l6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 143 



aspect ratio, 2.19) and fairly large legs (7.76 percent). In short flights 

 he appears slow and feeble, but on long journeys he flies strongly and 

 swiftly. 



Cyclarhidae. — Concerning peppershrikes it need only be noted 

 that they have large leg muscles (9.46 percent) and that their flight is 

 deliberate and weak. 



Vireonidae. — Vireos, feeding mostly among the leaves, are moder- 

 ately endowed with muscles: heart, 1.06 to 1.43 percent; flight 

 muscles, 21 to 25 percent; leg muscles, 5.89 to 7.63 percent. They 

 do, however, have large wings (buoyancy index, 3.44 to 3.88). 



Coerebidae. — Honeycreepers, being quick in the air, have flight 

 muscles ranging from 23 to 34 percent and large hearts (1.25 to 

 1.44 percent). Their wings are large (buoyancy index, 3.37), but 

 their legs are only moderate in size (muscles, 5 to 8 percent). 



Parulidae. — Although the wood warblers range from the treetops 

 (black-throated green warbler) through lower levels of the forest 

 (magnolia warbler) to the ground (Kentucky warbler), their flight 

 muscles do not differ greatly, as their activities in the air are similar. 

 These muscles are not large, ranging mostly from 20 to 25 percent of 

 the body, with many around 22 percent. The wings (buoyancy index, 

 3.27 to 4.16) and tails are large, making the glide area as high as 

 10 cm. 2 per gram in some species. The muscles of the lower extremi- 

 ties are largest in Basileuterus (9 to 10 percent) and as low as 5 per- 

 cent in others. The hearts range from 0.95 to 1 .39 percent. 



Ploceidae. — The house sparrow {Passer domesticus) is typical of 

 many small perchers; large heart (1.39 percent) and flight muscles 

 (25.4 percent) ; wings designed for quick takeoff (buoyancy index, 

 3.05; aspect ratio, 1.88) ; and moderate lower extremities (muscles, 

 6.47 percent). 



Icteridae. — Icterids show characteristics similar to those given 

 above: hearts, 0.85 percent in Sturnella magna to 1.2 percent in 

 Icterus galbula; flight muscles, 19 percent in Amblycercus to 28 per- 

 cent in Leistes; buoyancy index, 3.13 for Sturnella to 4.4 for Cacicus; 

 aspect ratio, 1.31 for Amblycercus to 2.03 for Psarocolius; lower 

 extremities, 7.46 percent for Icterus spurius to 15.2 percent for 

 Amblycercus. 



Thraupidae. — Thraupids show a greater range in heart size than 

 the fringillids, Rhodinocichla possessing the smallest (0.63 percent), 

 the male Habia rubica the largest (1.46 percent). Flight muscles 

 also show a somewhat greater range : 1 percent in Chlorospingus and 

 29 percent in Thraupis. Buoyancy index likewise runs from 2.82 in 



