Off-campus UNL users: To download campus access dissertations, please use the following link to log into our proxy server with your NU ID and password. When you are done browsing please remember to return to this page and log out.
Non-UNL users: Please talk to your librarian about requesting this dissertation through interlibrary loan.
Behavioral ecology of the antipredator vigilance of thirteen-lined ground squirrels (Sciuridae: Spermophilus tridecemlineatus)
Abstract
I used differentially-occluded Plexiglas® foraging boxes containing peanut butter to manipulate the visual obstruction presented to free-ranging ground squirrels in five of six described experiments. Adult ground squirrels greatly increased their vigilance when their lateral field of view is obstructed, especially their long-range, lateral field of view. Using 'eaves' on the boxes, I obstructed the squirrels' view of the sky to determine whether a significant amount of their vigilance is directed at avian predators. The squirrels increased their vigilance, thus indicating that being able to view the sky is an important predation risk variable. When visual obstruction and distance to nearest burrow were manipulated together, the ground squirrels appeared to base most of their antipredator decisions upon the visual obstructiveness of the box. Although I did not find a distance effect upon vigilance (0. 5 & 5 m), trial duration decreased as distance to burrow increased. Since the squirrels had behavioral control over trial duration, they incurred a foraging cost in lost food, but spent less time exposed to predators. I also manipulated the cost of performing antipredator vigilance (in the form of travel time) and found that the squirrels actually decreased vigilance as box length increased. This was despite the appearance that the longer boxes were perceived as places of higher risk. Juvenile ground squirrels were found to be much less vigilant than adult ground squirrels. I tested to see if the increased foraging demands of juveniles was significantly associated with their decreased vigilance by supplementing two groups of juveniles, one with peanut butter and oats, and another with lettuce. Over a short period of supplementation, videotape analysis of squirrel time budgets showed that juveniles that received peanut butter and oats exhibited adult-like levels of vigilance, while the other group of juveniles exhibited very low vigilance and displayed an apparent negative trend in vigilance over time.
Subject Area
Zoology|Behaviorial sciences
Recommended Citation
Arenz, Cody Lee, "Behavioral ecology of the antipredator vigilance of thirteen-lined ground squirrels (Sciuridae: Spermophilus tridecemlineatus)" (1998). ETD collection for University of Nebraska-Lincoln. AAI9917819.
https://digitalcommons.unl.edu/dissertations/AAI9917819