and repeatedly fed at the same visit. Indeed the movements are so rapid that it is not certain that they are effective in every ease. These conditions lead to irregular muting, and to practical difficulties in regard to the sanitation of the nest, or more particularly of the nest-site. To the acts recorded above we have to add (g) incidental behavior at the nest, more or less related to care of the young, as brooding, shielding or spreading over the nestlings in heat (Figs. 1 and 2), or rain, whether sitting or erect, bristling, puffing or swelling out the throat,—possibly with air-sacs distended,—preening, gaping in hot weather, stretching and yawning, with the guarding and fighting instincts,
Fig. 7. Black-billed Cuckoo approaching Nest with Food. First stage in reaction of nestlings; wings vibrating in young which gives most vigorous response.
called into evidence as occasion may arise. Sporadic-additions are sometimes made to the nest, and I have seen the white-bellied martin return to her nest-box a feather which the wind had blown out (Fig. 13). Eagles and hawks will occasionally bring fresh sprays of hemlock or seaweed to their eyries and the great herring gull while incubating or brooding will sometimes bend over and pull fresh grass and weeds within the reach of her bill, and tuck them under her body. Most of these acts are probably instinctive in origin, but they are far from predictable.
