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...
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...
Caspian terns (Hydroprogne caspia) and double-crested cormorants
(Phalacrocorax auritus) nest in large colonies on East Sand Island in the Columbia
River estuary, the largest known colonies for the two species in the world. Both
species of piscivorous colonial waterbirds have been identified as predators with a
significant impact on the...
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...
The purpose of this study was to investigate the primary factors affecting colony size, reproductive success, and foraging patterns of Double-crested Cormorants (Phalacrocorax auritus albociliatus) nesting at East Sand Island in the Columbia River estuary, the largest colony of this species on the Pacific Coast of North America. This colony...
This study was designed to enhance understanding of factors influencing foraging distribution, diet composition, and overall
reproductive success of Caspian terns (Sterna caspia) nesting on East
Sand Island in the Columbia River estuary. This colony of nearly
10,000 breeding pairs is of concern to regional resource managers
because Caspian terns...
This research was designed to evaluate the Fatty Acid Signature (FAS) technique as a non-lethal alternative to more traditional, and sometimes destructive, methods of studying the diet composition of piscivorous birds. Specifically we tested the technique with Caspian terns (Hydroprogne caspia) which currently nest in large numbers in the Columbia...