ID CHALLENGE on Women Birders Australia 1 June 2020, by Janine Duffy
All respondents identified her correctly as a Silver Gull, even though (she) doesn’t have the normal adult red beak and legs, or silver back.
Now for the Advanced bit. How old is (she)? (BTW I always say “she/her” if in doubt – females are the original form and should be the default IMO. But I’ll put she in brackets).
Firstly, everyone noticed that (she) has brown chequered feathers on her wings and back. A common juvenile feature. (She) also has a little shading on her head and ear area – Silver Gulls seem to lose this pretty quickly, I don’t often see this feature on the beach. (She) also has very dark, nearly black bill and legs.
What gives her age away, most of all, is the length of her primaries (or lack thereof). They are the black feathers sticking out above her tail. In an adult, even in a flying juvenile, these primary feathers are a lot longer than the tail. Here they are about the same length.
If you look closely, only two primaries are just projecting past the coverts/secondaries (the brown chequered feathers on the ‘back’ – see the feather diagram below).
But if you look at Jannette Manins pic of a similarly-plumaged juvenile bird… see the difference in the primaries? I’ve outlined the primaries (red) and tail (blue) on Jannette’s bird, and overlaid it on my bird. Jannette’s bird can fly. My bird can’t. She just doesn’t have enough petrol (wing) in the tank. She doesn’t have much tail either, but that’s not a problem – birds can fly without tails.
What else can you see? A single “immature” silver feather, here outlined in red. I don’t know enough about moult to know if this is a new feather, or a longer juv feather.
Informative comments:
Sonja Ross: “I think it’s quite young as immature birds have fewer feathers with the brown colouring. It’s bill and legs are black. Just noticed what appears to be a couple of bands of dark on the tail feathers, whereas the adults have an all white tail.”
Sue Lee: “going for juvenile…..perhaps 1st few weeks of age. Dark eyes, brown buffy mottled feathers, a bit of smudging.around the head……ABG suggests that that disappears soon after fledging”
Julie McLennan: “juvenile as the bill, eye and legs are still black. The wings are mottled with brown and there is still a small brownish patch back behind and down from the eye. But I don’t think it’s as young as a photo of one I’ll post soon, which was quite fluffy” Pic below.
Julie McLennan: “Photo above taken same day. I don’t think it was flying that day but I spotted it a few times over the weeks later. I think these 2 photos are the only ones I took. It struck me that you never really see baby seagulls, I think this is the youngest I’d ever seen, and it wasn’t at the beach”
Jannette Manins: “I’d say it’s a juvenile Silver Gull; very young. It was seen in November and breeding is August to December. It might be newly fledged as the faint brown smudges on the head are lost soon after fledging. It may also be the reason it didn’t fly. The brown and buff chequering on the saddle and wing coverts are typical. Here is a bird photographed at Carnarvon, WA, a little older. For a start, it’s flying, and the feet are slightly red.”
Jannette Manins: “Notice the wide sub-terminal band and lack of mirrors on wing tips, noting a WA bird. Pic above.
Jannette Manins: “This juvenile was seen in Fortesque Bay TAS, in February. Again the legs are pinkish and it still has the brown smudges on the head…so I don’t know why!” Pic above
Jannette Manins: “No longer juvenile, this is a first yr immature bird seen in Cairns in May ‘18.” Pic above.
Jannette Manins: “Another 1st yr immature, from Darwin, seen in July ‘18. It has only one tiny mirror, maybe significant as a far Nth bird, very little brown on the saddle but still with a black bill and rather prominent sub-terminal band.” Pic above.
Jannette Manins: “Finally an end of first year immature?..seen in Cairns in September ‘17. Much more of the early plumage is replaced with white.” Pic above
Marie Yamamota: “Seen last week just N of Brisbane.” Pic above.
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