The breeding biology of western grebe was studied at Bear River Migratory Bird Refuge, Utah in 1973 and 1974. More than 300 nests were located and data gathered on nesting habitat and success. Western grebe at Bear River selected nest sites for nearness to open water of approximately 30 em in depth. At least one young was hatching in 21 percent of the nests. Avian predation and abandonment of nests following drops in water levels caused the greatest loss of nests. Chlorinated hydrocarbons monitored in western grebes showed DDE, DDD, PCB, 1260, and PCB 1254 levels in 24 breast muscle samples (wet weight) to average 12. 8, 0. 8, 3. 8, and 3. 5 ppm respectively. Contaminant concentration was found to be correlated to the condition of the bird as determined by visceral fat content. A significant (p<. 01) 2. 3 percent decline in western grebe eggshell thickness between preand post-DDT use periods was found. DDE was significantly (p<. 05) negatively correlated with eggshell thickness in western grebe. Contaminants were not linked to any reproductive failure in western grebe at Bear River MBR.

Since its inception, the National Wildlife Refuge System has been administered for management and restoration of habitat essential to the propagation and welfare of resident and wintering wildlife species. Acquisition of additional System units has been primarily directed to the benefit of the migratory bird resource. As of July 1, 1968 about 250 of the 321 refuge units were managed for the waterfowl resource (U. S. Department of Interior, 1968a). However, this growth of the System has been accompanied by an increase in recreational use of the refuges. In 1962, Public Law 87-714, the Refuge Recreation Act, was passed to provide direction for recreational development. The Act recognized that recreation must be limited in type and scope to avoid conflict with the primary wildlife management objectives. Although the primary function of the Refuge System is to meet the needs of wildlife, the entire System is based on the philosophical precept that the wildlife on these refuges is for the enjoyment of the public. It thus follows that refuges should provide for some public use. In recent analyses of America's resource picture, the fastest rising curves and projection are those of travel and the recreational use of wildlands (Clawson, 1963). Attendance records at our wildlife Refuges have grown at a rate of 12 percent annually. Except for boating and fishing at reservoir sites, the fastest growth in outdoor recreation since World War II has been in the use of National Wildlife Refuges (Clement, 1964).