NO. I 



LOCOMOTOR MECHANISMS OF BIRDS — HARTMAN 



27 



the wings are largely responsible for the glide area. This is true for 

 wrens, tinamids, the stilt, grebes, herons, and some others. 



DISCUSSION 



All values in this study are based on body weights, which, of course, 

 vary with the state of nutrition, hydration, and food content. By using 

 only healthy, well-nourished birds and collecting them during the 



SQ. cm. 

 1000 



200 



100 



80 



60 

 40 



10 

 8 



6 



4 



CUCULIDAE 

 NYCT1B1IDAE 



ACCIPITRIDAE 

 MOMOTIDAE 

 RHAMPHAST10AE 

 TROGONIDAE 

 HELI0RN1 TH1DAE 

 CAPRIMULGIOAE 

 CORVIOAE 

 PSIT T ACIDAE 

 MIMIDAE 

 PTILOGNAT IDAE 

 TURDIOAE 

 FRINGI LLIDAE 

 T YRANNIDAE 

 TROCHILI DAE 

 FURNAR IIOAE 

 HIRUNOINIDAE 

 PARIOAE 

 C0EREB1DAE 

 THR AUPIDAE 

 PARULIDAE 

 _ VIREONI DAE 



SYLVHDAE 

 'MOTACILLIDAE 

 SI t T1 DAE 

 PIPRIDAE 

 TR0GL0DYT10AE 



FREGATIOAE 

 CATHARTIDAE 

 PELECANIDAE 

 ICONII OAE 



FALCONIOAE 

 PHALACROCORACIDAE 

 STRI Gl DAE 

 ARDEIDAE 

 TYTONIOAE 

 PHASI ANIDAE 

 — ALCEDINIDAE 

 LARIDAE 



THRESKI0RN1TH1DAE 



ANATIOAE 

 ■BUCCONIDAE 

 COTINGIDAE 

 RECURVIROSTRIDAE 

 C0LUMB1DAE 

 I CTERIOAE 

 PI C I DAE 



CAPI TONIOAE 

 1 — TIN AM I DAE 

 CYGLARHIOAE 

 SCOLOPACIDAE 

 FORMI CARIIOAC 

 JACANIDAE 



LANI1DAE 



J 1_J_ 



_L_ 



_l L_J_ 



_I_ 



_L 



a 10 



40 60 80 100 200 



BODY grams 



400 600 1000 2000 4000 



Fig. 7. — Selected plottings of tail areas against body weights (log scales). 



morning hours, the conditions are standardized as well as could be 

 expected. In a few species that have large capacity and gorge them- 

 selves periodically, food contents should be considered. By having a 

 sufficient number of individuals in a species, these variables are re- 

 duced. When values are far from the mean, as occurs occasionally, 

 they have not been included. 



Our observations show that muscle weights are related to activity. 

 Muscles represent potential power but do not indicate the extent of 

 their use. A large muscle may produce powerful contractions, either 

 brief or sustained depending upon the heart that supports it. A small 



