Trends in the diets of common, arctic and roseate tern chicks on Eastern Egg Rock Island, Maine

Boyce, Jennifer
Tom Wessels, MA
Department of Environmental Studies
Seabirds are highly visible wide-ranging, upper trophic level consumers that frequent areas of high oceanic productivity and should be highly valued for their ability to serve as a sensitive indicator to the quality of our marine environment (Furness and Monaghan 1987). Seabirds and marine fish share mutual habitats and food webs but little contact between the two disciplines that study the organisms has been established. The seabird Restoration Program of the National Audubon Society has collected data on the species and amount of fish fed to Common, Arctic and Roseate Tern chicks on eastern Egg Rock Island in Muscongus Bay, Maine for the past six years through a Tern Chick Provisioning Study. The purpose of this thesis was to determine if any one fish was fed significantly more than other species on Eastern Egg Rock on any given year of the five years of the study. The paper will also determine if the amount of major fish species fed to chicks varied significantly over the five years of the study. Common Terns (Sterna hirundo) and Roseate Terns (Sterna dougallii) were observed specifically for the chick provisioning study for the past five years. Additionally, Arctic Terns (Sterna paradisaea) were observed in 1993 and 94. Approximately sixteen nests of each species were monitored from hatching to fledging each year. Statistical tests were conducted using Statview for Students. The results showed that the levels of dominant fish species fed to Common and Roseate Tern chicks varied significantly for the five years of the study and that white hake was the dominant fish species in Roseate and Common Tern chick diet for four of the five years of the study. The results of this study highlight the important role that the health of the marine environment plays in supporting tern populations on Eastern Egg Rock and other colonies along the Maine coast.

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