124 



THE AMERICAN NATURALIST 



[Vol. LI 



The Case of the Belted Kingfisher 

 It is to be observed that specialization for getting a particu- 

 lar kind of food invariably brings with it restriction of range to 

 the territory providing that kind of food. The northwestern 

 belted kingfisher (Ceryle alcyon caurina) is a good example of 

 this. In California we find this bird present at various times 

 of the year both along the seacoast and along various fish-support- 

 ing streams, from the Colorado River to the Klamath River and 

 up the mountain streams to at least as high an altitude as Yosem- 

 ite Valley. The kingfisher is seen during migration in many 

 places away from streams, but it tarries at such times only where 

 its natural diet can be procured, as, on occasion, at fish ponds in 

 city parks. There is a unique instance of a kingfisher observed 

 on the desert catching lizards, but exceptional occurrences of 

 this kind are of course not to be given consideration in making 

 generalizations. 



It is observable further in regard to this species of kingfisher, 

 that it must have earth banks in which to excavate its breeding 

 tunnels. Lack of these along any stream, otherwise favorable, 

 prevents the bird from staying there through the season of re- 

 production. Furthermore, there is also obvious temperature re- 

 striction ; for, given a fish-producing stream, with banks appar- 

 ently well suited for excavation of nesting places, such as is the 

 Colorado River and its distributaries, and the summer tempera- 

 ture must be at least below that of southern California south of 

 the 35th parallel. That all such streams are well supplied with 

 kingfishers in winter, and are forsaken only during the hot sum- 

 mer, seems to show that a relatively cool temperature is for them 

 in some way or another essential to successful reproduction. 



We find, then, in the case of the belted kingfisher, that the fac- 

 tors of a requisite kind of food, and a requisite kind of nesting 

 place, both having to do with the structural powers and limita- 

 tions of the bird, together with the factor of the temperature of 

 the summer season, are those that account for the distribution 

 of the species within the state of California, as we find it. 



The Case of the Meadowlark 



The western meadowdark (Sturnella neglecta) is a bird of 

 relatively omnivorous diet. Note that I say relatively, for the 

 word omnivorous unmodified would apply only to such an ani- 



