Merrick, M. J., S. R. Bertelsen, and J. L. Koprowski. 2007. Characteristics of Mount Graham red squirrel nest sites in a mixed conifer forest. The Journal of Wildlife Management 71: 1958-1963.

thackerk1 — Tue, 23 Jul 2019 23:39:01 +0000

Authors

Melissa J. Merrick

Sadie R. Bertelsen

John L. Koprowski

The Mount Graham red squirrel (Tamiasciurus hudsonicus grahamensis) is constrained to the Pinaleńo Mountains in southeastern Arizona, USA. The population’s endangered status and extensive forest damage from insects and fire warrants a better understanding of habitat variables important for nest site selection. We examined characteristics of cavity (n 1⁄4 91) and drey (n 1⁄4 38) nests and compared these to random sites (n 1⁄4 113). Dreys were found primarily in Engelmann spruce (Picea engelmannii) and corkbark fir (Abies lasiocarpa var. arizonica). Cavity nests occurred primarily in aspen (Populus tremuloides) and corkbark fir. Squirrels selected nest sites with higher canopy cover and more corkbark fir, decayed logs, and living trees. Forest management plans emphasizing thinning must consider how altering these habitat characteristics could affect availability and suitability of tree stands for nesting squirrels. (JOURNAL OF WILDLIFE MANAGEMENT 71(6):1958–1963; 2007)

Additional Information

Characteristics of Mount Graham Red Squirrel Nest Sites in a Mixed Conifer Forest

Date of publication:

2007

Topics

Arizona

habitat selection

Mount Graham Red Squirrel

nest-site selection

Edelman, A. J. and J. L. Koprowski. 2005. Selection of drey sites by Abert's squirrels in an introduced population. Journal of Mammalogy 86(6): 1220-1226.

thackerk1 — Tue, 25 Jun 2019 01:24:39 +0000

Authors

Andrew J. Edelman

John L. Koprowski

Abert’s squirrels (Sciurus aberti) are reported to depend on ponderosa pine (Pinus ponderosa) for food and nest sites. Introduced Abert’s squirrels in the Pinaleño Mountains of Arizona, however, occupy mixed-conifer forests that contain almost no ponderosa pine (about 2%). We examined selection of drey sites in this introduced population. Dreys (i.e., spherical nests) were built adjacent to the trunk at 75% of the tree height. Dreys were found in 5 different conifer species and ,2% were in ponderosa pine. Drey trees were larger and had more access routes than did random trees. Drey sites were steeper, had more large trees, Douglas-fir (Pseudotsuga menziesii), and southwestern white pine (Pinus strobiformis), and less corkbark fir (Abies lasiocarpa var. arizonica) than random sites. The structural characteristics of drey trees in the Pinalen ̃os population also were very similar to drey trees used by natural populations of Abert’s squirrels in ponderosa pine forests. Our results suggest that the dependence of Abert’s squirrels on ponderosa pine is not as strong as previously reported. Structural features such as tree size and access routes appear to be more important to selection of drey sites than tree species.