conservation.arizona.edu - tree squirrel

Ramos-Lara, N., and J. L. Koprowski. 2015. Spacing behavior of a non-larder-hoarding Tamiasciurus: a study of Mearns's squirrels in xeric coniferous forests. Ethology 121: 196-205.

thackerk1 — Tue, 30 Jul 2019 17:43:48 +0000

Authors

Nicolás Ramos-Lara

John L. Koprowski

In ecosystems with seasonal fluctuations in food supply many species use two strategies to store food: larder hoarding and scatter hoarding. However, because species at different geographic locations may experience distinct environmental conditions, differences in hoarding behavior may occur. Tree squirrels in the genus Tamiasciurus display variation in hoarding behavior. Whereas red (Tamiasciurus hudsonicus) and Douglas’s (Tamiasciurus douglasii) squirrels in mesic coniferous forests defend territories centered around larder hoards maintaining non-overlapping home ranges, red squirrels in deciduous forests defend small scatter-hoarded caches of cones maintaining overlapping home ranges. As in other rodent species, variation in hoarding behavior appears to influence the spacing behavior of red and Douglas’s squirrels. In contrast, Mearns’s squirrels (Tamiasciurus mearnsi) in xeric coniferous forests neither rely on larder hoards nor appear to display territorial behavior. Unfortunately, little is known about the ecology of this southernmost Tamiasciurus. Using radiotelemetry, we estimated home-range size, overlap, and maximum distance traveled from nest to examine the spacing behavior of Mearns’s squirrels. Similar to scatter-hoarding rodents, maximum distance traveled from nest was greater for males during mating season, whereas those of females were similar year round. Although no seasonal differences were detected, male home ranges were three times larger during mating season, whereas those of females were smaller and displayed a minor variation between seasons. Home ranges were overlapped year round but contrary to our expectations, overlap was greater during mating season for both sexes, with no detectable relationship between male home-range size and the number of females overlapped during mating season. Overall, the results appear to support our hypothesis that in the absence of larder hoards, the spacing behavior of Mearns’s squirrels should be different from larder- hoarding congeners and more similar to scatter-hoarding rodents.

Additional Information

Spacing Behavior of a Non-Larder-Hoarding Tamiasciurus: A Study of Mearns’s Squirrels in Xeric Coniferous Forests

Date of publication:

2014

Topics

hoarding behavior

mating system

spacing behavior

tree squirrel

Mearn’s squirrel

red squirrel

Douglas's squirrel

Palmer, R. R. and J. L. Koprowski. 2015. How do Neotropical pygmy squirrels (Sciurillus pusillus) use seasonally flooded forest in the Peruvian Amazon? Journal of Mammalogy DOI:10.1093/jmammal/gyv138.

thackerk1 — Wed, 24 Jul 2019 22:20:30 +0000

Authors

Rosa R. Palmer

John L. Koprowski

Tree squirrels are important components of ecosystems but to understand their role, we must learn how squirrels select and use habitat. Tree squirrel species richness is highest in the tropics and, according to the International Union for Conservation of Nature, is also where the greatest number of data deficient species occurs. The Neotropical pygmy squirrel (Sciurillus pusillus) is one of these species. In 2009 and 2010, we conducted distance sampling to estimate population density, we measured vegetation variables to investigate forest characteristics that influence habitat selection at 3 different scales, and conducted observations to obtain knowledge about activity patterns and behavior of Neotropical pygmy squirrels in igapó forest in the Peruvian Amazon. Density of squirrels was 0.10 and 0.14 individuals/ha, respectively, for each year. Squirrel activity peaked at 0800h, individuals were found mainly in the canopy and never on the ground, and frequency of squirrel behaviors differed by time and story level. Squirrels mainly used high and low restinga and areas that had more trees that were ≥ 30 cm diameter at breast height (DBH)/ha compared to random areas in our site in igapó forest. Squirrels used trees that were larger in DBH, taller, and had a larger live crown compared to random trees. Neotropical pygmy squirrels are associated with features related to mature forests.

Additional Information

How do Neotropical pygmy squirrels (Sciurillus pusillus) use seasonally flooded forests in the Peruvian Amazon?

