Gull help

[Gaucho25]

I saw this gull while looking for the Slaty-backed Gull that showed up in NYC today. (Didn’t see it). I think this is a Great Black-backed gull - 2nd winter. Saw it in Central Park’s reservoir. 

 

 

 

[IKLland]

Ring billed gull, first winter. 

Edited February 3, 2022 by IKLland

[IKLland]

Distinguished from greater black backed by small bill, and this bird is way smaller than a great black backed gull would be. 
 

Those are two easy marks, the rest are in the plumage, which is also distinctive. 

[Gaucho25]

@IKLland Thank you! 

[Charlie Spencer]

8 hours ago, IKLland said:

Distinguished from greater black backed by small bill, and this bird is way smaller than a great black backed gull would be. 

While I agree with your use of bill size, how are you telling the overall size of the bird with nothing to compare it with?

Thanks!

[Avery]

4 hours ago, Charlie Spencer said:

While I agree with your use of bill size, how are you telling the overall size of the bird with nothing to compare it with?

Thanks!

It's shaped like a small gull. 

[IKLland]

24 minutes ago, Avery said:

It's shaped like a small gull. 

This. @Charlie Spencer sorry, I should’ve been more descriptive.

[Jerry Friedman]

1 hour ago, Avery said:

It's shaped like a small gull. 

This brings up an interesting question: Can you explain the difference between a small gull's and a big gull's shape in a way that's helpful to someone who doesn't have much experience with big gulls?  I can't.

[Avery]

30 minutes ago, Jerry Friedman said:

This brings up an interesting question: Can you explain the difference between a small gull's and a big gull's shape in a way that's helpful to someone who doesn't have much experience with big gulls?  I can't.

To me at least they appear more elongate, and small-headed in comparison. 

[IKLland]

2 minutes ago, Avery said:

To me at least they appear more elongate, and small-headed in comparison. 

I’m not sure why but to me their heads appear rounder.

[Charlie Spencer]

7 hours ago, Jerry Friedman said:

This brings up an interesting question: Can you explain the difference between a small gull's and a big gull's shape in a way that's helpful to someone who doesn't have much experience with big gulls?  I can't.

Thanks for asking.  I was willing to accept the differences exist, and chalked up my not discerning them to a lack of experience.  If the bird is an adult RBGU, HEGU, BOGU, or LAGU, I have about a 50% shot at getting it right.

[Jerry Friedman]

10 hours ago, Avery said:

To me at least they appear more elongate, and small-headed in comparison. 

 

9 hours ago, IKLland said:

I’m not sure why but to me their heads appear rounder.

You're both talking about smaller gulls (more elongate, small-headed, round-headed)?  After looking at some pictures of Ring-billed and Great Black-backed, those are the impressions I get.

[DLecy]

10 hours ago, Jerry Friedman said:

This brings up an interesting question: Can you explain the difference between a small gull's and a big gull's shape in a way that's helpful to someone who doesn't have much experience with big gulls?  I can't.

It's a really good question. It's not an easy thing to explain when you have a single gull in isolation in a single photo. That's one reason it pays in spades to spend time observing birds in the field and noting their differences (size is just one field mark, and an often unreliable one). Photos with other known species also aid ID.

For example, a RBGU is about half the overall length of a GBBG and one third of the weight. So, it's essentially akin to a photo of a terrier being compared to that of a labrador retriever (size-wise anyways). We have all seen labs and terriers and can readily tell the difference. But if you've never seen either one, maybe it's more difficult and nuanced, especially if they are the same color. Or perhaps that's a poor example because they are different breeds; maybe it's more like comparing a single photo of a toy poodle to a standard poodle of the same color. Either way, you get the point.

With regards to this bird, the bill of a GBBG alone is MUCH more massive than a RBGU's relatively dainty one. There are numerous other field marks that separate the two, but the differences in structure alone (head-to-body size ratio, where the bulk on a bird is concentrated, primary projection, the bird's 'posture" and so on) should do the trick right off the bat.

[IKLland]

1 hour ago, Jerry Friedman said:

 

You're both talking about smaller gulls (more elongate, small-headed, round-headed)?  After looking at some pictures of Ring-billed and Great Black-backed, those are the impressions I get.

Yes.