conservation.arizona.edu - habitat selection

Movement response of small mammals to burn severity reveals importance of microhabitat features

aburnett93 — Wed, 25 Sep 2024 21:36:28 +0000

Authors

Sandy A. Slovikosky

Melissa J. Merrick

Marina Morandini

John L. Koprowski

Additional Information

Journal of Mammalogy

Date of publication:

2024

Topics

wildfire

fire intensity

habitat selection

Research Categories

Disturbance Ecology Spatial Ecology

Shrub avoidance by an open-adapted ground squirrel in a shrub-encroached environment

aburnett93 — Wed, 25 Sep 2024 21:29:42 +0000

Authors

Alexandra D. Burnett

John L. Koprowski

Additional Information

Plos One

Date of publication:

2024

Topics

shrub encroachment

habitat selection

Research Categories

Behavioral Ecology Disturbance Ecology Spatial Ecology

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

Zugmeyer, C. A. and J. L. Koprowski. 2009. Habitat selection is unaltered after severe insect infestation: Concerns for forest-dependent species. Journal of Mammalogy 90: 175-182.

thackerk1 — Tue, 30 Jul 2019 22:07:07 +0000

Authors

Claire A. Zugmeyer

John L. Koprowski

Severe disturbance may alter or eliminate important habitat structure that helps preserve food caches of food- hoarding species. Recent recolonization of an insect-damaged forest by the endangered Mt. Graham red squirrel (Tamiasciurus hudsonicus grahamensis) provided an opportunity to examine habitat selection for midden (cache) sites following disturbance. From September 2003 to December 2005, we examined surface temperature and physical and vegetative characteristics associated with random locations and midden sites in insect-damaged forests. Red squirrel use of midden sites that are similar in structure to those used before insect infestation indicates that insect infestation did not eliminate midden habitat. However, differences between occupied middens and historical middens that are unoccupied reflect the severity of insect infestation tolerated by red squirrels. Occupied middens had ,64% tree mortality, high basal area of live trees, and cooler surface temperatures during snow-free months. Forest areas with greater tree mortality would likely not represent habitat, threatening the persistence of an isolated population. Although conservation efforts can protect remaining habitat, disturbance events continually represent a threat. Habitat loss and predictions of increased disturbance due to climate change highlight the importance of documenting response to disturbance.

Additional Information

HABITAT SELECTION IS UNALTERED AFTER SEVERE INSECT INFESTATION: CONCERNS FOR FOREST-DEPENDENT SPECIES

Date of publication:

2009

Topics

disturbance

Mount Graham Red Squirrel

ecological trap

habitat selection

isolation

midden

larderhoard

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

Palmer, G. H., J. L. Koprowski, and A. J. Pernas. 2013. Nest tree and site selection of an introduced population of red-bellied squirrels (Sciurus aureogaster). Journal of Mammalogy 94:1274-1281.

thackerk1 — Wed, 24 Jul 2019 21:30:22 +0000

Authors

Geoffrey H. Palmer

John L. Koprowski

Anthony J. Pernas

Nests play a crucial role in the life history of tree squirrels, and can be a critical component of their biology that enables them to be a successful invasive species. Red-bellied squirrels (Sciurus aureogaster) were introduced to Elliott Key, Florida, in the late 1930s, and spread to nearby islands. Red-bellied squirrels were believed extirpated by Hurricane Andrew in 1992, but were rediscovered on Elliott Key in 2005. In 2006 and 2007, we surveyed for squirrel nests and measured vegetation to evaluate forest characteristics associated with nest-site selection by squirrels, and compared these data to measurements collected at random locations. Squirrels placed nests in large trees with more canopy linkages in mixed-hardwood forest, and the nest trees were in areas with large trees, high tree density and canopy cover, and lower recent hurricane damage. Red-bellied squirrels selected characteristics of nest trees and forest structure in similar ways to individuals in their native range, and to other species of tree squirrels in general. Results from our research allowed land managers to assess possible management actions and provided important information for them to develop an effective management strategy. Park officials are currently working toward complete eradication of the introduced population of red-bellied squirrels from the Florida Keys. We suggest that behaviors of individuals in native ranges may elucidate patterns for individuals introduced to novel environments; however, we also caution that care must be taken in further extrapolation. Our findings emphasize the importance of understanding ecology of introduced species for effective management.

