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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 …

A Comparison Of Nocturnal Restlessness Of Caged Thrushes And Migration Of Free Thrushes, Charles Goodwin Kjos

Masters Theses

Nocturnal activity (Zugunruhe) of eight caged, radio-tagged thrushes (Hylocichla spp.) was compared by signal analysis with the occurrence of migration in 16 free, radio-tagged thrushes over a 37-night period during the autumn of 1970 in central Illinois. The study was conducted to determine the extent of synchrony of Zugunruhe and migration in these nocturnal migrants in fall. Zugunruhe frequently occurred on nights when there was no migration, but migration occurred only on nights when at least 50 per cent of the caged birds were active. Except for one departure which was atypical in several respects, migration occurred …