EASTERN WHITE-CROWNED SPARROW 1285 



Mortality. — It seems to me better to get away from the connotations 

 of the word "enemy" and simply to point out that the white-crown 

 is subject to the usual factors that cause attrition in animal popu- 

 lations, whether disease, the complex of factors engendering winter 

 mortality, or direct predation by accipitrine hawks, shrikes, weasels, 

 and the like. 



It has its normal share of parasites, both external and internal. 

 Oscar M. Root has kindly furnished a note on the identification of 

 Hippoboscid louse-flies, Ornithomyia fringillina, found on immature 

 birds by Gary C. Kuyava in Minnesota; Francis Harper (1958) has 

 taken a mite of the genus Lealaps from a juvenile specimen in Quebec; 

 and Robert A. Norris (1954) found biting lice (Mallophaga) on dried 

 skins and also found that four out of nine specimens examined in 

 Georgia had protozoan infections of the blood (Leucocytozoon), and 

 one of these, a smallish individual which had not begun its prenuptial 

 molt on March 17, was doubly infected with the malarial parasite, 

 Plasmodium. One adult was heavily infected with abdominal 

 helminths, the filarid nematode Diplotriaena. The individual infected 

 with Plasmodium also had foot tumors caused by the virus Epithelioma 

 contagiosm. Alfred O. Gross (1937) reports the mallophagan Philop- 

 terus subtiavescens (Geof.) from young on the Labrador coast, and 

 Herbert Friedmann (1938) reports parasitism by the cowbird at 

 Okotoks, Alberta. 



Of greater population significance, probably, is the loss of young 

 birds during the first migration. For the Quebec-Labrador segment, 

 especially, this must be a significant decimating factor because the 

 young of the year are often wind-drifted out to sea, where they perish 

 unless they are fortunate enough to reach an island from whence they 

 can return. I have been particularly impressed with this problem in 

 their lives at Block Island, R.I., where hundreds of white-crowns 

 appear in autumn, when cold fronts pass out to sea, all of them 

 immatures. 



Fall and winter. — Young were on the wing as early as July 11, 1945, 

 at Indian House Lake in northern Labrador, and Austin (1932) 

 saw young flying on July 1G, 1928 on the coast, although late 

 July is a more normal date there. In August at Indian House Lake 

 they were in loose family groups, feeding and playing in the alder 

 strand that fringes the George River, and by mid-September when 

 they leave the region, they are usually restricted to dwarf birch 

 thickets in timberline areas on the slopes. On July 31 and again on 

 August 3, 1957, at Scheffeville, Henri Ouellet noted a goodly number 

 of both adults and young in the open, "feeding very little, and 

 seemingly on the move." E. P. Wheeler's last date for Kutsertakh 

 on the Atlantic slope of Labrador is Oct. 5, 1934. 



