Western Grebe (Aechmophorus occidentalis)   NMPIF level: Biodiversity Conservation Concern, Level 2 (BC2) NMPIF assessment score: 13 NM stewardship responsibility: Low NAWCP status: Moderate Concern New Mexico BCRs: 16, 18, 35 Primary breeding habitat(s): Emergent Wetlands and Lakes   Summary of Concern Although fairly common in appropriate habitat, Western Grebe has a relatively small population size. Breeding colonies are vulnerable to disturbance and habitat deterioration, particularly with changing water levels.    Associated Species Eared Grebe (SC2), Clark’s Grebe (SC2), Gadwall, Mallard, American Coot   Distribution Like the closely related Clark’s Grebe, Western 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. Western 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, Western Grebe breeds at Elephant Butte Lake and locally elsewhere, including Las Vegas and Maxwell NWR and other northern lakes. It has a somewhat more northerly distribution than Clark’s Grebe (Parmeter et al. 2002).    Ecology and Habitat Requirements Western 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). Western Grebes may tend to forage in shallower water, closer to shore, than Clark’s Grebes. Their diet includes a wide variety of fish species (Storer and Nuechterlein 1992).    Conservation Status Species Assessment   DISTRIBUTION  3  THREATS  4  GLOBAL POPULATION SIZE  2  LOCAL POPULATION TREND  3  IMPORTANCE OF NEW MEXICO TO BREEDING  1  COMBINED SCORE  13 Western Grebe is a Biodiversity Conservation Concern, Level 2 species for New Mexico, with a total assessment score of 13. It receives a vulnerability score of 4 from NAWCP for threats to breeding and non-breeding areas.     Population Size NAWCP estimates a North American breeding population of 110,000 (Kushlan et al. 2002). Total population for New Mexico is unknown, and year-to-year populations fluctuate depending on local conditions..   Population Trend Nationally, populations appear stable (Kushlan et al. 2002). No trend data are available for New Mexico. NMPIF assigns a score of 3 for local population trend, indicating 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 Maintain breeding populations at Las Vegas and Maxwell National Wildlife Refuges, Elephant Butte and the Jicarilla Lakes.    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.  Parmeter, J., B. Neville, and D. Emkalns. 2002. New Mexico bird finding guide. New Mexico Ornithological Society, Albuquerque, NM.  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.