KIRTLAND'S WARBLER 425 



suddenly increased in speed toward the middle and dropped slightly 

 in pitch near the end. 



Kirtland's warblers usually scold very little unless the provocation 

 is great. They use a note for scolding described by Axtell (1938) 

 as varying from tsyip to tshyooh^ and like the "common scolding note 

 of the Oven-bird" {Seiurus aurocapillus) . Adults use a low churk 

 to arouse the nestlings at feeding time. On the Kirtland's winter- 

 ing grounds in the Bahamas, Maynard (1896) heard only a "harsh 

 chirp." 



Unlike many warblers, this species continues to sing throughout the 

 incubation period and even while raising the young. However, most 

 individuals have stopped entirely, or almost entirely, by mid July ; late 

 records are July 24, 1939 (Verne Dockham, Oscoda County), and 

 August 1, 1932 (Leonard Wing, Crawford County). 



Field marks. — Kirtland's warbler is a large, rather slow-moving 

 warbler, described by Peterson (1939) as "gray above and yellow 

 below, with some large sparse spotting on the breast and sides. * * * 

 The bird wags its tail much like a Palm Warbler; no other gray- 

 lacked Warbler has this habit." (As previously noted, the "wagging" 

 is an up-and-down motion.) After their first winter, the two sexes 

 are easily distinguished even in the field; males, especially if fully 

 adult, are more blue above than females, and the black in front of 

 their eye and about the base of their bill (absent in females) always 

 gives the appearance of a dark mask. Kirtland's warblers are usually 

 discovered by hearing the song, and a study of Axtell's excellent de- 

 scription (1938) should enable an observer with previous experience 

 of bird song to recognize a Kirtland readily. 



In fall, even the adult plumage is very brown above, and all plumage 

 markings are less distinct; few people are able to identify a fall- 

 plumaged Kirtland in the field. 



ETiemies. — There have been oddly contradictory statements about 

 the adverse factors in the life of Kirtland's warbler. In his first 

 paper on the species, N. A. Wood (1904) mentioned the fires that 

 sweep the jack-pine plains, and in a later paper he (1926) stated 

 that "fire is without doubt the greatest menace to the Kirtland war- 

 bler colonies, since it destroys the habitat as well as the nests of the 

 birds." It is, of course, quite true that a fire, if it occurs in their 

 breeding area before mid July, will destroy the nests in its path. 

 However, since this warbler nests exclusively in the dense stands of 

 jack-pine that spring up after a fire, one can truly say that fires are 

 the Kirtland's greatest need. Not only do fires in the older jack-pine 

 stands result in suitable nesting conditions, but fires that occur in 

 areas largely covered with red and white pine (never inhabited by 

 the Kirtland's) promote the spread of jack-pine. Completely sue- 



