Merlin

Clark's Grebe Life History

Habitat

Habitat Marshes

Clark’s Grebes nest on large freshwater lakes and marshes whose edges have emergent vegetation such as 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 to so-called staging areas. These are lakes where they molt their wing feathers, becoming flightless during that period. Once their new flight feathers have grown in, most Clark’s Grebes then migrate to saltwater or brackish habitats, including ocean shores, sheltered bays, rivers, and estuaries. Smaller numbers winter inland on lakes and rivers.

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Food

Food Fish

Clark’s Grebes feed mostly on fish but also salamanders, crustaceans, marine worms, grasshoppers, and many aquatic insects and their larvae. They dive deeply when hunting, swimming around with wings mostly closed. When prey is found, the bird quickly jabs with the bill to spear it or captures it between the mandibles. Most hunting is probably done in the upper part of the water column, but some prey items are taken from the bottom.

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Nesting

Nest Placement

Nest Floating

Clark’s Grebes build floating nests near the water’s edge among 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.

Nest Description

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 log or ​root, so that it is less subject to wind and wave action. Males are larger, with larger bills; they contribute larger stalks and stems while 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.

Nesting Facts
Clutch Size:2-3 eggs
Number of Broods:1 brood
Egg Length:2.2-2.2 in (5.5-5.7 cm)
Egg Width:1.5-1.6 in (3.7-4 cm)
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Behavior

Behavior Surface Dive

Clark’s Grebes are usually seen resting on the water’s surface or diving for food. Their dives tend to involve more of an upward leap than those of Western Grebe, probably because they tend to forage in deeper water, farther from shore. Like Western Grebe, Clark’s is rarely seen in flight, which is swift and direct. Clark’s Grebe spectacular courtship displays are essentially identical to those of Western Grebes. The famous “rushing ceremony” begins with the birds delivering a rolling creet (unlike the double call of Western). Then the birds lower themselves in the water, giving a grating, ratchet-like call with crest raised and throat distended. The next step involves dipping the bill and head into the water, then raising and shaking the head. Then comes the spectacular rushing: both birds rise up in the water onto their feet, side by side, and simultaneously “run” for long distances across the surface of the water, wings held up and back, necks gracefully arched, 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 males also often execute it together, presumably to attract females. A separate display is known as a “weed ceremony” and occurs between members of a mated pair. In this coordinated display, the male and female stretch their necks, bob their heads, and dive to collect pieces of weeds. At this point, the two birds 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. Both parents help raise the young, which are often seen riding on the adults’ backs.

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Conservation

Conservation Restricted Range

Clark’s Grebe populations appear to be declining. Partners In Flight estimates an overall 8% population decline between 1970 and 2017, and a global breeding population of just 11,000 individuals. Clark’s Grebe rates a 14 out of 20 on the Continental Concern Score and is on the Yellow Watch List for species with restricted ranges. Clark’s Grebes are sensitive to many environmental changes, including pesticides and other pollutants, drainage of lakes, cutting of marsh reeds (especially in Mexico), oil spills, gill netting, underwater explosives, and human disturbance, especially by motorized watercraft.

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Credits

Kushlan, J. A., M. J. Steinkamp, K. C. Parsons, J. Capp, M. A. Cruz, M. Coulter, I. Davidson, L. Dickson, N. Edelson, R. Elliott, R. M. Erwin, S. Hatch, S. Kress, R. Milko, S. Miller, K. Mills, R. Paul, R. Phillips, J. E. Saliva, W. Sydeman, J. Trapp, J. Wheeler and K. Wohl (2002). Waterbird conservation for the Americas: The North American waterbird conservation plan, version 1. Washington, DC, USA.

Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2017). The North American Breeding Bird Survey, Results and Analysis 1966–2015. Version 2.07.2017. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, USA.

Storer, Robert W. and Gary L. Nuechterlein. (1992). Clark's Grebe (Aechmophorus clarkii), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

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