Differential Response of Native Arizona Gray Squirrels and Introduced Abert's Squirrels to a Mosaic of Burn Severities in the Santa Catalina Mountains

Persistent Link:
http://hdl.handle.net/10150/578635
Title:
Differential Response of Native Arizona Gray Squirrels and Introduced Abert's Squirrels to a Mosaic of Burn Severities in the Santa Catalina Mountains
Author:
Ketcham, Shari Lynn
Issue Date:
2015
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Disturbance events can alter habitat properties, leading to species displacement, isolation and/or local extinction. In addition, introduced species have been recognized as a threat to biodiversity of native species. Understanding the interacting impacts of fire on native and introduced wildlife species, and the influence on a native species of competition with an introduced species after ecosystem change is critical. Tree squirrels are indicators of forest health; we used two species to determine thresholds and assess behavioral responses to determine adaption to habitat alterations. We studied native Arizona gray squirrels (Sciurus arizonensis), which are believed to favor riparian habitat, and introduced Abert's squirrels (S. aberti), which prefer open parklike ponderosa pine (Pinus ponderosa) in the Santa Catalina Mountains, Arizona, USA. We examined how native but reportedly declining Arizona gray squirrels and introduced Abert's squirrels use areas within widespread fires that burned the study area in 2002-3. Fires burned in a mosaic pattern of unburned, low, moderate, and high burn severity patches. To determine how fire may affect squirrel habitat and behavior, we examined how fire altered habitat use and occupancy, and used distance sampling to determine squirrel abundance, distribution and use within a mosaic of burn severities. Occupancy and habitat use indicate that introduced Abert's squirrels are better adapted to post-fire conditions whereas native Arizona gray squirrels may be adversely impacted by fire disturbance. Our results suggest that Arizona gray squirrel populations may be locally imperiled due to post-fire habitat alteration and loss exacerbated by competition with Abert's squirrels. Abert's squirrels predominantly occupied unburned ponderosa pine and mixed conifer zones with open understories. In contrast, Arizona gray squirrels were documented at only four sites and primarily occupied unburned to low burn riparian areas with dense understories. Abert's squirrels predominately nest and feed in unburned coniferous areas whereas Arizona gray squirrels nest in unburned to low burn nonconiferous areas. Arizona gray squirrels have a reduced distribution and potentially in decline but only remain at lower elevations on the Santa Catalina Mountains. Fire management and restoration efforts should include examination of the differential impacts of fire on native and invasive species.
Type:
text; Electronic Thesis
Keywords:
Dreys; Feeding Sign; Habitat; Occupancy; Santa Catalina Mountains; Natural Resources; Arizona
Degree Name:
M.S.
Degree Level:
masters
Degree Program:
Graduate College; Natural Resources
Degree Grantor:
University of Arizona
Advisor:
Koprowski, John L.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen
dc.titleDifferential Response of Native Arizona Gray Squirrels and Introduced Abert's Squirrels to a Mosaic of Burn Severities in the Santa Catalina Mountainsen_US
dc.creatorKetcham, Shari Lynnen
dc.contributor.authorKetcham, Shari Lynnen
dc.date.issued2015en
dc.publisherThe University of Arizona.en
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en
dc.description.abstractDisturbance events can alter habitat properties, leading to species displacement, isolation and/or local extinction. In addition, introduced species have been recognized as a threat to biodiversity of native species. Understanding the interacting impacts of fire on native and introduced wildlife species, and the influence on a native species of competition with an introduced species after ecosystem change is critical. Tree squirrels are indicators of forest health; we used two species to determine thresholds and assess behavioral responses to determine adaption to habitat alterations. We studied native Arizona gray squirrels (Sciurus arizonensis), which are believed to favor riparian habitat, and introduced Abert's squirrels (S. aberti), which prefer open parklike ponderosa pine (Pinus ponderosa) in the Santa Catalina Mountains, Arizona, USA. We examined how native but reportedly declining Arizona gray squirrels and introduced Abert's squirrels use areas within widespread fires that burned the study area in 2002-3. Fires burned in a mosaic pattern of unburned, low, moderate, and high burn severity patches. To determine how fire may affect squirrel habitat and behavior, we examined how fire altered habitat use and occupancy, and used distance sampling to determine squirrel abundance, distribution and use within a mosaic of burn severities. Occupancy and habitat use indicate that introduced Abert's squirrels are better adapted to post-fire conditions whereas native Arizona gray squirrels may be adversely impacted by fire disturbance. Our results suggest that Arizona gray squirrel populations may be locally imperiled due to post-fire habitat alteration and loss exacerbated by competition with Abert's squirrels. Abert's squirrels predominantly occupied unburned ponderosa pine and mixed conifer zones with open understories. In contrast, Arizona gray squirrels were documented at only four sites and primarily occupied unburned to low burn riparian areas with dense understories. Abert's squirrels predominately nest and feed in unburned coniferous areas whereas Arizona gray squirrels nest in unburned to low burn nonconiferous areas. Arizona gray squirrels have a reduced distribution and potentially in decline but only remain at lower elevations on the Santa Catalina Mountains. Fire management and restoration efforts should include examination of the differential impacts of fire on native and invasive species.en
dc.typetexten
dc.typeElectronic Thesisen
dc.subjectDreysen
dc.subjectFeeding Signen
dc.subjectHabitaten
dc.subjectOccupancyen
dc.subjectSanta Catalina Mountainsen
dc.subjectNatural Resourcesen
dc.subjectArizonaen
thesis.degree.nameM.S.en
thesis.degree.levelmastersen
thesis.degree.disciplineGraduate Collegeen
thesis.degree.disciplineNatural Resourcesen
thesis.degree.grantorUniversity of Arizonaen
dc.contributor.advisorKoprowski, John L.en
dc.contributor.committeememberKoprowski, John L.en
dc.contributor.committeememberFalk, Donald A.en
dc.contributor.committeememberSchwalbe, Cecilen
All Items in UA Campus Repository are protected by copyright, with all rights reserved, unless otherwise indicated.