Download observations on the ecology of the endemic mearns`s squirrel

OBSERVATIONS ON THE ECOLOGY OF THE ENDEMIC MEARNS'S
SQUIRREL (TAMIASCIURUS MEARNSI)
Author(s) :John L. Koprowski, Nicolás Ramos, Bret S. Pasch, and Claire A. Zugmeyer
Source: The Southwestern Naturalist, 51(3):426-430. 2006.
Published By: Southwestern Association of Naturalists
DOI: http://dx.doi.org/10.1894/0038-4909(2006)51[426:OOTEOT]2.0.CO;2
URL: http://www.bioone.org/doi/full/10.1894/0038-4909%282006%2951%5B426%3AOOTEOT
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426
vol. 51, no. 3
The Southwestern Naturalist
OBSERVATIONS ON THE ECOLOGY OF THE ENDEMIC MEARNS’S
SQUIRREL (TAMIASCIURUS MEARNSI)
JOHN L. KOPROWSKI,* NICOLÁS RAMOS, BRET S. PASCH,
AND
CLAIRE A. ZUGMEYER
Wildlife Conservation and Management, School of Natural Resources, University of Arizona, Tucson, AZ 85721
*Correspondent: [email protected]
ABSTRACT Mearns’s squirrel (Tamiasciurus mearnsi) is an endemic species of the montane forest
of the Sierra de San Pedro Mártir in Baja California. Despite having been described for the first
time in 1893 and a listing as threatened by Mexican authorities, no information is available on
the ecology of this southernmost Tamiasciurus. We observed the ecology of Mearns’s squirrels
during 2004 and 2005. Mearns’s squirrel apparently does not form larderhoards, known as middens, or leaf nests commonly built by other members of this genus. We observed Mearns’s squirrels
to feed heavily on tree seeds and fungi. We noted males with scrotal testes and a female in estrus
in late spring. We did not observe eastern gray squirrels (Sciurus carolinensis), introduced to the
western Sierra in 1946, within the areas that we searched for T. mearnsi. Mearns’s squirrels might
possess unique adaptations for their persistence in the dry, open forest of the Sierra de San Pedro
Mártir.
RESUMEN La ardilla de San Pedro Mártir (Tamiasciurus mearnsi) es una especie endémica del
bosque de montaña de la Sierra de San Pedro Mártir en Baja California. A pesar de haber sido
descrita por primera vez en 1893 y a que se encuentra catalogada como amenazada por las autoridades mexicanas, no hay información disponible sobre la ecologı́a de esta Tamiasciurus más
austral. Observamos la ecologı́a de las ardillas de San Pedro Mártir durante 2004 y 2005. La ardilla
San Pedro Mártir parece no formar cúmulos de comida conocidos como basurales, o nidos de
hoja comúnmente construidos por otros miembros de este género. Observamos a las ardillas de
San Pedro Mártir alimentarse principalmente de las semillas de los árboles y de hongos; notamos
machos con testı́culos escrotados y una hembra en celo a finales de la primavera. No observamos
a las ardillas Sciurus carolinensis, introducidas en la parte oeste de la Sierra en 1946, dentro de las
áreas donde buscamos a las T. mearnsi. Las ardillas de San Pedro Mártir pueden poseer adaptaciones únicas para su persistencia en el bosque abierto y seco de la Sierra de San Pedro Mártir.
Conservation of endemic organisms presents one of the greatest challenges for ecologists. Northwestern Mexico possesses one of
the most diverse floras and faunas in the world,
in part due to the montane sky islands that
often harbor endemics (Turner et al., 1995;
Koprowski, 2005a). Fauna of peninsular Baja
California is especially distinct given a long
evolutionary history in isolation (e.g., Welsh,
1988; Hafner and Riddle, 1997). In many cases,
knowledge of peninsular endemics, especially
montane species, is extremely poor. The
Mearns’s squirrel (Tamiasciurus mearnsi) in the
Sierra de San Pedro Mártir of Baja California,
Mexico (Wilson and Cole, 2000) is one such
example. Mearns’s squirrels are closely related
to Douglas’s squirrels (T. douglasii) in the Sierra Nevada of California, USA, with specific
status contentious (Lindsay, 1981; Arbogast et
al., 2001). Not a single ecological paper has
been published on Mearns’s squirrels despite
over 100 years since the species was first described (Allen, 1893; Townsend, 1897); it currently is listed as threatened under Mexican
law (Ceballos et al., 2002). The basic ecology
of Mearns’s squirrel such as diet, habitat, and
reproduction is poorly known (Yensen and Valdés-Alarcón, 1999) other than that inferred
from distributional and comparative anatomical and genetic studies (Lindsay, 1981; Arbogast et al., 2001). In addition, the introduction
of eastern gray squirrels (Sciurus carolinensis) in
1946 might pose a threat (Huey, 1964) as evidenced in other countries where intentional
releases have occurred (Gurnell, 1987). Herein, we present observations on the reproduction, food habits, vocalizations, and interspecific interactions of Mearns’s squirrels.
September 2006
Notes
Our study area was the 65,000-ha Parque Nacional Sierra de San Pedro Mártir located
about 100 km east of San Telmo, Baja California, Mexico. Open forested parklands (Minnich et al., 2000) at elevations above 2,100 m
are dominated by Jeffrey pine (Pinus jeffreyi),
lodgepole pine (P. contorta), ponderosa pine
(P. ponderosa), sugar pine (P. lambertiana), and
white fir (Abies concolor). We visited forests in
the Vallecitos, La Corona de Abajo, Arroyo Los
Alamillos, La Grulla, and La Zanja areas of the
national park during 4 to 7 November 2004
and 16 to 20 March, 23 to 24 April, and 19 to
24 May 2005. We visually assessed all trees and
surrounding ground cover within the open forests of our study sites on foot in search of
Mearns’s squirrels as well as sign, including
leaf nests (Young et al., 2002) and larderhoards of cones known as middens (Finley,
1969) that typically indicate the presence of
Tamiasciurus. The open forest structure and a
paucity of downed trees (Stephens and Gill,
2005) greatly facilitated observations. Once we
located an individual, we noted its behavior
and attempted to determine sex and reproductive condition from external genitalia.
We observed Mearns’s squirrels (Fig. 1) on
17 occasions (5 female, 6 male, 6 unknown
sex) in the Vallecitos and Arroyo Los Alamillos
areas as we surveyed approximately 4,000 ha of
forest. Notably, we did not detect any middens
or leaf nests during our surveys. Tamiasciurus
hudsonicus can nest in cavities or burrows (Yahner, 1980; Young et al., 2002), and the large
number of overmature trees and snags (Stephens and Gill, 2005) might permit reliance
on such nest types. Furthermore, T. mearnsi
seems not to rely on larderhoards of cones.
