Chen el al • SEARCH BEHAVIOR OF MIGRATORY SONGBIRDS 
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Hop (%) 
FIG. I. Search rate of arboreal insectivorous migrants (n = 29 species) was positively correlated to proportion of hop in 
search movements at Gulf Coast stopover sites in spring. 1993-1995. We excluded the Acadian Flycatcher and the Eastern 
Wixxl-Pewee in this analysis as they primarily used hops to change direction instead of searching tor prey. 
linear models did not show any significant effect 
of environmental and social factors or their 
interactions on search rates and movement dis¬ 
tances for warblers and vireos. 
DISCUSSION 
Search Movements of Migrants .—Suites of 
intercorrelated foraging characteristics are called 
foraging modes (Eckhardt 1979. Huey and Pianka 
1981). and search movements and associated 
prey-attack maneuvers are considered important 
pans of foraging mode (Remsen and Robinson 
1990), Species that hop frequently between 
perches tend to use near-perch maneuvers, 
whereas species that fly between perches mostly 
sally for prey (Remsen and Robinson 1990). The 
ordination of migrants in the dendrogram (Fig. 5) 
indicates that closely related species had similar 
foraging modes with “widely foraging’ warblers 
at the top and “sit-and-waif ’ flycatchers at the 
bottom. The grouping of species in the dendro¬ 
gram corresponds largely to their phylogenetic 
relationships. Movement distances were in pro¬ 
portion to morphological measurements, and 
search behavior of these en route migrants is, in 
part, constrained by body size and wing length. 
FIG. 2. Search rate of arboreal insectivorous migrants (n = 31 species) was negatively correlated to flight distance 
^If Coast stopover sites in spring, 1993-1995. 
