ing habitat from 1958 to 1963; Low production rates caused population declines. 



Winter Redheads winter from southern British Columbia in the west and 

 southern New York in the east to southern Mexico and Guatemala and the Gulf 

 Coast States (Map 19), with a few in the Caribbean (Palmer 1976b). However, a 

 substantial majority of the winter population is found along the western Gulf 

 coast in Texas and Mexico. Texas and the east coast of Mexico combined held 

 77.8% of the approximately 703,000 Redheads counted on the January 1975 winter 

 waterfowl survey (Goldsberry et al. 1980). During the 1976 survey, approxi- 

 mately 718,000 birds were found (Larned et al. 1980). 



The next largest wintering concentration (ca. 50,000 birds) occurs in Apal- 

 achee Bay on the Gulf coast of Florida (Palmer 1976b). Smaller, but also im- 

 portant, concentrations occur in North Carolina and on the north-central Atlan- 

 tic coast of Florida (Map 19). 



Migration The principal migration corridors are overland from breeding 

 grounds in Idaho, Alberta, Saskatchewan, and Manitoba to the southern Gulf coast 

 of Texas and Mexico. Most of the Pacific coast wintering birds originate in the 

 west. Some birds from the northern prairies move eastward to the Great Lakes 

 and south to Chesapeake Bay or the Gulf coast of Florida. Migration is discus- 

 sed in detail by Lincoln (1934), Weller (1964) and Bellrose (1976). 



HABITAT 



Nesting The Redhead nests in dense stands of plants, preferring bulrushes, 

 cattails, or sedges on and around marshes and potholes of the prairies and park- 

 lands. Redheads prefer extensive marshes with shallow water openings (Palmer 

 1976b); hardstem bulrush ( Scirpus acutus ) is the preferred nesting cover over 

 much of the range (Bellrose 1976, Palmer 1976b). Nest sites are usually over 

 water, but some are on islands or on land near water (Bellrose 1976). 



Feeding Redheads feed more in shallow marshes and ponds than do many of 

 the diving ducks (Bellrose 1976). During migration they are often found on 

 shallow, slow-moving rivers and lakes (Palmer 1976b), and on fresh and slightly 

 brackish estuarine bays with much submerged aquatic vegetation (Johnsgard 1975). 



Winter and Offshore Redheads winter primarily on either saline waters that 

 are rich in plant foods , such as coastal bays and lagoons , or large inland lakes 

 and reservoirs (Palmer 1976b). Weller (i_n Johnsgard 1975) indicated that win- 

 ter habitat was typically well protected, fairly shallow, brackish or highly sa- 

 line waters along the coast. Migrants and wintering birds are often found in 

 compact rafts (Palmer 1976b) that may contain large numbers of birds. Rafts in 

 Florida contain from 5,000 to 20,000 ducks; as many as 80,000-90,000 have been 

 observed off Cedar Key, usually 5-15 mi (8-24 km) offshore. A raft in Texas 

 held some 76,000 birds. During windy weather on the lower Laguna Madre, these 

 birds may congregate in water so shallow they barely float (Palmer 1976b and 

 authors cited therein). Redheads wintering in the lower Laguna Madre clearly 

 preferred areas of shallow water over hard sand vegetated solely with shoalgrass 

 ( Halodule beaudetti ) . Areas with more luxuriant stands of shoalgrass in deeper 

 (1-2 m = 3.3-6.6 ft) water were rarely visited (Cornelius 1977). 



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