Ecology and Evolutionary Biology Commons^™

Urban Nesting Biology, Population Viability And Ecology Of The Willow Flycatcher, Empidonax Traillii, Stephanie Alexandra Byrne Doorly

Dissertations and Theses

Reproductive success, in any species, relies both on the habitat utilized to reproduce and on the successful reproductive output of individual animals within a population. Populations in turn rely on the reproductive fitness of the individual. Whether populations remain stable, grow, or decline ultimately relies on the combined reproductive output of the individuals within that population.

We studied the Willow Flycatcher (Empidonax traillii; henceforth WIFL), a well-studied Neartic-Neotropical migrant passerine whose breeding range extends from the east to west coast of North America. Across much of their range, and in particular in the western regions, breeding population are …

The Red-Tailed Hawk On Sauvie Island, Oregon, Kevin J. Lien

Dissertations and Theses

A study was undertaken to determine the abundance, distribution, perching heights, diets and territory sizes of Red-Tailed Hawks on Sauvie Island, Oregon. Sauvie Island supported a large wintering population of non-territorial Red-Tailed Hawks. The establishment of territories began around 10 January. Average perch height was found to be 14.2 m. Average perch height increased from fall to spring, corresponding-to the onset of the breeding season and to the onset of egg-laying and incubation. Voles (Microtus spp.) were the principal prey year-round, though waterfowl were more important in terms of biomass in the winter and early spring. Territory sizes on the …

Factors Affecting The Population Of Raptorial Birds On Sauvie Island, Oregon, Jeffry Gottfried

Dissertations and Theses

This study is an analysis of the various factors affecting the population of raptorial birds on Sauvie Island, Oregon. A census of diurnal and nocturnal raptors was carried out along with an analysis of food habits. Once the major prey species were determined they were censused, and the effects of the land management practices on their numbers was investigated. In addition, 100 randomly selected nest boxes were sampled so as to determine the extent to which raptors were making use of them. Red-tailed hawk and Great Horned Owl nests were located.

It was found that four diurnal raptors and three …