conservation.arizona.edu - endemic species

Ramos-Lara, N., J. L. Koprowski, and D. E. Swann. 2013. Nest-site characteristics of the montane endemic Mearns's squirrel (Tamiasciurus mearnsi): an obligate cavity-nester? Journal of Mammalogy 94:50-58.

thackerk1 — Tue, 30 Jul 2019 18:09:11 +0000

Authors

Nicolás Ramos-Lara

John L. Koprowski

Don E. Swann

Many animals depend on nests for their survival and reproduction, with some species considered obligate tree cavity-nesters. Mearns’s squirrel (Tamiasciurus mearnsi) is a species endemic to the Sierra de San Pedro Mártir, Baja California, Mexico, that relies on tree cavities for nesting. Federally listed as threatened in Mexico, and as endangered by the International Union for Conservation of Nature, the ecology of this southernmost Tamiasciurus is poorly known. The aim of this study was to examine the nesting requirements of Mearns’s squirrels. We used telemetry to locate the nests and 10-m-radius circular plots to compare habitat characteristics between nest sites and random sites, nest sites of males and females, and nest sites of breeding and nonbreeding females. Nest tree species, nest tree condition, nest tree size (diameter at breast height), canopy cover, and occurrence of white firs (Abies concolor) are important characteristics for nesting. Nest sites of males did not differ from those of females except for nest tree condition. Females apparently do not have specific nesting requirements for rearing young. Unlike other congeners that also build leaf nests and underground burrows for nesting, large trees and snags that facilitate cavity formation are critical for the conservation of this species.

Additional Information

Nest-site characteristics of the montane endemic Mearns’s squirrel (Tamiasciurus mearnsi): an obligate cavity-nester?

Date of publication:

2013

Topics

cavity nests

endemic species

nest sites

tree cavities

Mearn’s squirrel

Ramos-Lara, N., J. L. Koprowski, B. Kryštufek, and I. E. Hoffman. 2014. Spermophilus citellus (Rodentia: Sciuridae). Mammalian Species 46:71-87

thackerk1 — Tue, 30 Jul 2019 17:50:57 +0000

Authors

Nicolás Ramos-Lara

John L. Koprowski

Boris Kryštufek

Ilse E. Hoffmann

Spermophilus citellus (Linnaeus, 1766) is a medium-sized sciurid commonly called the European ground squirrel. The species inhabits grasslands in central and southeastern Europe on a range from short-grass steppes to meadow orchards, and from sea level to an elevation of 2,500 m. These squirrels live in colonies and construct burrows used for hibernation, reproduction, refuge, and resting. Due to serious declines in many portions of its range, the species is listed as ‘‘Vulnerable’’ by the International Union for Conservation of Nature and Natural Resources. It is also protected by the Bern Convention (Appendix II), and the European Union Habitats and Species Directive (Annexes II and IV).

Additional Information

Spermophilus citellus (Rodentia: Sciuridae)

Date of publication:

2014

Topics

European ground squirrel

endemic species

Europe

Sciurus sanborni

thackerk1 — Wed, 24 Jul 2019 22:15:49 +0000

Authors

Rosa R. Palmer

John L. Koprowski

Sciurus sanborni Osgood, 1944 is a rodent commonly called Sanborn’s squirrel or ardilla de Sanborn. S. sanborni is a small squirrel with olive brown dorsum, buff eye rings, and usually, white underparts. S. sanborni is 1 of 28 species in the genus Sciurus, and a rare endemic of Peru that is found in lowland Amazonian forest between 300 and 580 m elevation. The Peruvian Ministry of the Environment classifies S. sanborni as “Vulnerable” and the International Union for Conservation of Nature and Natural Resources considers the species to be “Data Deficient;” habitat destruction is the main threat.

Additional Information

Mammalian Species 49:93-96.

Date of publication:

2017

Topics

endemic species

Neotropics

Sanborn’s squirrel

tree squirrel

ardilla de Sanborn

Peru

Research Categories

Natural History

Koprowski, J. L. 2005. Management and conservation of tree squirrels: The importance of endemism, species richness, and forest condition. USDA Forest Service Proceedings RMRS-P-36: 245-250.

thackerk1 — Mon, 22 Jul 2019 23:19:59 +0000

Authors

John L. Koprowski

Tree squirrels are excellent indicators of forest health yet the taxon is understudied. Most tree squirrels in the Holarctic Region are imperiled with some level of legal protection. The Madrean Archipelago is the epicenter for tree squirrel diversity in North America with 5 endemic species and 2 introduced species. Most species of the region are poorly studied in keeping with an international dearth of data on this taxon; 3 of the 5 native species are the subject of <3 publications. Herein, I review literature on the response of squirrels to forest management from clearcutting to less comprehensive operations. Major threats to squirrel diversity in the Madrean Archipelago’s Sky Islands are the introduction of species, altered fire regimes, and inappropriate application of forestry practices.

