In this study, I first describe distribution and abundance of breeding Eared Grebes {Podiceps nigricollis) in British Columbia. Second, I characterize and examine the relationships between nesting habitat and nest site selection on breeding group size. Finally, I. examine effects of colony size, nesting chronology and nesting synchrony on reproductive success at Eared Grebe colonies. I surveyed 421 wetlands in 1985 and 1986 and located 47 lakes used by nesting Eared Grebes. Those 47 lakes accomodated from a low estimate of 1761 to a high estimate of 4474 pairs. Breeding abundance, calculated from adult, nest and young counts, ranged from single pairs to more than 590 pairs per lake. Breeding took place in shallow lakes of various sizes, subject to extensive variations in water levels. Breeding abundance was positively correlated with lake area. Fewer breeding pairs utilized nesting areas close to shore (in shallower water) than nesting areas far from shore (in deeper waters). Nesting areas close to shore were found in smaller lakes and were used less often in consecutive years than nesting areas far from shore, presumably because of lower habitat predictability. An experiment with unattended artificial nests showed that nest predation was higher far from shore than close to shore. Nesting areas close to shore were used by small groups. These maximized concealment by being located in denser vegetation. Nesting areas far from shore were used by larger groups and were located in more open areas. On both years, adults arrived at nesting lakes in April and May, started laying on 27 May and departed from, nesting areas in late July and- early August. Nesting was significantly earlier and reproductive success per pair was significantly higher in 1985 than in 1986. A .stepwise multiple regression examined effects of colony-size, synchrony and chronology on nesting success. Only nesting chronology accounted for differences in nesting success. Late nesters were not birds attempting to renest. Instead, there appeared to be qualitative differences across colonies that were related to ages of breeders. Eared Grebe colonies are likely not formed from passive aggregation at limiting resources and there are likely no foraging benefits from colonial nesting. Nesting colonies could increase detection and mobbing of predators, but no evidence supported this. Anti-predator benefits of coloniality might have been masked by differences in breeding chronology and synchrony, or were missed because of low sample size. / Science, Faculty of / Zoology, Department of / Graduate

No description available.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (M.S.)--University of Delaware, 2009. / Principal faculty advisor: W. G. Shriver, Dept. of Entomology & Wildlife Ecology. Includes bibliographical references.

Field work to determine possible causes of variation in avian social behavior in a nonbreeding community of 42 species was undertaken during two winter seasons in oak-juniper woodland of the Santa Rita mountains of southern Arizona. Transect observations are used to calculate monthly densities, frequency of social foraging, and size and composition of social groups for all species. Additional data taken to quantify the foraging logistics of 22 species includes foraging substrate, time spent at a foraging station, and distance travelled between foraging stations. These data are used to generate indices of logistic similarity and interspecific association for species pairs in order to test the hypothesis that species which are similar in their foraging logistics are more likely to associate than those which are not. Causes of solitary behavior and variation in intraspecific social behavior are also examined. Exclusively solitary foraging behavior is strongly associated with species that use sparse, unpredictable prey too small to share. These species, referred to as "extensive foragers," appear to be constrained from both intraspecific and interspecific association by being logistic mismatches with all but their closest competitors, with which the potential for interference competition is high. Evidence is presented to refute the hypothesis that solitary behavior is due to low vulnerability to predators. Species which are intraspecifically solitary tend to use evenly distributed resources, and gregarious species use patchy and abundant resources. Exceptions are most frequent among permanent residents, which may continue to maintain social and spacing systems used in the breeding season. Among gregarious species, permanent residents are more likely to maintain stable group sizes than winter residents. A correlation exists between similarity of foraging logistics and likelihood of interspecific association, but it is subject to considerable variance. Causes of this variance include the tendency of transient migrants not to associate with other species, and the tendency of certain species to form temporary associations, regardless of logistic similarities. Why some species form temporary ("opportunistic") associations while others do not remains unclear.

No description available.

Thesis (M.S.)--Humboldt State University, 2007. / Includes bibliographical references (leaves 31-35). Also available via Humboldt Digital Scholar.

Thesis (Ph.D.)--University of North Carolina Wilmington, 2008 / Title from PDF title page (viewed May 26, 2009) Includes bibliograpical references (p. 80-83) Includes bibliographical references (p. 80-83)