. The Canadian field-naturalist. 2000 SUYDAM, QUAKENBUSH, DiCKSON, AND OBRITSCHKEWITSCH: MIGRATION OF ElDERS 445 water. The site afforded a view of eiders migrating along the nearshore lead edge as well as along the beach approximately km to the east. For safety, we switched to a second site on 8 May, approximate- ly 200 m from the lead edge and the first site. We began counting migrating eiders on 1 May and con- tinued until 2 June. Two to four observers counted eiders for up to twelve hours a day ( two hours out of every four) during the 24 hours of daylight in the Arctic spring and
. The Canadian field-naturalist. 2000 SUYDAM, QUAKENBUSH, DiCKSON, AND OBRITSCHKEWITSCH: MIGRATION OF ElDERS 445 water. The site afforded a view of eiders migrating along the nearshore lead edge as well as along the beach approximately km to the east. For safety, we switched to a second site on 8 May, approximate- ly 200 m from the lead edge and the first site. We began counting migrating eiders on 1 May and con- tinued until 2 June. Two to four observers counted eiders for up to twelve hours a day ( two hours out of every four) during the 24 hours of daylight in the Arctic spring and summer (Figure 1). On some occasions (33 of the two-hour-counts periods), counts could not be conducted because of unsafe ice conditions or dense fog. We counted for a total of 330 hours (165 two-hour count periods) during spring migration. During summer and fall, we observed migrating eiders from the base of the Point Barrow spit (71 "21' N, 156° 36' W). One to three observers counted eiders for up to 10 hours a day, spread throughout the day, from 10 July to 16 October (Figure 2). During July and August, we usually counted for about 8 hours a day, but later the shortening day length limit- ed observation time. In October, we were able to count for only two hours a day. We counted for a total of 406 hours during summer/fall migration. We generally used the same methods to collect and analyze data as described by Suydam et al. (1997). For each counting period we collected data on weather (, cloud cover, fog, precipitation, etc.), temperature, visibility, wind speed and direction. For each flock sighted, we recorded time, direction of travel, species composition, number sighted, ratio of males to females for each species, and other perti- nent comments ( interesting behavioral observa- tions of migrating birds). We calculated point esti- mates for the total passage of King and Common eiders in a manner similar to how Suydam et al. (1997) calculated estimates for 19
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