Thursday, August 20, 2009

Gulls: The Lion and the Lamb Within

by Olivia Tai, Cornell University

At first glance, gulls are not like humans at all. But one bird scientist thinks otherwise.

“I think that gulls are appealing in a lot of ways because they sort of remind us of ourselves. They have a lot of greedy behavior and selfish behavior, but they can also be extremely caring with nurturing qualities,” says Dr. Julie Ellis, a seabird ecologist at Tufts University. Some of the students and colleagues inspired by her passion for gulls know her as the “Gull Queen.”

Whether gulls draw out affection from us, or annoy us to no end, they deserve a chance to be understood as a highly social bird.

Nowhere is gull social behavior on more vivid display than on Appledore Island, a rocky oasis six miles off the coast of New Hampshire and home to Shoals Marine Laboratory. The island houses one of the largest colonies for two gull species: Greater Black-Backed Gulls and Herring Gulls. Last year in June, I observed gulls up close when I joined an Animal Social Behavior class at the lab. The course introduced me to field research in the behavioral sciences, which is what I study as an undergraduate at Cornell University. We focused exclusively on Appledore’s gull community, learning gull behavior by spending innumerable hours at their nests. At some point during all of that observation, I was able to overcome my stereotypes about the bird and see why they’ve enthralled researchers.

People think of gulls as flying rats. You may know them as food-stealing, trash-eating nuisances that hang out in the parking lot at McDonald’s. But the excessive population of gulls that causes these annoyances is the same reason why researchers are fascinated by these coastal birds. In Here’s How We’ll Do It, a published account of the lab’s origin, the founders chose Appledore Island partially because of an extraordinary abundance of Herring gulls. Since then, the island’s gull colony and convenient lab facilities have lured interested researchers and students to the field station.

Learning the gull communication signals is crucial to understanding gull behavior. A signal can be seen or heard, but it always contains a message meant to create a response. To understand the hidden message in a signal, an observer must spend a long period of time watching the animals. At first, the observer will find a lot of confusing sounds and movements. But soon, an observer finds an action that seems interesting, and waits patiently for the gulls to repeat it over and over again. The more you see the action, the more details you will notice—such as what usually happens before or after, where does it happen, and who responds to the secret message.

“It is the ability to notice and interpret these small changes that separates the best field scientists from the rest, and there is no better place to hone these skills than Shoals Marine Lab,” says Dr. William Bemis, the current director of the lab. There are so many gulls living near each other on Appledore Island that an inexperienced observer will see a lot of repetitive action even after a few hours.

In a community of gulls, each couple would choose a patch of land that they mark as their territory. To warn intruders, gulls emit short bursts of shrill calls followed by intimidating gestures. Great Black-backs may stretch their wings out like a Batman cape, ready to take flight and descend upon you. Herring gulls may rip out grass ferociously to let you know that they’re strong and infuriated. But if they don’t see you back away soon enough, they read your presence as a willingness to fight. Negotiations to back off only last so long before the gulls resort to violence.

Fights do erupt often when neighboring gulls attempt to expand their real estate. But gulls don’t discriminate; they constantly defend their homes against predators and anyone else that walks through—including biologists.

Although Bill Clark has no formal training in gull biology, he became fond of Appledore’s gulls when he volunteered at Shoal’s four years ago. As a retiree, Clark responded to Ellis’s call for volunteers and remained involved with her research ever since. One of his most memorable experiences at Shoals Marine Lab involved a male Herring gull nicknamed “Angel of Death.”

Clark explains the bird’s reputation: “He tends to sit up on the porch and dive down on people. Some years it seems to be just about everyone that comes past. Other years, he seems to develop a fondness for diving at several people. They’re on his list, apparently.” Clark suspects that the male remembers a past experiment, in which his eggs were taped with thermostats at the bottom to measure nest humidity and temperature. Not only did he develop a grudge toward humans from then on, but he also eluded experimenters who wanted to tag him with an identification band.

During one fateful day, Clark was ambling through the island with a heavy net in hand. “I was just going somewhere and I had no intention of catching him. But he came up and started to attack me. What was I going to do? So I just dropped the net on him and we banded him. He never forgave me apparently,” Clark recalls. Two weeks later, the Angel of Death sought his bloody revenge by attacking Clark from behind and cutting his head.

Ellis swears that the notorious bird recognizes Clark. Gulls might not only recognize people, but they may build resentment towards those who endanger their chicks. The Angel of Death seems capable of doing both, but gulls are generally protective of their young.

“You know, I’ve heard this from a lot of people that haven’t been to a gull colony. They always say, ‘I haven’t ever seen a baby gull. Where do all the baby gulls grow up? You know what, what are the gulls like as parents?’” Ellis says.

Gulls give lot of attention to their chicks. Parents hunt and leave fish undigested in their throats, so that they can retch it back up when they return home. If the food is too big for the little ones, parents may break the food into smaller pieces. They regurgitate nearly on command whenever the chicks peck at the red spot on the tip of their beaks. Sometimes, feeding the chicks becomes an overwhelming burden on the parents to hunt more often for food. Yet gull parents almost give in to the chicks’ every whim.

Now that I’m revisiting Appledore Island at a different time of the year, I see the stark contrast in how gull parents act at various ages of their offspring. While chicks were still fuzzy and clumsy during early summer months, their parents need to guard them at all times. Towards the end of summer, gulls barely squawk at me as I pass by on the way to the dorms. The chicks are almost as big as their parents, but still require a little more flight training before they gain their independence. Gulls only become über-aggressive when they have vulnerable chicks to defend.

Like gulls, we humans can be extraordinarily kind to family and act against our selfish tendencies. But when we sense danger directed towards our loved ones or our country, we rage wars for decades.

Gulls do have reason to fend hard for their chicks. Every year, a female gull lays an average of three eggs. According to a documentary that was recently filmed on Appledore Island’s gulls, entitled “Signals for Survival,” most gulls will raise one chick to independence, or none at all. If a chick gets killed, its parents just lost a huge portion of their annual production. That’s why their hostile behavior seems to contrast the tender care their chicks receive.

“If we’re going to co-exist with these birds, we need to learn about how they live and what their needs are,” says Dr. Thomas Seeley in “Signals for Survival.” Seeley is an expert on animal social behavior, and chairman of the Department of Neurobiology and Behavior at Cornell University. The idea of gull overpopulation is a clear example of how we misunderstand the gulls. Ellis believes that the way we dump our waste allows the gulls to easily eat the trash and grow in greater numbers. Instead, people tend to vilify gulls for wanting to eat the trash. If our garbage is affecting the gulls’ existence by haphazardly increasing their population, then we need to know more about these creatures instead of ignoring them.

“If you want to get to know the gulls, then come up to the Shoals and just watch them for a day,” Ellis says.

But research on gulls is not for the faint of heart. Clark gives a disclaimer to all aspiring gull researchers: they’d better give the animal a test-run before they commit. “Because they’re mean, they’re nasty, they’re ugly, and they’re going to poop all over you. These are not little koala bears that you can cuddle and hug. They’re tough characters and very, very neat to work with.”


No comments:

Post a Comment