I watched a dark-mantled, black-tailed gull at Thomas Reservoir from about 12:30 to 12:50 today, when it flew off to the east. ideal viewing conditions with bright sunlight. It was mostly standing among ring-billed gulls, but sometimes sat, and made several short flights around the reservoir.
The gull appeared slightly larger than the ring-bills. Yellow legs, but somewhat darker than the ring-bill legs, with a muddy, slightly greenish tinge. The legs also seemed a bit stouter than the ring-bills. The mantle was a warm, dark gray. There was a narrow tertial crescent. A scapular crescent occasionally appeared as the gull shifted position, but was mostly not visible. It had extensive dense warm brown streaking on the nape and around to sides of breast, making a partial collar. The nape streaking contrasted with the lighter crown which was much more lightly streaked. The iris was dark, and I could not make out any coloring to the orbital ring. The bill, which was noticeably heavier than the bills of the ring-bills, was yellow with a black ring around the tip. A few times, when the bill faced the sun just right, faint reddish-pinkish coloring was visible on a small patch BEHIND the black ring on the lower mandible. In flight, the upper wings were dark gray overall; I did not make out any white on the tips. The tail had a broad black band with narrow white terminal. The white terminal was visible when the gull was standing, but I couldn't make it out in flight against the sky. Alan Bell Boulder -- Colorado Field Ornithologists: http://www.cfo-link.org/ Colorado County Birding: http://www.coloradocountybirding.com/ You received this message because you are subscribed to the Google Groups "Colorado Birds" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.as/group/cobirds?hl=en
