The catbird’s will surely stand until next fall, and remnants of it may be sometimes seen in the bush the year after that. For the catbird’s material is of more rugged quality. His foundation is often of pliant twigs or tough bark of the wild grapevine, though the nest I have before me as I write--the one which I could not see last summer when I passed it at the foot of the little island--has strong, coarse grasses loosely interwoven for its foundation. Then, within this loose, rough cup is a layer of tough oak leaves, the dry ones of the year before, wind-proofing the bottom of the structure. Then comes a layer of fine black roots, I think those of alder, taken where the stream had washed them bare. Then more oak leaves, and finally an inner lining of finer black roots from the same source as those already used.
The whole is firm, sanitary, wind-proof, but not air-proof, and sufficiently cup-shaped to hold the young securely, though not so deep as that of the blackbird. One kick would smash a blackbird’s nest to a handful of straw. You might kick a catbird’s all about the meadow, and I am quite sure the inner structure would remain interwoven.
I think the reason for the difference in the two is this. Though both often build over water and in similar situations, the blackbird has but one brood a season, and even a frail nest will do for this. The
[Illustration: A field mouse had appropriated this nest for an autumn storehouse]
catbird hardly has his first brood off the nest before preparations are in hand for a second; and the nest which can stand two broods of riotous youngsters in succession, even if fixed up a bit, must needs be of fairly firm texture.
The strength of the catbird’s nest often serves another purpose, though I doubt if this is taken into the calculations when it is planned and built. I found one of the half-dozen which line the brook conspicuously, now that they may be seen at all, half full of wild cherry stones. Evidently a field mouse had appropriated this nest for an autumn storehouse, perhaps planning, before the weather got too cold, to roof it over with a dome of soft grasses, this work of the field mouse being not so very different from that of the red squirrel, only on a smaller scale.