Petrochelidon lunifrons.
194 General Notes.
[ Auk April ]
Auk, XV, April, 1898, pp. 194-5-
Revival of the Sexual Passion in Birds in Autumn.— Under the above heading two short notes have already appeared in ‘The Auk,’ for January, 1886. The first (pp. 141, 142) is by Bradford Torrey who, on October 12, 1885, saw a pair of Bluebirds “toying with each other affectionately” and “once certainly . . . in the attitude, if not in the act, of copulation,” and he queries whether this may not account for the second period of song which many birds have. The other note (p. 286) is from Charles Keeler who noticed similar actions among some English Sparrows, which, in November and December, 1885, were even engaged in nest-building, the weather at the time being very mild.
To these observations it seems worth while to add the following account of an experience which I had at Lakeside, Coos County, New Hampshire (at the southern end of Lake Umbagog), a little more than a year ago. I quote from my journal of August 22, 1896.
At about sunrise this morning there were fully three hundred and fifty Swallows strung along on the wires of the fence in front of the hotel. I watched this flock for more than an hour (7 to 8 A.M.) and was amply repaid for the trouble. There had been a heavy rain during the night and the road was very muddy. The birds alighted about the edges of one of the larger puddles in great numbers and walked slowly about fluttering or quivering their half-opened wings like so many big butterflies. At first I supposed that they were drinking or picking up insects, but what was my astonishment to find that the Eave Swallows were filling their bills with mud, and the White-bellied and Bank Swallows gathering pieces of hay or straw. The Barn Swallows did not visit the pool in any numbers, and I did not happen to see them pick up anything. Each bird, on obtaining a satisfactory load of mud or grass, flew with it to the fence and after shifting it about in its bill for a few moments, finally dropped it and at once returned to the road for a fresh supply. From fifty to a hundred Swallows were thus constantly engaged for half-an-hour or more. Not one of them took its burden elsewhere than to the wire fence or retained it for more than two or three minutes after reaching its perch. What did it all mean? Two facts which remain to be recorded will, perhaps, explain.
The first is that, while the birds were clustered about the mud-puddle, scarce a minute passed when one or two pairs were not engaged in copulation. Perhaps I should say in attempted, rather than actual, copulation, for, as nearly as I could see, the sexual commerce was in no instance fully and successfully accomplished. The females (or at least the birds that acted that part) submitted willingly enough to, and in some instances, as I thought, actually solicited, the attentions of the males; the latter, however, displayed but mild sexual ardor and were very clumsy in their attempts at indulging it. Once I saw an Eave Swallow and a White-bellied Swallow in sexual contact.
The second fact apparently supplies the key to the whole mystery. It is simply that every one of the Swallows which visited the mud-puddle and engaged in collecting mud and straw or in attempted copulation, was a young bird! Of this I made sure by the most careful scrutiny with a glass at a distance of only 15 or 20 feet. There were a few old birds in the flock, but they remained constantly on the fence.
It seems evident, therefore, that the remarkable behavior of the birds which alighted in the road was simply an expression of premature development, in the young, of the instincts and passions of nest-building and procreation. It is, however, the only instance of this kind that has ever come under my observation.— WILLIAM BREWSTER, Cambridge, Mass.
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