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Full-Text Articles in Life Sciences
Explaining Migratory Behaviors Using Optimal Migration Theory, Jennifer D. Mccabe
Explaining Migratory Behaviors Using Optimal Migration Theory, Jennifer D. Mccabe
Electronic Theses and Dissertations
Bird migration is the regular seasonal movements between breeding and nonbreeding grounds. In general, birds that breed in the Northern Hemisphere tend to migrate northward in the spring to take advantage of increasing insect populations and lower predation pressures and fly south when food availability and weather conditions decline. Embarking on a journey that can stretch a thousand miles round trip is a dangerous and arduous undertaking. While en route migrants must stop and feed to replenish their depleted energy reserves, often in unfamiliar locations with unknown predation pressures. They also must react to weather conditions during flight and while …
Biogeography And Conservation Of Tidal Marsh Bird Communities Across A Changing Landscape, Maureen D. Correll
Biogeography And Conservation Of Tidal Marsh Bird Communities Across A Changing Landscape, Maureen D. Correll
Electronic Theses and Dissertations
Given the current mass extinction crisis and continued fragmentation of resources worldwide, the outlook is dire for global biodiversity. Rising global temperature, sea levels, and storm frequency all create environmental conditions that can drive change in species abundance and distribution across a landscape. Those species reliant upon a single type of habitat and resource for survival, termed “specialists”, are particularly vulnerable to change due to their inability to utilize a variety of resources well. As a result, specialism is now considered one of the dominant factors determining extinction of species. In this dissertation I explore the effects of disturbance on …
Intra- And Interspecific Variation In Demographic Rates And Niche Across The Range Of A Species, The Saltmarsh Sparrow (Ammodramus Caudacutus), Katharine J. Ruskin
Intra- And Interspecific Variation In Demographic Rates And Niche Across The Range Of A Species, The Saltmarsh Sparrow (Ammodramus Caudacutus), Katharine J. Ruskin
Electronic Theses and Dissertations
In this project, we examined various hypotheses that address one of the fundamental questions in ecology and evolution: what determines the range of a species? We used demographic data for saltmarsh sparrows (Ammodramus caudacutus) collected over the majority of the global breeding range. Saltmarsh sparrows are considered threatened by climate change, specifically sea level rise, which is predicted to result in loss of the tidal marsh habitat where saltmarsh sparrows live across their entire life cycle. For my dissertation, I investigated the reproductive biology of saltmarsh sparrows both to provide vital information for wildlife managers and to explore …
Reproductive Ecology Of Black Bears In Maine: Maternal Effect, Philopatry, And Primiparity, Alyssa A. Vitale
Reproductive Ecology Of Black Bears In Maine: Maternal Effect, Philopatry, And Primiparity, Alyssa A. Vitale
Electronic Theses and Dissertations
The American black bear (Ursus americanus) relies upon dens in order to successfully reproduce and protect their offspring. Black bears utilize a variety of den types, each providing a different degree of protection. Black bears also exhibit an extended maternal care period in which offspring stay with their mother for 18 months. Maine’s black bear population is one of the largest in the U.S. (>30,000 bears) and since 1975, the Maine Department of Inland Fisheries and Wildlife has conducted research and monitoring to manage the population. This unique dataset allowed for examination of several generations of multiple …
Seasonal Influences On Habitat Use By Snowshoe Hares: Implications For Canada Lynx In Northern Maine, Sheryn J. Olson
Seasonal Influences On Habitat Use By Snowshoe Hares: Implications For Canada Lynx In Northern Maine, Sheryn J. Olson
Electronic Theses and Dissertations
Snowshoe hares (Lepus americanus) respond to seasonal changes in vegetation in the northern and western portions of their range. During winter, hares use dense conifer stands that may provide thermal and predatory refugia, then during summer move to areas with more herbaceous food and cover. These movements influence hare demographics, with greater survival rates corresponding to seasonal use of dense, primarily coniferous stands. Different harvesting practices in commercial forests produce vegetative communities that may support differing hare densities among forest stand- types between seasons, but seasonal use of habitat had not been documented in northern Maine on a large spatial …