ML611640047

Age and sex

Immature Unknown sex - 1

Observation details

Originally found in Leamington Marina on the inner docks at 1:30pm while scanning resting gulls. I was ~50m away from the bird using my scope. The first thing on the bird that stood out to me was its large, thick, mostly black bill and I immediately knew I had something unusual. I changed my position to be able to view the primaries and that’s when I noted that they were a cold grey-brown in colour w/ white edging, basically matching the cold grey-brown of the terials and the rest of the patterning on the coverts. I took a few pictures and immediately sent them to Cameron Chevalier and Jacob Stasso to get their thoughts and let them know I potentially had a Glaucous-winged. I studied a few more features and decided to call Cameron to get him to come over immediately w/ his camera as I knew he was nearby. Unfortunately, moments after Cameron arrived, the bird took flight and we both decided to watch it w/ binoculars instead of attempting photos to see the field marks as best we could. In flight, we noted that it looked like a white-winged gull w/ no evidence of “webbing” or dark in the primaries as seen in Thayer’s. We remarked that it looked good for a pure GWGU and I put the post out on Discord. The bird was not refound that day. The following day, however, it was relocated by Andrew Weibe at Seneca Drive and Seacliff Drive next to Stink Creek (across from the Pollution Control Plant). This allowed for more people to see the bird and Donny Moore was able to take several photos of the gull in flight and in various lighting. After studying the field marks and structure of the gull, comparing it to Justin Peter’s bird in Barrie, and reviewing the general opinions online from the photos, we have concluded that this individual fits within the boundaries of “pure” GWGU.   Weather conditions were light winds and sunny skies throughout initial observation. Photos taken by Donny were in overcast light w/ light rain. Temperatures above freezing. The bird was observed until at least Nov. 27th. I had one additional viewing of the bird feeding at the Stink Creek outlet in rough waves and strong southwest winds.   Aged as a second winter bird based on two generations of feathers in the mantle; first year, somewhat mottled, brownish-grey feathers, and solid grey second year feathers. Mostly white tail above grey-brown tail band also indicated second winter plumage. Primaries appear to be somewhat rounded, also indicating a second winter bird.   Bare parts  Bill was large and thick w/ a prominent, bulbous gonydeal. The thickness and size of the bill were noticeable in the field. Bill was mostly black save for a bit of pink at the base of the upper and lower mandibles (more on the lower mandible). Gape and inside of mouth all pink when the bird yawned. Iris was dark brown in colour. Orbital ring was difficult to see but was pale pink in colour. Legs were a moderately dark greyish pink.   Plumage  Primaries were a cold grey-brown that nearly matched the colour and tone of the tertials though this was dependant on the angle the bird was viewed; sometimes they appeared slightly darker when not viewed in profile. Photos of the primaries and tertials both in the same light show a close match. On resting bird, primaries were edged w/ white, especially at the tips.   Mantle shade was a similar shade to HERG. Coverts were mostly white w/ cold grey-brown patterning matching the colour of the tertials and primaries. Greater and median coverts showed an intricate pattern of white and grey-brown (tertial edges showed the same pattern). Tail had a broad, cold grey-brown band closely matching the colour of the primaries and tertials. In flight, rump was pure white and uppertail was white w/ some grey smudging. Leading edge of primaries slightly darker grey than trailing edge in flight, reminiscent of Kumlien’s in pattern vs. the dark webbing of Thayer’s. Appeared as a white-winged gull visually in flight. From Donny’s flight photos, primaries show slightly darker grey-brown leading edges and tips. These darker primaries were quite subtle in the field when viewed in flight but appear more prominent in some photographs depending on the lighting. It was restricted to the outer six primaries, being most prominent on P7-8 and somewhat on P9. This pattern matches very closely if not exactly to that of the GWGU found by Justin Peter in Barrie. One small pale mirror was visible in P10 in flight shots. Underwing in flight in field and in photos show primaries that appear uniform light grey.   Belly, front, and head were white w/ grey-brown smudging, slightly more prominent around the face and eye and lots of smudging at the flanks. Structure  Bill was larger than that of HERG and thicker, w/ more prominent, bulbous gonydeal. The head shape in profile was relatively flat w/ a gentle slope to forehead. Eye felt far away from the bill and mostly centered in the head. This gave it a “gentler” look than the flat forehead and blocky head of HERG, which often give them a “mean” appearance. Primaries were noticeably short, w/ minimal extension beyond tail. Overall, the bird had a large, robust look. This was especially evident in flight w/ HERG.   Behaviour  During the initial observation, the gull mostly rested but did stand up to preen for a brief period as well before taking flight. In subsequent sightings, the bird was seen actively flying and feeding. On November 27th, when I viewed the bird at the Stink Creek outlet just east of Leamington Marina, it was actively feeding w/ several HERG and RBGU in crashing waves against the rocky shoreline. I noted that the GWGU appeared to handle the wave action much better than the rest of the gulls which took flight away from larger waves that were cresting. The GWGU stayed on the water in the crashing surf, continuing to fish unbothered.    

Additional species

• Ring-billed Gull Larus delawarensis

Technical information

Model

iPhone 12

Lens

iPhone 12 back dual wide camera 4.2mm f/1.6

ISO

32

Focal length

4.2 mm

Flash

Flash did not fire

f-stop

f/1.6

Shutter speed

1/1618 sec

Dimensions

2222 pixels x 2152 pixels

Original file size

752.47 KB