210 Saunders, An Ecological Bird Study. [April 



other of the two sloughs, or occasionally from a third slough out- 

 side the area. I rather suspected that there was a Bittern's nest 

 in the larger slough, with the four Red-wings, but I failed to find it. 



Summing up the five different associations, we have 112 pairs of 

 birds nesting on the area of 265 acres, making an average of 2.36 

 acres per pair. This however does not cover all of the birds found 

 on the area during that time. Others went there occasionally and 

 often stayed for several days. There were of course, many mi- 

 grants in spring, and some of these remained during the first half 

 of June. Other birds, evidently not migrants, that occurred more 

 or less frequently, are as follows. A male Red-eyed Vireo stayed 

 in the cottonwoods and sang for several days, late in June. He 

 was not there long enough to have had a mate and nested. A 

 Warbling Vireo that had a nest somewhere in the shade trees in 

 Choteau, occasionally visited the cottonwoods. A Cooper's Hawk 

 appeared one evening in July. I found it devouring the remains of 

 a young Brewer's Blackbird. On May 25 a pair of Bronzed 

 Grackles appeared. They were evidently mated and might have 

 nested on the area, but I had not at that time determined to make 

 an ecological study, and believing that they would jeopardize the 

 safety of other nesting birds on the area, I collected them both. 

 This is the only pair of these birds I have ever seen in this region, 

 which must be at about the western limit of their range. 



There may be some question concerning the value of such a 

 study as I have presented. The figures given represent only the 

 conditions on a small area, and more extensive studies will be neces- 

 sary to prove whether or not they will hold true if applied to a 

 larger tract. I hope to make further studies along this line, pro- 

 vided the opportunity is again presented. A census of breeding 

 birds could probably be most accurately obtained by studies of 

 associations on an acreage basis, supplemented by studies of a 

 whole region, which would give the proportion of the area of the 

 region covered by each association. The methods of work which I 

 have used will probably be of some value to others who wish to 

 make similar studies in the future, but they can undoubtedly be 

 improved upon. 



