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TEXAS J.
SCI. 48(2):159-162
MAY, 1996
OCCURRENCE O F THE ENDANGERED PRONGHORN
ANTILOCAPRA AMERICANA PENISULARIS IN COYOTE DIETS
FROM NORTHWESTERN MEXICO
Bernardo Sanabria, *Cerafina Arguelles-Méndez
and *Alfredo Ortega-Rubio
Oficina Secretaría de Desarrollo Social, Avenida Marcelo Rubio SN, Guerrero Negro,
B. C.S., México, and *Centro de Investigaciones Biológicas del Noroeste,
S. C. Apdo. Postal No. 128. CP 23000, La Paz, Baja California Sur, México
Abstract.-The stomach contents of 50 specimens of the coyote Canis latrans from the
Vizcaíno Deserí of northwestern Mexico were analyzed to determine prdation level of this
species upon the endangered population of Baja California pronghorn. Results indicate that
coyote diets consisted primarily of rodents and lagomorphs. The incidence of pronghorn
ingestion was found to be only four percent. Predation by Cank latrans is not considered
to represent a significant threat in the decline of this endangered subspecies of antelope.
Resumen.-El contenido de los estómagos de 50 espécimenes del coyote Canis latrans
del Desierto d e Vizcaino del noroeste de México fue analizado para determinar el índice de
la caza predatoria de esta especie sobre los berrendos de Baja California. Los resultados
indican que los coyotes principalmente comian roedores y lagomorfos. La incidencia de la
ingestión del berrendo peninsular era solamente de cuatro por ciento. La caza predatoria del
Canis latrans no es una amenaza significativa en la declinación del berrendo peninsular.
Antilocapra americana peninsularis is one of five subspecies of
pronghorn antelope native to North America (Hall 1981). It is endemic
to the Baja Peninsula of México where it is considered to be this
country's most endangered mammalian subspecies (González-Romero et
al. 1991). It has been proposed that one of the major constraining
factors to the restoration of populations of this endangered subspecies in
the Vizcaíno Desert is predation by coyotes, especially during the winter
fawning period (SEDUE 1984; Jaramillo et al. 1985). While this proposa1 appears plausible, there is a lack of experimental data to support
this premise as it relates to the pronghorn population of the Baja Peninsula of México. Instead, it appears to be based soley upon the report of
pronghorn predation by coyotes in the United States by Connolly (1978).
This investigation was undertaken in order to determine the level of
coyote predation upon pronghorn populations in the Vizcaíno Desert of
the Baja Peninsula of northwestern México.
The study area is located on the west coast of the Vizcaíno Desert,
Baja California Sur, México (26" 30' to 28" N and 114" to 115" W).
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THE TEXAS JOURNAL OF
SCIENCE-VOL.
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NO. 2
The climate is dry with an annual precipitation ranging from 50.13 to
83.69 mm. The average annual temperature ranges from 18 to 22' C.
Altitude of the area varies from sea leve1 to 200 m. Primary
vegetational types as reported by León et al. (1991) include: saltbush
with species of Atriplex and Salicornia; halophyte scrub with species of
Ambrosia, Bursera, Bouteloa and Muhlenbergia; coastal dunes with
species of Abronia, Dalea and Plantago, and the Sarco-crasicaule scrub
with species of Acacia, Jatropha, Larrea, Opuntia and Yucca.
METHODSAND MATERIALS
Fifty coyote specimens were obtained during the winter of 1985 as the
result of a federal program designed to control populations of this
predator in the Vizcaíno Desert. Oniy specimens collected from January
to March were examined. These months represent both the time of
winter concentration of pronghorns in the area as well as the fawning
period (SEDUE 1984; Jaramillo et al. 1985). This is the oniy area of
the Vizcaíno Desert where coyote and pronghorn populations are
sympatric during the winter months. A census of the area during the
period of winter concentration in 1985 revealed a population of 70
individuals (SEDUE 1986) of Antilocapra americana peninsularis.
Coyote traps were baited with fish carcasses, placed two km apart at
sunset and checked each morning. The study area consisted of a total
of 25 km2. Stomachs were removed and washed with water.
Laboratory analysis basically followed those of Korschgen (1980).
Contents were separated, classified, and weighed. A reference collection of plants, mammals, reptiles and birds of the area was used to identify stomach contents. The percent of each food item was calculated on
a per stomach basis; percent occurrence refers to the number of
stomachs in which the presence of the specific food item was recorded.
RESULTSAND DISCUSSION
The results (Table 1) of this study reveal that the primary dietary
items of wintering coyotes in the Vizcaíno Desert of México are rodents
and lagomorphs. These two groups of prey species together constituted
73.7% of the total weight of material removed from coyote stomachs.
Remains of Dipodomys were present in 40%, Thomomys in 20%, and
Lepus in 10% of al1 coyotes examined. Plant material, reptiles, and
arthropods were also recovered as common food items.
