conservation.arizona.edu - predation

Foraging Behavior Response of Small Mammals to Different Burn Severities

aburnett93 — Mon, 25 Sep 2023 21:26:18 +0000

Authors

Marina Morandini

Maria Vittoria Mazzamuto

John L. Koprowski

Additional Information

Fire

Date of publication:

2023

Topics

wildfire

wildfire effects

behavior

behavioral response

GUD

predation

Mt. Graham red squirrel

Research Categories

Disturbance Ecology Sky Islands Threatened and Endangered Species

Zugmeyer, C. A. and J. L. Koprowski. 2007. Avian nestling predation by endangered Mt. Graham red squirrel. The Southwestern Naturalist 52(1): 155-157.

thackerk1 — Tue, 30 Jul 2019 22:19:02 +0000

Authors

Claire A. Zugmeyer

John L. Koprowski

Studies using artificial nests or remote cameras have documented avian predation by red squirrels (Tamiasciurus hudsonicus). Although several direct observations of avian predation events are known in the northern range of the red squirrel distribution, no accounts have been reported in the southern portion. We observed predation upon a hermit thrush (Catharus guttatus) nestling by the Mount Graham red squirrel (T. h. grahamensis), an endangered subspecies living at the southern terminus of the distribution of the red squirrel.

Additional Information

AVIAN NESTLING PREDATION BY ENDANGERED MOUNT GRAHAM RED SQUIRREL

Date of publication:

2007

Topics

red squirrels

predation

hermit thrust

Mount Graham Red Squirrel

artificial nests

Wood, D. J. A. 2007. Forest disturbance and the long term population persistence of the Mt. Graham red squirrel: a spatially explicit modeling approach. M. S. Thesis. University of Arizona, Tucson, AZ. 119pp.

thackerk1 — Tue, 30 Jul 2019 21:37:40 +0000

Authors

David J. A. Wood

We combined field data with high-resolution satellite imagery and a spatially explicit population model to predict long-term population dynamics of the endangered Mt. Graham red squirrel (MGRS: Tamiasciurus hudsonicus grahamensis), with the goal of examining effects of disturbance on MGRS population dynamics. We found that modeling MGRS dynamics improved with population specific data. Our results indicate that predation and competition potentially have large, adverse effects on population abundance. Habitat quality analysis indicates much of the spruce-fir forest is degraded to the point that it cannot support MGRS, therefore, the future of the species will rely on management in the mixed conifer zones. Our models predict that future populations will not show the variability exhibited in abundance over the past 20 years, likely due to degradation of spruce-fir forests, and that even low levels of fire and insect disturbance have the potential to drive MGRS population below critical population thresholds.

Additional Information

Forest Disturbance and the Long Term Population Persistence of the Mt. Graham Red Squirrel: A Spatially Explicit Modeling Approa

Date of publication:

2007

Topics

Mount Graham Red Squirrel

population dynamics

predation

competition

Dietary niche partitioning among black bears, grizzly bears, and wolves in a multiprey ecosystem

thackerk1 — Tue, 23 Jul 2019 22:56:14 +0000

Authors

Jerod A. Merkle

Jean L. Polfus

Jonathan J. Debridge

Kimberly S. Heinemyer

Identifying mechanisms that promote coexistence of sympatric species is important for predicting ecological effects of anthropogenic change. Many caribou (Rangifer tarandus (L., 1758)) populations are declining, and it is unclear to what extent sympatric predators consume caribou or how alternative prey affect caribou–predator relationships. We used stable isotope mixing models to estimate diets of black bear (Ursus americanus Pallas, 1780), grizzly bear (Ursus arctos L., 1758), and grey wolves (Canis lupus L., 1758) during early, middle, and late summer of 2009–2010 in northwestern British Columbia, Canada. Although we expected wolf diet to be primarily composed of moose (Alces alces (L., 1758)) — as they exist at twice the density of caribou — wolf diet consisted principally of caribou, and to a lesser extent moose and beaver (Castor canadensis Kuhl, 1820), with little change occurring throughout summer. Black bear diet consisted mainly of vegetation and moose, shifting from moose to vegetation through summer. Grizzly bear diet consisted primarily of vegetation and moose, and did not change throughout summer. Our results demonstrate the role of dietary niche partitioning in bear and wolf coexistence, and that caribou may be primary prey for wolves in an ecosystem with relatively high moose abundance and low human development.

Additional Information

Canadian Journal of Zoology

Date of publication:

2017

Topics

black bear

grizzly bear

grey wolf

caribou

predation

niche

diet

trophic relations

stable isotope analysis

Research Categories

Natural History Population Ecology Threatened and Endangered Species

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