102 YELL W-BELLIED FL YCA TCHER. 



ground. Alder swamps which are so filled with undergrowth that it is difficult to force 

 one's way through them, are the favorite resorts of these Flycatchers. It is extremely 

 difficult to detect the presence of these little birds in such places, not only on account of 

 the luxurious vegetation, but principally because they are extremely quiet, the only note 

 which they utter during the migrations being a plaintive pea given only at intervals and, 

 so low as to be inaudible a few yards distant. I have frequently entered a swarnp in 

 which I was certain some of these Flycatchers had taken refuge and have, at first, been 

 unable to find a single specimen, but upon remaining quiet for a moment, I would hear the 

 low peas in all directions. Guided by the sound of the nearest, I would proceed cautious- 

 ly in its direction and, after a moment's search, would see the bird as he sat on some low 

 twig, occasionally launching outward for a short distance to catch a passing insect which 

 his keen eye had informed him was especially palatable. As long as I remained perfect- 

 ly still, the Flycatcher would pursue his vocations but upon my making the slightest 

 movement, he would observe me and, giving a quick, upward flirt of his tail, would flit 

 silently but with marvelous celerity among the brown stems of the alders, and skillfully 

 wending his way through the labyrinth of twigs, vines, and leaves, he would almost in- 

 stantly disappear. 



Although the Yellow-bellied Flycatchers are not sluggish birds, yet when compared 

 with the allied species, they appear somewhat inactive. This is due, however, to the fact 

 that there is but little need of them leading a bustling life. The orchards which are the 

 chosen domains of the Least Flycatchers are also the resorts of hundreds of other birds and 

 consequently the Flycatchers must keep wide-awake in order to gain a livelihood and they 

 do it, as I have endeavored to show. Traill's have a less disputed field but still there are 

 enough other avian inhabitants of the locality in which they find a home to make insects 

 tolerably scarce, so these birds cannot be idle; while as I have already described, the Aca- 

 dians usually live in localities where many species of the feathered tribe are abundant. 

 With the birds under consideration, this is quite different for they occupy spots where but 

 few others occur and where insects abound; thus they are not obliged to lead a very active 

 life and therefore their habits have become decidedly modified by the circumstances in 

 which they are placed. 



The lives which the members of this genus lead have apparently had some effect upon 

 their physical organization. Thus we find that the Least Flycatcher is not only the best 

 flier, but it also has the best development of laryngeal muscles, consequently has the most 

 variety of notes, it being understood, however, that this partial development does not al- 

 ways mean that the voice of their possessor is the most musical. Next in order follows 

 Traill's, differing but slightly from the one last described, and then comes the Acadian 

 with weaker laryngeal muscles, for the broncho-trachealis is but slightly developed and 

 consequently the twittering notes are given less frequently than by the two preceding; 

 last in the list comes the Yellow-bellied Flycatcher. The low and slowly given pea and 

 a gravely rendered ke-lick, the first as a single note and the second repeated only at long 

 intervals, are the only sounds which I ever heard them utter for they make no attempt at 

 the twittering song. I was not surprised, therefore, when, upon examining the larynx, I 



