Snakes as Nest Robbers
Snakes as Nest Robbers
During the spring and summer of 1916, while collecting near Colton, California, we had the unpleasant experience of returning to many nests, which had a few days before contained incomplete sets or been ready for eggs, only to find them empty. Suspicion was not directed towards the birds themselves because of the great variety of species in which this occurred, nor could it be directed towards jays, for none were present within several miles. Cats, weasels, skunks and foxes were to be eliminated, for in no case was a nest found to be in the least ruffled or disturbed, the eggs having been extracted as deftly as we could have done ourselves, perhaps more so. Lack of any snakes in evidence and the large numbers of nests thus violated prevented a charge being made at the time against them. It almost seemed as if some other collector was dogging our steps and getting our booty.
One day, however, as a nest of a Least Vireo, which was due to have a full set, was approached, a great twittering, crying and chattering from the parent birds was heard. As the nest came into view the cause of the disturbance also appeared. It consisted of a nice slim brown and white snake nicely poised above the nest which was now quite empty. It can not be said with certainty, but it appeared that some of the egg was still upon his chin!
On the same day attention was called to a nest of the Black-chinned Sparrow by the cries of the bird, and examination disclosed a thin striped snake with his head actually inside the cup of the nest. The nest was empty and the snake was evidently looking for more.
Another instance which came to our notice, but was not observed by us, showed the collecting proclivities of the snake. In this case a nest of the Pacific Black-headed Grosbeak, which was placed seven feet from the ground in a small sycamore tree, was robbed by a gopher snake. The robbery was witnessed by a boy and reported to us. The snakes concerned in these three instances were of different species: A Milk or King Snake (Lampropeltis boylii) got the vireo eggs; a Garter Snake (Thamnophis hammondz) got the sparrow eggs; a Gopher Snake (Pituophis catenifer) got the grosbeak eggs.
From the large number of robbed nests which came to our notice, it would appear that snakes, probably nearly all varieties present, depend in part during the nesting season on eggs and possibly small young for food. Nearly all the nests so robbed were placed in low bushes and were easily reached by snakes. The fact that a bird will raise a hue and cry as a snake, itself unaware, approaches the nest, probably leads the snake to look for the cause of the anxiety on the part of the bird, and the nest is found. It seems to me improbable that a snake can find a nest without being directed by the bird.
Now while a snake has a perfectly good right to hunt his prey, it seems too bad that they cut into our field. At the same time it does not seem justifiable to kill at sight each and every snake; much better take off the hat to him and then chase him well into the next county where he will do the most good.
J. R. Pemberton, H. W. Carriger
Colton, California