Other Tamiasciurus are known to scatterhoard
and larderhoard food items in logs or snags
(reviewed in Gurnell, 1987; Steele, 1998,
1999). Tamiasciurus hudsonicus scatterhoard
where food types or environmental conditions
are not conducive to midden formation and
maintenance (Hurly and Robertson, 1986).
Lack of larderhoards could reflect the xeric
conditions inhabited by this southernmost
member of Tamiasciurus (Lindsay, 1981),
where cool moist conditions that retard cone
opening (Smith, 1968) might not occur.
All male squirrels that we observed possessed scrotal testes (1 male on 20 May, 1 male
on 21 May, 4 males on 22 May 2005). One fe-
427
male Mearns’s squirrel possessed an enlarged
pink vulva and was pursued by 2 or possibly 3
males on 22 May 2005 in a mating chase. Our
scant observations on reproductive males and
female in late spring suggest similarity with
other Tamiasciurus (Steele, 1998, 1999). In particular, the similarly isolated and endangered
Mount Graham red squirrel (T. hudsonicus grahamensis) of southern Arizona can breed in the
spring and summer (Koprowski, 2005b).
Mearns’s squirrels were observed feeding on
cones of the current year of Jeffrey pine (2 females, 2 males) and white fir (1 male), branch
tips of white fir (1 female), and basidiomycete
fungi, veiled polypores (Cryptoporus volvatus),
found on the upper trunk of white fir (2 females, 3 males). Feeding sign on Jeffrey pine
was found commonly in areas that we visited,
with the exception of La Zanja. Other Tamiasciurus also feed heavily on fungi, conifer seed,
and conifer branch tips during spring and early summer (Steele, 1998, 1999).
At least 6 distinct vocalizations are known
from Tamiasciurus (Gurnell, 1987). We discerned 3 calls based on our observations. On
3 occasions (1 male, 2 unknown sex), we heard
a call similar to the territorial ‘‘rattle’’ of T.
hudsonicus and T. douglasii (Smith, 1978) but of
seemingly higher pitch. Mearns’s squirrels also
gave a ‘‘chirp’’ call (Smith, 1978) on 3 occasions (2 females, 1 male) when aggravated and
a woofing bark or ‘‘buzz’’ call (Smith, 1978)
when startled or mildly aggravated (1 female,
1 male).
We observed 4 interspecific interactions. On
7 November 2004, a red-tailed hawk (Buteo jamaicensis) chased a T. mearnsi through the canopy of sugar and lodgepole pines for ⬍10 s
before disappearing from sight. Western bluebirds (Sialia mexicana) mobbed a solitary adult
female Mearns’s squirrel on 2 occasions (20
and 22 May 2005). Lastly, we observed a coyote
(Canis latrans) passing under a tree where a
Mearns’s squirrel rested 8 m aboveground on
22 May 2005. This elicited only a raised head
from the adult male squirrel.
Mearns’s squirrels seem to be uncommon
and reclusive in the Sierra de San Pedro Mártir. Most biologists have referred to the species
as occurring in low densities (Leopold, 1959;
Huey, 1964; Yensen and Valdés-Alarcón, 1999).
Our brief observations on the ecology of T.
mearnsi suggest that some aspects of their bi-
428
The Southwestern Naturalist
vol. 51, no. 3
September 2006
Notes
ology, such as food habits, reproduction, and
vocalizations, are similar to those of other
members of Tamiasciurus (Steele, 1998, 1999).
However, absence of obvious larderhoards and
leaf nests indicates that Mearns’s squirrels
might have unique adaptations to dry and
open forests of this southernmost extension of
the genus Tamiasciurus.
Eastern gray squirrels were introduced at La
Zanja and Arroyo San Rafael on the western
slopes of the Sierra de San Pedro Mártir in
1946 (Yensen and Valdéz-Alarcón, 1999). However, we did not observe any individuals or sign
during our visit to La Zanja. The last report of
eastern gray squirrels at La Zanja is from 1956
(Huey, 1964). We were not able to assess the
status of eastern gray squirrels in Arroyo San
Rafael.
Our observations suggest the need for research into several aspects of the ecology of T.
mearnsi. The significance of the lack of middens and leaf nests must be assessed to elucidate important selective pressures faced by
Mearns’s squirrels. Because these conspicuous
signs of squirrel presence are not available,
census techniques must be developed to effectively monitor population status of T. mearnsi.
Furthermore, investigation of the status of introduced eastern gray squirrels is necessary to
formulate conservation strategies for the endemic Mearns’s squirrel.
We thank the Desert Southwest Cooperative Ecosystem Studies Unit, the Intermountain Region International Conservation Office (IMRICO) of the
National Park Service, and the Arizona Agricultural
Experiment Station for funding. The Consejo Nacional de Ciencia y Tecnologı́a (CONACYT) provided a scholarship to Nicolás Ramos (158208). L. Norris, D. Swann, and N. Kline of the National Park Service in the United States and W. Zúñiga, Á. López,
and M. Valles of the Parque Nacional Sierra de San
Pedro Mártir supported the concept of the project.
J. Franco, P. Strittmatter, B. Powell, J. Sasian, J. Bohigas, D. Hiriart, D. Carrasco, A. Garcia, I. González,
and E. Valdés facilitated housing logistics at Observatorio Astronómico Nacional (UNAM). W. Shaw
and R. Mannan assisted with fieldwork. L. Bojór-
429
quez, S. Stephens, R. Minnich, J. Vargas, C. Porras,
E. Meling, E. Mellink, E. Salgado, B. Mackintosh,
and G. Mackintosh graciously shared their knowledge of the Sierra. Research was conducted under
permits from Dirección Forestal y de la Fauna
Parque Nacional Sierra de San Pedro Mártir, Dirección General de Vida Silvestre (SEMARNAT), and
the Institutional Animal Care and Use Committee,
University of Arizona.
LITERATURE CITED
ALLEN, J. A. 1893. On a collection of mammals from
the San Pedro Mártir region of Lower California,
with notes on other species, particularly of the
genus Sitomys. Bulletin of the American Museum
of Natural History 5:181–202.
ARBOGAST, B. S., R. A. BROWNE, AND P. D. WEIGL.
2001. Evolutionary genetics and Pleistocene biogeography of North American tree squirrels
(Tamiasciurus). Journal of Mammalogy 82:302–
319.
CEBALLOS, G., J. ARROYO-CABRALES, AND R. A. MEDELLı́N. 2002. The mammals of Mexico: composition, distribution, and conservation status. Occasional Papers, Museum of Texas Tech University
218:1–28.
