Journal of Raptor Research
Mark S. Martell, Richard O. Bierregaard Jr., Brian E. Washburn, John E. Elliott, Charles J. Henny, Robert S. Kennedy, Iain MacLeod
Fall migration patterns of North American Ospreys have been described and studied disproportionately more than, the spring migration of these birds. We used satellite telemetry to: (1) determine the timing, duration and migratory routes of spring migrations; (2) determine if differences in spring migration patterns existed between the sexes and (3) compare consecutive fall and spring migrations of individual Ospreys.
The median dates for departure from the wintering grounds and arrival on the breeding grounds did not differ significantly between adult male and female Ospreys. Nonetheless, the male almost always arrives a few days before the female.
Compared to their fall migrations, Ospreys spent fewer days on migration, fewer days in stopover periods along the migration route and traveled farther (on average) each day during spring.
Our findings suggest that, although sex and breeding location might influence the spring migration strategy used by individual Ospreys, both males and females minimize the time spent on migration to ensure a timely arrival on the breeding grounds to establish or defend a nesting territory.