Summary of Spring Migration Findings Peter Nye The following summary is based on satellite data from 11 Bald Eagles that were tracked for multiple years; one for 4 complete springs. Data on total of 57 seasons: 35 spring season, 22 fall seasons. Departure Dates Arrival Dates Number of Days in Migration Distance Traveled Routes Followed Spring Migration Departure Dates Bald Eagles leave New York over an 8 week period. The median departure date is March 18. The majority of birds depart during a 2-3 week period in March. Females leave later than males (median is 5 days later). Eagles left earliest from New York’s southern-most study site Mongaup), during the first week of March. Eagles left latest from New York’s northern-most study site (St. Lawrence), 3 weeks later, March 24. Spring Migration Arrival Dates Eagles arrive over an 8-week period, between March 9 - May 2; (median April 5). The median arrival of females is a week earlier than males (so they are leaving later and arriving earlier). New York’s southern-most study site (Mongaup) arrived latest (and left first!). Number of Days in Spring Migration The average of all Bald Eagles studied took 18 days migrating to summer areas. Males took longer (26 days) than females (13 days). (Makes sense for females-they are leaving later and arriving earlier; takes less time). Mongaup Valley birds taking significantly longer than all other areas: 37 days versus 12 days. Distance Traveled The mean distance for all eagles = 1039 km Great range of travel distance: 298 km (St. Lawrence adult female) versus 1914 km (Mongaup adult male). Males travel significantly farther than females. No surprise, they left earlier, arrived later, and took longer to get there. Mongaup Valley eagles moved significantly farther than all other locations (Also makes sense: they early departure, greatest total days in migration, latest arrival date). St. Lawrence eagles shortest average distance to summer grounds, consistent with late departure, short travel time and early arrival date, averaged only 727 km move. Routes followed: Followed compass headings pretty directly and appeared to take direct and quick route in spring (compared to fall; wander, longer time). Sometimes followed major water courses (rivers or coast). Atlantic coast, St. Lawrence River, Ottawa River, and Great Lakes--major landmarks used? All but one (of 21) summered in Eastern. Canada: 1 found to be Adirondack resident – only one! The majority traveled north and northeast. No differences based on gender.   Copyright 2003-2004 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form