FINLEY, R. B. J. 1969. Cone caches and middens of
Tamiasciurus in the Rocky Mountain region. Miscellaneous Publications, University of Kansas Museum of Natural History 51:233–273.
GURNELL, J. 1987. The natural history of squirrels.
Facts on File, New York.
HAFNER, D. J., AND B. R. RIDDLE. 1997. Biogeography
of Baja California peninsular desert mammals.
In: T. L. Yates, W. L. Gannon, and D. E. Wilson,
editors. Life among the muses: papers in honor
of James S. Findley. Museum of Southwestern Biology, University of New Mexico, Albuquerque.
Pages 39–68.
HUEY, L. M. 1964. The mammals of Baja California,
Mexico. Transactions of the San Diego Society of
Natural History 13:85–168.
HURLY, T. A., AND R. J. ROBERTSON. 1986. Scatterhoarding by territorial red squirrels: a test of the
optimal density model. Canadian Journal of Zoology 65:1247–1252.
KOPROWSKI, J. L. 2005a. Management and conservation of tree squirrels: the importance of endemism, species richness, and forest condition. In:
G. Gottfried, B. Gebow, L. Eskew, and C. Ed-
←
FIG. 1 An adult female Mearns’s squirrel (Tamiasciurus mearnsi) descending a white fir (Abies concolor)
on 22 May 2005, Parque Nacional Sierra de San Pedro Mártir, Baja California, Mexico. Photograph by B.
S. Pasch.
430
The Southwestern Naturalist
minster, editors. Connecting mountain islands
and desert seas: biodiversity and management of
the Madrean Archipelago II. RMRS-P-36. U.S. Department of Agriculture Forest Service, Rocky
Mountain Research Station, Fort Collins, Colorado. Pages 245–250.
KOPROWSKI, J. L. 2005b. Annual cycles in body mass
and reproduction of endangered Mt. Graham
red squirrels. Journal of Mammalogy 86:309–313.
LEOPOLD, A. S. 1959. Wildlife of Mexico. University
of California Press, Berkeley.
LINDSAY, S. L. 1981. Taxonomic and biogeographic
relationships of Baja California chickarees (Tamiasciurus). Journal of Mammalogy 62:673–682.
MINNICH R. A, M. G. BARBOUR, J. H. BURK, AND J.
SOSA-RAMÍREZ. 2000. Californian mixed-conifer
forests under unmanaged fire regimes in the Sierra San Pedro Mártir, Baja California, Mexico.
Journal of Biogeography 27:105–129.
SMITH, C. C. 1968. The adaptive nature of social organization in the genus of tree squirrels Tamiasciurus. Ecological Monographs 38:31–63.
SMITH, C. C. 1978. Structure and function of the vocalizations of tree squirrels (Tamiasciurus). Journal of Mammalogy 59:793–808.
STEELE, M. A. 1998. Tamiasciurus hudsonicus. Mammalian Species 586:1–9.
STEELE, M. A. 1999. Tamiasciurus douglasii. Mammalian Species 630:1–8.
STEPHENS, S. L., AND S. J. GILL. 2005. Forest structure
and mortality in an old-growth Jeffrey pine-mixed
conifer forest in northwestern Mexico. Forest
Ecology and Management 205:15–28.
TOWNSEND, C. H. 1897. Descriptions of a new eagle
from Alaska and a new squirrel from Lower Cal-
vol. 51, no. 3
ifornia. Proceedings of the Biological Society of
Washington 11:145–146.
TURNER, D. S., S. BRANDES, M. FISHBEIN, AND P. W.
HIRT. 1995. Preserve design for maintaining biodiversity in the sky island region. In: L. F. DeBano, P. F. Ffolliott, A. Ortega-Rubio, G. J. Gottfried, R. H. Hamre, and C. B. Edminster, editors.
Biodiversity and management of the Madrean Archipelago: the sky islands of southwestern United
States and northwestern Mexico. U.S. Department of Agriculture Forest Service, GTR RM-264,
Fort Collins, Colorado. Pages 524–530.
WELSH, H. H. 1988. An ecogeographic analysis of the
herpetofauna of the Sierra San Pedro Mártir Region, Baja California, with a contribution to the
biogeography of the Baja California herpetofauna. Proceedings of the California Academy of Sciences 46:1–72.
WILSON, D. E., AND F. R. COLE. 2000. Common names
of mammals of the world. Smithsonian Institution Press, Washington, D.C.
YAHNER, R. H. 1980. Burrow system use by red squirrels. American Midland Naturalist 103:409–411.
YENSEN, E., AND M. VALDÉS-ALARCÓN. 1999. Family
Sciuridae. In: S. T. Álvarez-Castañeda and J. L.
Patton, editors. Mamı́feros del Noroeste de México. Centro de Investigaciones Biológicas del Noroeste, S.C., México. Pages 239–320.
YOUNG, P. J., V. L. GREER, AND S. K. SIX. 2002. Characteristics of bolus nests of red squirrels in the
Pinaleño and White mountains of Arizona.
Southwestern Naturalist 47:267–275.
Submitted 28 June 2005. Accepted 9 December 2005.
Associate Editor was Philip D. Sudman.
RECENT RECORDS OF DESERT BIGHORN SHEEP
(OVIS CANADENSIS MEXICANA) IN EASTERN SONORA AND
NORTHWESTERN CHIHUAHUA, MEXICO
KARLA PELZ-SERRANO, EDUARDO PONCE-GUEVARA, RODRIGO SIERRA-CORONA, RURIK LIST,
AND GERARDO CEBALLOS*
Universidad Autónoma de Querétaro, Facultad de Ciencias Naturales. Cerro de las Campanas sin número,
Col. Niños Héroes, Querétaro, CP 76010, México (KP-S, EP-G, RS-C)
Instituto de Ecologı́a, UNAM, A.P. 70-275, México D.F. 04510, México (KP-S, EP-G, RS-C, RL, GC)
*Correspondent: [email protected]
ABSTRACT The desert bighorn sheep (Ovis canadensis mexicana) was extirpated from most of its
range in northern Mexico and the southwestern United States by the 1980s. Several populations
have been established through reintroductions in both countries, but none in the Chihuahua–
Sonora border region, where we report here 3 recent records. These records suggest the possibility
September 2006
Notes
431
of reintroducing bighorn sheep in northwestern Chihuahua and northeastern Sonora to increase
the long-term viability of the species in the region.
