Nests and eggs of colonial birds nesting in Malheur Lake, Oregon, with notes on DDE

We describe the nests and eggs of 7 species of colonial birds that nested on Malheur Lake in Malheur National Wildlife Refuge, Oregon, in 1980 and 1981. All nests were constructed over water in stands of hardstem bulrush (Scirpus acutus). We compared nest measurements among species and found significant differences. Nest size was highly correlated with bird body mass. The heavier the bird, the larger the nest and the higher the nest crown was above water. Egg volume was also highly correlated with body mass. We found evidence of shell thinning and DDE residues in great egret eggs and low levels of pesticide residues in eggs of Franklin's Gull. We summarize all available DDE and shell thickness data from colonial bird eggs collected from Malheur Lake.