The Black-Legged Kittiwake

In our recent blog post about the Northern Fulmar, we originally included three photos of what we believed to be Northern Fulmars. However, some eagle-eyed readers saw that one of those photos was actually of a different bird species. We corrected the error in the Northern Fulmar blog by removing the offending photo. However, that photo stuck with me in the days that followed that revelation. I wanted to know more about this bird species that we thought was a Northern Fulmar. Fortunately, our wonderful readers knew what the bird species was: the Black-legged Kittiwake. So, in this blog post, we're going to give you a more complete introduction to this beautiful bird species, and give it the full spotlight it deserves.

Introduction and Range
The Black-Legged Kittiwake (scientific name: Rissa tridactyla) is a small, oceanic gull that spends most of its life in the waters off the coast of both the Pacific and Atlantic Oceans. Like the Northern Fulmar, the Black-Legged Kittiwake is not an easy bird to spot. Your chances of seeing one on land are very low. You will most likely need to take a boat trip to spot one. However, stray juveniles do turn up from time to time on beaches and in reservoirs, especially in New England. During storms, they can be seen from the shoreline of either coast.

While most Black-Legged Kittiwakes do most of their migration offshore, a few younger birds make their way inland to complete their southbound migrations in the fall. During the winter, this species makes its home in the Pacific Ocean waters, ranging from Alaska to Baja California. In the Atlantic Ocean, their winter range starts roughly around Newfoundland and proceeds south to North Carolina's Outer Banks. Some birds travel a bit further south, towards Central Florida. In the summer, Black-Legged Kittiwakes make their homes primarily in Alaska, Labrador, Newfoundland, and far Northern Canada.

The Black-Legged Kittiwake prefers to live in areas of upwellings. Sometimes, they will concentrate over the edge of the continental shelf. They can tolerate an array of sea conditions, from moderately warm waters all the way to the edges of pack ice. When they make their way onto land, they nest on the ledges of steep cliffs near Northern waters, such as those in Alaska, Newfoundland, and Labrador. In these places, they are usually seen perched facing the cliff wall, with their tails sticking out over the edge.

Size and Appearance
Black-Legged Kittiwakes are small gulls with round stomachs. They have short notched tails, slim and short bills, and wings that are long and narrow (their wingspan is an impressive 37 inches (94 centimeters) long). These features help to make the Black-Legged Kittiwake look elegant while flying. Males and females both weigh anywhere from 10.8 to 18.5 ounces (305 to 525 grams), and are 15 to 16.1 inches long (38 to 41 centimeters). Breeding adults are colored in a delicate shade of pale gray with black wingtips. They have yellow bills and "clean white" (3) lower bodies. Their feet and legs are "jet black" (3) in color. Nonbreeding adults have a similar color scheme, with the only addition being a "dusky patch" (3) that is located behind their ear.

Juvenile Black-Legged Kittiwakes are mostly white, with "a black M pattern" (3) across the upper wing that is visible when they are in flight. They also sport a collar across the back of their neck that is either gray or black in color. Their bills are black, as is their tail tip. To seabird enthusiasts, Juvenile Black-Legged Kittiwakes are known as "tarrocks" (2).

Feeding
Like most bird species, the Black-Legged Kittiwake forages in order to find the food that it eats. Much of their foraging takes place while they are in flight. They dip down to grab items right from the surface or plunge into the water to take prey that is located beneath the surface. When they are swimming, they will feed by grabbing items right from the surface. The Black-Legged Kittiwake feeds primarily on small fish, generally concentrating on one or two species, such as Pollock or Sand Lance, that are in abundance where they are at. If the amount of available fish is low. Black-Legged Kittiwakes will turn their attention towards crustaceans. Their favorite crustacean to eat is Euphausiid Shrimp. They also eat insects, mollusks, marine worms, and small squid. Black-Legged Kittiwakes only eat plant material on rare occasions, and unlike most gulls, do not feed at landfills.

Breeding Pairs and the Nest
Black-Legged Kittiwake form their first breeding pairs at three to five years of age. Males put on displays to attract females by going through what are known as "choking" (1) motions. These motions include jerking their heads up and down while gradually opening their bills. Pairs of Black-Legged Kittiwakes display by crossing their necks and nodding their heads. Males feed females until the young are born, at which point both parents take on feeding responsibilities for themselves and their offspring. The Black-Legged Kittiwake's preferred nest site is on the ledge of narrow cliffs. Sometimes, they will nest on top of boulders, building ledges, roofs, or on the ground. Both parents help to build the nest, which is made out of seaweed, grasses, and mud. A small depression is located at the center of the nest.

Eggs and the Young
Black-Legged Kittiwakes lay anywhere from one to three eggs. The eggs are variable in color, ranging from pale and olive blue to tan. The eggs are speckled with spots of gray or dark brown color. The incubation process runs for just under one month, and is handled by both parents. The young remain in the nest full time until they are ready to fly. They typically make their first flights at 34 to 58 days. For several weeks afterwards, the young may return to the nest at night, though not all of them do.

Other Cool Facts
The Black-Legged Kittiwake is a member of the Laridae family which includes both gulls and terns. The species is named for its distinctive nasal bird calls that resemble their name. The call goes "ki-ti-waak" (1), and is made through an array of loud, harsh notes. Ornithologists recognize two subspecies of the Black-Legged Kittiwake, which include the smaller R. t. tridactyla (native to Arctic and North Atlantic Oceans) and the larger R. t. pollicaris (native to the North Pacific Ocean). The hind toe on the Black-Legged Kittiwake's foot is very small, resembling a tiny bump. This gives the bird its species name tridactyla, which means "three-toed" (2).

References
1. https://www.audubon.org/field-guide/bird/black-legged-kittiwake
2. https://www.allaboutbirds.org/guide/Black-legged_Kittiwake/overview
3. https://www.allaboutbirds.org/guide/Black-legged_Kittiwake/id

© Ian D. Caldwell, March 2022