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The Relation of Birds to an Insect Outbreak in Northern California during the Spring and Summer of 1911

1911; Oxford University Press; Volume: 13; Issue: 6 Linguagem: Inglês

10.2307/1361966

1938-5129

Harold C. Bryant,

Plant Parasitism and Resistance

The first, which has been mentioned above in connection with that of the Canvasback, was a mere burrow in the side of the musk-rat house, without any downy lining whatever, and only a few inches above the water level. On May 31 it contained ten eggs, on June 8, eleven, two of which were Canvasback's or Redhead's; and on June 30 all but two Ruddy's and one other egg had hatched, although one duckling had died while hatching. Meanwhile on June 8, the Canvasback's nest was found on the opposite side of the musk-rat house and about four feet from it; and a new Ruddy's nest containing three fresh eggs was found on top of the house, and about midway between the other two nests and somewhat higher up. This was a mere unlined depression in the litter composing the house, entirely without concealment of any kind, and the great snowy white eggs could be seen from a distance of many yards. On June 22 the nest contained eight eggs, and on June 30 the set had not yet hatched. The third nest, found June 15, 1907, hardly deserved the dignity of the term. It was merely a depression formed by trampling a tuft of tender marsh grass down to form a flimsy platform just at water level in a dense cat-tail swamp between two small lakes. When found it was over about two inches of water, and the under sides of the eleven fresh eggs were wet. A week later the water'in the swamp had risen slightly and the nest was deserted. This was about ten yards from the nest containing thirteen Redhead's eggs mentioned above, and three of the eleven eggs it contained were indistinguishable from eggs in the Redhead's nest. In all our visits to these three nests we did not see the birds leave a single time, although they sometimes swam about in front of us, some distance out on the lake. The apparent indifference of the brooding Redheads, Ruddys and Canvasbacks was in marked contrast to the devotion of the Teal and Pintails to their nests; and is very difficult to understand when the characteristic timidity of the last named species during the migration period is taken into consideration.