SANABRIA, ARGUELLES-MÉNDEZ& ORTEGA-RUBIO
161
Table 1. Results of stomach content analysis of 50 specimens of Canis latrans from the
Vizcaíno Desert of the Baja Peninsula of México.
Percent
Occurrence
Weight
Recovered
Percent
of Total
Weight
Rodents
Dipodomys sp.
Thomornys umbrinus
Peromyscus sp.
Neotoma Iepida
Perognathus sp.
Lagomorphs
Lepus sp.
Silvilagus sp.
Reptiles
Cnemidophorus sp.
Sceloporus magister
Phrynosoma coronatum
Colubridae sp.
Arthropods
Diptera
Coleoptera
Orthoptera
Chilopoda
Lepidoptera
Pronghom antelope
Birds
Domestic livestock
Gray Whale
Plant material
Sand
Unidentified
The occurrence of pronghorn antelope was found to be quite low in
comparison with rodents and lagomorphs. Only two coyote specimens
(4%) were found to contain remains of Antilocapra americana
peninsularis. It was not ascertained whether pronghorn consumption
represented coyote predation or carrion ingestion.
One noteworthy result of this study is the fírst documentation of
coyote consumption of the gray whale Eschrichtius robustus. Laguna
Ojo de Liebre (Scamon's Lagoon), which constitutes a part of the
northern border of the study area, is a known habitat of the gray whale
(Maravilla 1991). Although not documented by field observations, this
report of consumption of whale carrion is almost certainly the result of
coyotes feeding upon the remains of a stranded or beached individual.
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THE TEXAS JOURNAL OF SCIENCE-VOL. 48, NO. 2
While this study does in fact document evidence of pronghorn consumption by coyotes in the Vizcaíno Desert, the frequency of occurrence
was found to be quite low and the amount consumed relatively small.
The decline of populations of pronghorns in this area of the Baja Peninsula cannot be attributed solely to the occurrence of coyote predation
during the fawning season. Other parameters such as the effects of habitat loss and unauthorized hunting must be considered and investigated.
This work was supported jointly by the Secretaría de Desarrollo
Social, Delegación Estatal Baja California Sur, the Consejo Nacional de
Ciencia y Tecnología and the Centro de Investigaciones Biológicas del
Noroeste.
Field work was carried out as a part of programs
implemented by the Departamento de Protección y Restauración Ecológica de la Secretaría de Desarrollo Urbano y Ecología. We wish to thank
Marcelino Aguero and Fernando Jaramillo for assistance with the field
work. We would also like to thank Dr. Thomas E. Lee and one anonymous review for suggestions on an early draft of the manuscript.
Dolores Vázquez and Verónica Hirales provided expert secretaria1
assistance.
LITERATURE
CITED
Connolly, G. E. 1978. Predators and predator control. I n Big Game of North America:
Ecology and Management. Wild. Manag. Inst. Washington D.C. pp. 369-394.
González-Romero, A., J. Cancino, P. Galina & S. Alvarez. 1991. El berrendo peninsular.
I n La Reserva de la Biosfera El Vizcaíno en la Península de Baja California (A. Ortega
& L. Arriaga, d . ) . Centro de Investigaciones Biológicas de Baja California Sur.
México. Publicación No. 4. 317 pp.
Hall, E. R. 1981. The mammals of North America. 2nd. ed. John Wiley & Sons, N.Y.,
Vol. II:601-1181+90.
Jaramillo, F., A. Castellanos & J. Cancino. 1985. El Berrendo de Baja California, su
Situación Actual y Perspectivas de Manajo. SEDUE. Internal Report. 20 pp.
Korschgen, L. 1980. Procedures for food habits analyses. Pp. 113-119, in Wildlife
Management Techniques Manual. Wild. Soc.
León, J. L., J. Cancino & L. Arnaga. 1991. Asociaciones Fisonómico- Florísticas y Flora.
I n La Reserva de la Biosfera El Vizcaíno en la Península de Baja California (A. Ortega
& L. Arriaga, d . ) . Centro de Investigaciones Biológicas de Baja California Sur.
México. Publicación No. 4. 317 pp.
Maravilla, 0 . 1991. La Ballena Grís de California. Asociaciones Fisonónuci- Florísticas
y Flora. I n La Reserva de la Biosfera El Vizcaíno en la Península de Baja California,
A. Ortega & L. Arriaga ( 4 . ) . Centro de Investigaciones Biológicas de Baja California
Sur. México. Publicación No. 4. 317 pp.
SEDUE. 1984. Secretaría de Desarrolo Urbano y Ecología. El Berrendo de Baja
California. Internal Report. 20 pp.
SEDUE. 1986. Secretaría de Desarrollo Urbano y Ecología. Censo anual del Berrendo
peninsular. Internal Report. 34 pp.