Black- billed or red-billed gull id

General birdwatching discussion, help with bird identification, and all other things relating to wild birds and birding in NZ that don't fit in one of the other forums.
Clinton9
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Re: Black- billed or red-billed gull id

Postby Clinton9 » Sun Apr 10, 2022 6:05 pm

Here's photos...

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Jim Kirker
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Re: Black- billed or red-billed gull id

Postby Jim Kirker » Sat Aug 06, 2022 12:38 am

Another gull where I favour black billed but request expert opinion please.
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Gull at Karaka Lake 06/08/22
P1230978.JPG (261.49 KiB) Viewed 334 times
fras444
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Re: Black- billed or red-billed gull id

Postby fras444 » Sat Aug 06, 2022 2:24 am

That's definitely Black-billed gull mate, it's got that hunched black-billed stance, I want to say it's a softer lighter grey that almost blends into the white (anyone else also notice that in between the two??) that slightly slim build in body and in the bill. Bill is jet black too
Jim Kirker
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Re: Black- billed or red-billed gull id

Postby Jim Kirker » Sat Aug 06, 2022 11:28 am

Thanks that's a useful point about the posture and the grey fading into the white. I instantly thought BBG when I first saw it near some RBGs but the red foot webs and upper legs made me doubt it.
wghabbott
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Re: Black- billed or red-billed gull id

Postby wghabbott » Tue Sep 13, 2022 11:24 am

I’ve always assumed that immature red bills had a different bill shape to adults. Wrong again.
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Weka1
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Re: Black- billed or red-billed gull id

Postby Weka1 » Wed Sep 14, 2022 5:26 pm

My observation is that female Red-billed Gulls have less robust, slightly thinner bills than the males.
This could make it more slightly more confusing in identifying immature female Red-bills from immature Black-bills.
I live in the Bay of Islands, an area with few Black-billed observations, but when in the South Island I did think that the Black-bills flight was more 'tern-like' than Red-bills.
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Oscar Thomas
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Re: Black- billed or red-billed gull id

Postby Oscar Thomas » Wed Sep 14, 2022 8:59 pm

How do you know the thinner billed ones are female?
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Weka1
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Re: Black- billed or red-billed gull id

Postby Weka1 » Thu Sep 15, 2022 9:30 am

OK. Fair question.
I lived on a boat for eight years. I had a pair of red-bills who 'adopted' me. Yes I did feed them.
The birds became very familiar with me and would alight onto the boat some 1/2 a nautical mile from my mooring and sit about a metre from me as I sailed onto the mooring. (I always said that pretend sailors have parrots. Real sailors have seagulls).
They were very obviously a pair, need I say more? The male had a thicker, more robust bill.
They eventually 'divorced' and the male showed up with a new partner, again with a slightly smaller bill.
How did I know it was a 'new' female? The old partner had lost part of her leg. She showed up at the boat several times when the newly formed couple were aboard and was always vigorously chased away by the male (the one with the more robust bill).
I have noticed this bill difference amongst other obviously paired birds and am sure that it is a characteristic example of sexual dimorphism exhibited by red-billed gulls.
I cannot comment on this secondary sexual characteristic re black-bills.

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