134 BULLETIN 195, UNITED STATES NATIONAL MUSEUM 



with the territory song. Likewise, the song has none of the spon- 

 taneity and vigor of the spring song ; rather it is a low rambling warble. 

 They are abnormal songs resembling those that are sometimes heard 

 early in spring. Likewise there comes at this time a correlated change 

 in the behavior of the birds. They no longer cling to the vicinity of 

 human habitations and are more apt to be found inhabiting the rocks 

 and shrubs of wild and unfrequented localities. 



Albert K. Brand (1938) has made recordings of numerous bird 

 songs on film, a medium from which sounds can be studied objectively. 

 Such a film reveals a picture of the number of vibrations per second 

 that determines the pitch of sound. He has found that the average 

 pitch of passerine bird songs is 4,280 vibrations, or a quarter of a note 

 higher than C7, the highest note on the piano keyboard. The approxi- 

 mate mean of the notes of the house wren is 4,100. The highest note in 

 its song reaches 7,125, while the lowest is about 2,050 vibrations per 

 second. 



In the table below are Brand's determinations of the pitch of the song 

 of the house wren placed alongside those of the crow, which has a low- 

 pitched voice, and those of the black-polled warbler, a bird with an 

 extremely high voice. This table will serve to facilitate a comparison 

 in the pitch of these three very different songs. 



Black-polled 

 House Wren Crow Warbler 



Approximate mean 4, 100 1, 500 8, 900 



Highest note 7,125 1,650 10,225 



Lowest note 2,050 1,450 8,050 



EneTTiies. — As is true with many birds, the house wren is host to a 

 number of external parasites. Peters ( 1936 ) lists five species as having 

 been found on the house wren : Two lice, Menopon sp. and Philopterus 

 subfavescens (Goef .) , and three species of mites, Dermanyssus galUnae 

 (Deeger), Liponyssus sylviarum (C. & F.), and Tromhicula lohartoni 

 Ewing. Wliile the presence of lice and mites is not usually fatal to the 

 birds, heavy infestations are very annoying and may prove harmful 

 especially to the nestlings, which have no means of ridding themselves 

 of the pests. 



Baldwin (1922) cites a specific example in which there was a lone 

 house wren in a nest that received all the food and attentions of the 

 adult birds. This nestling, instead of growing rapidly in size and 

 weight, as might be expected, was far below normal, greatly under- 

 nourished, and a miserable skinny-looking specimen. This condition 

 prevailed until a heavy infestation of lice was discovered and a poultry- 

 louse killer applied on the twelfth day. After that there was some 

 improvement, and a considerable gain in weight was noted. 



No records of internal parasites and diseases of the house wren have 

 come to my attention, but doubtless a thorough examination of many 

 specimens would reveal them. 