RESUMEN El borrego cimarrón (Ovis canadensis mexicana) fue extirpado de la mayor parte de
su área de distribución en el norte de México y el suroeste de los Estados Unidos hacia la década
de 1980. Mediante reintroducciones, se han establecido varias poblaciones en ambos paı́ses, pero
ninguna en la región fronteriza entre Chihuahua y Sonora, de donde se reportan 3 registros en
esta nota, indicando la posibilidad de reintroducir al borrego cimarrón en el noroeste de Chihuahua y noreste de Sonora para incrementar la viabilidad a largo plazo de la especie en al región.
The desert bighorn sheep (Ovis canadensis
mexicana) was once distributed from southern
Canada to northern Mexico, along the main
mountain massifs of western North America
(Hall, 1981). For more than a century, desert
bighorns have been one of the main species
for trophy-hunting in North America, and
thus, subject to legal and illegal hunting that,
coupled with competition with cattle, diseases
from cattle, and habitat fragmentation, decreased bighorn distribution to small and often isolated groups in inaccessible areas (Leopold, 1959; Smith and Krausman, 1988; Krausman et al., 1999; Guerrero et al., 2003). The
species is listed as under special protection in
Mexico (SEMARNAP, 2002) and threatened in
the USA (Rubin, 1998; New Mexico Game and
Fish Department, 2002). Recovery efforts in
Mexico have centered on the establishment of
reintroduced populations within the former
geographic range, conservation of original
habitat, and provision of incentives to conservation by promoting sustainable hunting. A
well-known example of a successful recovery
program is that on Tiburón Island (Sonora),
where scientists from the National University
of Mexico and non-governmental organizations organized a solid hunting program that
has provided the Seri Indians, owners of the
island, incentives to become wardens of both
the sheep and its habitat (Medellı́n et al., 1999,
2005).
The historical distribution of O. c. mexicana
in Mexico included the Baja California Peninsula, Sonora, Chihuahua, and Coahuila (Leopold, 1959; Hall, 1981). In the southwestern
United States, desert bighorn sheep were
found in California, eastern Arizona, and New
Mexico (Hall, 1981; Shackleton, 1985; Hoffmeister, 1986). It was estimated that a million
bighorn sheep historically inhabited the arid
environments of the United States, but by
1980, the total population was approximately
12,000 individuals (Smith and Krausman,
1988). This critical decline prompted reintroduction efforts in Arizona, New Mexico, California, Colorado, Texas, Utah, and Nevada to
recover populations across the historical range
(Lee, 1999; New Mexico Game and Fish Department, 2002). In 1998, larger populations
were reported in southwestern Arizona, and
isolated populations in the Peloncillo and Catalinas mountains of Arizona (Lee, 1999). In
2002, small but relatively stable populations
were reported in the Red Rock Wildlife Area,
the Ladron Mountains (26 individuals), the Peloncillo Mountains (30 individuals), the Fra
Cristobal Mountains (66 individuals), and the
Big Hatchet Mountains (40 individuals) (New
Mexico Game and Fish Department, 2002).
Presently, desert bighorn sheep in Mexico
survive in the Baja California Peninsula and
Sonora, but they have been extirpated from
Chihuahua and Coahuila (Rubin et al., 1998;
Medellı́n et al., 1999, 2005; Hayes et al., 2000;
Guerrero et al., 2003). There are ongoing efforts to reintroduce the species in the Maderas
del Carmen region of Coahuila (P. Robles Gil,
pers. comm.) and in the municipality of Coyame in eastern Chihuahua (R. Uranga, pers.
comm.). Herein, we suggest that reintroductions of O. c. mexicana to northwestern Chihuahua or northeastern Sonora might create a
metapopulation with populations in southwestern New Mexico or southeastern Arizona, increasing viability of desert bighorn in the region. We have 2 recent reports of bighorn
sheep in northwestern Chihuahua by local
people (Fig. 1). The first report was in 1995,
when a male was hunted by local cowboys
working at an unspecified location at Las Palmas Ranch, a 30,000-ha property that borders
New Mexico, just south of the Alamo Hueco
Mountains and 27.8 km south from the nearest
known population of bighorns in the Big
Hatchet Mountains. In 2002, a male was seen
432
The Southwestern Naturalist
vol. 51, no. 3
FIG. 1 Distribution of desert bighorn sheep (Ovis canadensis mexicana) in the southwestern USA and
northwestern Mexico, including historical and current distribution, and new records (modified from Hall,
1981; Leopold, 1985; Shackleton, 1985; Hoffmeister, 1986; Lee, 1999; New Mexico Department of Game
and Fish, 2002).
crossing Federal Highway 2 ( Janos–Asención)
near La Lagunita ( J. Harris, pers. comm.), 68
km southeast from the closest population in
the Big Hatchet Mountains. The dominant vegetation in that area is desertscrub, with low
plant density.
To these we add our own sighting of a male
bighorn on Los Ojos Ranch, Sonora, on 4 August 2003. We estimated this ram to be 6 to 8
years old, according to criteria defined by
Smith and Krausman (1988). Los Ojos Ranch
is private property from which cattle were removed in 1998; the ranch currently is used for
habitat conservation and restoration. The ram
September 2006
Notes
climbed a rocky slope, crossed the road we
were driving, climbed another escarped slope,
and descended to a rocky canyon. This sighting was 5.7 km south of the Arizona-Sonora
border (UTMs 12R 0690985 E, 3436038 N),
33.5 km south from the nearest known population of bighorn sheep in the Peloncillo
Mountains of Arizona. We saw this individual
at a location near 2 artificial ponds and a permanent arroyo, in interior chaparral and
thornscrub (Brown, 1994). This open forest
community includes trees ranging from 5 to 10
m high, composed of blue Mexican oak (Quercus oblongifolia), shrub live oak (Q. turbinella),
one-seed juniper (Juniperus monosperma), desert
acacia (Acacia farneciana), and thorn acacia (A.
constricta), with an understory of beargrass (Nolina microcarpa), Parryi agave (Agave parryi),
and sotol (Dasiliryon wheeleri). The climate is
subtemperate-humid (Garcı́a, 1988).
The observation from 2002 suggests that
bighorn sheep can disperse farther than the
previously reported maximum of 48 km
(Shackleton, 1985). We have no documentation of the movement of ewes or the establishment of new populations in the Sonoran–Chihuahuan region. However, because of the
proximity of these 3 observations to established populations in New Mexico and Arizona, it is feasible that these individuals came
from the Big Hatchet and Peloncillo mountains, respectively (Fig. 1), during their summer movements. Both Los Ojos and Las Palmas ranches contain large areas of continuous
habitat with the topographical and biological
features required by this species; thus, these areas should be considered for future reintroductions. Reduction of populations in the Big
Hatchet and the Peloncillos makes them highly
prone to extinction by predation through the
Allee effect (Mooring et al., 2004). Reintroductions of bighorn sheep in the mountains of
northwestern Chihuahua or northeastern Sonora would increase the opportunities for dispersing individuals to find mates, thereby increasing the long-term viability of the species
in the region, assuming that reintroductions
would be accompanied by education of local
residents to prevent hunting until new, stable
populations are established.
