Documentation of Black-legged Kittiwake
2013-313

Observer Information

Reporter: Steven Mlodinow 530 Peregrine Circle, Longmont, CO 80504-8806
E-mail: smlodinow@gmail.com
Other Observers:

Species, Date, Time and Location Information

Species: Black-legged Kittiwake
First Date/Time: 11/6/2013 1:35:00 AM
Last Date/Time: 11/6/2013 1:55:00 AM
Duration (total time in view): 5 minutes +
County: Weld
Specific Location: Lower Latham Reservoir
Number: 1
Age: Adult
Sex: Unknown
Plumage: Non-breeding

Viewing Conditions

Optics: Kowa 88mm scope with 20-60x eyepiece
Distance:
Light: fair

Description of the Bird

I was watching a couple hundred gulls swirl around L Latham Reservoir in fairly good lighting that afternoon, ignoring the birds farther away and in unfavorable lighting. One of the closer birds caught my eye, as its outer wing was paler than the inner wing, with a whitish/pale gray sheen, not unlike the impression imparted by a Forster's Tern. Having just come back from the Washington coast, BL Kittiwake came quickly to mind. I looked at the wing tips which had the appearance of being neatly dipped in black, with no white mirrors (which were fairly easily seen on the nearby RB Gulls). Some dusky on the posterior head/nape could also be seen, and the bird was distinctly smaller than the RBGUs, but not as small as a FRGU would appear. The bird did land in the water, swimming near some RB Gulls, where the size difference was easier to note. The bill looked to be unmarked yellow, though some RBGUs black was hard to see under those conditions/distance. The bird flew again, landed again.

So, medium gray backed gull, smaller than RBGU, larger than FRGU, with distinct contrasting paler sheen on primaries uppersurface. Neat black tips to wings without white mirrors. Underwing white, with black tip similar to that of upperwing, but appearing more limited. Underparts completely white. Head with dusky gray on rear crown and/or hind neck and/or posterior auriculars, exact position and shape not determined. Bill appeared unmarked yellow, but can not rule out small dark mark as some RBGUs possess.

I watched the bird take off and land and then fly around in circles several times.

Similar Species Discussion

RB Gull- included because commonest gull, and closest regularly occuring gull in size. The white mirrors on the many nearby RB Gulls could be seen without much difficulty in flight. The shape of the black on the wingtip was clearly different as well. The bird was smaller than the RB Gulls and had gray smudging on head that is inconsistent with RB Gull. Finally, the paler sheen on the upperside of the primaries is distinctive for this species

RL Kittiwake - darker backed, without sheen on outer primaries

Resources Used

None

Previous Experience

Extensive with BLKI and RBGU. None with RLKI

Notes

Notes made DURING observation

Materials Available

No files uploaded.

Date Documentation Submitted

11/10/2013 5:54:00 PM

Location Map

The marker on the map shows an approximation of the location of this report. The marker is generated using a prioritized Logic base:
1) If the observer has entered coordinates, they will be shown.
2) No specific coordinates are available but the location is mappable.
3) A generic location with no specific coordinates is mapped to the center of the reported county.

Documentation of Black-legged Kittiwake 2013-313