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Reproductive Parameters and Egg Contaminant Levels of Great Lakes Herring Gulls
A. P. Gilman, G. A. Fox, D. B. Peakall, S. M. Teeple, T. R. Carroll and G. T. Haymes
The Journal of Wildlife Management
Vol. 41, No. 3 (Jul., 1977), pp. 458-468
Stable URL: http://www.jstor.org/stable/3800517
Page Count: 11
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Poor reproductive success and declines in colony size of herring gulls (Larus argentatus) have occurred in Lake Ontario at a time that dramatic increases of this species have been reported on the Atlantic seaboard. In 1975 herring gull productivity on Scotch Bonnet Island, Lake Ontario, was 0.15 chicks per pair of adults, one-tenth the productivity of colonies studied on Lakes Erie, Huron and Superior. Reduced nest site defense and decreases in eggs found, egg hatchability and chick survival were observed in the Lake Ontario colony. The major causes of egg failure were disappearance and embryonic death. Hatching success of Lake Ontario eggs by artificial incubation was 23-26 percent compared to 53-79 percent for eggs from other areas. Analyses of eggs from 9 gull colonies for organochlorine contaminants indicated that the pattern of relative contamination was: Lakes Ontario > Michigan > Superior > Huron > Erie. Mirex levels were nearly 10 times higher in Lake Ontario than in the other lakes. Movements of herring gulls within the Great Lakes basin are offered as an explanation of variation in individual egg residues in each colony and the moderately high levels of chemical residues in some Lake Superior eggs.
The Journal of Wildlife Management © 1977 Wiley