conservation.arizona.edu - survival

Zugmeyer, C. A. and J. L. Koprowski. 2009. Severely insect-damaged forest: A temporary trap for red squirrels? Forest Ecology and Management 257: 464-470.

thackerk1 — Tue, 30 Jul 2019 21:55:53 +0000

Authors

Claire A. Zugmeyer

John L. Koprowski

Recent insect infestations in the spruce-fir forest in the Pinaleño Mountains of southeastern Arizona provided an opportunity to document response to severe forest disturbance and existence of an ecological trap for an endemic montane isolate, the endangered Mt. Graham red squirrel (Tamiasciurus hudsonicus grahamensis). From September 2003 to December 2005 we assessed habitat selection and home range dynamics, and monitored potential correlates of fitness (body mass, reproduction, survivorship) in red squirrels living in insect-damaged forest, while drawing comparisons to squirrels inhabiting undamaged mixed-conifer forest. Although Mt. Graham red squirrels demonstrate equal- preference for habitat within insect-damaged forests and reproduce as well as individuals in undamaged forest, poor survivorship and reduced potential to reproduce suggest insect-damaged forest may function as an ecological trap. In addition, areas selected within insect-damaged forest had <69% dead trees, suggesting an upper limit to the extent of tree mortality tolerated by red squirrels. Habitat selection and sensitivity to disturbance will influence use of insect-damaged areas by forest-dwelling species. Although insect-damaged forest may retain habitat patches for a few individuals, low survivorship may generate an ecological trap.

Additional Information

Severely insect-damaged forest: A temporary trap for red squirrels?

Date of publication:

2008

Topics

Mount Graham Red Squirrel

isolation

home range

habitat selection

survival

Pinaleño Mountains

Koprowski, J. L. 1991. Response of fox squirrels and gray squirrels to a late spring-early summer food shortage. Journal of Mammalogy 72(2): 367-372.

thackerk1 — Tue, 23 Jul 2019 00:02:58 +0000

Authors

John L. Koprowski

The response of adult and juvenile fox squirrels (Sciurus niger) and gray squirrels (S. carolinensis) to a shortage in their two major May-June foods was monitored and compared to a year of typical food abundance. Squirrels foraged more frequently, but less efficiently, during the year of fruit failure than during the typical year. Juvenile survival of both species was reduced during the year of fruit failure, but adult survival remained high. Juvenile losses occurred during late June when weights of adults and juveniles were lower than in the year of typical fruit abundance. By influencing juvenile survival and body condition of adults, late spring-early summer can be a critical period for populations of tree squirrels.

Additional Information

Response of Fox Squirrels and Gray Squirrels to a Late Spring-Early Summer Food Shortage

Date of publication:

1991

Topics

fox squirrel

juvenile

food shortage

survival

body condition

Cudworth, N. L., and J. L. Koprowski. 2014. Survival and mortality of the Arizona gray squirrel (Sciurus arizonensis). The Southwestern Naturalist 59:423-426.

thackerk1 — Thu, 20 Jun 2019 23:28:54 +0000

Authors

Nichole L. Cudworth

John L. Koprowski

Arizona gray squirrels (Sciurus arizonensis) are endemic to the southwestern United States and northwestern Mexico. Despite classification as a species of concern in portions of its range, little is known about Arizona gray squirrels. We investigated survival and causes of mortality for a population of squirrels in the Huachuca Mountains in 2007 and 2008. Adult survival was high and did not differ between sexes, with probability of survival >0.70 one year postcapture. Predation was the most common known cause of mortality; consequently, management plans should account for habitat characteristics that provide protection from predators when managing for Arizona gray squirrels.

Additional Information

Survival and mortality of the Arizona gray squirrel

Date of publication:

2014

Topics

Arizona gray squirrel

survival

causes of mortality

predation