The case of bighorn sheep in the Sonora–
Chihuahua and Arizona–New Mexico international border is just one of many examples of
433
species, including the ocelot (Leopardus pardalis), jaguar (Panthera onca), pronghorn antelope
(Antilocapra americana sonorensis), white-sided
jack rabbit (Lepus callotis), black-tailed prairie
dog (Cynomys ludovicianus), and thick-billed
parrot (Rhynchopsitta pachyrhyncha), considered
at risk of extinction in one or both countries
and requiring immigration of individuals
across the border to maintain viable populations (Ceballos and Navarro, 1991; Ceballos et
al., 1998, 2005; List et al., 1999). There is an
urgent need to address this important conservation issue in both countries to ensure the
long-term survival of these taxa.
We thank the J. M. Kaplan Fund, the DGAPA (National Autonomous University of Mexico), and the
Turner Foundation for supporting our research in
northern Mexico. M. S. Mooring provided useful
comments that greatly improved the manuscript. V.
and J. Austin allowed us to work at their property.
LITERATURE CITED
BROWN, D. 1994. Biotic communities in the southwestern U.S. and northwestern Mexico. Utah
University Press, Salt Lake City.
CEBALLOS, G., R. LIST, J. PACHECO, P. MANZANO, G.
SANTOS, AND M. ROYO. 2005. Prairie dogs, cattle
and crops: diversity and conservation of the grassland-shrubland habitat mosaic in northwestern
Chihuahua. In: J.-L. E. Cartron, G. Ceballos, and
R. S. Felger, editors. Biodiversity, ecosystems, and
conservation in northern Mexico. Oxford University Press, Oxford, United Kingdom. Pages
424–438.
CEBALLOS, G., AND D. NAVARRO. 1991. Diversity and
conservation of Mexican mammals. In: M. A. Mares and D. J. Schmdly, editors. Latin American
mammalogy: history, biodiversity, and conservation. University of Oklahoma Press, Norman.
Pages 167–198.
CEBALLOS, G., P. RODRÍGUEZ, AND R. MEDELLIN. 1998.
Assessing conservation priorities in megadiverse
Mexico: mammalian diversity, endemicity, and
endangerment. Ecological Applications 8:8–17.
GARCÍA, E. 1988. Modificaciones al sistema de clasificación climática de Köepen. Instituto de Geografı́a, Universidad Nacional Autónoma de México, Mexico, D.F.
GUERRERO, C. I., I. TOVAR, AND S. ALVAREZ. 2003. Factores que afectan la distribución espacial del borrego cimarrón Ovis canadensis en la Sierra del
Mechudo, B.C.S., México. Anales del Instituto de
Biologı́a, Universidad Nacional Autónoma de
México 74(1):83–98.
434
The Southwestern Naturalist
HALL, R. 1981. The mammals of North America.
John Wiley and Sons, New York.
HAYES, C. L., E. S. RUBIN, M. C. JORGENSEN, R. A.
BOTTA, AND W. M. BOYCE. 2000. Mountain lion
predation of bighorn sheep in the peninsular
ranges of California. Journal of Wildlife Management 64:954:959.
HOFFMEISTER, D. F. 1986. Mammals of Arizona. University of Arizona Press, Tucson.
KRAUSMAN, P. R., A. V. SANDOVAL, AND R. C. ETCHBERGER. 1999. Natural history of desert bighorn
sheep. In: R. Valdez and P. Krausman, editors.
Mountain sheep of North America. University of
Arizona Press, Tucson. Pages 139–191.
LEE, R. 1999. Arizona. In: D. E. Toweill and V. Geist,
editors. Return to royality. Boone and Crockett
Club and Foundation for North American Wild
Sheep, Missoula, Montana. Pages 160–163.
LEOPOLD, A. S. 1959. Wildlife of Mexico: the game
birds and mammals. University of California
Press, Berkeley.
LIST, R., G. CEBALLOS, AND J. PACHECO. 1999. Distribution and conservation status of the North
American porcupine (Erethizon dorsatum) in Mexico. Southwestern Naturalist 44:400–404.
MEDELLIN, R., F. COLCHERO, C. MANTEROLA, F. RAMIREZ, AND G. CEBALLOS. 1999. The Tiburón island
bighorn sheep program: an example of binational, interinstitutional cooperation and sustainable
development in a Mexican Indian and protected
area. Wild Sheep, Spring:71–72.
MEDELLÍN, R., C. MANTEROLA, M. VALDÉZ, D. G. HEWITT, D. DOAN-CRIDER, AND T. E. FULBRIGHT. 2005.
History, ecology, and conservation of the prong-
vol. 51, no. 3
horn antelope, bighorn sheep, and black bear in
Mexico. In: J.-L. E. Cartron, G. Ceballos, and R.
S. Felger, editors. Biodiversity, ecosystems, and
conservation in northern Mexico. Oxford University Press, Oxford, United Kingdom. Pages
387–404.
MOORING, M. S., T. A. FITZPATRICK, T. T. NISHIHIRA,
AND D. D. REISIG. 2004. Vigilance, predation risk,
and the Allee effect in desert bighorn sheep.
Journal of Wildlife Management 68:519–532.
NEW MEXICO DEPARTMENT OF GAME AND FISH. 2002.
Desert bighorn sheep. Wildlife Notes, New Mexico Department of Game and Fish, Santa Fe.
RUBIN, E. S., W. M. BOYCE, M. C. JORGENSEN, S. G.
TORRES, C. L. HAYES, C. S. O’BRIEN, AND D. A.
JESSUP. 1998. Distribution and abundance of
bighorn sheep in the peninsular ranges, California. Wildlife Society Bulletin 16:539–551.
SECRETARÍA DEL MEDIO AMBIENTE Y RECURSOS NATURALES. 2002. Norma Oficial Mexicana NOM-059ECOL-2001. Protección ambiental-Especies nativas de México de flora y fauna silvestres-Categorı́as de riesgo y especificaciones para su inclusión, exclusión o cambio-Lista de especies en
riesgo. México City, D.F.
SHACKLETON, D. M. 1985. Ovis canadensis. Mammalian Species 230:1–9.
SMITH, N., AND P. R. KRAUSMAN. 1988. Desert bighorn
sheep: a guide to selected management practices.
U.S. Fish and Wildlife Service Biological Report
88(35), Washington, D.C.
