Birder’s Notebook: Glaucous Gulls – Clever opportunists of the Arctic
It’s late November and almost all migratory birds are long gone from the region. However, as long as open water remains, a few hardy seabirds will hang on to fish and forage in marine waters. One of those birds of the ice edge is the glaucous gull.
The informal term “seagull” refers to a large variety of gull species, some of which never go near the sea. At least a dozen different types of gulls can be seen in the Bering Strait region, but by far the most common gull here is the large, white, graybacked glaucous gull.
Glaucous gulls are birds of the far north that breed in Arctic and subarctic regions around the globe. Many remain in cold northern waters throughout the year, sometimes wintering along the edge of the ice pack.
Glaucous gulls are one of the first migratory birds to arrive in the spring and one of the last to leave. In five of the last six years some were even still on the scene in December for Nome’s Christmas Bird Count. As fast as Norton Sound is freezing up now, it seems unlikely that they will be counted again this year, but if open water remains around St. Lawrence Island, some may stay there all winter.
Glaucous gulls nest throughout the coastal and interior lowlands of the Seward Peninsula, along lakes and major rivers in the uplands and at sea cliffs on the mainland and islands of the region. Pairs nest singly or in small colonies and often nest on islands in association with other species such as common eiders.
Marking studies show that glaucous gulls form long-term pair bonds and return faithfully to traditional nesting sites where the pair reunites each year. Birds returning without a mate seek one along the coast where unattached males gather in bachelor “clubs.” The males defend their personal space by assuming an upright posture and occasionally chasing intruding males on foot. Unpaired females visit these groups, walking amongst the males, circling possible mates with heads tucked to their chests. Prospective mates toss their heads and mew at each other until eventually a pair bond is formed, at which point they leave in search of a nesting territory.
The pair works together to build a bulky nest from surrounding vegetation. Egg laying can begin in late May when spring comes early and may be up to two weeks later when spring conditions are late.
One to three eggs are laid and the parents share incubation for an average of 26 days. As subsistence egg harvesters well know, these gulls will renest if their eggs are lost early in incubation. The chicks, which are downy and active at hatch, leave the nest within a few days but stay in the immediate area. Both parents feed and protect the young until they fledge. That period varies from 40 to 63 days, probably depending on diet and food availability. Both parents defend the nest area, driving away other gulls or potential predators. They also defend a foraging territory around the nest.
On the Seward Peninsula, fledging typically begins during the second week of August and continues into September for later hatching young.
Glaucous gulls are extremely versatile and opportunistic about diet and feeding behavior. They are clever and adept predators as well as effective scavengers that clean up dead animal matter, recycling nutrients back into the ecosystem.
Diet varies greatly from place to place depending on what is available, and individual birds may specialize in particular food sources. Commonly scavenged food items include fish carcasses, carrion, marine invertebrates washed onto beaches, remnants of marine mammal birthing, hunting scraps and offal from fish processing. They are a common sight at village landfills.
Glaucous gulls are expert fishers, feeding mostly on small fish close to the surface in nearshore waters. They seldom fish at sea unless associated with whales, seals or walruses on ice floes. They spot fish and plunge dive from the air, but don’t submerge deeper than a few feet. Swimming buoyantly and riding high in the water, they paddle with webbed feet.
The largest of arctic gulls, they are able to steal fish from other gulls, from seabirds returning to feed their young and from loons and grebes when they bring fish to the surface. Recently, I’ve watched glaucous gulls steal sea stars brought to the surface by king and common eiders feeding along the coast near Nome.
These clever gulls are forever on the lookout for opportunities to catch small prey including birds, small rodents and least weasels. They frequently predate bird nests for eggs and will follow foxes as they prowl through seabird colonies, grabbing eggs and young in the chaos. Insects and marine algae are on their menu and it is common in the fall to see glaucous gulls sitting in the tundra picking berries.
Away from their nesting sites, glaucous gulls are gregarious. Large flocks of nonbreeding adults and subadults gather in the summer along the coast to feed, rest and preen. Near river mouths and lagoon inlets where food is readily available, groups can grow very large as summer progresses and they are joined by breeders, newly fledged young and gulls from elsewhere.
When at a food source, there is continuous conflict and squabbling among these feisty, noisy gulls. Their large size and aggressive disposition allow them to displace other gulls and other seabird species when in mixed flocks. Older birds displace younger gulls and males displace females, including their mates. Glaucous gulls have only a few predators which include bears, foxes and gyrfalcons.
This regal and entertaining gull appears thus far to be faring well in our changing environment and is one of only a few arctic seabirds whose population is believed to be stable. Perhaps the glaucous gull’s adaptable diet and habits make it more resilient to climate change than are most other northern bird species.