NORTHERN PINE WARBLER 413 



data on tlie song period, but in the New Jersey pine barrens birds are 

 still in song in the middle of July." 



In New England, pine warblers sing more or less all summer and 

 up to the middle of September or a little later. Francis H. Allen, 

 who has heard one singing while feeding on the ground, tells me: 

 "The ordinary song is, of course, a simple, sweet, liquid trill, but not 

 infrequently I hear a song consisting of two trills, the second pitched 

 lower than the first. On April 18, 1932, at Pembroke, Mass., I heard 

 from a pine warbler a number of times a slow wip loip wip wip wip, 

 etc., followed sometimes by the rapid trill of the ordinary song. And 

 on April 17, 1935, at Westwood, Mass., I found several singing in 

 white pine woods with a good deal of variety in rapidity and pitch, 

 and sometimes a downward inflection at the end of the trill. I have 

 noticed on two or three occasions that when the bird sings the bill is 

 opened and closed with each note of the trill and the bird quivers all 

 over, fluttering the wings very noticeably. 



"I have heard from a young bird in August a confused, lisping 

 song, warblerlike but not at all like the regular song of the species. 

 From young birds in September I have heard a chatter, while they 

 were being fed, that ended in a heavy note ; I recorded it as tip tip tip 

 tip sip. The call-note resembles that of the black-poll warbler but, 

 as I have heard it, seems somewhat more prolonged and fainter. 

 Another is a sharp, high chip or tip, lighter and clean-cut." 



Albert R. Brand (1938) records the number of vibrations per second 

 in the song of the northern pine warbler as varying from 5,125 to 

 3,300, with an approximate mean of 4,150. The latter is the lowest 

 figure for any of the Dendroicae. 



Enemies. — The pine warbler seems to be a rare victim of the cow- 

 bird ; I have been able to find only seven records in the literature. 



Harold S. Peters (1936) lists only one tick, Haemaphysalis leporis- 

 palustris Packard, as an external parasite on this warbler. 



Field marks. — ^The adult male has a bright greenish-yellow breast, 

 greenish-olive upper parts, two whitish wing bands, and white patches 

 at the ends of the two outer tail feathers. The female is duller 

 throughout, with less yellow on the breast. Both sexes are duller 

 and more brownish in the fall. Young birds are very plainly colored, 

 with no bright colors, and are decidedly brown above, but the dull 

 whitish wing bands and white markings in the tail are good field 

 marks. 



Winter. — As the pine warbler spends the winter in approximately 

 the southern third of its breeding range, it becomes exceedingly abun- 

 dant in the southern States at that season. A few hardy individuals 

 occasionally remain in winter as far north as Massachusetts, but the 

 great majority join the resident birds from Virginia and southern 