Additional Information

Nest tree and site selection of an introduced population of red-bellied squirrels (Sciurus aureogaster)

Date of publication:

2013

Topics

habitat selection

invasive species

Mexican gray squirrel

nesting behavior

species eradication

tree squirrel

red-bellied squirrels

Biscayne National Park

Palmer, G. H., J. L. Koprowski, and A. J. Pernas. 2014. Distribution and spread of an introduced insular population of red-bellied squirrels (Sciurus aureogaster) in Florida. Mammalia 78: 67-73

thackerk1 — Wed, 24 Jul 2019 21:24:17 +0000

Authors

Geoffrey H. Palmer

John L. Koprowski

Anthony J. Pernas

Introduced populations of species pose one of the greatest threats to the persistence of native species. Documentation of distribution, range expansion and habitat use of introduced populations are key components of developing effective management strategies for the control and eradication of invasive species. In 2006 and 2007, we surveyed four islands in Biscayne National Park for nests to evaluate the presence of red-bellied squirrels (Sciurus aureogaster) and the distribution and index of dispersion of their nests in the Florida Keys archipelago within the Atlantic Ocean. Red-bellied squirrels were initially introduced to Elliott Key, Florida, USA in in 1938. We documented evidence of squirrels on two additional islands, Sands Key and Old Rhodes Key, which adds to concerns of spread of this introduced squirrel to areas with endangered endemic insular mammals. Squirrel nests were documented only in mixed-hardwood forest, and nests had a clumped distribution within this forest type. Range expansion was a chief concern to the National Park Service, as continued spread could result in squirrels exiting the park, and prompted management action. Understanding nest site selection and distribution was critical for developing an eradication strategy for the introduced population of red-bellied squirrels from south Florida.

Additional Information

Distribution and spread of an introduced insular population of red-bellied squirrels (Sciurus aureogaster) in Florida

Date of publication:

2014

Topics

colonization

habitat selection

invasive species

red-bellied squirrels

species eradication

Merrick, M. J., S. R. Bertelsen, and J. L. Koprowski. 2007. Characteristics of Mount Graham red squirrel nest sites in a mixed conifer forest. The Journal of Wildlife Management 71: 1958-1963.

thackerk1 — Tue, 23 Jul 2019 23:39:01 +0000

Authors

Melissa J. Merrick

Sadie R. Bertelsen

John L. Koprowski

The Mount Graham red squirrel (Tamiasciurus hudsonicus grahamensis) is constrained to the Pinaleńo Mountains in southeastern Arizona, USA. The population’s endangered status and extensive forest damage from insects and fire warrants a better understanding of habitat variables important for nest site selection. We examined characteristics of cavity (n 1⁄4 91) and drey (n 1⁄4 38) nests and compared these to random sites (n 1⁄4 113). Dreys were found primarily in Engelmann spruce (Picea engelmannii) and corkbark fir (Abies lasiocarpa var. arizonica). Cavity nests occurred primarily in aspen (Populus tremuloides) and corkbark fir. Squirrels selected nest sites with higher canopy cover and more corkbark fir, decayed logs, and living trees. Forest management plans emphasizing thinning must consider how altering these habitat characteristics could affect availability and suitability of tree stands for nesting squirrels. (JOURNAL OF WILDLIFE MANAGEMENT 71(6):1958–1963; 2007)

Additional Information

Characteristics of Mount Graham Red Squirrel Nest Sites in a Mixed Conifer Forest

Date of publication:

2007

Topics

Arizona

habitat selection

Mount Graham Red Squirrel

nest-site selection

Evidence of natal habitat preference induction within one habitat type

thackerk1 — Tue, 23 Jul 2019 23:24:14 +0000

Authors

Melissa J. Merrick

John L. Koprowski

Natal habitat preference induction (NHPI) is a mechanism for habitat selection by individuals during natal dispersal. NHPI occurs in wild animal populations, and evidence suggests it may be a common, although little studied, mechanism for post-dispersal habitat selection. Most tests of NHPI examine the influence of distinct, contrasting natal habitat types on post-dispersal habitat selection. We test the hypothesis that NHPI can occur within a single habitat type, an important consideration for habitat specialists. The Mount Graham red squirrel (Tamiasciurus hudsonicus grahamensis) is an endangered forest obligate restricted to a single mountain primarily within mixed-conifer forest. We test for NHPI by comparing intra-individual differences in natal and settlement habitat structure and composition to expected random pairwise differences. Dispersing juveniles appear to select settlement locations that are more similar to natal areas than expected in several forest structure and composition variables that include canopy cover and live basal area. Our results provide support for NHPI as a mechanism for post-dispersal habitat selection in habitat specialists that occupy a single vegetation community type.

Additional Information

Proceedings of the Royal Society B

Date of publication:

2016

Topics

natal dispersal

natal habitat

habitat selection

Arizona

Mount Graham Red Squirrel

behavior

Research Categories

Behavioral Ecology Sky Islands Spatial Ecology Threatened and Endangered Species