Page:Bird-lore Vol 01.djvu/418

 igo Bird -Lore throughout the winter, and evidences of joy and conviviality in the midst of December. SUGGESTIONS FOR THE MONTHS' STUDY Food and Distribiili'on. — Observe relation between the food supply, as it is con- trolled by temperature, and the departure of the last migrants (see preceding articles). Compare the food of migratory, summer-resident birds with that of winter birds ; the former being insect- and fruit-eaters, the latter, seed- or flesh-eaters. Note variation in the food of certain birds, such as the Flicker, Bluebird and Robin, which, insec- tivorous in summer, later subsist on fruit, including winter berries, and are thus some- times found throughout the year as far north as Massachusetts. Are these birds represented by the same individuals at all seasons ? What permanent residents are resident in the strict sense of the word ? During the winter the relation between food and distribution is especially marked, a failure of the food-supply at the north occasion- ally bringing us great numbers of boreal birds. (See Fisher and Loring, Evening Grosbeaks in New York, ' Forest and Stream,' XXXIV, 1890, p. 64 ; Brewster, Evening Grosbeak in New England, Ibid., p. 44 ; Butler, ' Some Notes Concerning the Even- ing Grosbeak,' 'The Auk,' IX, 1892, p. 238; Brewster, 'A Remarkable Flight of Pine Grosbeaks,' 'The Auk,' XII, 1895, p. 245; Chapman, 'The Season's Flight of Cross- bills,' Bird-Lore, II, 1900, pp. 25, 59.) The presence of food may induce birds which generally winter further south to remain through the winter. A small flock of Doves passed the winter at Englewood, N. J., feeding exclusively, as far as was observed, on the grain in a pile of chaff from buckwheat, winnowed in the field. Myrtle Warblers are common at the same locality during the winter when there is an abundance of bayberries, but when there are no berries there are no Warblers. Observe how the daily wanderings of flocks of Juncos, Tree Sparrows, etc., are governed by food. Are these flocks composed of the same individuals ? Have they a regularly frequented roosting place ? Note the roosting habit of Crows (see Stone, Bird-Lore, I, 1899, 177). Food thus exerts so great an influence on a bird's range at this season, when the supply may be limited, that we may govern at least the local distribution of birds by supplying them with proper food. (See Torrey, in this number of Bird-Lore; Daven- port, in Lange's ' Our Native Birds ; ' Merriam, ' Birds of Village and Field ;' Bird-Lore, I, 1899, pp. 19. 55. 185.) Ecofiomk Value of IVinler Birds. — At this season, Hawks and Owls, by destroying harmful rodents. Sparrows, by eating the seeds of injurious weeds, and Creepers, Wood- peckers, Nuthatches, Chickadees and Golden Kinglets, by devouring the eggs and larvae of insects, are of inestimable benefit to man. (See Weed, ' Winter Food of the Chicka- dee, ' publications of the New Hampshire Agricultural Experiment Station, Durham, N. H.; Forbush, Mass. Crop Rep. for July, 1895, pp. 20-32; Beal, 'Food of Wood- peckers," Bull. No. 7, Biological Survey, U. S. Dept. of Agriculture;* Judd, 'Birds as Weed Destroyers,' Yearbook of Dept. of Agriculture* for i8g8, pp. 221-232; Fisher, 'Hawks and Owls in Relation to Agriculture.') Bird-Census. — The comparatively small number of birds present during the win- ter, together with the absence of foliage, except on coniferous trees, make it possible to estimate the number of individuals occupying a given area. Such estimates are not only of interest in themselves, but they are of assistance in determining the economic value of birds. (See beyond, 'A Christmas Bird Census. ')
 * For all government publications apply to the Supt. of Documents, Washington, D. C.