High-resolution spatial data reveal foraging strategies in golden-mantled ground squirrels

New research from KCRL PhD student Kira Hefty documents a novel method for obtaining high-resolution space use data in a small mammal.  For her Master’s research, Kira investigated foraging and space use behaviors of golden-mantled ground squirrels (Callospermophilus lateralis) in the Sierra Nevada Mountains. Using mini-GPS technology, Kira documented fine-scale spatio-temporal space use behavior to determine foraging strategies and and how individuals perceived risk as a function of cover type and distance from refuge and burrows.  Individuals exhibited foraging and movement strategies that maximized energy intake and minimized predation risk.

Read more here:

Hefty, K. L. and K. M. Stewart. 2018. Novel location data reveal spatiotemporal strategies used by a central-place forager. Journal of Mammalogy DOI:10.1093/jmammal/gyy019.



Low survival, high predation pressure are conservation challenges for endangered Mt. Graham red squirrels

New research published this week by KCRL’s Melissa Merrick, John Koprowski, and alum Emily Goldstein  estimates survival and mortality in known-fate, radio-collared Mt. Graham red squirrels as well as examines the relative hazard of death from avian and mammalian predators, as well as unknown causes.  Annual survival in Mt. Graham red squirrels is low (37%) and annual mortality estimates (68% adults, 74% juveniles) are among the highest reported in North America. Birds or prey were responsible for the majority of deaths, and juveniles were even more likely to succumb to avian predation (75%) compared to adults (65%).  The Pinaleño mountains in southeastern Arizona are part of the unique sky island archipelago known for high biodiversity and endemism.  Many species of avian predators also call the Pinaleños home and two species, Mexican spotted owls (Strix occidentalis lucida) and Northern Goshawks (Accipiter gentilis) are themselves threatened or of conservation concern.  The presence of an ecologically similar, but non-native tree squirrel, the Abert’s squirrel (Sciurus aberti), may subsidize the hungry raptors and support higher predator densities than would occur with red squirrels alone. Increased control of Abert’s squirrels along with habitat augmentation to increase food, nest sites, and structural complexity are recommended conservation actions along with long term forest restoration efforts.

Read more here:

Goldstein, E. A., M. J. Merrick, and J. L. Koprowski. 2018. Low survival, high predation pressure present conservation challenges for an endangered endemic forest mammal. Biological Conservation 221:67-77.

New publication reveals how little we know about the effect of keystone species reintroductions on ecosystems

Keystone species play disproportionately large roles in their ecosystems, and their removal often results in cascading negative effects on the ecosystem.  Anthropogenic factors such as overexploitation, land development, and human-wildlife conflict have resulted in a decline of keystone species, so keystone reintroductions are often proposed as a restoration tool for degraded ecosystems.  KCRL Alum, Sarah Hale, conducted a literature review to examine if and to what extent ecosystem-level effects of keystone species reintroductions had been investigated in peer-reviewed literature.  Her review returned little information on how reintroductions of keystone species affect the ecosystem, which highlights a need for more studies into the efficacy of such reintroductions as a conservation and ecosystem restoration tool.  This publication seeks to bring attention to this knowledge gap and highlights the need for more studies that add to the body of knowledge on the occurrence and extent of ecosystem restoration driven by keystone species.
Read more here:

New book on Andean bears in Colombia

KCRL PhD student I. Mauricio Vela-Vargas in collaboration with Corporación Autónoma Regional del Guavio – CORPOGUAVIO, Parques Nacionales Naturales de Colombia (Parque nacional Natural Chingaza, Dirección Territorial Orinoquía) & Projecto de Conservación de Aguas y tierras – ProCAT Colombia have published a new book about the ecology of the Andean bear (Tremarctos ornatus) in the Chingaza Massif of Colombia.  Dr. K wrote the foreword, and Mauricio is lead author for Chapter 3, Generalidades del Oso Andino.

Vela-Vargas, I. Mauricio, J. Sebastián Jiménez-Alvarado, Diego A. Zárrate-Charry, C. Moreno-Diaz, A. Parra-Romero, and J. F. González-Maya. 2017. Capítulo 3: Generalidades del Oso Andino (Tremarctos ornatus: Ursidae). In El Oso Andino en el Macizo de Chingaza. J. F. González-Maya, R. Galindo-Tarazona, M. M. Urquijo Collazos, M. Zárate Vanegas, and A. Parra-Romero Eds. Bogotá: Empresa de Acueducto, Alcantarillado y Aseo de Bogotá D. C.. EAB-ESP, Corporación Autónoma Regional del Guavio – CORPOGUAVIO, Parques Nacionales Naturales de Coombia (Parque nacional Natural Chingaza, Dirección Territorial Orinoquía) & Projecto de Conservación de Aguas y tierras – ProCAT Colombia. Pp. 58-120.

