394 MEMOIRS OF THE NUTTALL ORNITHOLOGICAL CLUB. 



lilacs, which were then fairly well covered with young foliage. During the whole 

 of May the roost was frequented nightly by fifty or more birds, all apparently old 

 males. By the middle of June these were joined by the first broods of young, 

 and a month or so later by the old females with their second broods. Thus the 

 number of Robins steadily increased until early in August, when it probably 

 reached its ma.ximum and when we sometimes noted upwards of seven hundred 

 birds in the course of a single evening. The frecjuent presence of members of 

 my family on the back piazza (which is only a few yards from the lilacs) when 

 the evening flight was coming in, gave the Robins some concern at first, but they 

 soon became perfectly reconciled to it. They occupied the roost for the third 

 time in 1904, and for the fourth time in 1905, but during both years they were 

 somewhat less numerous than in 1903. 



As the piazza faces a little opening about which the lilacs are grouped on 

 the remaining three sides, it commands an unobstructed view of the roost and 

 affords rare facilities for watching the birds at close range. I have been inter- 

 ested to learn that a sound resembling the pattering of hail, which is heard when 

 they are fluttering among the foliage and which I had formerly supposed to be 

 caused by their wings striking the leaves, is really made, at least in part, by 

 their bills. When two or more of them are contesting for possession of the 

 same perch they first threaten one another with wide-opened beaks and then 

 bring their mandibles rapidly and forcibly together, thereby producing the sound 

 above described. After they have quite ceased their calling and fluttering one 

 may pass — even in bright moonlight — within a yard or two of branches where 

 they are roosting by dozens without disturbing them. They invariably begin to 

 lea\'e the roost at daybreak, usually departing singly or in small parties, and scat- 

 tering in every direction. When the exodus is performed in this manner, it 

 often continues until sunrise. On several occasions, however, I have seen 

 practically the entire body of birds leave simultaneously in the morning twilight, 

 in one immense flock, with a prodigious whirring of wings. The evening flights 

 vary similarly in character but to a less degree. Ordinarily the incoming birds 

 are arriving more or less continuously for half an hour or more, but occasionally 

 the majority of them will appear in the course of ten or twelve minutes, this 

 usually happening when the weather is stormy. 



The original selection of our garden for a roosting place by the Robins was 

 due, no doubt, to the fact that it is completely surrounded by a cat-proof fence. 

 Although the birds are certainly not molested by cats, something — perhaps 

 a Screech Owl — has alarmed them greatly on several recent occasions, when, 

 in the middle of the night, they have been heard to leave the roost with loud, 

 excited calling. On the whole, however, they evidently find the lilac copse a 

 safe and congenial sanctuary despite the fact that it lies so near the heart of a 

 large city. 



