MARSH BIRDS OF THE CONNECTICUT RIVER ESTUARY: A 20-YEAR PERSPECTIVE

This study reports the summer distribution of marsh birds of the lower Connecticut River for the 1994 breeding season. It compares findings with similar observations made between 1974 and 1987, and serves as a 20- year update on the first 1974 surveys. In addition, habitat change over the 20-year interval is qualitatively assessed, and preliminary date are presented that examine the use of cattail and invasive reed habitats by selected marsh bird species. In 1994, I found 21 marsh-breeding species and 24 marsh-using species at the Connecticut River marshes. During the study period, populations of species like the American Black Duck, Sharp-tailed Sparrow, Red-winged Blackbird, Herring Gull, and Bank Swallow declined, whereas species like the Mute Swan, Canada Goose, Willet, Great Blue Heron, and Osprey increased. Moreover, species like Blue-winged Teal, Common Moorhen, and Black- crowned Night Heron that were summer residents in 1974 were absent in 1994. Most notable among habitat changes that have occurred in the Connecticut River marshes were contraction of salt meadow patches at transitional marshes, progressive replacement of cattails by reeds at Great Island, Upper Island, Ragged Rock Creek, Ayer's Point, and Lord's Cove, dying back of Iva frutescens at Great Island and Black Hall River, a small increase in cattail cover at Wetherfi eld Meadows, expansion of cover by Lythrum salicaria, and late growth by vegetation at freshwater marshes during years of heavy June flooding. Data on use of cattail and invasive reed habitats suggested that certain species like the Least Bittern, Marsh Wren and Red-winged Blackbird used reeds extensively, but particularly the Virginia Rail most frequently occupied cattail habitats. This study reports the summer distribution of marsh birds of the lower Connecticut River for the 1994 breeding season. It compares findings with similar observations made between 1974 and 1987, and serves as a 20-year update on the first surveys. It examines also changes in habitats that have occurred during this period, and provides preliminary data on use by marsh birds of cattail habitats versus invasive reed communities. The data reported here provide a rare look at long-term changes in bird populations and distributions. Examining community changes such as these provide insights into the dynamics of the system. Previous investigators of the Connecticut River avifauna include Clark (1884, 1897), who described the nest of the Black Rail (Laterallus jamaicensis), and Poulson (1969), who studied the physiology of the Seaside (Ammodramus maritima) and Sharp-tailed (A. caudac uta) sparrows. Ames and Mersereau (1964), Ames (1966), Wiemeyer et al. (1975), Spitzer (1977), Spitzer et al. (1978), and Spitzer and Poole (1980) studied nesting Ospreys (Pandion haliaetus), and Peterson (1969) briefly discussed population changes of raptorial and fish-eating birds of the river. More recently, Craig (1990) described the historic distributions of marsh birds in this system. The most complete analysis of avian community ecology in the Connecticut River system is that by Craig and Beal (1992). In this study, species richness of marsh breeders was found to be most closely associated with marsh size, although richness of marsh-using species (species that feed in marshes but nest elsewhere) was most closely associated with proximity to additio nal marsh habitat. In comparing species richness of series of small vs. a single large marsh, small marshes were found to hold similar numbers of species to the large site, but the large marsh accumulated rarer species.