Date of publication:

2015

Topics

activity pattern

population density

rainforest

tree squirrel

tropical forest

Neotropical pygmy squirrel

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

Palmer, G. H., J. L, Koprowski, and T. Pernas. 2008. Tree squirrels as invasive species: conservation and management implications. Pp 273 - 282 in G. L. Witmer, W. C. Pitt, K.A. Fagerstone (eds.), Managing vertebrate invasive species: proceedings of an in

thackerk1 — Wed, 24 Jul 2019 22:02:20 +0000

Authors

Geoffrey H. Palmer

John L. Koprowski

Tony Pernas

The impact of invasive species on native biodiversity is increasing worldwide. Mammalian invaders are formidable ecological and economic threats, and tree squirrels are models of such challenges. We review the worldwide distribution of tree squirrel introductions and detail their nearly universal success. The biological characteristics of tree squirrels that enable success as invasive species are: high reproductive potential, high vagility, diverse food habits, ability to construct nests, and plasticity in human-impacted landscapes. We document costs and benefits of tree squirrel introductions, and discuss existing management strategies planned for some species. We focus on an introduced population of Mexican red-bellied squirrels (Sciurus aureogaster) found in Biscayne National Park, Florida, United States. Originally introduced to Elliot Key in 1938, the population expanded until Hurricane Andrew in 1992. Thought to be extirpated, recent sightings initiated a project to assess status and distribution within the Park. A field study has provided valuable information on potential and realized impacts that the squirrel population has on the native ecosystem that includes several species of conservation concern. Management strategies for Mexican red-bellied squirrels can be formed after research to develop prudent and effective means to meet the challenges that result from control measures to deal with this exotic species.

Additional Information

TREE SQUIRRELS AS INVASIVE SPECIES: CONSERVATION AND MANAGEMENT IMPLICA TIONS

Date of publication:

2007

Topics

invasive species

red-bellied squirrels

tree squirrel

management strategies

Palmer, G. H., J. L. Koprowski, and A. J. Pernas. 2013. Nest tree and site selection of an introduced population of red-bellied squirrels (Sciurus aureogaster). Journal of Mammalogy 94:1274-1281.

thackerk1 — Wed, 24 Jul 2019 21:30:22 +0000

Authors

Geoffrey H. Palmer

John L. Koprowski

Anthony J. Pernas

Nests play a crucial role in the life history of tree squirrels, and can be a critical component of their biology that enables them to be a successful invasive species. Red-bellied squirrels (Sciurus aureogaster) were introduced to Elliott Key, Florida, in the late 1930s, and spread to nearby islands. Red-bellied squirrels were believed extirpated by Hurricane Andrew in 1992, but were rediscovered on Elliott Key in 2005. In 2006 and 2007, we surveyed for squirrel nests and measured vegetation to evaluate forest characteristics associated with nest-site selection by squirrels, and compared these data to measurements collected at random locations. Squirrels placed nests in large trees with more canopy linkages in mixed-hardwood forest, and the nest trees were in areas with large trees, high tree density and canopy cover, and lower recent hurricane damage. Red-bellied squirrels selected characteristics of nest trees and forest structure in similar ways to individuals in their native range, and to other species of tree squirrels in general. Results from our research allowed land managers to assess possible management actions and provided important information for them to develop an effective management strategy. Park officials are currently working toward complete eradication of the introduced population of red-bellied squirrels from the Florida Keys. We suggest that behaviors of individuals in native ranges may elucidate patterns for individuals introduced to novel environments; however, we also caution that care must be taken in further extrapolation. Our findings emphasize the importance of understanding ecology of introduced species for effective management.

