392 BULLETIN 17 9, UNITED STATES NATIONAL MUSEUM 



peared to be minute insects almost too small to be seen ; also of their 

 catching insects on the wing under the lea of a hillside. 



John J. Elliott (1939) during his study of a company of tree 

 swallows that wintered on Long Island, N. Y., collected their ex- 

 crement. He reports that "analysis of the fecal material by the 

 U. S. Biological Survey showed that crustacean material {Orchestia 

 platensis) formed the bulk of the food, along with water-boatmen, 

 spiders, bulrush, sedge, bayberry and smartweed seeds, and frag- 

 ments of rose thorns." 



George Nelson had an interesting experience with tree swallows in 

 Florida on November 24, 1938. He was crossing a hammock about 

 10 o'clock in the morning when he noticed, rising straight up from 

 the path in fi'ont of him, a thin pillar of what he took to be a wisp 

 of smoke no bigger round than a pencil. Following the column 

 upward with his eyes, he noted that, at a height of 10 to 12 feet 

 above ground, it swayed in the light breeze, broke up, and became 

 dispersed. When he stepped up close to the wisp of smoke, he saw 

 that it was not smoke at all, but a closely packed column of winged 

 red ants issuing in countless numbers from a board walk. They 

 mounted straight toward the zenith and then spread out like a 

 funnel and scattered over the space of an acre. Soon a tree swallow 

 flew past, up in the air where the insects had separated. It turned 

 back and flew over and over again through the swarm, snapping 

 up the insects. Before long more tree swallows appeared, until 

 within 15 minutes many hundreds had collected, all swooping back and 

 forth at great speed where the insects were flying. In less than 

 half an hour the insects had disappeared and not a swallow was in 

 sight. 



Mr. Nelson was surprised to see so many tree swallows together, 

 for at this season of the year the bird is not abundant in Sebastian 

 where the incident occurred. They had assembled, apparently, in 

 the way sea birds collect at points in the ocean where food is plenti- 

 ful, bird after bird being drawn to the spot by seeing from a distance 

 others feeding. 



On another occasion, when Mayflies were rising from an extensive 

 marsh, Mr. Nelson saw tree swallows gathered in a great cloud, so 

 thick and dense that in the bright sunlight the flock cast a dark 

 shadow on the marsh. 



Behavior. — As we watch swallows in flight we notice that they do 

 not all fly in the same fashion, and after long watching we become 

 able to tell them apart when they are far away, or at least to suspect 

 which is which. For example, perhaps the most distinctive in its 

 manner of flying is the barn swallow. It is characteristic of this 

 species to drive along through the air, seemingly with a strong push. 



