BIRDS OF THE CAMBRIDGE REGION. 5 



laying may be looked for in the Cambridge Region. These dates do not include, 

 in all cases, the very earliest dates at which eggs have been found, nor has any 

 attention been given to dates which may be assumed to relate to sets not of the 

 first laying. In compiling the nesting dates I have frequently consulted notes 

 relating to extralimital localities, but little or no consideration has been given to 

 records which concern localities lying to the southward of Cambridge or distant 

 from it more than twenty or thirty miles in any other direction. 



In the use of scientific names I have followed rigidly those adopted by the 

 American Ornithologists' Union's Committee on Nomenclature, up to and includ- 

 ing the Thirteenth Supplement to the A. O. U. Check-List, which was published 

 in the Auk for July, 1904. In one case, however, that of the Arctic Horned 

 Owl, I have used a name not yet passed upon by the Committee. While I do 

 not think that a faunal paper, such as the present one, is an appropriate place for 

 discussions of technical points of nomenclature, yet in the single instance above 

 noted the circumstances seem to warrant the remarks which I have made on this 

 intricate and peculiar case. All the A. O. U. English names also are used, and 

 to them I have frequently added names in current local use (past or present) in 

 or about Cambridge. 



I have included in their appropriate systematic order (i) birds which are 

 known to have inhabited or visited the Cambridge Region in former times, but 

 which no longer do so ; (2) birds which have repeatedly occurred very near but 

 not actually within its boundaries ; (3) birds which have been introduced by the 

 direct agency of man ; (4) birds which have been reported only on what appears 

 to be insufficient or inconclusive evidence. In all these cases the fact that the 

 particular species or subspecies is not considered entitled to a present place in 

 the natural fauna of the Region, is made sufficiently clear by omitting the usual 

 number before the name, as well as by enclosing the name and the accompany- 

 ing text in brackets. 



My early training and experience have led me to believe that — with certain 

 exceptions about to be specified - — the occurrence of birds in localities or regions 

 lying outside their known habitats should not be regarded as definitely estab- 

 lished until actual specimens have been taken and afterwards determined by 

 competent authorities. No doubt it is becoming more and more difficult to live 

 up to this rule because of the ever increasing and, in the main, wholesome, 

 popular feeling against the killing of birds for whatever purpose. Nevertheless 

 I cannot admit that mere observation of living birds met with in localities where 

 they do not properly belong, or where they have not been ascertained to occa- 

 sionally appear, should often be considered as establishing anything more than 

 possible or probable instances of occurrence — according to the weight and char- 

 acter of the evidence. 



