ML46745131

Age and sex

Adult, Unknown sex - X

Media notes

There were several hundred gulls sitting in the casino parking lot as I drove past, so I pulled in and began scanning through them. There were many Herring Gulls of different ages, which usually means there is likely to be other things mixed in with them. Within a few seconds of scanning I spotted a dark-mantled Gull in basic definitive plumage that at first I thought was a Lesser Black-backed Gull, but I quickly noticed the broad white arch at the back of the bird formed by the white tipped tertials. Then I saw the pink legs, chunky body, and bold white primary tips. There were also a couple of inner primaries, maybe P 5 or 6, hanging below the outer primaries which showed extensive white with just a little black, which is not present in any of the other large gulls. These field marks all seemed right for a Slaty-backed Gull. The overall size of the bird was nearly identical to the nearby Herring Gulls. The head was rounded and streaked with brown and the nape was more heavily spotted with brown. Fine streaking around the eye made the area especially dark. The bill was not quite as robust as the herring Gulls and seemed a bit straighter. There was a red spot at the gony and a salmon colored patch on the upper mandible above the Gony spot. Otherwise the bill was greenish yellow. The iris appeared to be pale yellow. The mantle was dark grey, but not as dark as the nearby adult Great Black-backed Gulls. The scapulars were also broadly tipped in white. The underside of the bird and the tail was pure white. The legs were pale pink, not as bright pink as I expected. After taking a few photos I creeped up on the bird in hopes of seeing it spread its wings or fly and it did, but was quickly lost in the mass of Herring Gulls. However, I got a brief look at the back of the bird as it flew directly away from me and I could clearly see a broad white trailing edge to the secondaries. I never did get a look at the primaries spread. I have never seen this species before, so I sent photos to many people who have seen them before for their opinions and they all agreed that it was right for a Slaty-backed Gull.

Technical information

Model

Canon EOS 60D

ISO

1250

Focal length

33.5 mm

Flash

Flash did not fire, auto

f-stop

f/14.0

Shutter speed

1/1600 sec

Dimensions

1000 pixels x 667 pixels

Original file size

612.98 KB