conservation.arizona.edu - ponderosa pine

Differential response of native Arizona gray squirrels and introduced Abert's squirrels to a mosaic of burn severities

thackerk1 — Mon, 22 Jul 2019 21:22:42 +0000

Authors

Shari L. Ketcham

John L. Koprowski

Donald A. Falk

Disturbance events can alter habitat properties, leading to species displacement, isolation, and/or local extinction. Therefore, understanding the interactions of potential ecological drivers on native and introduced wildlife species post-fire is critical to understand influences on distribution. We studied native Arizona gray squirrels (Sciurus arizonensis), which are believed to favor dense riparian habitat, and introduced Abert’s squirrels (S. aberti), which prefer open ponderosa pine (Pinus ponderosa) forests. We examined how uncommon native Arizona gray squirrels and introduced Abert’s squirrels used areas previously burned by widespread fires more than a decade prior to our study. To determine how past fire may affect squirrel habitat, we examined squirrel use and occupancy within fire altered habitats and used distance sampling to determine squirrel distribution, feeding, and nest use within a mosaic of burn severities. Occupancy and habitat use indicated that introduced Abert’s squirrels readily used post-fire conditions more than native Arizona gray squirrels, likely due to the opening of a dense understory. Arizona gray squirrels remained in unburned riparian areas; therefore, fire affected riparian areas can be directly targeted for management to increase abundance of the native species.

Additional Information

Mammal Study 42:247-258.

Date of publication:

2017

Topics

Arizona gray squirrel

Abert’s squirrels

ponderosa pine

wildfire effects

occupancy

habitat

feeding signs

dreys

Research Categories

Disturbance Ecology Sky Islands Threatened and Endangered Species

Hutton, K. A., J. L. Koprowski, V. L. Greer, M. I. Alanen, C. A. Schauffert and P. J. Young. 2002. Use of Spruce-Fir and Mixed-Conifer Forests by an Introduced Population of Abert's Squirrels (Sciurus Aberti). The Southwestern Naturalist 48: 257-260.

thackerk1 — Mon, 22 Jul 2019 18:45:45 +0000

Authors

Kelly A. Hutton

John L. Koprowski

Vicki L. Greer

Marit I. Alanen

Carol A. Schauffert

Paul J. Young

Abert’s squirrels (Sciurus aberti) are thought to depend on ponderosa pine (Pinus ponderosa) for food sources, cover, and nest sites. Records of Abert’s squirrels using other food sources, forest types, and nest trees are rare. In the 1940s, Abert’s squirrels were introduced to ponderosa pine forests on Mount Graham in the Pinaleño Mountains of southeastern Arizona. Since 1989, while studying Mount Graham red squirrels (Tamiasciurus hudsonicus grahamensis), we recorded Abert’s squirrel sightings. In over 41,000 field-hours of studying Mount Graham red squirrels, we documented 498 Abert’s squirrel sightings in both mixed-conifer and spruce-fir forests. Behaviors observed included feeding, collecting nest material, nest building, intraspecific chases, and interactions with the endangered red squirrels in this nontraditional habitat.

Additional Information

USE OF MIXED-CONIFER AND SPRUCE-FIR FORESTS BY AN INTRODUCED POPULATION OF ABERT'S SQUIRRELS (SCIURUS ABERTI)

Date of publication:

2002

Topics

Abert’s squirrel

Pinaleño Mountains

Mount Graham Red Squirrel

mixed-conifer forest

spruce-fir forest

behavioral observations

ponderosa pine

Edelman, A. J. and J. L. Koprowski. 2006. Characteristics of Abert's squirrel (Sciurus aberti) cavity nests. The Southwestern Naturalist 51(1): 64-70.

thackerk1 — Tue, 25 Jun 2019 01:18:08 +0000

Authors

Andrew J. Edelman

John L. Koprowski

Cavity nests are rarely used by Abert's squirrels (Sciurus aberti) in ponderosa pine (Pinus ponderosa) forests. Introduced Abert's squirrels in the Pinaleño Mountains of Arizona, however, exhibit occasional use of cavity nests (ca. 10%). We examined characteristics of cavity nest sites in this introduced population. Cavity nests were located at two-thirds of the tree height and were found mainly in both dead and live aspen (Populus tremuloides). Aspen cavity trees were larger than aspen random trees. Aspen cavity sites had more large snags and less ponderosa pine and were less steep than aspen random sites. Abert's squirrels possibly use cavities in large aspen trees because thick trunks and older trees might allow larger cavities to form, might provide greater thermal and wind protection, or both. The greater use of cavity nests by the Abert's squirrels in our study could be due to the higher frequency of cavity-forming aspens or harsher winter conditions in mixed-conifer forests of the Pinaleño Mountains than in ponderosa pine forests where Abert's squirrels typically occur or both.

Additional Information

CHARACTERISTICS OF ABERT'S SQUIRREL (SCIURUS ABERTI) CAVITY NESTS

Date of publication:

2006

Topics

Abert’s squirrels

cavity nests

aspen

ponderosa pine

mixed conifer forests

Pinaleño Mountains