EASTERN HERMIT THRUSH 157 



York. Most of my records come from those two localities. The 

 Adirondack birds average two tonesWer an octave, and the Allegany 

 Park ones nearly three tones less than an octave. The average bird, 

 from my records, has six different phrases, but some have as few as 

 three, several have nine, while one bird in Allegany Park had 14. 



"Nearly every individual has one or two phrases pitched consider- 

 ably higher than the rest, and these very high phrases sound weak 

 and of poorer quality than the others. This may be due, however, 

 not to actual poorer quality but to man's inability to perceive the 

 overtones of the very high notes. It is the overtones that cause the 

 poor or rich quality or timbre of a sound." 



Albert R. Brand (1938) writes that in his study of bird recordings 

 on film it is revealed that certain high notes are inaudible to the 

 human ear, and his field observations of certain birds including the 

 hermit thrush seem to confirm the suspicion. He states that he 

 has observed birds singing nearby through field glasses, he has seen 

 their bills open as if emitting notes, yet he heard no sound. Mr. 

 Brand (1938) reports the lowest note recorded for the hermit thrush 

 was 1,475 vibrations per second, the highest 4,375 vibrations, with 

 an approximate mean of 3,000 vibrations per second. 



Henry Oldys (1913), after describing the usual song of the hermit 

 thrush and comparing it with the human voice, analyzes an unusual 

 song in developing a theory of the independent evolution of bird song. 

 Mr. Oldys heard the unusual hermit thrush song at Pompanoosuc, Vt.., 

 in which he noted a very perceptible normal order in the basal notes 

 and their independent phrases, and that order made a harmonic pro- 

 gression such as completely satisfies the requirements of human music. 

 He concludes "that the evolution of bird music independently parallels 

 the evolution of human music and that, therefore, such evolution in 

 each case is not fortuitous, but tends inevitably toward a fixed ideal." 



At Lost River, N. H., located in the midst of the White Mountains, 

 both the hermit and olive-backed thrushes nest, and there I had an 

 unusual opportunity to compare the songs and notes of these two 

 songsters. The musical ability of the hermit is more varied than that 

 of the oliveback. Its usual song dies out without the rising inflection 

 of the latter and there is a pause after the first syllable, while in the 

 oliveback's song there is no pause and the second syllable is strong- 

 ly accented, the whole song being quickly delivered. 



The alarm notes of the two thrushes are also quite different. The 

 oliveback thrush when disturbed utters a metallic note, short and 

 sharp, often ending in a querulous call. The alarm note of the hermit 

 has a catbird quality about it, lower pitched and less metallic than 

 that of the oliveback. The hermit has a nasal note of complaint 

 uttered in two syllables, a chuck like that of the blackbird, and a 



