Very protective parents, the seagulls

These vagabonds of the bird world lurk around beaches, waiting to nab a morsel from an unprotected picnic. They despoil docks and form raucous flocks in McDonald’s parking lots, where they tussle for the last spilled french fry.

But you can see a different side of seagulls.
On their coastal breeding grounds, where they nest in colonies of thousands, seagulls engage in a series of elegant, complex social behaviors. Their unruly flocks actually consist of choreographed postures and finely graded vocalizations that impose order, communicating everything from the presence of food or predators to anger, submission, hunger, cooperation, and pair-bonding.

Walking into a seagull colony is like a scene from Hitchcock’s The Birds, but with more sensory overload. You may have seen something like it if you’ve ever watched a mob of seagulls descend on a bag of spilled chips on the beach, screeching and diving in a chaotic frenzy with hundreds of swirling wings, stabbing beaks, and flailing feet circling in a tight ball overhead. Yet it’s all executed with almost balletic grace by the swarm of birds.

When a predator is closer, and thus more threatening, gulls give YEOW calls with increasing rapidity. These calls are also shriller with staccato elements that immediately draw the attention and aggressive response of listening gull neighbors.
When the perceived threat level is low, more time passes between successive YEOW calls and the calls themselves are less shrill, evoking a more moderate, cautious response from other seagulls.

Seagulls also communicate with their mates during the summer breeding season. The choking display is part of an often contentious debate between members of a pair over where to nest. Although two patches of ground may be indistinguishable to us, gulls spend considerable time discussing the attributes of the exact spot where the precious eggs will be laid. Choking displays involve a repetitive, delicate murmur given by one member of the pair who thinks it has found the ideal spot for the nest. The bird leans forward and points at the proposed spot on the ground where the nest should be built while producing the huoh-huoh-huoh choke call.

Its partner will usually walk in a circle around the point, pondering the proposal in a most deliberate manner, and only joining in the choke display if she agrees. This is an important decision, and one that is not always made. At least one pair of Great Black-backed Gulls on Appledore Island spent their entire summer placing sticks in different areas of their territory and choking, but never reaching a final agreement.

For gulls, successful reproduction requires the complete attention of both parents, excellent communication and coordination, and a series of complex negotiations within their community—the nesting colony.
Seagull parents split their duties, with one foraging for food while the other stays home to protect the nest.

When an outsider such as a fox appears, those suspicious neighbors become the best of allies. Neighbors will join forces against the fiercest predators, including eagles, raccoons, and even humans. 
Intruders who get too close to a nest are blindsided with a whack in the back of the head by the equivalent of a four-pound dumbbell. If the intruder is too disoriented from the impact to hastily retreat, the gull parents will rile up the neighborhood with YEOW! calls, calling in a squadron to squirt hefty amounts of putrid excrement on the intruder’s head, or maybe even a hearty helping of partially digested gull food.