Western Grebes nest on large freshwater lakes and marshes edged with reeds and rushes. Nesting in tidal areas is unusual. On very large lakes, colonies may number in the hundreds of pairs. After the breeding season, many move first to lakes where they molt their wing feathers, becoming flightless during that period. Once their new flight feathers have grown in, most Western Grebes then migrate to saltwater or brackish habitats, including ocean shores, sheltered bays, rivers, and estuaries. Smaller numbers winter inland on lakes and rivers.Back to top
Western Grebes eat mostly fish. They also consume salamanders, crustaceans, marine worms, grasshoppers, and many aquatic insects and their larvae. They dive deeply when hunting, swimming around with wings mostly closed. They stab their prey with a quick jab of the bill or capture it between the mandibles. They occasionally take prey items from the lake bottom.Back to top
Western Grebes build their nests near the water’s edge in emergent vegetation, usually rushes or reeds, less often in pondweed or milfoil. Water depth below the nest is usually less than a foot, and most nest sites are sheltered from wave action. Both male and female build the nest together.
The nest is a mound of vegetation with a depression for the eggs in the center, built of aquatic vegetation and anchored to vegetation or an underwater snag, so that it is less subject to wind and wave action. Males are larger, with larger bills, and they contribute larger stalks and stems. Females bring wet material such as algae to bind the nest and form the central depression. Nests can be 2–3 feet across or even larger.
|Clutch Size:||2-3 eggs|
|Number of Broods:||1 brood|
|Egg Length:||2.2-2.4 in (5.5-6 cm)|
|Egg Width:||1.5-1.6 in (3.8-4 cm)|
|Incubation Period:||24 days|
Plain pale bluish, often stained brownish by sodden nest material.
|Condition at Hatching:|
Alert and covered with blackish or silvery down; leaves nest and rides on back of parent after hatching.
Western Grebes are rarely seen flying, as they migrate at night and have little need for flight at other times. Their feet are set far back on their bodies, and their movements at the nest are awkward. They are seldom on land unless grounded during storms while migrating. During the breeding season, this species appears anything but awkward. Western Grebe’s main courtship “ceremonies” have become emblematic examples of bird courtship. There are two main displays, called ceremonies because each involves a specific set of behaviors performed in sequence with an almost mechanical precision. The first is called the rushing ceremony. It begins with a behavior called advertising, when birds deliver a rolling cree creet call. The display then moves to ratchet-pointing, in which birds lower themselves in the water, giving a grating, ratchetlike call with crest raised and throat distended. The next component, dip-shaking, involves dipping the bill and head into the water, then raising up and shaking the head from side to side. Then comes the spectacular rushing: both birds rise up in the water onto their feet, side by side, and simultaneously “rush” or run long distances across the surface, wings held up and back, necks curved, pattering with their powerful feet in what looks like a perfect bird ballet. The display concludes with a sudden dive. Pairs perform this display together, but two males may also execute it, presumably to attract females. The other display, known as the weed ceremony, is similarly complex but occurs later in the nesting season between a mated pair. The male and female move through behaviors dubbed neck-stretching, bob-shaking, and weed-diving, before coming to the astonishing weed-dancing, in which male and female face each other with aquatic vegetation in the bill and rise up vertically, their feet in constant motion, necks extended and bills rising upward, and then begin spiral movements around one another, their bills gracefully turning as they pivot around their partner. Males select the nest site and feed females during the early part of the nesting season; both are territorial at the nest. Each parent has a role in raising the young, which are often seen riding on the adults’ backs.Back to top
Populations of Western Grebe were stable or declining from 1968 to 2015, according to the North American Breeding Bird Survey. Estimates suggest a steep decline of 2% per year, but these figures have a wide margin of error because of the difficulty of monitoring this species. Partners in Flight estimates a global breeding population of 87,000 individuals, ranks them a 14 out of 20 on the Continental Concern Score, and places them on the Yellow Watch List for species with declining populations. Although the species has benefited from the creation of reservoirs and other wetlands, loss of natural wetlands and extensive hunting certainly led to historical declines in their populations. Like many waterbirds, Western Grebe is sensitive to pesticides, habitat degradation, disturbance by humans (when nesting, especially from motorized watercraft), oil spills, and gill nets.Back to top
Hayes, F. E., and D. G. Turner. 2017. Copulation behavior in Western Grebe (Aechmophorus occidentalis) and Clark’'s Grebe (Aechmophorus clarkii). Waterbirds 40 (2): 168-172. https://doi.org/10.1675/063.040.0209.
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