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Common Tern Island IBA Complex
Location:Franklin, Grand Isle
Bird Conservation Region: BCR 13
Size: Four small islands on Lake Champlain, Popasquash, Rock, Grammas and Hen
Latitude:
Longitude:
IBA Criteria:
- Vermont Endangered and Threatened Species (Criteria 1)
- Single species Concentrations (Criteria 4a and 4c)
- Long-term research and monitoring (Criteria 5)
Land Ownership:Green Mountain Audubon Society, The Nature Conservancy
Habitats:Rocky islands
Land Use: Wildlife conservation, research
Threats: Human disturbance, predation, over-crowding by gulls and cormorants
Site Description
The Common Tern Island IBA Complex consists of 4 small (< 0.5 acres) islands on Lake Champlain. All four islands are located in the northeast arm of the lake known as the Inland Sea. The two islands that regularly support nesting terns, Popasquash and Rock, are sparsely vegetated with grasses and forbes. Rock Island has some small trees and shrubs. Hen and Grammas islands are used irregularly. Hen island is similar to Popasquash and Rock island in size and vegetation type. Grammas Island is the largest of the four and is 75% vegetated with some large trees and numerous shrubs.
Birds
The islands of this IBA Complex support the entire nesting population of Common Terns in Vermont Terns were first documented using Popasquash Island in the late 1800's and spread to the three other islands in the 1960's. Ring-billed Gulls also nest on Rock and Popasquash islands with the occasional Herring and Greater Black-backed nesting on all four islands. Recently Double-crested Cormorants have tried to establish a nesting colony but active management of these birds has deterred colonization. The first confirmed nesting of Caspian Tern was documented on Popasquash Island in 2002.
Conservation
A decrease in the number of adult breeders and reduced breeding success of Common Terns on Lake Champlain in the 1970's and 1980's resulted in this species being declared an endangered in 1989. Documented causes of this decline include predation, disturbance to nesting birds, and over-crowding by gulls. Since the establishment of monitoring efforts in 1980, the Lake Champlain Common Tern population size and productivity have increased but have continued to fluctuate due to predation. Continued conservation efforts, including population monitoring, management, education and banding, prove crucial to the viability of the Common Tern colonies on Lake Champlain.
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