Experimental effects of habitat type on the movement ecology and stopover duration of spring migrant Northern Waterthrushes (Parkesia noveboracensis)

摘要

Long-distance migratory animals typically stop-over between migratory movements to rest and refuel. In species lacking stopover site fidelity, including most songbirds, timely arrival to breeding areas with sufficient energy stores for reproduction requires that migrants rapidly locate suitable stopover habitat in unfamiliar landscapes. Few studies have examined movement ecology in such species during stopover, and even fewer have addressed how these migrants adjust movement behaviors in response to encountering preferred or non-preferred habitats. We experimentally translocated spring transient Northern Waterthrushes (Parkesia noveboracensis) to preferred (bottomland) and non-preferred (upland) forest habitats and characterized subsequent fine-scale movements and stopover duration using radiotelemetry. Minimum stopover duration averaged 4.1 days and was 1.5 days longer in bottomland-released birds than in upland-released birds. Minimum stopover duration decreased by 1.4 days per week over the spring migratory period. For upland-released and bottomland-released birds, respectively, maximum distance moved from the release point was 635 +/- 58 m and 326 +/- 51 m on the day of the release and 773 +/- 109 m and 504 +/- 83 m on the following day. Upland-released individuals traveled nearly twice as far from the release point on day 1 as bottomland-released birds. Upon reaching bottomland habitats within 2.0 +/- 0.3 h of release, subsequent distance moved on day 1 by upland-released birds was similar to that of bottomland-released birds. Cumulatively, these results indicate that initial exploratory movements were facultative and habitat dependent and that waterthrushes can successfully locate suitable stopover habitats in a heterogeneous landscape at the spatial scales we investigated.