To the above comprehensive list there is little to be added, although wild cranberries and the berries of the poison sumac might have been included. Myrtle warblers are doubtless instrumental in spreading the seeds of poisonous species of Rhus, which is not to their credit; they also help to disseminate the red cedar, as they digest only the outer covering of these three and the bayberries. These warblers are often seen on the beaches and sand dunes eating the seeds of the beachgrass, or in open fields feeding on grass seed and doubtless various weed seeds. They frequent the fresh holes bored by sapsuckers to drink the flowing sap and eat the insects that are attracted to it. In Florida, in winter, they drink the juice of fallen oranges in the groves and even the broken oranges on the trees.
They are somewhat expert as flycatchers, taking mosquitoes and gnats in the air. Knight (1908) writes: “During the fall months they enter the city gardens and orchards, climb over the roofs and along the gutters of houses, peering into every nook and cranny. They hover on beating wings about such crannies of the clapboards and finish where they may have spied some delicious, big fat spider, chrysalis or other delectable morsel, and such finds are speedily devoured. Now peering, now hovering, and now springing into the air after some winged insect, they stop about a building for a few hours or days, slowly but surely retreating southward.”
Behavior.—Much of the behavior of this friendly little bird has been referred to in connection with its activities about our homes and gardens and its nesting habits. Tilford Moore tells me that “these birds seem to have a tendency toward ‘creeperism,’ in that they are often seen hanging to the bark of a vertical trunk or branch, and are usually on the larger branches rather than among the smaller twigs. They often flutter a lot when hanging to the bark.” And Wendell Taber sends me this note: “On May 5, 1940, Richard Stackpole and I watched a flock in West Newbury, Mass. The birds were running about on the grass near a stream. Again, they would alight at the base of a tree and run up it several feet. I think all the birds that performed this feat were females. They were most deceptive, and we kept thinking we were seeing brown creepers until we put field glasses on them.”
William Brewster (1938) writes of the behavior of a female about her nest, 35 feet from the ground in a hemlock: “The female Yellow-rump was sitting and for some time she absolutely refused to leave her eggs. Watrous first shook the branch and then with a long stick poked and shook smartly the twigs within an inch or two of her head. At length she hopped out of the nest and stood for a moment or more on its rim looking about her. Then she fluttered down towards the ground with quivering wings and wide spread tail, moving slowly and alighting several times on a branch or cluster of twigs where she would lie prostrate for a moment beating her wings feebly and simulating the movements of a wounded or otherwise disabled bird.”
Dr. Stone (1937) describes the flight of the myrtle warbler very well:
We soon learn to identify their rather jerky flight as they rise from the bushes, and with a series of short wing flips turn now to the right, now to the left, in their zigzag progress, rising somewhat with the beats, and falling in the intervals. Sometimes a bird will go but a short distance, flitting from bush to bush, while others will climb higher and higher in the air, drifting in their jerky way across the sky like wind-blown leaves. * * *
As soon as a Myrtlebird alights on a bush there is a short, sharp flip of tin tail, not a seesaw action, but one involving the body as well, and as it comes to rest the head is drawn in and the plumage ruffled up making the outline more nearly globular, while the wings are dropped slightly so that their tips are a little below the base of the tail.
Francis H. Allen has sent me the following notes on the behavior of this species: “Aug. 27, 1915, Mt. Sunapee, N. H. On the summit of the mountain an immature myrtle warbler, very tame, flitted and hopped about on the ground, over moss and rocks, and in bushes and trees, feeding industriously on small insects. It seemed to pay no attention to my companion and me, and at one time hopped between us when we stood about 6 feet apart, and came within 2 feet of my outstretched hand as I held a crumb out towards it. I followed it about a little and found it quite fearless, except when I made a sudden movement. The bird could fly well and seemed perfectly well able to take care of itself.
“July 5, 1931, Mt. Whiteface, N. H. One or more were seen flying up fifty or a hundred feet above the tops of the low spruces and darting about up there after insects—doubtless the black flies which were abundant on the summit.