Claire A. Zugmeyer
Disturbance events create temporal and spatial heterogeneity of resources that can cause short- and long-term changes to habitat and disrupt interactions between individuals and resources. Severe disturbance may dramatically alter habitat structure, causing reduced reproductive success or site abandonment. Rates and impacts of natural disturbances are predicted to increase with current trends in climate change, thus highlighting the need to understand species' response to disturbance.
My research examined the response of the endangered Mt. Graham red squirrel to severe insect infestation. The Mt. Graham red squirrel (Tamiasciurus hudsonicus grahamensis) occupies high elevation spruce-fir and mixed-conifer forests of the Pinaleño Mountains in southeastern Arizona. Recent recolonization of insect-damaged forest provided an opportunity to examine response of red squirrels to insect infestation. I examined habitat selection, home range, body mass, and demography of Mt. Graham red squirrels inhabiting insect-damaged forest and drew comparisons to squirrels living in undamaged forest.
The following is a summary of the major findings of my research. I found that 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 undamaged forest. Squirrel body mass and reproductive condition did not differ between forest types, suggesting that insect-damaged forest provided adequate resources. However, squirrels inhabiting insect-damaged forest experienced lower survivorship and 50% fewer potential reproductive events than squirrels in undamaged forest, indicating the presence of a temporary ecological trap. Preservation of remaining undamaged forest is a priority for management of this endangered species.
I graduated in May 2007 and in October 2007 I have began working for the Sonoran Institute, a Tucson based conservation non-profit. I am part of a team working on a large conservation effort of the Santa Cruz River. Our work includes ecological monitoring, restoration, and policy work on a regional and binational scale.
