleuterio Martinez
Olguin and: Gabriela Anaya: Rie yiniay sarees eee yD

Distribution and Host for Four Symbiotic Crustaceans of the Mexican Pa-
cific (Stomatopoda and Decapoda). By Ernesto Campos, E. F. Félix-
Pico/and' F: Garcia-Dominguez, 2a 176

COVER: Arroyo San Antonio de Murillos ca. Rancho San Antonio, Sierra San Pedro Martir, Baja
California, México. June 17, 1992. Photograph by Gorgonio Ruiz-Campos.

2