Patterns of movement during passerine migration on an island stopover site

We used mist nets to examine the directional movement of 20,019 passerines on Appledore Island, Maine, during spring and fall migration, Based upon the seasonal trend of North American migration, the hypothesis was that migrant birds would be moving north in the spring and south in the fall. Results, however, indicate that in both seasons, birds were more likely to be flying north than south and were more likely to be flying west than east. The data for the most commonly captured species support the directional patterns observed among all individuals. Although all captures as well as captures in the first hour after sunrise indicate northward movement in both seasons, spring captures in the northward direction were significantly more prevalent than fall captures, Therefore, we suggest that the general migratory direction and the presence of an ecological barrier, the Atlantic Ocean, appear to influence the directional capture of stopover migrants. Recaptured birds generally showed a lack of directional movement in both seasons, although subsequent recaptures indicate northward movement by these migrants in the spring. Age did not appear to affect directional movement.