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Sept., 1914 SURVEY OF BREEDING GROUNDS OF DUCKS 237 pointed to find that it had been destroyed. Let me cite several instances. We marked a Cinnamon Teal's nest containing-five eggs and a Gadwall's nest containing nine eggs. On returning we found both of them raided and every egg destroyed. A Pintail's nest found one day, when examined the next morn- ing was found to have been raided and all but four eggs destroyed (see fig. 70). On one occasion we found a Cinnamon Teal incubating three eggs, while aro?nd the nest there were evidences that several other eggs had been de- stroyed. On returning to the nest later we found that two other eggs had been removed and the bird had deserted her nest. A Fulvous Tree-duck's nest con- raining twelve eggs and well concealed on a weed-covered island was raided during our stay and every egg broken. Our attempts to find out the particular species of animal doing the work proved unavailing. In most instances nests were placed in a growth of grass or sedge where no tracks were discernible. In other cases the soft mud at the bottom of the shallow water did not permit tracks to remain long in evidence. Raccoons were extremely common, and in some places near clumps of rules paths were found where their foot prints were plentiful. The fact that in some cases the animal had to wade through water to reach the nest which we found destroyed, also lends support to the theory that coons were largely responsible for the depredations. A number of weasels were seen during our stay, and coyotes were said to be common. It is possible that these two predaceous ani- mals also took part in the destruction of nests. Irrigation as praticed at Los Ba5os is also responsible for the destruction of many nests. Mr. Paul J. Fair, who has worked in this vicinity for some time, told me that he found many inundated nests. In some places the water was clear enough for him to see nests and eggs completely submerged a foot below the surface of the water. Dr. Frank M. Chapman, when visiting this locality in the summer of 1903, found similar conditions. He states: "Evi- dently the abnormal and sudden rise of the water, as well as the equally un- usual fall, prevents many birds from rearing young. I found numbers of flooded nests in May, which had been built when the water was still rising, while disappearance must have been even more disastrous." Water is contin- ually rising or lowering. The rising of the water floods the nests and the low- ering allows the approach of predaceous animals to the nesting sites. Still another factor is found in the large herds of cattle which are pastured here. We found two nests which had been trampled by cattle, and Mr. Fair tells me that he also found several nests which had been destroyed in like man- ner. A rather remarkable state 'of affairs therefore exists in this locality. The nesting grounds were made available by the formation of pasture ]and out of originally arid plains, and yet the same factor, irrigation, instrumental in cre- ating these excellent grounds, is responsible for the destruction of many nests. The reclamation, even of swamp land, does not always entirely destroy the nesting grounds of ducks. A letter from Mr. Win. N. Dirks dated May 18, 1914, records the discovery of two nests of Mallard, one of Pintail and five of Cinnamon Teal. These were uncovered while the grain was being mowed on a ranch at Alvarado, Alameda County, California. On Lower Klamath Lake we were told by a rancher that he had found several Mallard's nests in his rye field earlier in the season. Other ranchers told us that Mallards and Teal com- monly nested in grain and alfalfa fields. It is certain, therefore, that some of our ducks adapt themselves to. changed conditions.