Bonaparte's Gull

Chroicocephalus philadelphia

By Andy McCormick

  • Length          13.5 in
  • Wingspan      33 in 
  • Weight           7 oz
  • AOU Band code    BOGU

“The Bonaparte’s has a graceful, buoyant flight, which is rather ternlike” (Alderfer). It can easily be overlooked if it is flying with terms. It is one of the smallest North American gulls and is quite attractive in both breeding and winter plumage. In breeding plumage it has a slaty black hood, and red legs. In winter the hood molts to white and a round, black dot remains near the ear. In all plumages adults have a small, black bill. Conspicuous in flight is the flash of a triangular wedge of white along the leading edge of the outer part of the wing.


The genus name Chroicocephalus is from the Greek chroma, color, and cephalus, head (Wikipedia) referring to the black hood. Following mitochondrial studies the American Ornithological Union moved Bonaparte’Gull in 2008 to Chroicocephalus which contains 13 species of gulls. This gull was named after Charles Lucien Bonaparte, a nephew of Napoleon Bonaparte and an ornithologist who spent about five years in America. The gull was named for him by George Ord of Philadelphia who found the gull in that city (Mearns). 


The Bonaparte’s is fully migratory and will move through Washington in April and May on its way to nesting grounds in the boreal forest. Although it will migrate in large numbers sometimes into the thousands at a time, it nests in small, remote, scattered colonies in trees. The nest is usually an open platform of sticks lined with moss and grass built on a horizontal branch in a spruce or other conifer (Kaufman). Because Bonaparte’s Gulls nest in such a remote environment we have little knowledge of their breeding habits. 


Usually three olive to buff colored eggs are deposited and both parents are thought to incubate them. The young hatch in about 24 days. The diet in this northern region consists mostly of insects, which both parents bring to the nest (Kaufman). The time needed before the nestlings’ first flight is not known. 


Although Bonaparte’s Gulls can be seen anywhere in Washington in winter, they spend most of their time near water. Those that winter in Washington congregate around Puget Sound and the Pacific Coast and can often be seen in the company of Red-throated Loons, Western Grebes, and Red-breasted Mergansers (Dunne). They feed on forage fish, crustaceans, marine worms and insects, foraging by plunging into the water or dipping from the surface (Burger and Gochfeld). Congregations of Bonaparte’s Gulls are often found near upwellings at sea, and along tidal rips, sewage outfalls, and lagoons. Unlike the larger gulls they are rarely found foraging at landfills.


Population numbers appear to be stable and there is no conservation management plan. They are not considered pests and have not been managed as one (Burger and Gochfeld). 

Photo by Mick Thompson

Photo by Mick Thompson

Caspian Tern

Sterna caspia

By Hugh Jennings

  • Length          21 in
  • Wingspan      50 in 
  • Weight           1.4 lb
  • AOU Band code    CATE

The Caspian Tern (CATE) is about 21” long with a wingspan of 50” and weight of 1.4 lb (660g). The genus name Sterna (STIR-nah) is Latin stemming from Anglo-Saxon stearn , tern. The species name caspia is Latin of Caspian Sea where a specimen was collected for which the species was named by Pallas in 1770. This is the largest of the terns. The CATE nests on five continents. In North America, it is common along both coasts and locally inland, mainly around large bodies of water. In Washington state, non-breeders are abundant summer residents in coastal bay in inland marine waters.


It is a fairly common summer resident in Eastern Washington on a few major lakes and the Columbia River. They are often seen flying constantly 20 to 50 feet above the water, with bill pointing downward, looking for fish. It catches fish by diving completely underwater, but also may pick fish off the water surface. It may steal fish from other seabirds.


