4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I43 



out by Carl Albrecht, Kent Bruno, Barbara Caldwell, David Gillespie, 

 Elmer E. Hartman, Donald Neal, and Kenneth Teague. This study 

 was aided by grants from the Comly-Coleman Fund and the Graduate 

 School of the Ohio State University. 



RESULTS 



Data on more than 360 species in 70 families are included in this 

 report. The muscle weights are calculated as percent of body weight. 

 The wing and other areas are given as cm. 2 per gram of body weight. 

 Glide area is the area included in wings, tail, and body. 



In the master list (table 1, pp. 38-87) the number of individuals in a 

 species is shown in parentheses, with the mean values and standard 

 error of the means, or the individual values are given if less than three. 

 Sexes are separated for body weights and for other determinations 

 where the differences between sexes are significant ; otherwise the data 

 of the two sexes are combined. Although the data from a single indi- 

 vidual may not be representative of a species, they have been included 

 if the species is sufficiently interesting. 



Before embarking on a consideration of the muscles I wish to call 

 attention to certain species in which there is a significant difference 

 in body weight between the sexes. Those in which males are larger 

 are : Podiceps dominicus, Casmerodius albus, Gallus gallus, Aramus 

 guarauna, Porphyrida martinica, Columba speciosa, Brotogeris jugu- 

 laris, Crotophaga major, Crotophaga ani, Crotophaga sulcirostris, 

 Nyctidromus albicollis, many trochilids, Centurus rubricapillas, Cen- 

 hirus chrysauchen, Dendrocincla homochroa, Sittasomus griseicapillus, 

 Xiphorhynchus guttatus, Anabacerthia striatic ollis, Manacus vitellinus, 

 Fluvicola pica, Cyanocitta cristata, Parus carolinensis, Parus bicolor, 

 Parula pitiayumi, many icterids, and Arremonops conirostris. In the 

 following species the females are larger: Jacana spinosa, Tyto alba, 

 Speotyto cunicidaria, Cotinga ridgwayi, Corapipo leucorrhoa, Thryo- 

 thorus modestus, and Selasphorus scintilla. 



Let us now consider the distinctive values in each family and their 

 possible relation to habits (table 1). 



Tinamidae. — The tinamous are most unusual birds, possessing 

 extremely large flight muscles (37 to 40 percent of the body weight, 

 of which the pectoralis is 63 percent) and large leg muscles (13 to 

 17 percent) but the smallest heart (0.19 to 0.25 percent) of all birds. 

 The pectorals are so large that they extend beyond the keel of the 

 sternum. In Crypturellus the sternum is submerged 7 to 8 mm. below 

 the bulging pectorals. The same condition is present in Nothocercus 



