Osprey virtually disappeared from Clear Lake in the application era, and the decline of western grebes was the basis for a classic paper on food chain accumulation of chlorinated hydrocarbons. Osprey have had 13-20 successful nests each year on Clear Lake and fledging rates are consistent with at least maintenance reproduction.
Western grebes are abundant, but are breeding at very low rates, despite apparently good condition.
In comparison to western grebes at control Klamath and Eagle Lakes, grebes at Clear Lake have significantly higher mercury burdens. The situation with chlorinated hydrocarbons is quite different. DDT metabolites such as DDE are at regional background levels. DDD body burdens have fallen dramatically from levels in the 1960s and 70s. Future work will concentrate upon better understanding the current effects of mercury contamination at Clear Lake and upon reconstructing the past exposures of birds to the multiple stress of chlorinated hydrocarbons and mercury.