Page:Condor21(2).djvu/21

 Ma., 1919 LOSSES SUFFERED BY BREEDING BIRDS 67 seasonal conditions elsewhere) they cannot be totally disregarded in the gen- eral summing up of results. A great many instances of loss through ignorance of man might be named. In this section the Valley Quail has a penchant' for placing its nest in the orange groves. Many nests are destroyed in such places when the orchard is cultivated. Loss through sterility is probably less than from other causes. Yet every active collector can remember scores of instances in this category. A striking example is that of a pair of California Woodpeckers which nest every year in a large live sycamore near my house. The first set taken from them contained four eggs, three of which were infertile. Another set, the following year, con- tained one fertile and two infertile eggs. The next year the nest had one young bird and three infertile eggs, while sets numbers four and five, in succeeding years, each had five eggs, four in each set being infertile. Th. is is' an extreme case, but I believe that the Picariae are more subject to this condition than nost avian groups. I have only touched upon a few high lights of this interesting subject, but the student of conservation will find food for thought and agree with me that, where Nature takes such toll, it requires but little to tip the balance in the wrong direction. A list of instances where losses were suffered by breeding birds in southern California as taken from my notes for the year 1918, follows. Colymbus ni9ricollis californicus. American Eared Grebe. A common loss is oc- casioned by eggs being kicked from the nest as the bird gets on or off. In eery breed- ' ing colony I have examined, numbers of eggs could be found at the bottom of the pond about the nests. $terna antillarurn. Least Tern. Cats are the greatest causes of loss with this species, I believe. I have found numerous deserted eggs and remains of birds among the colonies, and W. Lee Chambers mentioned a case where cats were practically extermi- nating an entire colony near Venice, California. /Egialitis nivosa. Snowy Plover. As with the Least Tern, cats do much damage. Lophortyx californica vallicola. Valley Quail. Two nests were destroyed by young children, a number of others in orange groves, and one by a house cat which ate the female bird. Lophortyx garnbeli. Gambel Quail. Wright M. Pierce and myself found a nest of this species in the Coachella Desert, from which the parent had been eaten by some ani- mal, judging from a number of broken eggs and other evidence present. Melanerpes forrnicivorus bairdi. California Woodpecker. Sterility common. Colapies caret collaris. Red-shafted Flicker. Sterility common. One set of six contained three addled eggs. Chordeiles virginianus hesperis.- Pacific Nighthawk. Sterility. One set of two had one egg addled. Archilochus alexandrl. Black-chinned Hummingbird. Nine nests were destroyed by jays after one egg in each case had been laid, two were destroyed by man, and ten by a heavy storm. Calypte costae. Costa Hmnmingbird. Thirteen nests were all destroyed, presum- ably, by jays, as several jays were caught in th act. A majority of these nests were sit- uated In cactus and were rather conspicuous. Six nests were ruined by a heavy rain- storm. Calypte anna. Anna Hummingbird. Four nests were destroyed by jays. Contopus richardsoni richardsoni. Western Wood Pewee. Ernpidonax difflcllis difficilis. Western Flycatcher. Several nests were destroyed by storm. I do not believe the rains did much damage, but undoubtedly they delayed the breeding season several weeks. Xanthocephalus xanthocephalus. Yellow-headed Blackbird. I found a nest of this species at Baldwin's Lake, Big Bear Valley, which was occupied by a large Garter Snake.