Microsite disturbances – including mounds created by burrowing mammals – increase local plant community diversity by supporting unique species assemblages. I investigated whether Richardson’s ground squirrel (Urocitellus richardsonii) mounds support unique plant assemblages within five Manitoba prairie pastures, and explored the factors contributing to the plant assemblages documented. Richardson’s ground squirrel mounds supported unique species assemblages relative to bare-ground disturbances with removal of vegetation but no soil disturbance. These detectable shifts in plant community structure on mounds appear to be attributable to mound-specific environmental conditions responsible for delaying vegetative recolonization and facilitating establishment of early-succession species. In contrast, seed bank distribution did not appear to influence species assemblages on mounds. Further investigation into site-specific changes in species distribution on Richardson’s ground squirrel mounds is needed to appreciate the role of these burrowing mammals in pastureland communities. / February 2017

No description available.

The purpose of this study is to provide a qualitative, detailed description of individual and social behavior in a free-living population of thirteen-lined ground squirrels. Behavioral differences in relation to various periods of the annual cycle are also evaluated.

The behavior and ecology of Uinta ground squirrels (Spermophilus armatus) at the Utah State University Forestry Field Station northeast of Logan, Utah were studied from 1964-1971 to determine the role of behavior in population regulation. From 1965 to 1968, data were collected to establish population norms. In 1968, the population density was reduced experimentally to help elucidate regulatory processes. This paper compares the dynamics of the population before and after the population reduction. Before the density reduction, juvenile survival was lower than that of yearlings and adults. The disappearance of juveniles was associated with their tendency to disperse from the natal burrow while still small. The litter size of yearlings was smaller than that of adults. The principal changes following the reduction were an increase in percentage of yearling squirrels breeding and a decrease in dispersal of juveniles. Litter size and proportion of adult females breeding did not change significantly. Dispersal of squirrels from the study area was the principal regulatory factor. Losses during hibernation, presumably to badger predation, also decreased after the reduction. Several conclusions were drawn. The importance of anyone of the complex of factors, which determined the dynamics of the population, varied with place, time, and population density. The value of habitat was affected by population density as well as the physical environment. Density pressures seemed to have more effect on subordinate than on dominant squirrels. Surplus animals from the prime habitat raised the population density in the surrounding area. Dispersing animals probably suffered higher mortality than those which stayed, but this did not imply that dispersal was maladaptive for the individual. (58 pages)

No description available.

Immunity and reproduction are important and costly life-history traits and a large part of eco-immunology focuses on trade-offs between investing in reproduction versus immunity. Male Cape ground squirrels (Xerus inauris) are a good organism to test these trade-offs as they invest heavily in sperm competition, evidenced by their large testes, and exhibit alternative reproductive tactics. My research objective was to determine 1) if testosterone suppresses immunity, or if immunity suppresses testosterone, and 2) if alternative reproductive tactics differ in their investments in immunity and reproduction. I found evidence that testosterone was suppressed after an immune challenge, and that manipulatively increased testosterone had no effect on immunity, body condition or parasites. The dispersing tactic males were in worse condition, had higher parasite abundances, but showed no difference in their innate immune ability to non-dispersing males. Males incur increased costs with dispersal and may focus their energy into reproduction instead of immunity. / October 2015

I studied round-tailed ground squirrels (Spermophilus tereticaudus) to determine if presence of water or green vegetation significantly increased reproductive success. I compared the number of juveniles produced, body weights, and diets of squirrels during 1981-84 on 2 plots with green vegetation and no free water, on 3 plots with free water and no green vegetation, and 2 control plots. Reproductive success and body weights of adult and juvenile squirrels were significantly higher (P ≥ 0.001) on plots with green vegetation than on either watered or control plots. Body weights of squirrels on plots with water only and control plots were not significantly different (P ≥ 0.05). Adult squirrels without access to green vegetation during winter and spring failed to reproduce even though free water was readily available. Percent of diet overlap, diversity, and evenness of squirrel diets on control and watered plots were not significantly different. Green vegetation appeared to be the limiting factor for round-tailed ground squirrels.

Predator harassment is an anti-predator behaviour that may increase a harasser’s risk of predation but decrease the potential for predation for other members of a group. The Cape ground squirrel (Xerus inauris) is a facultative cooperative breeder from southern Africa that harasses venomous snakes. The objective of my study was to examine predator harassment to determine: 1) whether predator harassment was part of alloparental care by comparing harassment behaviour among age and sex classes; 2) how individuals adjusted their behaviour against different snake species; 3) whether olfaction was used in discrimination of snakes; and 4) if individuals possessed venom resistance against venomous snakes. I found that females with juvenile offspring harass snakes longer and more intensely than other individuals, suggesting that predator harassment was a maternal behaviour. Squirrels increased harassment, inspection and vigilant behaviours with risk when exposed to both live snakes and snake odours suggesting they can use olfaction to discriminate snake predators. I also found no venom resistance in Cape ground squirrels concluding the cost of envenomation was significant.

Predator harassment is an anti-predator behaviour that may increase a harasser’s risk of predation but decrease the potential for predation for other members of a group. The Cape ground squirrel (Xerus inauris) is a facultative cooperative breeder from southern Africa that harasses venomous snakes. The objective of my study was to examine predator harassment to determine: 1) whether predator harassment was part of alloparental care by comparing harassment behaviour among age and sex classes; 2) how individuals adjusted their behaviour against different snake species; 3) whether olfaction was used in discrimination of snakes; and 4) if individuals possessed venom resistance against venomous snakes. I found that females with juvenile offspring harass snakes longer and more intensely than other individuals, suggesting that predator harassment was a maternal behaviour. Squirrels increased harassment, inspection and vigilant behaviours with risk when exposed to both live snakes and snake odours suggesting they can use olfaction to discriminate snake predators. I also found no venom resistance in Cape ground squirrels concluding the cost of envenomation was significant.

Thesis (Ph. D.)--University of California, San Diego, 2007. / Title from first page of PDF file (viewed January 8, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 112-124).