PRODUCTIVITY OF NESTING SPECTACLED EIDERS ON THE LOWER KASHUNUK RIVER, ALASKA

We studied the chronology and success of nesting Spectacled Elders (So materia fischeri) along the lower Kashunuk River on the Yukon-Kuskokwi m Delta from 1991-1995. Nest initiation dates ranged from 16 May-22 Ju ne. Median nest initiation dates were correlated with the break-up of ice on the Kashunuk River. Clutch sizes declined seasonally, and mean clutch size varied among years ranging from 4.8-5.6 eggs. The frequenc y of nests containing inviable eggs (24% of successful nests, (x) over bar = 0.6 unhatched eggs per successful nest) did not differ among ye ars or nest initiation dates, and may be related to exposure to contam inants. The rate of partial depredation also did not vary among years or initiation dates (23% of nests, (x) over bar = 0.5 eggs taken/succe ssful nest). We detected no effect of marking or visitation on daily s urvival rate of nests. Nests initiated early in the year were more suc cessful than late nests; thus, early nesting females laid larger clutc hes and were more likely to nest successfully than late nesters. Nest success varied among years and declined from 73% in 1991 to 18% in 199 4. Nest success increased to 76% in 1995 when we reduced the Mew Gull (Larus canus) population on the study area. While inviability and part ial depredation averaged over 1 egg per successful nest, the productio n lost in nests that were abandoned or completely destroyed by predato rs was much greater. Our data indicate that Spectacled Elders nesting on our study area experience relatively high production; however, with out information regarding annual survival and recruitment. it is not p ossible to draw conclusions about population growth rates.