2IO Correspondence. [April 



26. Falco femoralis. 



27. Ectopistes migratoria. Not found by me on western slope, except in 



Montana. 



28. Melopelia leucoptera. 



29. Meleagris mexicana. 



30. Callipepla squamata. 



Total 66. 

 Those from Lower California he supposed must soon be found north of 

 the boundary, but so far but few have been obtained, chi fly in Arizona. 

 As to the rest I ought not to be quoted for their occurence either in Cali- 

 fornia or anywhere on the Pacific slope, as my part of the work relates 

 only to California birds. — J. G. Cooper, M. D., Hay-wards^ Cala. 



CORRESPONDENCE. 



f ( \>) respondents are requested to write briefly and to the point. No attention will 

 be paid to anonymous coni7nunications^\ 



Recording the Numbers of Birds Observed. 

 To the Editors of the Auk : — 



Dear Sirs: — In an interesting article in ' The Auk ' a year ago Mr, 

 Witmer Stone speaks of the difficulty of estimating the number of birds 

 in a given locality, and declares it "wellnigh impossible." Although, this 

 difficulty is, perhaps, not so great as it seems, yet it has been so gener- 

 ally recognized that almost all field observers seem to have accepted the 

 case as hopeless, and to have contented themselves with entering a bird 

 in their note-books, as well as in published lists, as 'abundant,' 'rare,' 

 or 'rather common,' words of such pleasing indefiniteness that they sel- 

 dom mean the same thing to two different observers, or to the same per- 

 son in regard to different species. The result is that we have but the 

 vaguest idea of the relative abundance of different birds or of the fluctu- 

 ations of any one species in different years or from day to day through 

 its period of migration. 



To take a complete census — except perhaps during the breeding season 

 — may be out of the question, but there is no reason why an observer 

 should not make his work exact as far as his opportunities and abilities 

 permit, — i.e., why he should not keep a record of the exact number of 

 birds of each species met with each day. This of course would not re- 

 present the actual number present in any locality, for varying circum- 

 stances of length of time spent in the field, extent and nature of the 

 country covered during the day, weather, etc., would considerably modify 

 the results, but, by entering all these facts in the day's journal, and giv- 

 ing them due consideration in making subsequent comparisons of the 

 figures obtained, results can be reached that, if not exact, are at least an 

 approach toward it, and of vastly more value than the record of a vague 



