Friday, January 12, 2018

Gull ID Tips, Plus a Hybrid Gull (as if gull identification could possibly get more confusing)

A couple of weeks ago I spent a day birding in two of my favorite places: Pacific Grove and Moss Landing (both along the Monterey Bay on the central coast of California).  I was on the look-out for a number of specific species (as I always am) and was hoping to find a few interesting gulls mixed in amongst the numerous Western Gulls.  An Iceland Gull (formerly Thayer's Gull), Glaucous-winged Gull and Bonaparte's Gull were all on my list but evaded me.  I did see a few Heermann's Gulls, which are striking now in their winter plumage, brilliant white heads contrasting with slate gray bodies and bright red bills.  But my attention was drawn away from them, and the intriguingly pale bird in the photo below caught my eye and held my interest.

Would this gull have caught your eye?  It was noticeably paler than others around it, a clue
that it was something special.  (Monterey Bay, December)

This gull's pale gray back and wingtips (the "spotted" part sometime mistakenly referred to as the tail) puzzled me.  Not feeling that I had yet reached the level of expert in gull identification, I sought input from birders who are far more experienced than I am.  The consensus is that this bird is a Glaucous-winged x Western gull hybrid. 

That's right: some gulls hybridize.  (Because the wide range of plumage variations for one species of gull is not complicated enough, let's throw in the possibility that it's actually a cross between two species!) 

If you've spent any amount of time watching birds along the coast, I have little doubt that you too have wondered over the numerous varieties of gull that seem to be before you.  But really, there are only a small handful of gull species you must come to grips with, and a few tips to learn, in order to gain a fairly decent handle on gull identification along the California coast.

First, you must realize that the coloration of gulls' plumage changes wildly over the first several years of an individual's life, and also varies from season to season (breeding vs. non-breeding plumage, for example).  I'll use the Western Gull as an example, since they are abundant on California's coast and you can easily go out and see them for yourself. 

Western Gulls (Moss Landing, May)  Adult breeding plumage.  Note the brilliant white, unstreaked necks.

Western Gulls in their first and second winters of life are often (if not usually) mistaken for a completely different species by beginning birders, and it's an entirely honest mistake!  First winter birds are brown, with black bills (pictured below); by their second winter, they have acquired a little more white mottling in their brown feathers. 

Young Western Gull entering its first winter plumage (Carmel River State Beach, August)
These gulls were still begging their mothers to be fed; a definite sign that they are juveniles,
about to begin their first winter.  Note the entirely dark bill as well.

In their third winter, Western Gulls can look superficially like a Ring-billed Gull, except that the latter is significantly smaller, with yellow rather than pink legs.  It is not until about their fourth year of life that these birds take on the characteristics of a typical adult Western Gull: a dark gray back and virtually unstreaked white head and neck, pale or dark eyes (it varies), pink legs, and a heavy yellow bill marked by a red spot on the lower mandible.  

Western Gull (Monterey Bay, August)  Adult plumage.

Having told you all of that... be careful not to mix up Western Gulls with similarly-sized Herring Gulls and only slightly smaller California Gulls, which both spend winters on California's coast but also range inland (Western Gulls stick close to salt water).

Herring Gull  (Merced NWR, December) Adult, non-breeding plumage.  (Not a great photo, but the best I could find!)

In contrast to Western Gulls, Herring Gulls (pictured above) have pale gray backs and streaked heads and necks, pale eyes, pink legs, and a heavy yellow bill marked by a red spot on the lower mandible.  California Gulls (pictured below) have medium gray backs and streaked necks, dark eyes, yellow legs and both red and black marks on a yellow bill (be careful not to confuse them with Ring-billed Gulls... pictured two photos down).

California Gull (Monterey Bay, August)

When identifying gulls, it is helpful to note the color of their eyes (light or dark) and legs (pink or yellow), as well as marking on their bills.  The lightness or darkness of their backs and wing tips relative to each other is sometimes a good field mark as well.

Ring-billed Gull  (Moss Landing Harbor, May)
But there is far more to gull identification than just color.  Relative bill proportions are also important; is the bill very heavy, as in a Western Gull, or relatively short, like a Ring-billed Gull?  Knowing what species to expect in a certain place at a certain time of the year goes a long way in aiding positive identification as well.  This is especially handy when you begin to delve into the wonderful world of identifying gulls in their first, second, sometimes even third winter plumages, which are typically very different from the adult plumage.  For example, a typical gull scene on a beach looks something like this:
Carmel River State Beach, August

How many species do you see here?  In the photo above, the bird in the foreground is recognizable as a California Gull.  The dark birds are first winter birds; they appear to be Western Gulls, judging by their dark color and dark, heavy bills.  If you notice in the back, there are also a few gulls with very red bills: these are Heermann's Gulls.  The white-chested bird to the left of the Heermann's Gulls looks to me like a third winter Western Gull, based on the dark ring around its bill and pink legs.  But, I am open to correction!  (See, we're all learning together.)

Here's another one:

Carmel River State Beach, August
In the photo above, the large gull strutting in the foreground is clearly a Western Gull, based on its dark gray back, pure white neck and head, pink legs, and very heavy bill.  Behind it is a mixed flock of Heermann's Gulls and Western Gulls of varying ages.  But I think there are a couple of smaller, yellow-legged California Gulls here too.  Can you pick them out?
So you can easily see that while gulls are fairly large, conspicuous birds, not often overly shy and affording birders excellent chances for up-close viewing and photography, they can be deceptively difficult to learn at first.  I've been struggling for a few years to sort out my Western, Herring and California Gulls, and while by no means fail-safe, I have put together a little chart to help keep them all straight. 

Click on the chart above to make the image larger and clearer!

And of course, just when you think you have gulls figured out, you'll come across something new, like this Western x Glaucous-winged hybrid, and you'll want to throw your hands up in frustration!

Western x Glacous-winged Gull.  A hybrid of the two species.  (Monterey Bay, December)

But perseverance and practice always pay off.  I am certainly better at identifying gulls today than I was a year ago!  The more you familiarize yourself with gulls and spend time watching them, the more adept you will become at noticing their sometimes subtle differences, and the more comfortable you will feel identifying them.  And what better excuse to take a trip to the beach?