Zugmeyer, C. A. 2007. Trailblazers in the forest: response of endangered Mt. Graham red squirrels to severe insect infestation. M.S. Thesis. University of Arizona, Tucson, AZ. 73 pp

thackerk1 — Tue, 30 Jul 2019 22:29:25 +0000

Authors

Claire A. Zugmeyer

I examined habitat selection of middens within insect-damaged forest and compared home range and survival for Mt. Graham red squirrels (Tamiasciurus hudsonicus grahamensis) in insect-damaged and healthy forest. Squirrels used habitat in areas with < 69% tree mortality. Basal area, canopy cover, and log volume were greater at middens than random locations. Within midden sites, only greater basal area of live trees distinguished occupied sites from unoccupied sites. Surface temperature at occupied middens tended to be cooler than unoccupied middens. Squirrels living in insect-damaged forest had larger home ranges than in healthy forest. Squirrel body mass and reproductive condition did not differ between forest types, suggesting that insectdamaged forest provided adequate resources. However, squirrels inhabiting insectdamaged forest experienced lower survivorship and 50% fewer potential reproductive events than squirrels in healthy forest, implicating presence of an ecological trap. Preservation of remaining healthy forest is a priority for management of this endangered species.

Additional Information

Trailblazers in the Forest: Response of Endangered Mt. Graham Red Squirrels to Severe Insect Infestation

Date of publication:

2007

Topics

Mount Graham Red Squirrel

habitat selection

insect damage

home range

healthy forest

Wood, D. J. A., S. Drake, S. P. Rushton, D. Rautenkranz, P. W. Lurz, and J. L. Koprowski. 2007. Fine-scale analysis of Mount Graham red squirrel habitat following disturbance. The Journal of Wildlife Management 71(7): 2357-2364.

thackerk1 — Tue, 30 Jul 2019 21:19:23 +0000

Authors

David J. A. Wood

Sam Drake

Steve P. Rushton

Doug Rautenkranz

Peter W. W. Lurz

John L. Koprowski

Habitat destruction and degradation are major factors in reducing abundance, placing populations and species in jeopardy. Monitoring changes to habitat and identifying locations of habitat for a species, after disturbance, can assist mitigation of the effects of human- caused or -amplified habitat disturbance. Like many areas in the western United States, the Pinalen ̃o Mountains of southeastern Arizona, USA, have suffered catastrophic fire and large-scale insect outbreaks in the last decade. The federally endangered Mt. Graham red squirrel (Tamiasciurus hudsonicus grahamensis) is only found in the Pinalen ̃o Mountains, and to assess effects of forest disturbance on habitat we modeled their potential habitat by identifying characteristics of cover surrounding their centrally defended middens. We classified high-spatial resolution satellite imagery into ground cover classes, and we used logistic regression to determine areas used by squirrels. We also used known midden locations in conjunction with slope, elevation, and aspect to create a predictive habitat map. Squirrels selected areas of denser forest with higher seedfall for midden sites. Among active middens, those in the densest and least damaged forests were occupied in more seasons than those in more fragmented and damaged areas. The future conservation of red squirrels and the return of healthy mature forests to the Pinaleño Mountains will rely on preservation of mixed conifer zones of the mountain and active restoration of spruce–fir forests to return them to squirrel habitat. Our ability to evaluate the spectrum of fine- to coarse-scale disturbance effects (individual tree mortality to area wide boundaries of a disturbance) with high-resolution satellite imagery shows the utility of this technique for monitoring future disturbances to habitat of imperiled species. (JOURNAL OF WILDLIFE MANAGEMENT 71(7):2357–2364; 2007)

Additional Information

Fine-scale analysis of Mount Graham red squirrel habitat following disturbance

Date of publication:

2007

Topics

Mount Graham Red Squirrel

forest disturbance

insect damage

catastrophic fire

conservation.arizona.edu - insect damage

Zugmeyer, C. A. 2007. Trailblazers in the forest: response of endangered Mt. Graham red squirrels to severe insect infestation. M.S. Thesis. University of Arizona, Tucson, AZ. 73 pp

Authors

Additional Information

Topics

Wood, D. J. A., S. Drake, S. P. Rushton, D. Rautenkranz, P. W. Lurz, and J. L. Koprowski. 2007. Fine-scale analysis of Mount Graham red squirrel habitat following disturbance. The Journal of Wildlife Management 71(7): 2357-2364.

Authors

Additional Information

Topics