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Gulls are found worldwide; mostly in the Northern Hemisphere but still worldwide. Many are related to salt water and pretty much all of them are related to water. Those that may nest in the continental interior usually fly to the coast for the non-breeding part of their year. Some migrate, many don’t. Some are very large and a few are quite small. Many are white-headed and others are black-headed. There is not such thing as a “sea gull”. They are all gulls and some do live near the sea – are usually seen by the sea – but the phrase “sea gull” is really quite meaningless to a birder or naturalist.
These are obvious and gregarious birds. They nest in colonies and on the ground. Because they are large and noisy they can drive off many predators; in fact they can be quite predatory themselves. They prefer open areas where they can take advantage of winds and are often found gathering at places where humans deposit waste materials. As a matter of fact the most significant management action taken by humans that impacted gulls was the closing of open dumps and trash pits. Gulls are opportunistic feeders and the open dumps provided easy food. Over the past decade or two landfills have been covered and capped and wintering gulls have had a harder time finding food.
An interesting thought regarding gulls at this moment; they are evolving as we watch. The average gull may be white-headed and gray (or black) backed and seen most anywhere in the world. But the reality is that they range in size and color pattern in a step by step by step way from small and light to large and dark. Many of them (are they all species really?) can interbreed with other gull types.
The standard north American gull may be what we call the Herring Gull (HEGU), but it has nearly identical genetic cousins in the Mew Gull (MEGU), the Heermann’s Gull (HEEG), the Ring-billed Gull (RBGU), the California Gull (CAGU), the Thayer’s Gull (THGU), the Iceland Gull (ICGU), the Glaucous-winged Gull (GWGU), and the Glaucous Gull (GLGU)– and these are just its gray-backed relatives. There are another cadre of five types of near-Herring Gulls that are black-backed. That means that there are 15 types, or species, that are all cast from the same mold; or have descended from the same gull ancestor. There is another group of gulls that have black heads and are closely related to each other and less closely to these 15 species; these are the Little (LIGU), Bonaparte’s (BOGU), Black-headed (BHGU), Franklin’s (FRGU), and Laughing Gulls (LAGU). Then there are five species of Arctic gulls that we see infrequently. But it is very exciting to see when we do see them (Sabine’s (SAGU), Ross’s (ROGU), Red- (RLKI) and Black-legged Kittiwakes (BLKI), and Ivory (IVGU)). And this is just in North America – phew.
So let’s take a look at some assorted gulls – mostly US gulls. I won’t cover the various age plumages that gulls pass through but let me just say that what makes them troublesome is that there are many different plumage arrays as they age toward maturity. The larger gulls usually take four years to reach that adult plumage and the smaller gulls take two or three years. That creates a big mess of plumage stages that gulls go through. It isn’t always easy to age an individual – but as I said, we will look only at adults. There is one from outside North America included – but there are a few gulls in New Zealand, Australia, and southern South America. Maybe we will look at those family members some day.