NO. I LOCOMOTOR MECHANISMS OF BIRDS — HARTMAN 13 



they have large lower extremities (9 to 12 percent). Specimens of 

 Pteroglossus torquatus found at sea level are smaller (P<o.o5 for 

 males, and P<o.oi for females) and have a smaller heart (P<o.oi) 

 than those of Pteroglossus frantzii obtained at 4,300 feet above sea 

 level. Pectoralis plus supracoracoideus muscles show corresponding 

 proportions in the two species. 



Picidae. — The woodpecker, aptly called "carpintero" by Spanish- 

 speaking natives, devotes much of his time to chiseling holes in tree 

 trunks for food or nest. His legs (6 to 11 percent) and his heart 

 (0.81 to 1. 4 1 percent) are fairly large. Sizable flight muscles (22 to 

 29 percent) and large and broad wings (buoyancy index, 3.39 to 4.25 ; 

 aspect ratio, 1.62 to 2.07) give him the power for his characteristic 

 undulating flight marked by a series of graceful dips. The largest 

 woodpeckers studied, of the genus Phloeoceastes, possessed the small- 

 est wing and glide areas but the largest legs. The downy woodpecker 

 flies rapidly, the pileated woodpecker, slowly but vigorously, at times, 

 like a crow, otherwise in short swings and dips like other woodpeckers. 



Dendrocolaptidae. — Woodhewers, like the woodpeckers, climb 

 trees in search of food, frequently making short, strong flights to a 

 new tree, where the quest is repeated. The hearts are large (1.10 to 

 1.48 percent) in the smaller species and of medium size (0.65 to 

 0.93 percent) in the others. The pectoralis plus supracoracoideus 

 muscles are larger in the male than in the female in Xiphorhynchus 

 guttatus and Lepidocolaptes affinis (P<o.oi). The legs are similar 

 in size to those of the woodpeckers. The buoyancy index is large 

 (3.65 to 4.20). 



Furnariidae. — In the ovenbirds there is a wide variety of habits, 

 ranging from those of terrestrial species to those of species that climb 

 trees, bracing with the tail. Flight is weak to strong (flight muscles, 

 16 to 30 percent), and the wings are large (buoyancy index, 3.0 to 

 4.0). As might be expected, the muscles of the lower extremities are 

 large (8 to 13 percent). The heart muscles are moderate (mostly 

 1.0 to 1. 16 percent) except in Anabacerthia (1.49 percent) and 

 Automolus (1.48 percent) . 



Formicariidae. — Like the ovenbirds, antbirds may be arboreal or 

 terrestrial. All have large muscles in the lower extremities (8 to 

 14 percent) but small to medium flight muscles (16 to 23 percent) 

 except for Formicarius (30.5 percent). As in other birds that fly 

 among close vegetation, their wings are large (buoyancy index, 3.15 to 

 3.75) and broad (aspect ratio, 1.45 to 1.59). Hearts range from 

 0.58 to 1.26 percent. 