Additional Information

Nest tree and site selection of an introduced population of red-bellied squirrels (Sciurus aureogaster)

Date of publication:

2013

Topics

habitat selection

invasive species

Mexican gray squirrel

nesting behavior

species eradication

tree squirrel

red-bellied squirrels

Biscayne National Park

Merrick, M. J., J. L. Koprowski, and R. N. Gwinn. 2012. Sciurus stramineus (Rodentia: Sciuridae). Mammalian Species 44: 44-50

thackerk1 — Tue, 23 Jul 2019 23:31:56 +0000

Authors

Melissa J. Merrick

John L. Koprowski

R. Nathan Gwinn

Sciurus stramineus Eydoux and Souleyet, 1841, is a large-bodied squirrel commonly called the Guayaquil squirrel. S. stramineus is characterized by a distinct grizzled-gray pelage with dark feet and ears, a long tail, and a distinctive white ‘‘collar’’ behind the ears. It is native to the western slope of the Andes, occurring from dry or humid tropical forests at sea level to high- elevation montane forests up to 2,000 m in Ecuador and Peru. S. stramineus is adaptable, adjusting to anthropogenic changes and living close to human settlements, in coffee plantations, with an introduced population in Lima, Peru. Because of a tolerance for living in proximity to humans, S. stramineus is also a concern for transmission of diseases such as leptospirosis and Chagas disease.

Additional Information

Sciurus stramineus (Rodentia: Sciuridae)

Date of publication:

2012

Topics

Guayaquil squirrel

Ecuador

introduced species

tree squirrel

sciurid

Peru

Merrick, M. J., S. L. Ketcham, and J. L. Koprowski. 2014. Sciurus ignitus (Rodentia: Sciuridae). Mammalian Species 46:93-100.

thackerk1 — Tue, 23 Jul 2019 23:26:36 +0000

Authors

Melissa J. Merrick

Shari L. Ketcham

John L. Koprowski

Sciurus ignitus (Gray, 1867) is a Neotropical tree squirrel commonly known as the Bolivian squirrel. It is a small-bodied, understory and mid-canopy dweller that occurs within the evergreen lowland and montane tropical rain forests along the eastern slope of the Andes in Peru, Bolivia, and extreme northern Argentina, and the western Amazon Basin in Brazil and Peru between 200 and 2,700 m in elevation. S. ignitus is 1 of 28 species in the genus Sciurus, and 1 of 8 in the subgenus Guerlinguetus. The taxonomic status of this species, as with other small sciurids in Peru and Bolivia, remains ambiguous. S. ignitus is currently listed as ‘‘Data Deficient’’ by the International Union for Conservation of Nature and Natural Resources.

Additional Information

Sciurus ignitus (Rodentia: Sciuridae)

Date of publication:

2014

Topics

Andes

Bolivian squirrel

Neotropics

Peru

tree squirrel

Sciurus anomalus (Rodentia: Sciuridae)

thackerk1 — Mon, 22 Jul 2019 21:33:18 +0000

Authors

John L. Koprowski

Leah Gavish

Sandra L. Doumas

Sciurus anomalus Güldenstädt, 1785 is a rodent commonly called the Caucasian squirrel. S. anomalus is a medium-sized squirrel with chestnut gray to grizzled buff dorsum, buff eye rings, and chestnut to buff-yellow underparts. S. anomalus is 1 of 28 species in the genus Sciurus and is found in forests of the Middle East and extreme southwestern Asia. The International Union for Conservation of Nature and Natural Resources considers S. anomalus to be a species of “Least Concern;” habitat destruction is the main threat.

Additional Information

Mammalian Species 48:48-58.

Date of publication:

2016

Topics

Caucasian squirrel

golden squirrel

Persian squirrel

tree squirrel

southwestern Asia

Middle East

Research Categories

Natural History

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

Jessen, R. R., G. H. Palmer, and J. L. Koprowski. 2013. Maternity nest of an Amazon red squirrel in a bromeliad. Mastozoología Neotropical 20:159-161.

thackerk1 — Mon, 22 Jul 2019 19:08:38 +0000

Authors

Rosa R. Jessen

Geoffrey H. Palmer

John L. Koprowski

Animal-plant interactions are important in the life history of many animal and plant species but our knowledge is often limited. We documented a maternity nest of the poorly studied Amazon red squirrel. The nest was located in a bromeliad and contained two young, a male and a female. We measured nest and forest characteristics and also documented a predation attempt on the adult female while we observed the nest and squirrels.

Additional Information

MATERNITY NEST OF AN AMAZON RED SQUIRREL IN A BROMELIAD

Date of publication:

2013

Topics

hook-billed Kite

nesting habits

tree squirrel

Amazon red squirrel