This Arctic Tern was photographed at Mitchell Lake Audubon Center, San Antonio, Bexar County, Texas on May 10, 2008; Only the first photo shows the bill as it appeared to myself and Sheridan in real life - the severe overexposure used to get sufficient underparts detail against a pale gray sky seems to have caused some distortion of the bill in the subsequent images. There is a small bit of dark at the base of the maxilla and at its tip, but none on the mandible. The structure (long outer wings, long tail, rather short head, rather dumpy shape to underbody with bulge in front half of the underbody), plumage (paler underprimaries compared to coverts, thin and tapering black trailing edge to outer seven primaries (with black tips fairly even width), strongly contrasting white rump/tail, curved edge between black forecap and white lores) and primary molt stage (all primaries seem to be the same generation, with no sign of a molt boundary from above) are all classic for Arctic Tern:
