Page:BirdWatchingSelous.djvu/215

 sometimes to be the case if unmodified fish were pulled up, but not if these were in a soft, porridgey condition. Always, too, the actions of the parent bird suggested that particular process which is known as regurgitation, and which may be observed with pigeons, and also—as I have seen and recorded—with the nightjar.

Cormorants, as they sit on the nest, have a curious habit of twitching or quivering the muscles of the throat, so that the feathers dance about in a very noticeable manner, especially if that rare phenomenon, a glint of sunshine, should happen to fall upon them. Whilst doing so they usually sit quite still, sometimes with the bill closed, but more frequently, perhaps, with the mandibles separated by a finger's breadth or so. I have watched this curious kind of St Vitus's dance going on for a quarter of an hour or more, and it seems as though it might continue indefinitely for any length of time. All at once it will cease for a while, and then as suddenly break out again. It is not only the old birds that twitch the throat in this manner. The chicks do so too in just as marked a degree, and on account of the skin of their necks being naked it is, perhaps, more noticeable in their case than with the parent birds. I have observed exactly the same thing, though it was not quite so conspicuous, in the nightjar, so that I cannot help asking myself the question whether it stands in any kind of connection with the habit of bringing up food for the young from the crop or stomach—the regurgitatory process. I will not be sure, but I think that the same curious tremulo of the throatal feathers may be observed in pigeons as they sit on the