Breeding and Postlarval Migrations of the Redspotted Newt, Notophthalmus Viridescens, in Massachusetts

Abstract

Intrapopulation variation in migrant size and number was observed during a 2—yr study of the movement of efts and postlarval metamorphs at a pond in Charlton, Massachusetts. Rainfall strongly influenced the timing of both migrations and increased the growth rates of efts. In the wetter of the 2 yr efts were larger and more numerous, and the proportion of female migrants increased. Sex differences among efts in timing and magnitude were attributed to differences between males and females in the minimum size required for migration. Annual differences in larval density were associated with variation in the duration of the migration and mean size of emigrating metamorphs.