Sept., 1914 SURVEY OF BREEDING GROUNDS OF DUCKS 235 Grass, grain or alfalTa fields at a distance Mallard, Pintaft, Cinnamon Teal from water Sage or other brush in vicinity of water Mallard The same sort of preference for particular associations was noted in con- nection with the shore-birds. Killdeer almost invariably chose. the alkali flats or bare dry ground; Avocets were found to choose muddy or grassy islands or margins of ponds, whereas Stilts almost invariably chose the muddy islands or margins of ponds. In explanation of this associational distribution I need but quote from Grinnell (Univ. Calif. Publ. Zool., 12, 1914, p. 96): "... associational restric- tion appears to be governed by the following three factors, of relative import? ante in the order named. "1. Kind of food supply afforded, with regard to the inherent structural powers of each of the animals concerned to make it available. "2. Presence of safe breeding-places, adapted to the varying needs of the animals, in other words, depending upon the respective inherent powers of construction, defense and concealment in each species concerned. "3. Presence of places of temporary refuge for individuals, during day time or night time, or while foraging, when hard pressed by predatory enemies, again correlated with the respective inherent powers of defense and concealment of each species in- volved." OUR NATIVE BREEDING STOCK OF DUCKS AS COMPARED WITH THE WINTER SUPPLY OF MIGRATORY DUCKS The supply of ducks in California is derived from two seasonal categories of birds, one consisting of those which nest wholly to the north of us and come here only in the winter season, and the other, of those which nest here and either remain throughout the year within our borders or go farther south for the winter. Hunters depend at the beginning of the seaso? chiefly upon the supply of native ducks and always maintain that these are the most desirable for the table. Home bred ducks are nearly all grain feeders and so lack the fishy taste so often found among the northern bred ducks. Numbered among the more desirable resident ducks are the Mallard, Pintail, Gadwall, Redhead and Cinnamon Teal. It is only the native contingent which we are in a position to control during the breeding season. The most important time for applying methods of conserving our duck supply therefore falls during spring and sum- mer. It is a well-known fact that so long as game birds are unmolested on their breeding grounds they are best able to withstand a considerable toll each year. It thus becomes extremely desirable that California direct especial attention to the breeding grounds of the ducks which are strictly her own, and over which she exercises control at all seasons. If the native stock could be well conserved there would always be a supply which could be depended upon no matter what became of the winter birds. Our summer birds, too, are those likely to be seen and studied by the summer vacationist and which therefore give most pleasure to those people who do not hunt. It is pre-eminently the duty of the State to conserve our native ducks, first, because they are highly desirable as food, second, because they are alto- gether our own and under our control, and third, because our native ducks are the ones available during the most favorable season for esthetic enjoyment by the people of the state. SUCCESS AND FAILURE AMONG NESTING DUCKS There are many factors which contribute to the success which attends