Its summer plumage: large, crested, black cap and big blood-red bill (sometimes the bill is slightly darker at the tip). The bird is overall gray above and light below. The plumage in winter is like the summer, but the cap is splotchy and gray. Juveniles are like winter adults, but bill is orange and upper parts lightly marked with dark bars and V’s. The adult calls include a low, harsh scream “kwok” and “cahar”. The Caspian Tern first breeds at about 3 years. This tern nests singly or in colonies. The nest being a depression in the ground lined with grasses and seaweed, located on sandy beaches. There are usually 2-3 eggs which are pinkish with darker markings. Incubation is 20-22 days. The young may leave the nest a few days after hatching. If colony is not disturbed, the young may stay at the nest until ready to fly. Both parents bring food to the young. The age at first flight is 28-35 days. The young terns are noted for their long adolescence, with the young dependent on their parents for many months. Even in late winter many adult Caspian Terns are trailed by a begging youngster from the previous nesting season. During migration, the terns fly high with bill pointing forward. It is the least sociable of all terns and travels singly or in small groups. Inland breeders move to the coast and fly south for winter, some wintering south to West Indies and northern South America.

Photo by Mick Thompson

Photo by Mick Thompson

Mew Gull, Ring-billed Gull, California Gull

Larus canus/ Larus delawarensis/ Larus californicus

By Andy McCormick

  • Length                   16 in             17.5 in          21 in
  • Wingspan              43 in            48 in            54 in
  • Weight                   15 oz            1.1 lb            1.3 lb
  • AOU Band code    MEGU           RBGU         CAGU

In the northwest we have three species of gulls with white heads and yellow legs: Mew Gull, Ring-billed Gull, and California Gull.  They differ in size, bill markings, mantel color, and wing tip appearance.  In this article we will compare and contrast only the adult plumage birds.  All three species are in the very large (23 species) genus Larus, from the Greek, laros, a ravenous seabird.  The Mew Gull has the species name canus, from the Latin for white haired in reference to its plumage.  Mew is old English for gull.  The Ring-billed is delawarensis referring to the Delaware River where it was found.  The California is californicus referring to the state where it was collected (Holloway).  

It may be most helpful for identification to learn the Ring-billed Gull very well.  This bird is ubiquitous in North America and has a population of 3-4 million individuals making it our most populous gull.  Its medium size makes it a good reference bird for comparison with many other gulls.  It has a medium-size bill with a clean-cut, black subterminal ring (Alderfer).  Its eyes are pale with a dark orbital ring.  In winter the head becomes finely streaked.  The black wing tips are set off by white mirrors toward the end of the outer two primary feathers (numbered P9 and P10).  

The Mew Gull is smaller than the Ring-billed and it has a much smaller, unmarked bill. The Mew also has black wing tips but the mirrors are much larger and reach to the tips of P9 and P10, and look large when the bird is in flight. This gull has a floating flight pattern and compared to the Ring-billed is more delicate with a gentle expression (Sibley).  It is seen along coastal waters in winter.  It breeds in boreal lakes in Alaska and northern Canada, but is seldom seen inland outside of breeding season.  In first and second winter birds the legs can be fleshy or greenish colored.

The California Gull is larger than the Ring-billed with a stouter, but straighter bill.  There is a narrow black ring on the bill, and next to it is a red spot at the gonys, the area on the lower mandible between the tip and angle of the bill.  The eye is dark with a red orbital ring. The legs are yellow and sometimes have a greenish tinge.  The wing pattern is distinctive.  The tips are black with large mirrors on P9 and P10, and there is more black on P7 and P8 giving the wing a squared-off appearance (Alderfer).

All three species are opportunistic omnivores.  The Ring-billed especially can be found in parks, land fills, and feeding at garbage cans around fast-food restaurants.  Some Mew Gulls are also learning these behaviors, but generally eat fish, crustaceans, urchins, and inland will eat insects and earthworms.  California Gulls will eat fish and other marine life, and in summer will eat large numbers of insects.  So much so, that they are attributed with having saved the crops of Mormon settlers attacked by locusts in 1848, inspiring the gull monument in Salt Lake City (Kaufman).  

Photo by Mick Thompson

Photo by Mick Thompson

Glaucous-winged Gull, Western Gull, Herring Gull

Larus glaucescens/ Larus occidentalis/ Larus argentatus

By Andy McCormick

  • Length                   26 in            25 in            25 in
  • Wingspan              58 in            58 in            58 in
  • Weight                  2.2 lb            12.2 lb          2.5 lb
  • AOU Band code    GWGU         WEGU         HEGU