The Aleutian tern (Onychoprion aleuticus) is a species of high conservation concern in Alaska due to large declines at known breeding locations since the 1960s. Due to the small population size and ephemeral behavior of this species on the nesting grounds, there is little basic biological information available and data...
Marine heatwaves (“MHWs”) are discrete periods of anomalously warm ocean conditions that can lead to shifts in the distribution and abundance of marine organisms. Low-trophic level, pelagic forage species are frequently among those affected by MHWs, often resulting in considerable impacts upon their predators. In the North Atlantic Ocean, Atlantic...
A detailed understanding of the foraging ecology of species preying upon
threatened or endangered prey may contribute to identifying and evaluating
management options to reduce predation, when such management is deemed
appropriate. In the Columbia River estuary, Caspian terns (Sterna caspia) and
double-crested cormorants (Phalacrocorax auritus) have been identified as...
This dissertation focuses on the predator-prey relationship between two species of avian predators, Caspian terns (Hydroprogne caspia) and double-crested cormorants (Phalacrocorax auritus), and one of their important prey types, juvenile salmonids (Oncorhynchus spp.), in the Columbia River estuary of Oregon and Washington states during the period 1998 – 2007. I...
Double-crested cormorants (Phalacrocorax auritus) and Brandt’s cormorants (P. penicillatus) nest sympatrically in a large mixed-species colony on East Sand Island (ESI) in the Columbia River estuary. Ecological theory predicts that such morphologically similar species will partition prey resources when faced with resource limitations. During the summer of 2014, I investigated...
Year-round habitat use of marine predators provides knowledge of important marine areas throughout different life stages. Large-scale, environmental variability, both in space and time, causes changes in the behavior and distribution of marine predators that are important to quantify for conservation. In the Northern California Current System (NCCS), common murres...
Declines in wild salmonid (Oncorhynchus spp.) populations in the Columbia River basin have resulted in managers identifying that avian predation on juvenile salmonids is an important limiting factor for salmonid recovery. Caspian Terns (Hydroprogne caspia), particularly those nesting in the Columbia River estuary, were identified as key avian predators that...
Understanding the factors that contribute to or limit reproductive success is a fundamental objective of the field of ecology, providing insight into the ways ecosystems function and facilitating better management of natural resources. Behaviors that benefit offspring often increase costs to parents, and thus parents must adjust their level of...
North American bird populations have declined throughout the past half century. The majority of studies quantifying these declines have focused on spring and summer breeding birds; not the season of scarcity, winter. We re-surveyed 7 large study plots in Douglas fir forests initially surveyed in winter during the late 1960s...
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DonaldLyons, Committee Member, representing Department of Fisheries, Wildlife, and Conservation
Human-animal relationships, emerging as an aftermath of human-animal interactions, have been increasingly investigated in recent years. It is possible to see the results of the effects of these relationships on both human and animal welfare. This study predicted that caretakers with hands-on contact with their zoo animals would have significantly...