Timing of resource availability drives divergent social systems and home range dynamics in ecologically similar tree squirrels

mmerrick — Thu, 25 Jun 2020 23:15:21 +0000

Authors

Maria Vittoria Mazzamuto

Melissa Merrick

Francesco Bisi

John Koprowski

Luc Wauters

Adriano Martinoli

Intraspecific variation in home range size has important implications for the distribution of animals across landscapes and the spatial structuring of population, community, and ecosystem processes. Among species of similar trophic guild and body mass, differences in home range size can reflect extrinsic variables that exert divergent selective forces upon spacing behavior and social organization. We tested predictions about how resource availability and timing influence social system, home range size, and territoriality in two tree squirrel species of similar size and ecological niches but that differ in foraging strategy and social organization. We estimated home range size and intraspecific home range core overlap in the Mt. Graham red squirrel (Tamiasciurus fremonti grahamensis; Arizona USA; MGRS) and the Eurasian red squirrel (Sciurus vulgaris; Alps, Italy; ERS) as functions of species, sex, season, and individual’s body mass. However, body mass did not explain differences found between the two species. We found MGRS home ranges being three times smaller with higher core area exclusivity compared to ERS in all seasons. In fact, territorial MGRS evolved in a system of brief resource pulses and are larder hoarders, whereas ERS experience prolonged resource availability and are non-territorial. Only male MGRSs increased their home range during the breeding season, reflecting interspecific differences in social organization and mating behavior. Male ERS home ranges always overlap with several females to enhance mating success although male and female MGRS maintain nearly exclusive territories throughout the year. Only during spring and summer do males temporarily leave their food-based territory to increase mating opportunities with neighboring estrus females. Home range comparisons between ecologically similar species emphasize the importance of divergent extrinsic factors in shaping variability in body size–home range size scaling relationships. Timing in resource availability influenced the social structure and space use in tree squirrels of similar body size, highlighting how the coevolution of arboreal squirrels with conifer tree species has shaped their natural history.

Additional Information

Frontiers in Ecology and Evolution

Date of publication:

2020

Topics

seed predators

home range

Eurasian red squirrel

Mt. Graham red squirrel

forest ecosystems

Research Categories

Natural History Population Ecology Sky Islands Spatial Ecology Threatened and Endangered Species

Ketcham, S. L. and J. L. Koprowski. 2013. Impacts on wildfire on wildlife in Arizona: A synthesis. In Gottfried, Gerald J.; Ffolliott, Peter F.; Gebow, Brooke S.; Eskew, Lane G.; Collins, Loa C., comps. 2013. Merging science and management in a rapidly ch

thackerk1 — Mon, 22 Jul 2019 21:25:58 +0000

Authors

Shari L. Ketcham

John L. Koprowski

Due to a century of fire suppression practices, the Madrean Archipelago regions in Arizona have accumulated excessive fuel loads that increase wildfire sizes, intensities, and frequencies. Wildfire induced structural changes in forest ecosystems can either benefit or adversely impact wildlife species. Therefore, it is imperative to understand how wildlife species react to such ecosystem changes after wildfires in both the short-term and long-term time periods. We examined scientific literature to determine wildlife distribution, abundance, elevational migration, and behavioral changes (i.e. how wildlife use resources post-fire) in response to wildfire. Understanding the impacts of wildfire-induced habitat fragmentation and creation of edge effects on wildlife species will provide information about overall forest condition and forest management practices.