322 



U. S. NATIONAL MUSEUM BULLETIN 217 



dition, so that it is apparent that birds can survive to the point of 

 depletion of their visible reserves of fat. Even the birds which we 

 designated as very little fat still appeared active and in good con- 

 dition of plumage. They were not shrunken in other respects than 

 fatness. I believe that the birds in this category were not injured by 

 starvation. 



Table 15.- 



-Distribution of degrees of fatness among males of 21 species and 

 females of 9 species of common migrants to AnaJctuvuk 



Fatness 



Including redpolls 



Not including red- 

 polls 





Number 



Percent 



Number 



Percent 



Fat 



Medium fat 

 Little fat 

 Very little fat 



136 

 124 

 165 

 65 



28 

 27 

 34 

 11 



132 

 113 

 150 

 37 



30 

 26 



35 

 9 



Total 



(480) 



(431) 





The records of fatness of common migratory birds at Anaktuvuk 

 are shown in the Appendix (figs, 21-36) . For male birds of 21 com- 

 mon species and the female birds of 9 species the distribution in each 

 category of fatness is shown in table 15. The male and female hoary 

 redpolls (Acanthis hornemanni exilipes) and male common redpolls 

 {Acanfhis -fiammea -flammea) included in the first two columns of 

 figures, were less fat than the other migratory birds, having only 8 

 percent of fat birds. Since I suspect that redpolls winter not far 

 from Anaktuvuk, they are subtracted from the totals in the last two 

 columns to show the fatness of those species which migrate for long 

 distances. These records of fatness of migratory birds at Anaktuvuk 

 show that during the whole season only a small proportion were in 

 the lowest category of fatness. 



The records in figures 21 to 36 were mostly concentrated during 

 the early season when the birds came in as arriving migrants. Among 

 the males of 9 species {Anas acuta^ Aythya marila nearctica^ Liirmo- 

 dromus scolo'paceus^ Erolia hairdii, Ereunetes pusillus, EremopMla 

 alpestris arcticola^ Anthus spinoletta rubescens, Zonotrichia leuco- 

 phrys gainbelii, and Oalcarius lapponicus alascensis) the weight curve, 

 as judged visually by the best fitting line, declined between 10 and 

 15 percent after the first arrival of migrants in spring. Among 

 males of 4 species {Pluvialis dominica dominica, Heteroscelus inca- 

 nv/m^ Erolia minutilla and GalcaHus pictus) the declme was between 

 4 and 9 percent. The males of Spizella showed no change. The two 

 species of Acanthis, suspected of wintering nearby and probably 

 making only short migratory flights, showed no indication of chang- 