Additional Information

Management and Conservation of Tree Squirrels: The Importance of Endemism, Species Richness, and Forest Condition

Date of publication:

2005

Topics

forest health

tree squirrels

endemic species

introduced species

Madrean Archipelago’s Sky Islands

Koprowski, J. L., N. Ramos, B. S. Pasch, and C. A. Zugmeyer. 2006. Observations on the ecology of the endemic Mearns's squirrel (Tamiasciurus mearnsi). The Southwestern Naturalist 51(3): 426-430.

thackerk1 — Mon, 22 Jul 2019 23:06:13 +0000

Authors

John L. Koprowski

Nicolás Ramos

Bret S. Pasch

Claire A. Zugmeyer

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.

Additional Information

OBSERVATIONS ON THE ECOLOGY OF THE ENDEMIC MEARNS’S SQUIRREL (TAMIASCIURUS MEARNSI)

Date of publication:

2006

Topics

Mearn’s squirrel

endemic species

adaptations

montane forest

Sierra de San Pedro Mártir

Koprowski, J. L., S. L. Doumas, M. J. Merrick, B. Oleson, E. E. Posthumus, T. G. Jessen, and R. N. Gwinn. 2013. It's lonely at the top: Biodiversity at risk to loss from climate change. In Gottfried, Gerald J.; Ffolliott, Peter F.; Gebow, Brooke S.; Eskew

thackerk1 — Mon, 22 Jul 2019 21:36:58 +0000

Authors

John L. Koprowski

Sandra L. Doumas

Melissa J. Merrick

Brittany Oleson

Erin E. Posthumus

Timothy G. Jessen

R. Nathan Gwinn

Climate change is a serious immediate and long-term threat to wildlife species. State and federal agencies are working with universities and non-government organizations to predict, plan for, and mitigate such uncertainties in the future. Endemic species may be particularly at-risk as climate-induced changes impact their limited geographic ranges. The Madrean Archipelago is characterized by high levels of endemism, natural fragmentation, and increasingly poor connectivity among the mesic montane islands within an arid matrix of low elevation deserts and grasslands. The region already has experienced an increase in temperature and this trend is predicted to accelerate over the remainder of the century. We assessed patterns of elevational distribution of reptiles and mammals within the Madrean Archipelago. We examined incremental temperature increases and determined how much reptilian and mammalian biodiversity is at-risk to be lost from montane islands due to elevational and geographic restriction. We estimate that 15 to 20% of all reptile and mammal diversity is at risk of loss by 2100 based solely on predicted patterns of upslope migration of biotic communities driven primarily by climate change. With this significant proportion of native species, we suggest that this emphasizes the need to continue traditional management actions focused on habitat improvement, restoration and connectivity for the majority of species in combination with innovative and active management strategies directed at the subset that is most at risk of extirpation.

Additional Information

It’s Lonely at the Top: Biodiversity at Risk to Loss from Climate Change

Date of publication:

2013

Topics

climate change

endemic species

geographical range

biodiversity

Madrean Archipelago

restoration

habitat

connectivity

Tamiasciurus mearnsi (Rodentia: Sciuridae)

thackerk1 — Mon, 22 Jul 2019 21:30:50 +0000

Authors

John L. Koprowski

Michael A. Steele

Nicolás Ramos-Lara

Tamiasciurus mearnsi (Townsend, 1897) is a small-sized tree squirrel commonly called Mearns’s squirrel. One of 3 species that comprise the genus Tamiasciurus, T. mearnsi, is endemic to the Sierra de San Pedro Mártir in Baja California, Mexico; it is considered rare and occurs only at low densities. T. mearnsi is federally listed as “Threatened” in Mexico and is also included in the International Union for the Conservation of Nature and Natural Resources Red List of Threatened Species as “Endangered.” The introduction of the eastern gray squirrel (Sciurus carolinensis) may be a serious threat to this relict species.

Additional Information

Mammalian Species 48:66-72

Date of publication:

2016

Topics

Mearn’s squirrel

tree squirrel

endemic species

eastern gray squirrel

Sierra de San Pedro Mártir

Mexico

Research Categories

Natural History Threatened and Endangered Species