ML101027281

Age

Not specified

Sex

Not specified

Observation details

Record Accepted by AZ Bird Committee. 1) Size: the bird did not appear noticeably smaller than the swallows in the same flock, suggesting Chimney Swift (VASW would be distinctly smaller than swallows); 2) Wing shape: a distinct “primary bulge” is evident in many photos and was commented on in the field, suggesting Chimney Swift; 3) Relative wing length: quantitative analysis of wing length and width shows these measurements to be outside of the range observed for Vaux’s Swift, but in the expected range for Chimney (ABC report has details); 4) Rump color: this bird’s rump was not contrastingly lighter than the back, which is the expected pattern for Chimney; 5) Color of underparts: the light gray throat transitioned abruptly to a much darker belly, which is a more expected pattern for Chimney; 6) Terminal bar: the bird’s uppertail coverts appear in photos to reach the base of the tail barbs, this is expected for Chimney, but in Vaux’s the uppertail coverts would fall short of the base of the barbs. Supporting media: A series of 38 photos can be found at https://flic.kr/s/aHsmc48nL5

Technical information

Model

NIKON D3100

ISO

400

Focal length

300 mm

Flash

Flash did not fire, auto

f-stop

f/5.6

Shutter speed

1/1250 sec

Dimensions

1146 pixels x 857 pixels

Original file size

616.08 KB