Observations Upon the Night-roosting of an Anna Hummingbird

I was watching the quail going to roost at sunset on October 26 in a small live oak about tifteen feet from the west window of the living room of my house in Piedmont, California. An Anna Hummingbird (Calypte anna) darted into the scene and alighted upon a thin, dead twig of the adjoining tree, not more than five or six feet from the noisy quail, about eight feet from my place at the window, slightly lower than the floor of the room and perhaps eight or nine feet above the ground. It seemed probable that this was the hummingbird’s night roost; and, from time to time, until about ten o’clock that night, a flashlight was directed at the point and the bummer was seen each time, placidly occupying the roost, facing the window and apparently undisturbed by the beam thrown upon it.

The perching twig was in a very exposed location on the end of a drooping branch, the canopy of the tree itself being but thinly disposed. Except for the presence of the house to the east, the bird was exposed to all the winds that blow. There was no protection from ram and predators and it could be plainly seen from all directions. On the whole, it did not look like a good place for a hummingbird to roost. But the next night the bird was again on exactly the same twig and was observed at intervals up to eleven o’clock that night.

The bird was elsewhere the next four nights, but back again on October 31. November 1 was somewhat stormy and the roost was unoccupied; but from the 2nd to the 15th, inclusive, there were only two nights on which the hummer was not seen roosting upon the same twig. Since then the twig has not been used as a night roost, although Anna Hummingbirds are buzzing about the garden as usual during the day.

From this limited series of observations on but one individual, one is not, naturally, warranted in attempting generalizations. Nevertheless, it is at least clear that we have here an example of one solitary-roosting bird that returned repeatedly to the same roosting place, and it seems probable that its night-roosting habit follows a pattern similar to its day-perching behavior, but with song, preening and watchfulness omitted. There is at least one .resident Anna Hummingbird at this place (perhaps the same bird) that usually, when at rest in the day time, selects one of about seven known preferred locations. All of these places are within an area which would be circumscribed by a circle of about fifty feet diameter. For several days in succession one of these places will be occupied almost to the complete exclusion of all others; then a shift will be made, and so forth indefinitely. This action has extended over a period of several years and, it is thought, involves the same individual.

On three occasions a watch was kept on the night roost to determine the time of arrival of the bird with reference to sunset, and on each occasion the sun’s disk was either bisected by the western horizon formed by the hill-tops of San Francisco, or else it had disappeared in the same instant that the bird alighted.

The procedure was simple in the extreme: First, a bare ‘twig; then a whir; then a lump about the size of a small walnut miraculously appeared on the twig where nothing had been before. The bird invariably faced the window with its back to the sunset point; there was nothing unusual in its posture and while it may have put its head “under its wing”, it was not seen in that attitude. A caged bird of the same species, nursed back to normal and just released by a friend who received it from a lady who found it incapable of flight in her driveway, was under observation for several weeks and was not seen to place any portion of its head beneath its feathers.

Ernest I. Dyer

Piedmont, California, December 4, 1935