December 15, 1922] 



SCIENCE 



675 



the country are as follows : B3' the clearing of 

 brushlands, for example, in San Fernando 

 Valley, Los Angeles County; by the planting 

 of trees, afforestaftion, as exemplified in the 

 groves of trees around the Greek Theater and 

 on the Berkeley hills; by the cultivation of 

 dry grasslands, as on the coastal benches of 

 San Diiego County; and by the fonnation of 

 storage reservoii-s and canals, which, irrespec- 

 tive of the lands which ithey water, bring into 

 existence aqua-tic and riparian types of vege- 

 tation conducive to an abundant bird life. 

 Some of these it will be noted, check against 

 one another, so that status quo, in part of the 

 country, tends in some measure to be main- 

 tained. 



In general, then, my contention is that there 

 has been, on the average, as a result of the 

 settlement of California, a marked increase in 

 oui- bird population. Bird life at large has ben- 

 efited — and this in spite of various adverse fea- 

 tures which also have been imposed. My mes- 

 sage should be, therefore, one of optimism to 

 the bird-lover. It is to be understood that I 

 refer to birds of all groups together ; not to any 

 particular group. There are vastly more of 

 the so-called "song birds," numerically, than 

 there are of the "game birds" and ":bdrds-of- 

 prey." The latter two groups have been seri- 

 ously depleted, unquestionably, from various 

 causes associated with man; but probably not 

 more than ten per cent, of our original bird 

 population consisted of game birds and birds- 

 of-prey combined. 



Permit me now to link up with current no- 

 tions and beliefs in regard to the status of bird 

 life some of the ideas that I have been en- 

 deavoring to express. In a large proportion 

 of eases the reduction or disappearance of a 

 cherished species of hird, locally, such 'as may 

 have been laid to other entirely different causes, 

 has really been due simply and inevitably to 

 the reduction or complete effacement of the 

 kind of habitat the bird must have for its ex- 

 istence; in other words, its eeologic niche has 

 been reduced in volume, or destroyed. No one 

 could help it; nor can any one now stay 'the 

 process, except by restituting the lost factor; 

 for example, when land is bought or otherwise 



preserved from human use and devoted to the 

 use of the birds, as in national or state bird 

 or game reserves. Of ooui'se, in certain areas, 

 such as national parks and forest reserves, the 

 environments and the birds occupying them are 

 being preserved anyway, incidental to other 

 interests. 



The tendency among sentimentalists has usu- 

 ally been to seek out a cause for the disappear- 

 ance of birds that is directly concerned with 

 their fellow men. The hunter, the boy with 

 the sling shot, the eoUe-ctor, any one of them 

 or all, loom np as the "exterminators of birds" ; 

 whereas, in truth, I believe, it is only in rare 

 cases and then only very locally, that these 

 agencies have had any effect at all. In other 

 words, if my line of reasoning has been cor- 

 rect, legal protection, with ninety per cent, of 

 our bird species, is absolutely unnecessary, 

 save as it applies, and then pix)pei'ly so, to 

 parks, the suburbs of cities, and to logically 

 constituted game and wild-life preserves, where 

 shooting for any purpose is out of order. 



Recall the geometrical ratio of repix)duc- 

 tion, and the consequent powerful potentiality 

 for recovery on the part of bird species. Let 

 me cite here the case of the easfcem foluebird as 

 reviewed by Mr. P. A. Taverner in a recent 

 number of the Canadian Field-Naturalist 

 (XXXVI, April, 1922, pp. 71-72). In the 

 winter of 1895-9'6 a cold wave swept the South 

 Atlantic states, the sole wintering ground of 

 the eastern hluebird. As a result, famine and 

 death reduced the total bluebird population 

 almost, but not quite, to the vanishing point. 

 But in five years the species had recovered 

 "from almost nothing to practical normality." 

 After reaching normal, a "saturation ' point of 

 population" for the species, it ceased to in- 

 crease; or, as I would express it, its eeologic 

 niche, of fixed amplitude, was then full. The 

 operation of the "factor of safety" not only 

 saved, but very quickly brought hack, the 

 species. 



Another catastrophe, recorded by Dr. T. S. 

 Roberts {Auk, XXIV, 1907, pp. 369-377) hap- 

 pened to a sparrow-like species, the Lapland 

 longspur, in southwestern Minnesota, the mid- 

 dle of March, 1904. It was migration time, 



