Spatial behavior of medium and long-distance migrants at stopovers studied by radio tracking.

Spatial behavior and range of movements at daytime stopovers of three species of passerine nocturnal migrants (European robins, sedge warbler, and pied flycatchers) were studied by radio tracking. Both in spring and in fall, 94% of European robins remained within 350-400 m of their landing location (n = 51 and 65, respectively). Movements of robins became more area-restricted with more time spent at stopover. Sedge warblers never moved more than 335 m (n = 12). A reason for this could be their relatively narrow habitat use. However, four of seven pied flycatchers tracked covered at least several kilometers during their daytime movements. Pied flycatchers that moved longer distances also showed higher linearity of movements. Spatial behavior of three species of migrants was probably a result of a complex interaction between their habitat use, foraging habits, and weather conditions. No evidence is available that long-distance versus short-distance migratory habits are involved in shaping the spatial behavior of passerine migrants at stopovers.