Birds observed in KamcJiatka. 275 



to that of the environment generally. The ])henomena are 

 notj in fact, the product of a single influencing factor, but 

 of a combination of, probably highly complicated, influences, 

 and the working of any particular one of which can only be 

 positively identified when it acts with a force which greatly 

 exceeds that of all, or of the majority, of the remainder. 

 We have much evidence that dryness or moisture, absence 

 of sunshine, and dull skies, together with purely local con- 

 ditions, each have their influence on animal coloration, no 

 less than direct difl'erences in degrees of heat and cold, so 

 that I would not like to refuse to climatic influences their 

 due in the guidance of the evolution of the peculiar Kam- 

 chatkan birds until all other explanations have been found 

 wanting. 



The peculiar Kamchatkan birds are — Urogallus parvirostris 

 kamtschaticus, Astur candidissimus , Halia'etus Jiypoleucus, 

 Dryobates purus, D. immaculatus, Picoides albidior, 

 Pica camtschatica, Nucifraga kamchatkensis, Parus kamts- 

 diatkensis, and Sitta albifrons. 



Unfortunately we know very little about these peculiar 

 species. Of several of tliem even Dr. Stejneger had seen 

 no specimen. It is significant that one of those with which 

 we are most acquainted, viz. the Magpie, is not only charac- 

 terized by its whiteness, but is the largest form of Magpie 

 known to Dr. Stejneger (being larger even than the Central 

 Asiatic Pica leuconotos Brehm), so that, apart from its 

 coloration, its size reminds us of the representative northern 

 forms of some of our own common birds, such as the Redpolls, 

 Bullfinches, Wheatears, and Lapland Buntings, and seems 

 certainly indicative of severity of climate. One feature 

 seems to be common to all : they are birds in which 

 there is no conspicuous seasonal change of colour, so that 

 the plumage suitable for the colder seasons of the year must 

 be worn throughout the summer, or not at all. 



Lastly, these ten birds are nearly all sylvan forms, and 

 may be included among the more sedentary species resident 

 in Kamchatka throughout the year and unlikely to face the 

 passage of the surrounding oceans. It may be, then, that 



