We investigated colony size, productivity, and limiting factors for five piscivorous waterbird species nesting at 18 locations
on the Columbia Plateau (Washington) during 2004–2010 with emphasis on species with a history of salmonid
(Oncorhynchus spp.) depredation. Numbers of nesting Caspian terns (Hydroprogne caspia) and double-crested cormorants
(Phalacrocorax auritus) were stable...
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...
Colony size, nesting ecology and diet of Caspian Terns (Hydroprogne caspia) were investigated in the San Francisco Bay area (SFBA) during 2003-2009 to assess the potential for conservation of the tern breeding population and possible negative effects of predation on survival of juvenile salmonids (Oncorhynchus spp.). Numbers of breeding Caspian...
At the Siuslaw Estuary or some adjacent areas, U. S. Fish and Wildlife Service (USFWS) Biologists John Annear, John Cornely, and Roy Lowe conducted 67 censuses; Maureen Woolington made 90 censuses, and Range Bayer completed 429 censuses. Unfortunately, these censuses do not give a complete picture of the seasonality, abundance,...
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...
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...
Mangroves provide numerous ecosystem services, including biodiversity values such as nesting sites for piscivorous waterbirds. High concentrations of pisicivoirous birds are hypothesized to affect ecosystem dynamics, yet few studies have examined their effects in mangroves. We examined the effects of nutrient enrichment by colonial waterbirds at a mangrove rookery in...
Bird predation of juvenile salmonids and/or bird predation control are reviewed for 14 of the 18 mainstem dams on the Columbia and Snake Rivers, but there was little information for some of these dams. California gulls, ring-billed gulls, Caspian terns, double-crested cormorants, American white pelicans, and several other bird species...
I investigated Caspian terns (Sterna caspia) breeding at colonies on the Columbia Plateau (southeastern Washington and northeastern Oregon), with emphasis on the breeding and foraging ecology of Caspian terns nesting at colonies in the mid-Columbia River. I focused research at colonies where Caspian terns foraged on juvenile salmonids (Oncorhynchus spp.)...
Salmonid run sizes are strongly affected by their early marine stage. Fully understanding the life history of salmonids means understanding how they interact with their marine environment and with other fishes. Changes in the biological and physical environment off the Columbia River region affects the distribution and abundance of predatory...
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Chapter 3. Abundance and Distribution of Pelagic Piscivorous Fishes in
the Columbia River Plume