Summary

Description

As part of ongoing research into the status of Vermonts marsh birds, this is a report on a statewide census of the black tern nesting population that happened in 2001. The black tern nesting population showed a drop from the high of 100 pairs in 1999 to only 53 pairs found in 2001. All black tern nesting in Vermont in 2001 was found at Mud Creek Wildlife Management Area in Alburg and Missisquoi National Wildlife Refuge in Swanton. This is cause for concern because it means that all nesting is in one confined area, with no nesting at the south end of Lake Champlain or on Lake Memphremagog as in past. A minimum estimate of at least 29 young black terns fledged from the area around Missisquoi National Wildlife Refuge, approximately 0.5 fledglings per pair. This is not thought to be adequate to maintain the population, but the nature of the estimate makes it an absolute minimum. In addition, the survey of selected marshes in Vermont for other marsh birds piedbilled grebe, least bittern, American bittern, Virginia rail, sora, common moorhen, and American coot was continued. Fifteen marsh bird routes situated in emergent marshes within state Wildlife Management Areas, Missisquoi National Wildlife Refuge, or in marshes designated as Important Bird Areas were surveyed. Virginia rail is still the most common and abundant marsh bird surveyed, followed by the common moorhen, with least bittern, sora, American bittern, piedbilled grebe, and American coot being uncommon and sporadic. These ongoing activities together have two major objectives: to look at marsh bird population trends within the marshes of Vermont and to investigate the effect of water level and marsh vegetation changes on marsh bird numbers.