TREE SWALLOW 395 



doubled e, so that the note suggests our word, cheery. Real alarm 

 calls out greater poAver ; the tone now rises to a squeal, almost a shrill 

 whistle. 



Francis H. Allen (1913) speaks of the tree swallow as "one of the 

 very earliest singers in the morning concert." Of the song he says: 

 "It is really a remarkable performance regarded as an exhibition of 

 endurance." He describes thus the song of a bird singing at 2.53 

 A, M. : ''He sang continuously, apparently without interruption, from 

 the time I first heard him till 3.40. The song came and went, as the 

 Swallow flew about over the pond, now nearer, now farther away, 

 now to the right, now to the left, but never stopping, — a constant 

 tsip-prrup, tsip-prnvp-'prrup^ tsip-jyTrup, tsip-'prrup-'pTru'p-'prrup^ 

 tsip-pmip-prnip, tsip-prrup-pruup-prrup-pruup^ varied only by the 

 varying number of bubbling notes following each tsip. The ending 

 of the performance seemed to come gradually." 



Winton Weydemeyer (1934a) says: "Singing is done both in flight 

 and from perches near the nests. A series of phrases, repeated over 

 and over in slightly varying order", at the rate of 125 to 140 a minute, 

 is given for several minutes or as much as an hour without pause." 



Field TYiarks. — The underparts of the tree swallow are pure white. 

 It is the only swallow that shows this character except the violet- 

 green, which may be distinguished by an opalescent coloring of the 

 back. Jonathan Dwight (1900) speaks of "a very faint incomplete 

 sooty collar on the jugulum" m the juvenal plumage of the tree 

 swallow, but this mark is lost by the time the first winter plumage 

 is acquired in October and should never be confused with the broad 

 pectoral band that the bank swallow possesses in all plumages. 



John Treadwell Nichols (1920) points out two excellent diagnostic 

 points. He says : "When one gets a good view of them, our different 

 Swallows are well marked and easy to identify. They also present 

 differences in size, flight and call-notes which one learns to recognize. 

 However, it may aid in the determination of a bird darting by at a 

 difficult angle, to call attention to the white on the Tree Swallows' 

 flanks, which encroaches on the dark upper parts in front of the tail 

 so as to be conspicuous. The Tree Swallow also has an angle in the 

 posterior outline of the wing unlike the other species, as though the 

 primary feathers projected more abruptly beyond the secondaries." 



Enemies.- — The speed and agility of the tree swallow render it 

 comparatively safe from attacks by birds of prey. Tree swallows 

 come into competition for nesting sites with other hole-nesting birds, 

 but as shown under "behavior," often hold their own. 



A nest sent to the Bureau of Entomology-, Washington, D. C, by 

 Mrs. Kenneth B. Wetherbee (1932) "contained fifty-two ProtocaJli- 

 phora splendida, var. sialia, thirty Mormoniella vitrlpennis, and one 

 hundred and sixty fleas." 



