90 
BIRDS OF NEW MEXICO 
more near Salt Lake, Utah, was killed subsequently near Billings, Mon¬ 
tana (1926, p. 91). 
The habits of the Treganza Heron along the Rio Grande are described 
by Professor Merrill, who reports that it “stays along the Rio Grande 
in the big cottonwoods, going out in the edges of tow-heads and sand 
flats to feed when there is water in the river. In midsummer the 
river gets very low and sometimes entirely dry, so these birds go farther 
from their nesting habitat in the big trees and linger around the shal¬ 
low lakes and tule marshes. . . Solitary individuals may thus be seen 
some distance inland from the river. 
“In the more open places they are hard to approach but are less 
wary when in large trees in more inaccessible places. At Mesquite Lake 
they feed both in the open water and among the dead willow tangles 
where their color blends admirably with the blue-gray of the dead willow 
bark and their forms differ little from the willow stubs. 
“They feed on small fish and the stock of mud-cats diminishes 
rapidly in this shallow lake when summer reduces its waters to a mini¬ 
mum. Their appetites appear terribly hard to satisfy, judging by the 
time they put in fishing, for they stay on the grounds nearly all day if 
unmolested. 
“Their numbers are greater during migration, though they are never 
numerous.” And he adds, “I think some winter here as I have seen 
them in the Rio Grande in the middle of December, usually about our 
coldest season” (MS). 
On their migratory flights, when passing over large bodies of water, 
singularly enough these great long-legged waders sometimes drop down 
to rest on the surface of deep water, in one recorded instance on water 
at least two hundred feet deep (Grasett, 1926, p. 367). This would 
seem to necessitate oil glands for feather dressing, which they lack. 
The use of the powder-down patches, which they have, has long been 
in dispute, a favorite theory being that they were phosphorescent and 
of use in fishing at night. But by watching young developing birds, 
Doctor Wetmore has finally settled the question, proving that the 
greasy powder takes the place of oil from the oil glands of other birds, 
used in dressing the feathers. 
Additional Literature.—Bent, A. C., U. S. Nat. Mus., Bull. 135, 123-127, 
1926.— Carriger, H. W., and J. R. Pemberton, Condor, X, 78-81, 1908.— 
Court, E. J., Auk, XXV, 291-296, 1908.— Finley, W. L., American Birds, 
221-231, 1907.— Forbush, E. H., Birds of Massachusetts, I, 324-328, 1925.— Wet- 
more, Alexander, Condor, XXII, 168-172, 1920 (powder-down patches). 
SNOWY HERON; SNOWY EGRET,: Egretta thula thula (Molina) 
Plate 5 
Description. — Length: 20-27.2 inches, wing 8.2-10.5, bill 2.1-3.6, tarsus 3.1-4.5. 
Plumage wholly white. Adults in breeding plumage: Back of head with crest of 
