Radar Studies of Orientation of Songbird Migrants in Southeastern New England

This paper summarizes the results of studies of the orientation of songbirds on autunm night-migration, made at a radar station on Cape Cod, Massachusetts. In a general survey of the migration observed by radar in this area, Drury & Keith (1962) discussed primarily the effects of weather on the start of migration, and did not analyze the observed directions of flight. As found by Lack (1959-63) in Europe, migration over Cape Cod is made up of a number of discrete broad-front movements characterized by uniformity and consistency of direction. In this paper we describe the main autumn migration movements, paying special attention to the way in which directions of flight vary from hour to hour and from place to place, and to the effects of wind, clouds, rain, and fog upon the flight directions. We confine our attention, so far as practicable, to passerines and other small landbirds, and do not discuss in detail observations of eve sed ' migrations, "r r '