328 IT. S. NATIONAL MUSEUM BULLETIN 217 



weight diminished (see p. 323) . As an example of extreme utilization 

 of reserves, the small weight of warblers which arrived exhausted 

 after flight over the Caribbean (see p. 320) shows that they had made 

 extensive use of their substance during a long flight (Voous, 1958). 

 It appears that the body substance of birds can be rapidly consumed 

 and that at times it is used to meet current metabolic demands or 

 emergencies during migration. 



In comparing the weight of birds at the start of migration with 

 their weight at the terminus we are disturbed by the fact that a sample 

 of a migratory species taken on its wintering ground or along its 

 migratory route may be setting out for any part of its eventual nest- 

 ing grounds. There are many reports indicating that before depart- 

 ing for northbound migration birds wintering in temperate climates 

 acquire fat, but few reports show condition at the end of migration. 

 I will only refer to a few observers whose records of fatness appear 

 directly comparable with my observations at Anaktuvuk. 



In the discerning view of von Zedlitz (1926, 1927) the terminus 

 of migration in Sweden was a favorable place for observation because 

 all the birds were alike in proximity to their nesting place. On his 

 estate in central Sweden, where he had watched the birds through 

 many years, he reported careful records of the weight and condition 

 of the migrant birds which for the most part came to settle and nest 

 there. The list of birds is interesting because their names were all 

 assigned by Linnaeus whose residence had been nearby. Corvus comix 

 comix, Sturnus vulgaris vulgaris, Fringilla coelebs coelehs, Golumba 

 'pahmibus 'pdkim'bus, and Scolopax rusticola rusticola arrived fat and 

 then lost weight at mating time. Von Zedlitz' observations differ 

 from those of Weigold (1926) on Helgoland, a point along a migratory 

 route over water. There Weigold found variation in the weights of 

 examples from a number of species which he took to illustrate occa- 

 sional encounter with nutritional hardship during migration. Yon 

 Zedlitz' point of observation corresponds with mine in being at the 

 terminus of a normally completed migration. His conclusions agree 

 with mine that there is no evidence that successful migration leaves 

 signs of strain in the nutritional state of birds. 



To T. T. McCabe (1943), a long-experienced collector of birds in 

 British Columbia, it was apparent that the northbound migrants were 

 commonly fat and frequently very fat but that they lost weight rap- 

 idly on their breeding grounds. As an interesting contrast Mrs. Oake- 

 son found that the Puget Sound race of white-crowned sparrows 

 {Zonotrichia leucophrys) on arrival at their nesting ground at Tilla- 

 mook were not fat (Blanchard 1942). Unlike the birds considered 

 by McCabe these white-crowned sparrows had reached Tillamook after 

 only a short migration from a nearby wintering ground. These in- 



