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A BIOLOGICAL JOURNAL 



Vol. I. DECEMBER, 1890. No. 10. 



AN ORNITHOLOGICAL RETROSPECT. 



BY WALTER E. BRYANT. 



The irregular periodical abundance or scarcity of certain kinds 

 of birds in localities where they were considered moderately com- 

 mon and the permanent total absence of some species in places 

 where they had formerly been numerous, has frequently been 

 brought to my notice in recent years. Marked changes of a per- 

 manent nature have occurred during my observations of more than 

 twenty years in the region of the Bay Counties. 



Examples of land birds of periodical temporary abundance may 

 be cited in the cases of Lewis's woodpecker, pine siskin, cedar 

 waxwing, western golden-crowned kinglet, western robin, varied 

 thrush and mountain bluebird. The varying abundance of water 

 birds, particularly the different species of ducks, is annually dis- 

 cussed by sportsmen. 



Of species which have decreased or become entirely wanting in 

 localities during the last^ one or two decades, or have undergone 

 great change in respect to their fear of man, the following are good 

 examples : California vulture, yellow-billed magpie, American raven, 

 American crow, cliff swallow, California partridge and white and 

 gray geese. 



The causes for all of the changes are not readily traceable. Peri- 

 odical increase and diminution of the seven species first noted above 

 are largely due to causes which are known to act in governing the 

 migration of birds — meteorological conditions and food supply, the 

 latter I am convinced being but a small factor. These birds, with 

 the exception of Lewis's woodpecker, being well kno\vn migrants, 

 eren the woodpecker and sometimes the Jay are irregularly mi-' 

 gratory. Peculiar seasonal conditions were always found correla- 

 tive wath the increased abundance of any of these birds. Their 

 absence or rarity in a given locality has usually been taken as the 



