If the computed value of n was greater than 10 percent of N, the estimated 

 population size, then a revised n' was calculated to account for the finite- 

 ness of the population: 



n' = JT_ 



UN- 



COMMON MERGANSERS AND COMMON GOLDENEYES 



Common mergansers and common goldeneyes [Bueephala alangula) were 

 counted from the air as described above. All goldeneyes observed were 

 classified as common goldeneyes since no Barrow's goldeneyes (Bueephala 

 islandioa) were observed during ground surveys. Other studies performed 

 included merganser food habits analyses and brood observations of mergansers 

 and goldeneyes. 



Food habits analyses were qualitatively performed. The stomachs of dead 

 birds were opened and their contents identified. Where possible, the food 

 items were counted by kind; where not, the kinds of items were noted. 

 Mergansers, goldeneyes, white pelicans, and great blue herons were collected 

 with shotguns from boats on the river under the authority of federal and 

 state collecting permits. Appendix B shows the results of food habits 

 analyses for these four species. 



BALD EAGLES 



Bald eagle {Haliaeetus leuoooephalu) populations were also counted on 

 the census flights. Individuals with predominantly white heads and tails 

 were counted as adults (Southern 1967), and predominantly brown birds as 

 juveniles. Food items utilized were noted during both aerial censuses 

 and ground surveys. 



Bald eagles frequenting large nests near the river were closely observed 

 from the air to determine if the birds were nesting or simply roosting by 

 the nests. Similar reconnaissance was made of areas where marked eagles 

 had been reported. Attempts were made to relocate marked birds so that an 

 accurate description of the colored tags could be reported to the banders. 



GREAT BLUE HERONS 



Great blue herons {Avdea herodias) in rookeries and along the banks of 

 the river were counted on the census flights. The number of active nests 

 and the stage of laying, incubating, or brooding in some of the nests were 

 noted. Herons were observed in their feeding areas, and some were collected 

 for analyses of food habits. 



14 



