Chen et al • SEARCH BEHAVIOR OF MIGRATORY SONGBIRDS 
351 
1 “ 
| 1 
20.9 ± 0.8 
21.2 ± 1.1 
18.2 ± 0.9 
35.7 ± 2.4 
4.6 ± 0.9 
5.4 ± 0.9 
21.7 ± 0.2 
£ 
| 
I 1 
il 
75 (4.1) 190 (10.2) 1.856 
41 (4.9) 57 (6.8) 837 
44 (3.8) 263 (22.6) 1,166 
6(1.0) 57 (9.9) 576 
8 (4.7) 46 (26.7) 172 
12 (4.3) 61(22.1) 276 
2,253 (4.8) 5.194 (11.1) 46,775 
i 
1 
1,591 (85.7) 
739 (88.3) 
859 (73.7) 
513 (89.1) 
118 (68.6) 
203 (73.6) 
39.328 (84.1) 
*i 
96 
56 
89 
27 
20 
26 
2.603 
i« 
WEWA 
COYE 
HOWA 
CAWA 
SUTA 
SCTA 
TABLE 1. Continued. 
ii 
Common Yellowthroat (Geothlypis trichas) 
Hooded Warbler (Wilsonra citrina) 
Canada Warbler <W. canadensis) 
Summer Tanagcr (Piranga rubra) 
Scarlet Tanager (P. olivacea) 
Search rate varied among families: 24.9 
movements/min for warblers, 14.7 for vireos, 5.0 
for tanagers, and 1.0 lor flycatchers (Table 1). 
Warblers hopped an average distance of 12 cm, 
vireos 16 cm, and Yellow-billed Cuckoos (Coc- 
cyzus americanus). the largest species in this 
study, 23 cm (Table 2). The average distance of 
fluttering was 31 cm for warblers. 39 cm for 
vireos. and 66 cm for Yellow-billed Cuckoos. The 
average flight distance was 109 cm for warblers, 
110 cm for vireos. 252 cm for Yellow-billed 
Cuckoos, but 432 cm for flycatchers (Table 2). 
The distance traveled in a hop was roughly 
proportional to a bird’s body size, but flight 
distance was greatly influenced by type of 
foraging mode used by a bird. For example, 
flycatchers made significantly longer flights than 
warblers and vireos. The Hooded Warbler, among 
warblers, had the longest average flight distance 
(190 cm); this was partly due to its frequent use of 
wing-powered maneuvers. 
Search Movements Among Species. —Birds that 
hopped more tended to have a higher search rate 
(y = -71.43 + 1.13a: r = 0.77, P< 0.001; Fig. 1), 
partly because hopping takes the shortest time to 
complete. Most warblers had a high proportion of 
"hops,” and often had a higher search rate 
(Table 1). Search rate of migrants was negatively 
correlated to flight distance (y = 58.456e ,,<W2, ' A ; 
r 2 = 0.86, P < 0.000T. Fig. 2). Hop distance of 31 
migrant species was positively correlated to tarsus 
length (y = -3.93 + 0,99a; r 2 = 0.24. P < 0.01; 
Fig. 3), as was flight distance to wing length (y = 
-5.19 + 0.28.v; r = 0.24, P < 0.01; Fig. 4). 
Species were divided into three groups in the 
dendrogram: warblers, vireos and tanagers, and 
flycatchers (Fig. 5). Species were grouped mainly 
according to their phylogeny with a few excep¬ 
tions. The Hooded Warbler was clustered with 
vireos instead of warblers. The Blue-headed Vireo 
was clustered with the Yellow-billed Cuckoo and, 
as a group, they were linked with tanagers. A 
further division roughly separated vireos and 
tanagers, but the Blue-gray Gnalcatcher and 
Ruby-crowned Kinglet were grouped with war¬ 
blers. Two subgroups were identitied within 
warblers: Canada Warbler ( Wilson hi canadensis). 
Black-and-white Warbler (Mniotilta varia). Mag¬ 
nolia Warbler ( Dendroica magnolia), and Chest¬ 
nut-sided Warbler (D. pensylvanica ) as one 
subgroup, and all the other warblers except the 
Hooded Warbler as the other subgroup. The first 