Submitted 4 January 2005. Accepted 19 January 2006.
Associate editor was Cheri A. Jones.
MAXILLARY CANINES IN BIGHORN SHEEP
BRIAN D. JANSEN*
AND
PAUL R. KRAUSMAN
School of Natural Resources, University of Arizona, Tucson, AZ 85721
*Correspondent: [email protected]
ABSTRACT Bighorn sheep (Ovis canadensis) occasionally have small, procumbent maxillary canines that do not penetrate the gums. However, the frequency of these vestigial teeth is only 3%.
We collected 25 skulls from an isolated and indigenous population of bighorn sheep in the Silver
Bell Mountains, Arizona. We compared the frequency of maxillary canines with data reported in
scientific literature and in the mammalogy collection at the University of Arizona, and found a
significantly higher frequency of maxillary canines in bighorn sheep skulls from the Silver Bell
Mountains than in skulls collected throughout the southwestern United States. We separated skulls
by sex and age and found that male and female skulls (⬎6 months of age at death) from the
Silver Bell Mountains both had a significantly higher frequency of maxillary canines than did
skulls from the Southwest. Lamb skulls (⬍6 months of age at death) exhibited a higher frequency
of maxillary canines than did lamb skulls from throughout the Southwest; however, our small
September 2006
Notes
435
sample size (Silver Bell, n ⫽ 5; Southwest, n ⫽ 12) was statistically inconclusive. The trait for
maxillary canines might be maintained or inflated because of genetic isolation from other bighorn
sheep populations.
RESUMEN Los borregos cimarrones (Ovis canadensis) tienen ocasionalmente pequeños colmillos
maxilares acostados que no penetran las encı́as. Sin embargo, la frecuencia de estos dientes vestigiales es solamente del 3%. Recogimos 25 cráneos de borregos cimarrones de una población
aislada y nativa en las montañas Silver Bell, Arizona. Comparamos la frecuencia de los colmillos
maxilares con los datos obtenidos de la literatura cientı́fica y en la colección de mamı́feros de la
Universidad de Arizona, y encontramos una frecuencia significativamente más alta de colmillos
maxilares en los cráneos de O. canadensis de las montañas Silver Bell que en los recogidos a través
del suroeste de los Estados Unidos. Separamos los cráneos por sexo y edad y encontramos que
tanto los cráneos de machos como los de las hembras (⬎6 meses de edad a la muerte) de las
montañas Silver Bell tenı́an una frecuencia más alta de los colmillos maxilares que los cráneos
del suroeste de USA. Los cráneos de los cabritos (⬍6 meses de edad a la muerte) exhibieron una
frecuencia más alta de los colmillos maxilares que los cráneos a través del suroeste de USA; sin
embargo, nuestro pequeño tamaño de muestra (Silver Bell, n ⫽ 5; suroeste, n ⫽ 12) fue estadı́sticamente inconcluso. La caracterı́stica de tener colmillos maxilares se puede mantener o aumentar debido al aislamiento genético de otras poblaciones de borregos cimarrones.
Maxillary canine teeth occur uncommonly
among species of Bovidae (Benson, 1943).
When they occur, these canines are small and
procumbent, rarely penetrating the gum line
(Benson, 1943; Allred and Bradley, 1965).
Skulls of bighorn sheep rarely have maxillary
canines (Benson, 1943). Two of 53 bighorn
sheep skulls (4%) and 6 of 37 bighorn sheep
skulls (16%) from Washington had maxillary
canines (Benson, 1943; Dalquest and Hoffmeister, 1948). One male of 132 skulls (74
males, 48 females) from the Desert Game
Range, Nevada, bore maxillary canines (Allred
and Bradley, 1965).
During a radiotelemetry study of bighorn
sheep in the Silver Bell and Waterman mountains (32⬚24.5⬘N, 111⬚29.5⬘W), Arizona, from
2003 to 2005, we collected skulls of bighorn
sheep found during our regular fieldwork. We
noticed that the frequency of skulls with maxillary canines seemed higher than previously
reported. For 25 skulls collected with intact distal rostra, we recorded the presence or absence
of maxillary canines or alveoli. We subsequently used data reported by Welles and Welles
(1961), Allred and Bradley (1965), and Bradley and Allred (1966) to calculate frequencies
of maxillary canines in bighorn sheep from the
southwestern United States. We excluded data
reported by Benson (1943), because localities
were not included for all 53 skulls, and by
Deming (1952), because those data likely were
duplicated by Allred and Bradley (1965) and
the reported frequencies were similar to those
in other literature. We supplemented published data by examining skulls in the University of Arizona mammalogy collection representing O. canadensis that did not come from
the Desert Game Range and were collected after 1966 (the most recent publication date on
this topic). No specimens from the Silver Bell
Mountains were reported in other publications, and we excluded all data from the Silver
Bell Mountains from calculations regarding
the general population of bighorn in the
Southwest. We used a Fisher’s Exact Test to determine whether maxillary canines were present in a higher frequency of all, male, female,
or lamb skulls from the Silver Bell Mountains
than those of the general population.
We collected 25 skulls of bighorn sheep (4
male; 16 female; 5 lambs ⬍6 months old) with
intact distal rostra. Of these 25 skulls, 9 (2
male; 3 female; 4 lambs) had maxillary teeth;
that is, 36% (50% of the males; 19% of the
females; 80% of the lambs) of our sample from
the Silver Bell Mountains had maxillary canines.
We compared our 25 skulls with 477 skulls
from throughout the Southwest: 1 from Death
Valley, California (Welles and Welles, 1961);
122 from Desert Game Range (Allred and
Bradley, 1965); 316 skulls from Arizona, from
Joshua Tree National Monument and Death
Valley, California, and from the Desert Game
Range (Bradley and Allred, 1966); and 38
skulls from the University of Arizona from
throughout Arizona. Of the 477 skulls, 14 had
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The Southwestern Naturalist
maxillary canines, representing 3% of the sample from the Southwest. Of the 465 adult skulls
(291 male; 174 female), we found 9 males
(3%) and 1 female (⬍1%) with maxillary canines. Four of the 12 lamb skulls (33%) had
maxillary canines.
Skulls of bighorn sheep from the Silver Bell
Mountains had a higher frequency of maxillary
canines than those of bighorn sheep from
throughout the Southwest (2-tailed P ⬍
0.0001). Comparisons between sex and age revealed that adult males and females had a
higher incidence of maxillary canines (male,
2-tailed P ⫽ 0.007; female, 2-tailed P ⫽ 0.002)
than did males and females from throughout
the Southwest. Lambs (80%) also had a higher
incidence of maxillary canines than those from
elsewhere (33%); however, due to small sample size, our comparison was statistically inconclusive (2-tailed P ⫽ 0.131).
