Clark’s Grebe (Aechmophorus clarkii)
NMPIF level: Species Conservation Concern, Level 2 (SC2)
NMPIF assessment score: 14
NM stewardship responsibility: Low
NAWCP status: Low Concern
New Mexico BCRs: 16, 18, 35
Primary breeding habitat(s): Emergent Wetlands and Lakes
Summary of Concern
Although fairly common in appropriate habitat, Clark’s Grebe has a small population size. Breeding colonies are vulnerable to disturbance and habitat deterioration, particularly with changing water levels.
Associated Species
Eared Grebe (SC2), Western Grebe (BC2), Gadwall, Mallard, American Coot
Distribution
Like the closely related Western Grebe, Clark’s Grebe breeds widely across the interior western United States, from eastern Washington east to the Dakotas and south to Arizona, New Mexico and Texas. A separate, resident Mexican race occurs in central Mexico. Clark’s Grebes winter in coastal areas from Washington south to the tip of Baja California and throughout the Gulf of California region (Storer and Nuechterlein 1992).
In New Mexico, Clark’s Grebe breeds most frequently at Las Vegas and Maxwell NWRs and other northern lakes. It is known to breed at least occasionally as far south as Elephant Butte and Caballo Lake.
Ecology and Habitat Requirements
Clark’s Grebes breed on freshwater lakes and wetland areas with large expanses of open water, bordered by marsh vegetation. Breeding areas contain open water of at least several square kilometers. Nests are most often placed in flooded emergent vegetation, in water at least 25 cm deep. Sites in deeper water with submerged vegetation are also sometimes used. Colony size varies from hundreds to thousands; in general, larger lakes host larger breeding colonies. Initial nests serve as the nucleus around which the colony expands. Nests are vulnerable to destruction by wave action during wind storms, so more sheltered sites are preferred (Storer and Nuechterlein 1992).
On Lake Mead in Nevada, Clark’s Grebes remained in traditional breeding areas despite an unfavorable drop in water levels, and commenced breeding at atypical times of year (mid-August, and again in December) following a return of deeper water (Parmelee and Parmelee 1997). Clark’s Grebes may forage in deeper water and farther from shore than Western Grebes. Their diet includes a wide variety of fish species (Storer and Nuechterlein 1992).
Conservation Status
Species Assessment
|
DISTRIBUTION |
3 |
|
THREATS |
3 |
|
GLOBAL POPULATION SIZE |
3 |
|
LOCAL POPULATION TREND |
3 |
|
IMPORTANCE OF NEW MEXICO TO BREEDING |
2 |
|
COMBINED SCORE |
14 |
Clark’s Grebe is a Species Conservation Concern, Level 2 species for New Mexico, with a total assessment score of 14. It receives moderate vulnerability scores of 3 for most factors.
Population Size
NAWCP estimates a species population of 10,000-20,000 (Kushlan et al. 2002). Total population for New Mexico is unknown, and can be variable depending on local conditions.
Population Trend
Nationally, populations appear stable (Kushlan et al. 2002). No clear trends are apparent in New Mexico populations; a local trend score of 3 indicates uncertainty.
Threats
Quality of New Mexico breeding habitat is variable due to changing water levels. Colonies may be vulnerable to disturbance and boat wakes from recreational water users.
Management Issues and Recommendations
NMPIF Recommendations
-
Modify lake restrictions in appropriate areas from no wake to trolling speed only, to protect breeding colonies.
-
Manage grazing around lake shores to preserve shoreline vegetation.
-
Fence cattail/bulrush areas during dry years to speed later recovery when water levels return.
Species Conservation Objectives
NMPIF Objectives
Sources of Information:
Kushlan, J. A, M. J. Steinkamp, K. C. Parsons, J. Capp, M. A. Cruz, M. Coulter, I. Davidson, L. Dickson, N. Edelson, R. Elliot, R. M. Erwin, S. Hatch, S. Kress, R. Milko, S. Miller, K. Mills, R. Paul, R. Phillips, J. E. Saliva, B. Sydeman, J. Trapp, J. Wheeler, and K. Wohl. 2002. Waterbird Conservation for the Americas: The North American Waterbird Conservation Plan, Version 1. Waterbird Conservation for the Americas. Washington, DC, U.S.
Parmelee, D. F., and J. M. Parmelee. 1997. Western Grebe and Clark’s Grebe: Habitat necessity versus phenology. Colonial Waterbirds 20:95-97.
Storer, R. W., and G. L. Nuechterlein. 1992. Western and Clark’s Grebe. In The Birds of North America, No. 26 (A. Poole, P. Stettenheim, and F. Gill, Eds.). Philadelphia, PA: The Academy of Natural Sciences; Washington, DC: The American Ornithologists’ Union.
