Natural History of the Bell Vireo, Vireo bellii Audubon

the study area was traversed daily. No birds were detected until late afternoon of May 3, when one, presumably a male, was seen foraging.

Lawrence (1953:50) has reported that males of the Red-eyed Vireo precede females in the breeding area by as much as two weeks; the male Red-eyed Vireo forages but sings little in the pre-nesting period. The male Bell Vireo arrives first at the breeding area but precedes the female by only a few days. On the morning of May 4 the first male was singing from a number of perches while ranging over an area of seven acres. This area encompassed territories later occupied by three pairs, 2 (1960), 4 (1960), and 5 (1960). Late on the afternoon of May 4 the first courtship songs were heard and the first male was seen with a mate at 6:20 p.m. Eight additional males arrived from May 6 through May 18. A tenth male was discovered in the vicinity of territory 9 (1960) on June 18, 1960.

[Illustration: FIG. 2. Seasonal movement as indicated by the curve for spring arrival (A)