Bovids have lacked upper incisors and canines since the Oligocene (Benson, 1943).
Maxillary canine teeth seem to have no function (Benson, 1943). It does not seem that they
arise from a developmental anomaly, because
they occur in both neonates and adults. Because they do not penetrate the gums, these
teeth probably do not confer any advantages.
Reasons for these teeth, other than genetic
anomalies, are unknown.
Bighorn sheep populations in the Southwest
exist in naturally fragmented mountain ranges,
often far from neighboring populations
(Bleich et al., 1990). Furthermore, human development has added additional barriers that
might inhibit sheep movement into and away
from the Silver Bell Mountains through local
reduction or extinction of neighboring populations, interstate highways, aqueducts, fencing, and urban development. We suggest the
frequency of maxillary canines in the bighorn
sheep from the Silver Bell Mountains has been
inflated because of genetic isolation from other populations.
LITERATURE CITED
ALLRED, L. G., AND W. G. BRADLEY. 1965. Necrosis
and anomalies of the skull in desert bighorn
sheep. Desert Bighorn Council Transactions 9:
75–81.
BENSON, S. B. 1943. Occurrence of upper canines in
mountain sheep, Ovis canadensis. American Midland Naturalist 30:786–789.
BLEICH, V. C., J. D. WEHAUSEN, AND S. A. HOLL. 1990.
Desert-dwelling mountain sheep: conservation
implications of a naturally fragmented distribution. Conservation Biology 4:383–390.
BRADLEY, W. G., AND L. G. ALLRED. 1966. A comparative study of dental anomalies in desert bighorn
sheep. Desert Bighorn Council Transactions 10:
78–85.
DALQUEST, W. W., AND D. F. HOFFMEISTER. 1948.
Mountain sheep from the state of Washington in
the collection of the University of Kansas. Transactions of the Kansas Academy of Science 51:
224–234.
DEMING, O. V. 1952. Tooth development of the Nelson bighorn sheep. California Fish and Game 38:
523–529.
WELLES, R. E., AND F. B. WELLES. 1961. The bighorn
of Death Valley. U.S. Department of the Interior,
National Park Service, Fauna Series 6, Washington, D.C.
Submitted 27 August 2005. Accepted 19 January 2006.
Associate Editor was Cheri A. Jones.
DISTANCES MOVED BY STARTLED DESERT MULE DEER
PAUL R. KRAUSMAN,* JOSH AVEY, COLEEN F. BROWN, PATRICK K. DEVERS, JOHN C. TULL,
BRIAN D. JANSEN, AND JAMES W. CAIN, III
325 Biological Sciences East, School of Natural Resources, University of Arizona, Tucson, AZ 85721
(PRK, CFB, BDJ, JWC)
Arizona Game and Fish Department, 2222 West Greenway Road, Phoenix, AZ 85023 (JA)
Department of Fish and Wildlife Science, Virginia Polytechnic Institute and State University,
Blacksburg, VA 24061-0321 (PKD)
M S-314 Ecology, Evolution and Conservation Biology, University of Nevada, Reno, NV 89557 (JCT)
*Correspondent: [email protected]
September 2006
Notes
437
ABSTRACT The behavior of startled desert mule deer (Odocoileus hemionus eremicus) has been
described, but distances moved after being startled have not been reported. We located 8 radiocollared deer (6 females, 2 males) for 8 mo, intentionally approaching them afoot until we startled
them, waited 15 min, and relocated them (ⱕ90 min). The deer were startled and relocated 56
times. Mean time elapsed between startling and relocation was 34.5 min (SE ⫽ 3.9 min). Mean
distance moved was 893.2 m. When researchers disturb mule deer before obtaining data describing
movement or habitat use, they should abandon their attempts for 24 h to avoid bias in those data.
RESUMEN El comportamiento de los venados buros del desierto (Odocoileus hemionus eremicus)
cuando se asustan ha sido descrito, pero la distancia que se desplazan después de ser asustados
no ha sido registrada Monitoreamos 8 venados (6 hembras, 2 machos) con radio-collares por 8
meses, acercándonos intencionalmente a pie hasta que los asustamos, esperamos 15 min y los
volvimos a localizar (⬍90 min). Los venados fueron asustados y localizados nuevamente 56 veces.
El tiempo medio que transcurrió entre asustar al animal y la relocalización fue de 34.5 min (ES
⫽ 3.9 min). La distancia media que los animales se trasladaron fue de 893.2 m. Cuando los
investigadores molestan a los venados, antes de obtener datos sobre los desplazamientos o el uso
del hábitat, deben dejarlos por 24 h para evitar sesgo en los datos.
Radiotelemetry has become a standard tool
in research regarding movements and habitat
use of ungulates. For example, radiotelemetry
has allowed the study of large-scale movements
by desert mule deer (Odocoileus hemionus eremicus) during the day (Leopold and Krausman,
1987) and night (Hayes and Krausman, 1993).
However, researchers using radiotelemetry and
other research techniques can startle deer and
other ungulates, thus affecting their movements. Disturbance by aircraft has been documented (Krausman and Hervert, 1983; Krausman et al., 1986; Bleich et al., 1990), but little
is known about the immediate movements of
deer after they are startled by researchers on
foot using radiotelemetry.
Most of the information describing behavior
of startled deer in the United States has resulted from general studies of alarm behavior.
Mule deer usually run when startled, using a
stotting or bounding gait (Geist, 1981). If only
moderately startled, the deer will trot away and
stop frequently to look back at their pursuers
(Spencer, 1969; Geist, 1981).
If ungulates move long distances (e.g., long
enough to change vegetation associations)
when disturbed in the process of researchers
locating them with radiotelemetry, data regarding the disturbed animals might be of little value. For example, if an animal is startled
and enters a different vegetation association
before it is ‘‘located,’’ conclusions related to
habitat use could be erroneous. The estimated
size of home ranges also could be altered if,
when startled, animals are forced into areas
not usually used. For example, in Switzerland,
when chamois (Rupicapra rupicapra) were approached by joggers, hikers, and mountain bikers, chamois left the area (mean distance
moved ⫽ 200 m) (Ingold et al., 1996).
Kucera (1976) examined flushing distance
of white-tailed deer (O. virginianus) and reported that 389 of 1,034 deer he observed
were not sufficiently frightened to run. In 645
cases deer ran, but Kucera (1976) could not
determine whether deer were aware of his
presence or if any were aware but tolerated
him. He concluded, however, that deer were
startled more often when he was on foot than
when he was in a vehicle or on horseback. Our
objective was to determine how far desert mule
deer move when startled by researchers tracking them with radiotelemetry on the ground.
