Fire impacts on a forest obligate: western gray squirrel response to burn severity

mmerrick — Thu, 16 Apr 2020 21:22:10 +0000

Authors

Mazzamuto, Maria Vittoria

Mazzella, Maxwell N.

Merrick, Melissa J.

Koprowski, John L.

In the southwestern United States, climate change and climate–fire dynamics are affecting the distribution of natural and managed ecosystems. Forest obligate species on sky islands can experience a restriction in range with the increase of destructive forest fires. Using presence/absence data collected by hair tubes, we identified key habitat features that determine the western gray squirrel (Sciurus griseus) distribution on the sky island of the San Bernardino Mountains (California, USA) and determined post-fire differential use of burn severity in a landscape modified by fire. Gray squirrel presence was related to habitat features important for this species’ ecology and behavior, especially those associated with mature forests. The species was detected in areas with a high percentage of conifers that provide both an important food resource and good branches and cavities for nest sites. Gray squirrels occurred in all burn severities but occurred more in low and high severity sites than unburned sites. These results suggest that the gray squirrel can persist after a wildfire and can take advantage of the post-fire habitat structure if a mosaic of burn severities is maintained in the forest.

Additional Information

Mammalian Biology

Date of publication:

2020

Topics

hair tube

conifers

San Bernardino Mountains

Sciurus griseus

sky island

Research Categories

Disturbance Ecology Natural History Sky Islands Spatial Ecology

Functional semelparity drives population dynamics and endangers a peripheral population

thackerk1 — Thu, 27 Jun 2019 22:38:23 +0000

Authors

Emily A. Goldstein

Melissa J. Merrick

John L. Koprowski

Despite increased risk of extinction through stochastic events, peripheral populations are conservation priorities as the distribution of endangered species tends to contract to the periphery of historic ranges rather than toward the core. Trailing-edge populations and mountain isolates, which may become more common as climate change drives range shifts, are an important realm of inquiry and contain important reserves of genetic variation. We use long-term monitoring data from the southernmost population of a widespread species to test the hypothesis that peripheral populations display distinct demographic profiles from core populations. The red squirrel (Tamiasciurus hudsonicus) is predicted to recede from its southern border in response to climate-induced habitat change. We estimate key demographic parameters for this endangered population using survival and reproduction schedules and compare the dynamics to core populations of this and related species. This peripheral population exhibits higher adult mortality, and suffers associated impacts on reproductive output, which results in a demography distinct from core populations and phylogenetically similar species. Poor adult survival, similar to a population that experiences extremely high hunting pressure, has resulted in this normally iteroparous species becoming functionally semelparous at the periphery. Understanding differences in demographic function between peripheral and core populations is key if management strategies are to be effective in supporting continued persistence of at risk populations in the face of range shifts of species or habitats driven by environmental change.