I think it’s safe to say that the explosion in human populations around the globe has had a pretty big negative effect on other species. Habitat destruction, the introduction of foreign species, and outright slaughter has taken quite a toll on the plants and animals that share our planet. But there are some animals that have thrived because of the changes we’ve made to our landscape. Raccoons and skunks do quite well in suburban areas, as do coyotes and foxes. Rock doves (pigeons) and squirrels flourish even in our cities. Usually these species that survive in harmony with, or even benefit from, human interaction are those that would be most able to adapt to changing environments with or without us. One of the most successful of these creatures is the herring gull.
The natural environment of the herring gull is the sandy shores of lakes and oceans. But we can now find them in some of the most unusual places, thriving in the parking lots of fast food restaurants and landfills full of our garbage. Although there are many species of gulls, the most adaptable is the common seagull, or herring gull (Larus argentatus). Normally found along these coastal shores, they have greatly increased their range, expanding deep into the continent’s interior by exploiting the trash and development of people.
Many gulls even make a full time living simply following fishing boats. As the ship makes its way back to port, it is common practice to use this time to fillet or otherwise prepare the catch (including discarding bycatch animals) for the market. Gull colonies will often stay with a single vessel throughout the voyage just to feed on the discarded fish.
In fact, they have become so successful adapting to our trash-producing society that in many states it is illegal to build airports within six miles of a landfill (or vice-versa), in order to prevent bird-plane collisions which can result in this:
Now that I’ve established how well they adapt to our alteration of their habitat, I’d like to take a step back and look at how these birds would normally survive had we not had such a great environmental impact on their ecosystem. But before we do that, how about a short video of a seagull walking into a convenience store and stealing a bag of doritos?
Herring gulls normally survive by both scavenging dead animals and capturing live shallow-water prey. They are unable to dive into the water like terns and cormorants can, so they must depend on prey that lives along the shore. One of their favorite foods are mollusks and crustaceans.
The problem with feeding on these animals is they are both covered by a formidable defense. Crustaceans with an exoskeleton and mollusks with a hard calcareous shell. So, let’s say a gull captures a quahog. There is no way it can penetrate the shell with its beak, and the webbed feet would be pretty useless as well. How then can the bird get at the meat inside?
Pretty simple, really. The gull simply grabs the clam in its beak and flies up into the air. It then searches for a hard surface and hovers over it. This can be a rock, road or even a car. It then drops the clam, which plummets to the ground and smashes open. After dropping the food, the gull follows it down and feeds on the prey. I have a friend who actually tried to put in an auto insurance claim because an oyster was dropped through his windshield. The insurance company didn’t buy it.
Herring gulls breed in colonies along the coast, often mixed with other gull and tern species. And they are notorious nest raiders of other birds, feeding on the eggs and young of weaker colonymates. I’ll get into the nesting and rearing of young in a later diary, but there is a very cool reason why the adults have a red spot on their bills (see the top image).
True story: About fifteen years ago a new Chinese restaurant opened up in my town. My mother mentioned that she tried it out and it was one of the worst meals she ever had. She specifically said the chicken was especially bad. A few months later I read in the local paper that the town closed the business down because they were trapping seagulls on the roof, using leftovers for bait, and serving it in their dishes. Nice.
Other diaries in this series can be found here.