Effects of Human Persecution on European Raptors
Abstract
Persecution causes population declines only if it adds to the natural mortality and does not merely replace it. Large raptor species with slow breeding rates are less able to withstand heavy losses than are small species with fast breeding rates. Over the last 150 years, persecution has eliminated some of the bigger species from large parts of Europe and is still responsible for restricting the distribution of others. In Britain over this period, the ranges of several species have contracted and expanded again with the rise and partial decline in game preservation, with temporary expansions during two wars when gamekeepers were otherwise employed. Persecution is still restricting the breeding range of the Golden Eagle, the Buzzard, and the Hen Harrier in the British Isles to about half the potential.
In some lists of bounty payments, certain species declined or disappeared in the records during the operation of the scheme, suggesting that the killing itself reduced or exterminated them. But in other lists, no declines in numbers killed occurred over a long period, suggesting that hunters were merely cropping the population and causing no long-term decline. The importance of deliberate killing of raptors is shown by the large proportions of banded birds that were later recovered, and by the proportions of these recovered birds reported as shot. Recovery rates were as high (or higher) for some European raptors as for many game-bird and waterfowl populations exposed to regular hunting seasons. Widespread use of poison on meat baits has had the most damaging effects on European raptor populations, often where the procedure was aimed primarily against wolves or foxes. In recent years, the most commonly used poisons include strychnine, phosdrin, and alpha-chlorolos.
