1890.] Brewster oh Robin Roosts. ^6^ 



Cambridge, there is — or was in 1SS6 — a roost in birch and maple 

 woods on the banks of the Assabet River at Concord, remarkable 

 for the small number of birds — only about fifty — which assembled 

 there nightly, and a large colony at Melrose Highlands, discov- 

 ered by Mr. Torrey in the summer of 1SS9. There are doubtless 

 still others of which I have no knowledge scattered through this 

 region. 



Thus far I have spoken in only general terms of the number of 

 Robins which sometimes congregate at these summer roosts. Sev- 

 eral of my friends have attempted to count them, taking the best 

 available stations outside the roosts and noting each bird as it flew 

 in. This appears to be the only practicable method, for nothing 

 whatever can be done inside the wood ; but under the most favor- 

 able conditions it falls far short of absolute accuracy, especially at 

 the larger roosts into which, at the height of the flight, the birds 

 pour in such swarms that eye, brain and pencil are alike unequal 

 to the task of noting all that pass in open view, to say nothing of 

 the many that steal by close to the ground, under cover of bushes 

 or the gathering darkness. Nevertheless any count carefully and 

 conscientiously made, has this obvious value — it is sure to be well 

 within the truth. 



At the Beaver Brook roost Mr. Faxon with the help of an assis- 

 tant counted 1SS3 incoming birds on the evening of Sept. 2, 1SS9. 

 His next largest count, made without help Aug. 28 of the same 

 year, was 11S0. At Melrose Highlands Mr. Torrey, unaided, 

 counted 1267, July 29, 18S9, and 15 17 on the same date in 1890. 

 On July 2S, 1S90, with an assistant, he counted 2314. In both 

 cases the assistant stood near his principal and was employed 

 merely to divide the labor, no more ground being covered than on 

 the other occasions. 



On their face these figures indicate of course that the roost at 

 Melrose Highlands is larger than that on Beaver Brook. But Mr. 

 Torrey tells me that practically all his birds approach the woods 

 from the same side, whereas, as Mr. Faxon and I have both ob- 

 served, the Beaver Brook birds enter their roost in about equal 

 numbers from every side. Before the two colonies can be fairly 

 compared, therefore, it is evident that Mr. Faxon's count must be 

 multiplied by four at least, if not, as he himself believes, by five. 

 Any additions which should be made for birds that passed the 

 observers uncounted would probably be so nearly equal in both 



