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134 'THE CONDOR' Vol. XIV dange? of exterminating the quail on these dry ridges, where there is so much prickly pear cactus, in which they take refuge; and as 10ng as the breeding season is protected no diminution in the autumn and winter quail shooting will ever be observed. I find that even on the valley. farms of Alameda County the quail breed in the willows, and flocks of from 50 to 100 maintain them- selves in many of the orchards, and have done so ever since the occupation of the region'by Americans, though, of course, Shot down 'to a mere handful each winter." In his report on the "Birds of the Death .Valley Expedition," Fisher says of the valley quail: "Throughout the San Joaquin Valley Mr. Nelson found it common about ranches, along water courses, or near springs. It was especially abundant'at some of the springs in the hills about the Temploa Mountains and Car- rizo Plain. In the week following the expiration of the closed season two men, pot-hunting for the market, were reported to have killed 8400 quail at a solitary spring in the Temploa Mountains. The men built a brush blind near the spring, which was the only water within a distance of twenty miles, and as evening approached, the quail came to it by thousands. One of Mr. Nelson's infor- mants who saw the birds at this place, stated that the ground all about the water was covered by a compact body of quails so that ?he hunters mowed them down by the score at every discharge2" This was in 1893. Last summer and in April of this year parties from the Museum of Vertebrate Zoology of the University of California visited the same general ? locality, reporting that either none or but very few were to be seen at the watering places. These quotations give a fair idea of the point of view of competent'men twenty years ago. It is needless to call attention to the fact that in the very places mentioned by these men, conditions have changed and that quail are' not nearly as numerous as they were twenty years ago. In many places in the state, nevertheless, where there is little intensive cultivation, the protection afforded them the past few years has 'allowed them to hold their own and in some places to increase. Having now pointed out the fact that quail have greatly decreased in numbers in some parts of the state and have apparently increased in numbers in other parts, let.us pass on to a discussion of the factors governing the increase and decrease of birds in general and of quail in particular. Professor S. A. Forbes was one of the first to point out the importance of studying the natural order as'a whole, and understanding the'?disturbances to which it is subject. In a paper entitled "On Some Interactions of Organisms," he says: "While the natural order is directed to the mere maintenance of the species, the necessities of man usually require much more. They require that. the plant or animal should be urged to superfluous growth. and increase, and that all the surplus, variously and widely distributed in nature, should now be appropriated to the supply of human wants. From the consequent human interferences with the established order of things numerous disturbances arise,--many of them full of danger, others fruitful of positive evil. To avoid or mitigate the evils likely to arise, and to adapt the life of his region more exactly to his purposes, man must study the natural order as a whole and must understand the disturbances to which it has been subject. Especially he must know the forces which tend to the reduction of ihese 'disturbances and those which tend to'perpetuate or ag- gravate them, in order that he may reinforce the first and divert the second." There are at least six factors that have a direct influence on the numbers of any species of animal, the importance of each varying greatly according to