MEET THE ALCIDS

Do you know your alcids? Most people know what gulls and terns are, and sandpipers are familiar even if the multitude of species can't be distinguished. Skimmers and skuas are less known, but it doesn't take a stretch to believe it when you learn they are related to gulls and terns. These birds are all in the same order, Charadriiformes, indicating their close relationship. But there is another group in the order that is not so obviously related to the others. These are the alcids, members of the family Alcidae.

Alcids are diving birds, much like loons and grebes and ducks in their general appearance and habits. They are relatively short-necked compared with other diving birds, so that in flight they look as much like footballs as birds. These footballs have wings, of course, but they use them not only for swimming but also for flying. Very few birds swim underwater with their wings rather than their feet, but these birds do. This method of locomotion is called wing-propelled diving.

The best-known wing-propelled divers are penguins, but they can't fly. Alcids do both, and quite well. In flight their relatively small wings keep them from soaring or gliding like a gull or turning on a dime like a sandpiper, but as long as they keep them beating at high speed they do very well in powered forward flight. When they try to turn, they slide sideways in the air before changing direction.

Wing loading is weight divided by wing area. The wing loading of these birds is very high, so they have to run along the water to take flight, into the wind whenever possible. They try to get all the lift they can, so they flatten their body and spread out their tail and webbed feet to increase the lift surface. Sometimes they splash along the surface before actually getting airborne.

Four species of alcids are common in Puget Sound, and all are fish-eaters. Common Murres and Rhinoceros Auklets breed widely in large colonies, the murres on cliff ledges and the auklets in burrows they dig. Both species are present in the Sound primarily in winter, but the auklets breed as close as Protection Island, and many forage in the northern part of the Sound during that period.

Both of these species are adapted to go where the fish are, and as schools of herring and sand lance are local and on the move, the birds adopt the same strategy. In an area with currents, diving birds commonly float downcurrent through areas rich in marine life, often around upwellings, feed as they can, then fly upcurrent to make the same journey again. Obviously these activities change with the changing of the tides, and they can be seen best in rich areas with powerful tide exchange such as Admiralty Inlet.

Marbled Murrelets feed in the same areas and even on the same fishes, but they are much less common. That species is unique in being a forest breeder. Pairs remain together throughout the year, then fly into old-growth forests in the spring to nest on a branch high in a big Douglas-fir. Because they use old growth, their populations have declined greatly in historic times.

Pigeon Guillemots breed locally in the sound, either in holes they dig at the tops of banks or in crevices under docks. They feed primarily on bottom fishes such as sculpins and gunnels, and they are the only one of the group that uses their feet as well as their wings as paddles as they move slowly over the bottom searching for prey.

The alcids are characteristic and charismatic birds of Pacific Northwest marine environments, and ferry travel is a good way to see them. Spend time at and especially on Puget Sound and learn about them for yourself.

Dennis Paulson

THE GULLS OF PUGET SOUND

Gulls can be best viewed where we concentrate them, anywhere from fast-food restaurants (French fries are a favorite) to waterfront parks (white bread a staple of the menu) to a meat- or fish-processing plant where they relish the offal, awful as it is. For the most part, the large gulls dominate these assemblages, although if there are few of them, smaller species may be in attendance. The smallest species, Mew and Bonaparte’s Gulls, have different feeding habits and are not part of these spectacles.

As pointed out in a previous blog, the Glaucous-winged is the most common and certainly most ubiquitous gull in Puget Sound. It and the much smaller Mew Gull are the ones you see everywhere throughout the winter. During spring and fall migration, large numbers of Bonaparte’s Gulls appear, and during fall migration there are even larger numbers of California and Heermann’s Gulls.

In addition to these five species, several others are seen in much smaller numbers. Thayer’s and Western Gulls are uncommon during winter, Herring and Ring-billed Gulls even less common. After these nine regularly occurring species, any other species is much rarer. This discussion will concern itself with adult plumages; the immature plumages are usually quite different.

Heermann’s Gulls (Larus heermanni) are medium-sized and stand out by their entirely gray body and black tail; the bill is red, the legs black. In breeding season, the head is white, but we don’t see it in that plumage, as it is a fall visitor from breeding colonies in Baja California. It is more common in the northern part of Puget Sound, mostly in September and October.

Bonaparte’s Gulls (Larus philadelphia), usually seen in migration but remaining for the winter in small numbers, are easily distinguished by their small size, black bill and red legs, and extensively white wingtips. In breeding plumage, they have a black head. They tend to be in flocks, sometimes large ones, and they often feed along convergence lines, or “tide rips.”

All the other gulls have gray mantles, yellow bills, and white heads, bodies, and tails in breeding plumage. Mew Gulls (Larus canus) are the smallest of these, not much larger than Bonaparte’s. Adults have thin, almost pigeonlike, yellow bills and yellow legs. The eyes are brown, the mantle (back and upper surfaces of wings) medium gray. In nonbreeding plumage, the head and neck are strongly marked with gray. The extreme wingtips are black, with large white spots that furnish a characteristic field mark. Like Bonaparte’s, this species is most commonly seen feeding along convergence lines but is common and widespread throughout the region in winter.

The next larger is Ring-billed (Larus delawarensis), with mantle paler gray and contrasty black wingtips. The white tip spots are smaller than in Mew. The bill is yellow with a black ring, the legs yellow, and the iris yellow. This freshwater species is only occasionally seen on Puget Sound but is noteworthy for its very contrasty markings.

A bit larger, the California Gull (Larus californicus) is patterned about like the Ring-billed but has a darker gray mantle, like the Mew, and brown eyes. Note both mantle color and eye color alternate with progression from Mew to Ring-billed to California. The yellow bill features a black spot in front of the red spot characteristic of all the larger species.

The rest of the regularly occurring gulls, larger yet, have yellow bills with a red spot on the lower mandible and pink feet. Thayer’s (Larus thayeri) and Herring (Larus argentatus) are very similar, both with pale gray mantles and less black at the wingtips than either California or Ring-billed. Herring always has a yellow eye, Thayer’s usually a brown eye, but the eye is pale in some individuals. Thayer’s is slightly smaller, with a distinctly smaller bill and more rounded head shape. The wingtips of Herring are blackish above and below, while in Thayer’s, there is not only less black but it shows up scarcely at all from below. So wingtips black above and pale below are characteristic of Thayer’s.

Finally, the two largest species, Glaucous-winged (Larus glaucescens) and Western (Larus occidentalis), differ primarily in mantle and wingtip color. In Glaucous-winged, the mantle and wingtips are gray and darker gray, in Western dark gray and black, respectively. Very different-looking birds, they unfortunately (for the birdwatcher) hybridize freely in the Puget Sound area, and the hybrids come in all shades of gray. These have been called “Olympic gulls,” and they complicate field identification. The wings are always more uniform than they are in Herring and Thayer’s, in which the light gray mantle and black wingtips contrast strongly.

Western Gulls have slightly larger bills than Glaucous-winged and are more likely to have yellowish eyes. The skin around their eyes is yellow, the same in Glaucous-winged is pink. But again, the hybrids complicate the issue. Western is much less common in Puget Sound, but there are pure Westerns along with the hybrids. A pure Western usually retains a white head throughout the winter and doesn’t acquire a black smudge on the red bill spot as does Glaucous-winged.

See the Slater Museum’s gull web page (http://www.pugetsound.edu/academics/academic-resources/slater-museum/biodiversity-resources/birds/identification-of-pacific-nort/) for more images and further information on identification.

Dennis Paulson