Pheasants, buzzards, and trophic cascades.

The partial recovery of large birds of prey in lowland Britain has reignited conflicts with game managers and prompted a controversial U.K. government proposal to investigate ways of limiting losses to pheasant shooting operations. Yet best estimates are that buzzards are only a minor source of pheasant mortality-road traffic, for example, is far more important. Moreover, because there are often large numbers of nonbreeding buzzards, local control of breeding pairs may simply lead to their replacement by immigrant buzzards. Most significantly, consideration of the complexity of trophic interactions suggests that even if successful, lowering buzzard numbers may directly or indirectly increase the abundance of other medium-sized predators (such as foxes and corvids) which potentially have much greater impacts on pheasant numbers. To be effective, interventions need to be underpinned by far more rigorous understanding of the dynamics of ecosystems dominated by artificially reared, superabundant nonnative game species. [ABSTRACT FROM AUTHOR]