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. Farther down stream in a rough portion of the pasture, brambly but beautiful with barberries, is the chosen habitat of the yellow warblers of my neighborhood. Always they build in the barberry bushes here, nor have I ever found them anywhere else or in other bushes. It is not difficult to find them when the pasture is in the full leafage of late May, for you have but to go from one barberry bush to another till you have succeeded. But the yellow warbler is a shy bird, and I have known them to desert nest and eggs when these were too often visited. It is much better to hunt them now, when you have but to stand on a little hillock and count, then pluck the nest that you prefer and take it home with you without abraiding anybody’s feelings. The yellow warbler mother bird seems to have a great love for the tender buff wool of the young shoots of the cinnamon fern, which are just about ready to shed these delicate overcoats when nesting begins with the yellow warblers. In fact, her color scheme is perfect.