Read the entire volume here: González-Maya et al. 2017 Libro Oso Chingaza

Andean Bear 3

Andean bear (Tremarctos ornatus)

New research on differential response to fire by native and introduced tree squirrels

New research by KCRL alum Shari Ketcham examines the differential response of fire and associated burn severity by the native Arizona gray squirrel (Sciurus arizonensis) and introduced Abert’s squirrel (Sciurus aberti). Abert’s squirrels, native to northern and central Arizona mountains but introduced to the sky islands of southern Arizona in the 1940’s, tend to be more tolerant of landscapes impacted by fire, whereas native Arizona gray squirrels are associated with dense riparian forests with adequate trees for nesting. Ketcham et al found that in the Santa Catalina Mountains, where Abert’s squirrels were introduced, Abert’s squirrels readily used forest impacted by recent fire.  In contrast, Arizona gray squirrels were only detected in riparian areas that were not impacted by fire. This provides a management opportunity for the restoration of riparian areas that have burned in an effort to increase habitat for the native species.

Read more here: Ketcham, S. L., J. L. Koprowski, and D. A. Falk. 2017. Differential response of native Arizona gray squirrels and introduced Abert’s squirrels to a mosaic of burn severities. Mammal Study 42:247-258.


Arizona gray squirrel with ear tags in Ramsey Canyon, Huachuca Mountains Arizona


Abert’s squirrel in winter plumage, Pinaleño Mountains, Arizona

Whale & Dolphin magazine features research by KCRL’s Shambhu Paudel

The research of KCRL PhD student and World Wildlife Fund Fellow, Shambhu Paudel, was recently featured in Whale & Dolphin magazine.  Whale & Dolphin magazine is a publication of Whale and Dolphin Conservation, the leading global charity dedicated to the conservation and protection of whales and dolphins. Shambhu received WDC’s Bharathi Viswanathan award for innovative, non-invasive research earlier this year.

Click on photo below for full story!

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Congrats to KCRL’s Jonathan Derbridge on a successful PhD Defense!

Congratulations to Jonathan Derbridge on his successful defense of his dissertation yesterday! Jonathan shared his research on the impacts of introduced Abert’s squirrels on the critically endangered native species, the Mt. Graham red squirrels.

Jonathan’s dissertation abstract:

Ecology and Conservation of Endangered Territorial Species Under Invasion

 Biological invasions threaten biodiversity globally, and degraded ecosystems increase the potential for invaders to compete with threatened native populations.  In natural systems, niche partitioning minimizes interspecific competition, but introduced species may alter expected outcomes by competing with ecologically similar species for scarce resources.  Where food production is highly variable, coexistence of native and invasive competitors may depend on dietary niche flexibility.  Territorial species under invasion face additional challenges in maintaining economically defendable territories.  From 2011-2016, we conducted removal and behavior experiments to determine effects of non-territorial introduced Abert’s squirrels (Sciurus aberti) on diet, space use, and territoriality of endangered Mount Graham red squirrels (MGRS; Tamiasciurus fremonti grahamensis) in disturbed and fragmented habitat in the Pinaleño Mountains, Arizona.  We collected comparative data from Arizona sites of natural syntopy between Abert’s and Fremont’s squirrels (hereafter, red squirrels; T. fremonti).  Stable isotope analysis revealed similar dietary partitioning among populations.  Removals did not affect MGRS diet but did affect MGRS space use.  Territory sizes and body mass of MGRS were sensitive to conspecific population density and food production.  Behavioral experiments showed MGRS were more aggressive than other red squirrels.  Dietary flexibility of Abert’s squirrels may have facilitated coexistence with MGRS, possibly due to coevolved resource partitioning with red squirrels.  However, aggressive territoriality toward Abert’s squirrels may incur fitness costs for MGRS especially during poor food production years.  Climate change may reduce the advantage of ecological specialist species globally, and where introduced species are better-adapted to novel environmental conditions, native species may ultimately be replaced.


Jonathan Derbridge