Viability of Salt Marshes as Nesting Habitat for Common Terns in New York

Abstract

We examined Common Terns (Sterna hirundo) nesting between Jones and Fire Island inlets on the barrier beach and salt marshes of the south shore of Long Island, New York during 1986 and 1987. Controversy exists in the literature over whether beaches and salt-marsh islands are traditional nesting areas offering alternative viable breeding sites for Common Terns, or whether salt marshes are suboptimal habitat into which Common Terns are largely 'forced' after loss of beach habitat. Past studies usually compared geographically distant sites, thus introducing uncertainty about the role of local climatic and food conditions in affecting reproductive variables. We tested the null hypothesis that reproductive success does not differ between habitats for colonies bordering the same estuarine system. Interyear and intercolony differences were strong, and interhabitat differences were inconsistent. Despite generally lower hatching success and generally greater nest destruction in salt marshes, tern pairs in both habitats fledged similar numbers of chicks of similar sizes and weights. Movements of birds banded on beaches and in marshes indicated that birds tended to breed in the same habitat in which they hatched, and that breeding adults were likely to nest subsequently in the same habitat.