Mike’s photo of Corey and I (I’m the older and not so good looking one of the pair) in his typically evocative Put on a Happy Face post was taken at St. John’s Pond in Long Island, and just off to one side of the image is a Ring-billed Gull. Looking through the photos I’d taken at that same site I realised that I’d (inadvertently I admit) captured a 2nd Winter and an Adult Winter Ring-billed standing in almost identical poses, and neatly showing the differences between the two ages.

I’d hazard a guess that almost 100% of all birders can separate most immature gulls from adults - it’s not too difficult: the former are mottled brown, the latter are (in most cases) predominantly grey and white - but how do you start to separate a 2nd winter Ring-billed Gull from the apparently near-identical 3rd year adult? Assuming this is actually something you want to do (and you should, because if you can begin to age gulls correctly a whole new world of larid identification will open up in front of you), have a good look at the two photos below:

2nd Winter Ring-billed Gull (New York, February 2008)

Adult Winter Ring-billed Gull (New York, February 2008)

I know what some of you are thinking: those are the same birds Charlie! Well, they’re pretty similar, but they’re not the same - and if you know what to look for the differences are there to found.

Ring-billed Gulls are what are termed ‘three-year gulls’ - that is, it takes three years for this species to obtain adult plumage, going from a mottled-brown juvenile with a dark eye, a pink, dark-tipped bill and pink legs to a pale-mantled adult with pale eyes, a yellow bill with a dark ring, and yellowish legs. In the bird’s second winter it does look very similar to the adult (particularly around the head as the images above show), and most inexperienced birders - happy just to correctly identify the species - will be drawn straight to the head where the “ringed bill” the species is named for is to be found.

1st Winter Ring-billed Gull (Miami, November 2004)

Okay, we’ve identified the Long Island birds as Ring-billed Gulls, but how old are they? Neither has a pink bill with a dark tip and neither has dark eyes - even without looking at the birds’ bodies it’s clear that neither are first winters. Both have yellow/yellowish legs too, and clear grey mantles. Hurrah, they’re adults then…However, look closely at the primaries (the long dark wing feathers) and the tail, and the differences in their ages are there for all to see.

1st Winter gulls of many species have dark primaries (in simplistic terms black feathers are stronger than white ones, and young gulls - growing up in the nest jostling with their siblings and further scuffing their primary tips when they start to practice flying - need resilient primary feathers). Most adults gulls however have a range of white tips or internal white “dots” in their primaries that enable essentially very similar-looking species to correctly identify potential rivals or potential mates. In the photos above the gull labelled as a 2nd Winter still has mainly dark primaries like the 1st Winter, whilst the Adult Winter has primaries with a neat pattern of white tips on the upper surface of the feathers and a white oval or “mirror” on the under surface (visible on the wing furthest away from us in the photo).

Additionally many young gulls have dark-banded or all-dark tails. The vast majority of adult gulls have white tails (the obvious exceptions being very dark gulls like Heermann’s and the East Asian Black-tailed Gull). During the moults from juvenile to adult plumages those dark tail feathers are replaced: typically though many 2nd year (and in larger species, 3rd or even 4th year) gulls show some trace of the younger bird’s dark tail-band which show as irregular dark patches. A close look at the tail of the 2nd Winter gull reveals those tell-tale dark patches and thus accurately age the bird. If I’d later seen that same bird in flight those same dark patches would have been visible from hundreds of yards away, enabling me to age it as a second winter without the kind of close views I got earlier.

As experienced gullers will point out there are other (more subtle) differences between the two ages - the bill band of the 2nd Winter is less clear-cut and a little more smudgy than the Adult’s, the intensity of the yellow colour of the legs of the Adult is deeper than the 2nd Winter’s, and many of the 2nd Winter gull’s feathers are worn or “tatty” compared with the fresher feathers of the Adult - but the two features explained above are the simplest to look for in the field and are visible from a distance even in poor light when colour tones can be difficult to assess.

The next time you’re out looking at the gulls on your local lake give aging them a try and please let us here at 10,000 Birds know how you get on…