WHITE- THROATED SPARROW 1383 



decrease. Regular singing began in the morning and ended in the 

 evening at a light intensity of about 10 foot-candles. In mid-July 

 singing was more general throughout the day but by mid-August 

 only a few songs were heard at 4:30 a.m. and 7:00 p.m. On August 

 25th no birds sang. The increase in song in mid-July already men- 

 tioned was also observed by Dayton Stoner (1932) in the Oneida 

 Lake region of New York and by Lainevool, who noted that mated 

 birds sang more when their young became independent. She also 

 observed that unmated males defending territories sang more than 

 mated males during the breeding season. 



Lainevool (unpublished data) investigated the effects of weather 

 on singing by counting songs for 10 minutes at 7:30 a.m. in an area 

 where 12 birds could be heard. Between June 2 and July 27, 1959 

 she made 37 counts. Although the results were not conclusive, they 

 showed the birds tend to sing more on sunny than on cloudy days, 

 on warm rather than cold days, and during high rather than low 

 atmospheric pressures. There was very little song when the tem- 

 perature was below 50° F. 



A number of authors have reported hearing the primary song of 

 this species during migration and on the wintering grounds. A. A. 

 Saunders (1948) noted fall singing in southern Connecticut on the 

 average from October 6th to November 6th with the extreme dates 

 from September 26th to November 29th. He states that "Fall songs 

 are not commonly perfect and full. They are shortened or the pitch 

 of the last notes is badly flatted." George H. Lowery, Jr. (1955) 

 reports that the song is often heard in Louisiana in mid-winter and 

 describes patterns similar to those heard on the breeding grounds. 

 A. A. Saunders (1947) describing the onset of spring song, reports 

 hearing a white-throat as early as January 10th. The average date 

 when he first heard regular singing was March 26th, the earliest 

 February 18th, and the latest April 23rd. 



Thus far we have discussed the territorial or advertising song of 

 the white-throat. A good imitation or recording of this song will 

 cause a territorial male to become quite excited and to approach 

 the source of the sound. This suggests that the song functions as a 

 threat to other males. As females often respond by giving the pre- 

 copulatory trill, the song may also be a sexual stimulant to the female 

 (Lowther, MS.). 



Bruce Thorneyeroft (unpublished data) took young white-throats 

 from the nest and raised several groups in sound isolation. Their 

 vocalizations were recorded at intervals beginning in July of the first 

 year. During the fall and winter these birds tended to give a series of 

 whistling sounds falling and then rising in pitch sometimes ranging 

 over two octaves. The individual sounds were shorter than those in 



