Mar., 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 
eultivated. 
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. This is an extreme 
case, but I believe that the Picariae are more subject to this condition than 
most 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 nigricollis californicus. American Hared Grebe. A common loss is oc- 
casioned by eggs being kicked from the nest as the bird gets on or off. In every breed- 
ing colony I have examined, numbers of eggs could be found at the bottom of the pond 
about the nests. 
Sterna antillarum. 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. 
fEgialitis 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 gambeli. 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 formicivorus bairdi. California Woodpecker. Sterility common. 
Colaptes cafer 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 alexandri. 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 Hummingbird. Thirteen nests were all destroyed, presum- 
ably, by jays, aS several jays were caught in the 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. 
Empidonax difficilis 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. 