Our study was conducted in the Tucson
Mountains, Pima County, Arizona, west of Tucson, Arizona, during 3 seasons in 1998: winter
( January–March), spring (April–June), and
summer ( July–September). Elevations ranged
from 689 to 824 m. The area is in the Arizona
Upland Subdivision of the Sonoran Desert
(Brown, 1982; Rondeau et al., 1996). The area
has long hot summers, short mild winters, biseasonal rainfall peaks (i.e., winter and late
summer), low relative humidity, and high rates
of evaporation. Mean temperatures were 16⬚C
and 30⬚C in winter and summer, respectively.
Average annual precipitation was 27.9 cm.
We tracked 8 radiocollared desert mule deer
(6F, 2M) as part of a 2-y study in which we
examined movements (Tull and Krausman,
2001). Upon completion of that project, we be-
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vol. 51, no. 3
The Southwestern Naturalist
gan this experiment on 23 January 1998, completing it on 31 August 1998.
We located deer with a telemetry receiver
(model TR-2, Telonics, Mesa, Arizona) and
hand-held Yagi antenna, then plotted their positions with a geographic positioning system
(GPS; Magellan Systems Corp., San Dimas, California). After deer were located, we approached them, as if we were obtaining a radiolocation by homing (White and Garrett,
1990), until they left the area. We waited 15
min and relocated them within 90 min. If we
were able to relocate the deer, we recorded
their position using the GPS and the time
elapsed since we startled them. We measured
the linear distance from the first location to
the second (to the nearest meter) as the distance moved due to startling. We did not intentionally startle them a second time, and
deer that continued to move away from us after we began our second location effort were
not included in the analysis. We used one-way
analysis of variance (ANOVA) to determine
whether deer moved significantly farther after
being startled in any season.
We startled and relocated each deer ⱕ6
times (from dawn to 1200 h) during each season: 16, 22, and 18 times in winter, spring, and
summer, respectively. The mean time elapsed
between startling and relocation was 34.5 min
(SE ⫽ 3.9; range ⫽ 24 to 46 min). There was
no difference in distances moved among seasons (F2, 53 ⫽ 0.509, P ⫽ 0.64). Overall, the
mean distance moved from the startling point
to relocation was 893.2 m (SE ⫽ 134.3, range
⫽ 522 to 1,718 m).
During our previous project, the 8 individuals tracked during this study had been radiolocated ⱖ1 time/week from November 1995 to
December 1997 (Tull and Krausman, 2001).
Thus, deer likely were aware of the presence
of researchers even though we never intentionally disturbed them. However, when we intentionally startled them (i.e., by approaching
within 25 to 50 m) they moved an average of
893 m in 30 min (i.e., the mean time for a
relocation). When desert mule deer were disturbed by a small fixed-wing aircraft flying an
average of 80 m above ground level, 7 males
moved an average of 430 m and 2 females
moved 1,000 and 1,710 m (Krausman et al.,
1986). When startled, whether by aircraft or by
humans afoot, desert mule deer are displaced.
None of the deer that were alerted moved
outside of their home ranges (Tull and Krausman, 2001). Also, because the habitat that we
were working in was relatively homogeneous,
we did not document shifts in habitat use after
the deer were startled. However, if other deer
respond in a similar manner in heterogeneous
habitats, it is likely that disturbances could shift
use of habitats. This obviously would bias results if deer-habitat relationships were being
examined. Because deer moved ⱖ2 km due to
disturbance, we recommend that locations of
deer be abandoned for ⱖ24 h if deer are disturbed and move, and the researcher has to
pursue the animal. Biologists might not always
know whether they have caused disturbance,
but if disturbance is suspected, they should
pursue different deer.
This study was conducted with the approval of the
Institutional Animal Care and Use Committee, University of Arizona. The study was funded by the Arizona Agricultural Experiment Station, University of
Arizona, Tucson.
LITERATURE CITED
BLEICH, V. C., R. T. BOWYER, A. M. PAULI, R. L. VERNOY, AND R. W. ANTHES. 1990. Responses of
mountain sheep to helicopter surveys. California
Fish and Game 76:197–204.
BROWN, D. E. 1982. Biotic communities of the American Southwest: United States and Mexico. Desert
Plants 4:1–342.
GEIST, V. 1981. Behavior: adaptive strategies in mule
deer. In: O. C. Wallmo, editor. Mule and blacktailed deer of North America. University of Nebraska Press, Lincoln. Pages 157–223.
HAYES, C. L., AND P. R. KRAUSMAN. 1993. Nocturnal
activity of female desert mule deer. Journal of
Wildlife Management 57:897–904.
INGOLD, P., R. SCHNIDRIG-PETRIG, H. MARBACHER, U.
PFISTER, AND R. ZELLER. 1996. Tourism/sports de
loiser et faune sauvage dans la region alpine Suisse. Office federal de l’environnement, des forets
et du paysage (OFEFP). Cahier de l’environnement. Number 262.
KRAUSMAN, P. R., AND J. J. HERVERT. 1983. Mountain
sheep responses to aerial surveys. Wildlife Society
Bulletin 11:372–375.
KRAUSMAN, P. R., B. D. LEOPOLD, AND D. L. SCARBROUGH. 1986. Desert mule deer response to aircraft. Wildlife Society Bulletin 14:68–70.
KUCERA, E. 1976. Deer flushing distance as related
to observers mode of travel. Wildlife Society Bulletin 4:128–129.
September 2006
Notes
LEOPOLD, B. D., AND P. R. KRAUSMAN. 1987. Diurnal
activity of desert mule deer in relation to temperature. Texas Journal of Science 39:49–53.
RONDEAU, R. J., T. R. VAN DEVENDER, C. D. BERTLESEN, P. D. JENKINS, R. K. WILSON, AND M. A. DIMMITT. 1996. Annotated flora and vegetation of the
Tucson Mountains, Pima County, Arizona. Desert
Plants 12:1–284.
SPENCER, J. W. 1969. Hunting mule deer. In: W. P.
Taylor, editor. The deer of North America: the
white-tailed, mule, and black-tailed deer, genus
439
Odocoileus. Their history and management. Wildlife Management Institute, Washington, D.C. Pages 483–522.
TULL, J. C., AND P. R. KRAUSMAN. 2001. Use of a wildlife corridor by desert mule deer. Southwestern
Naturalist 46:81–86.
WHITE, G. C., AND R. A. GARRET. 1990. Analysis of
wildlife radio-tracking data. Academic Press, San
Diego, California.
Submitted 27 August 2005. Accepted 18 November 2005.
Associate Editor was Cheri A. Jones.