Bird of the Month: Western Grebe
Written by Andy McCormick
Andy McCormick, Volunteer and Former Board President of Eastside Audubon
A winter visitor to the coast of Washington, the Western Grebe is closely related to Clark’s Grebe, which was formerly considered a subspecies of Western Grebe.
Both Western and Clark’s Grebe (A. clarkii) breed in a small part of Central Washington, but the Western is more likely to winter off the Washington coast. This commentary will focus on the Western Grebe, but much of it will apply to both grebes, as they are similar in appearance and behavior. Some special considerations for Clark’s Grebe are included.
WATER WALKERS
Western Grebes have one of the most dynamic courtship displays in the avian world. The pair will begin their engagement in synchronous head bobbing and head turning. Later in the dramatic display, they will rise up on their feet and side-by-side will rush over the surface of the water with loud pattering of feet ending the rush with a dive into the water. Video of these displays can be found at the Macaulay Library.
It is all a prelude to mating which begins during spring migration and upon arrival on the breeding grounds among the reeds on freshwater lakes. Mating usually follows two to three days of mate feeding. Western Grebes nest in large colonies in the southern portion of the western Canadian provinces and in the western United States south through California. In Washington, breeding occurs at Moses Lake and the Potholes area in Grant County (Bell and Kennedy).
NESTS ON THE WATER
Western Grebe
Scientific Name: Aechmophorus occidentalis
Length: 25”
Wingspan: 24”
Weight: 3.3 lb (1,500 g)
AOU Alpha Code: WEGR
Both male and female grebes contribute to nest building by bringing material from under water and from the emerging growth in the vicinity of the nest site. They begin by gathering a mixture of both coarse and soft material into a pile on the water until the mass is solid enough for one of the grebes to climb onto it. Construction continues even after eggs are deposited to replenish the nest (LaPorte, et al).
The most successful nests are those that are located in the spaces among reeds and rushes so that they are protected from wave action and predators. Usually two to four eggs are deposited and are incubated by both parents for about three weeks. The young climb onto the back of the adults soon after hatching and are fed by parents. First flight is taken at about 10 weeks.
CONSERVATION AND MANAGEMENT
The Western Grebe population is strong and estimated at 87,000 individuals (LaPorte, et al). The species was hunted extensively in the period at the turn of the 19th and 20th centuries. The soft white feathers are silky and were desired for coats and hats. Oil spills and gill nets are current causes of death among grebes. Grebe colonies can be quite large and become a curiosity for humans and boaters in particular. Encroachment by humans is disruptive to the birds and they will leave the nest exposing eggs and chicks to predators.
The two grebes share the genus Aechmophorus, from the Greek, aikhmophorus, one who carries a spear with reference to the grebe’s long, sharp bill. The species epithet for Western Grebe is occidentalis which is from the Latin for western, referring to the natural range of the bird in western North America (Holloway). Clark’s Grebe is named for John Henry Clark (c.1830-c.1885) a U.S.-Mexico boundary surveyor and collector of zoological specimens which he shipped from the border to Spencer Fullerton Baird (1823-1887) at the Smithsonian Institution. Baird named the bird for Clark.
A BIT OF SYSTEMATICS HISTORY OF CLARK’S GREBE
Both Clark’s Grebe and Western Grebe were described in 1858, but by 1963 Clark’s Grebe was considered to be a color morph of Western Grebe and lumped as a single species. However, additional research found that the grebes practiced assortative mating, that is, they mated with their own species, even though they nest in common breeding areas. In 1985 the American Ornithological Union split the two into separate species. Nevertheless, there is some interbreeding of the two species (LaPorte, et al).
The plumage differences between these grebes is slight. In the breeding phase Clark’s Grebe has a bright yellow bill and the Western Grebe has a greenish-yellow bill. The white on the cheek surrounds the eye on the Clark’s Grebe, but the black of the Western comes below the eye. The Clark’s Grebe has more white feathers on the flanks.
Photo credit Mick Thompson. References available upon request from amccormick@eastsideaudubon.org.