The DDT doesn't break down or get excreted along the way, and the result is an osprey sick with a big load of DDT, and in particular, eggshells too thin to survive incubation. Happily, DDT was banned in the US in 1972, and since then many of our birds of prey have begun to recover, including the bald eagle, peregrine falcon, and the osprey. In some areas ospreys are again quite common, especially around the Chesapeake Bay and in the Pacific Northwest, including northern California. The breeding population was decimated in most areas early in this century by egg collectors, who coveted the beautiful eggs, and by gamekeepers, who considered raptors vermin. Under close supervision, ospreys have been recolonizing Scotland.
Ospreys remain from around the Baltic Sea eastwards.
I have seen ospreys in Estonia on the coast of Saaremaa Island and on a lake near the Latvian Border, as well as in Germany in the Lower Havel area of Brandenburg. This practice is devastating to migrating osprey and other birds. Habitat alteration or elimination is a general problem for all creatures, including the osprey. Reliable bets are the Blackwater National Wildlife Refuge on the Chesapeake and Mason Neck State Park and National Wildlife Refuge along the Potomac. These are the places where I have often seen the osprey, but they are found in many other places.