Herring gull: Gender ID from photo? (1 Viewer)

[martyrynin]

Hey guys,

I took some photos of two gulls that I assume to both be adult herring gulls.

What amazes me is the difference between them!

Particularly the bill size: length and gonydeal angle.
The head shape also looks different. One has a rounded dome; the other a flatter head.
Also while not as obvious in the photo, the gull on the ground was a fair bit larger as well.

Can you definitively tell the gender of these gulls from the photos? If so what clinches the gender ID?
Alternatively are they at different stages of adult hood? I know they can live for decades.

 

[martyrynin]

Also came across this on wikipedia:

• L. a. argentatus – Pontoppidan, 1763, the nominate form, sometimes known as the Scandinavian herring gull, breeds in Scandinavia and northwestern Russia. Northern and eastern populations migrate southwest in winter. It is a large, bulky gull with extensive white in the wingtips. The outermost primary, p10 often has a large white spot (called a mirror) that extends to the wingtip. The bill is longer and forehead flatter than argenteus.

Bulky gull with longer bill and flatter forehead does seem like a close description to me!
Not sure if a subspecies ID from those photos is warranted. The gull is tagged though, so I can always ask! Have posted on the BTO ringing scheme site

 

[martyrynin]

To follow up on this one, the BTO replied (a while back) and it was ringed in Belfast as part of an urban gulls study.

So I think it's safe enough to assume Argenteus.

Furthermore, reading Gulls of Europe, Asia and NA, it seems that you can make an educated guess at sex ID.

"The male is larger with a heavier, more bulbous-tipped bill, flatter forehead and squarer neck than the female, which may appear round-headed with a rather short bill"

From that description, I think it is reasonable to guess that these are photos of male and female respectively.

 

[pdwinter]

Furthermore, reading Gulls of Europe, Asia and NA, it seems that you can make an educated guess at sex ID.

"The male is larger with a heavier, more bulbous-tipped bill, flatter forehead and squarer neck than the female, which may appear round-headed with a rather short bill"

From that description, I think it is reasonable to guess that these are photos of male and female respectively.

For some reason I missed this thread altogether.

I find gulls change apparent size and shape (along with mantle colour) when they move / turn or whether they are resting or alert. I tend to be only able to guess the sex when there are two birds alongside / next to one another - preferably when they are a pair calling.

 

[lou salomon]

Telling the sex is usually easy when seeing a pair together. But even then there exist cases which aren't at all obvious. I find it easiest to sex Caspian Gulls with males often having an enormous bill with an appreciable gonys. Females sometimes are obvious (in all large gull taxa), if bill and overall impression is extreme in its neatness, but often I'd not try to sex them and at least 70% aren't safe to sex in HG I'd say. In these pics I'd leave 1 unsexed and 2 tentatively sex as male.

 

[martyrynin]

Telling the sex is usually easy when seeing a pair together. But even then there exist cases which aren't at all obvious. I find it easiest to sex Caspian Gulls with males often having an enormous bill with an appreciable gonys. Females sometimes often are obvious (in all large gull taxa), if bill and overall impression is extreme in its neatness, but often I'd not try to sex them and at least 70% aren't safe to sex in HG I'd say. In these pics I'd leave 1 unsexed and 2 tentatively sex as male.

Thanks for the response Lou!

That's surprising that it's that difficult to sex, but good to know!