Disease and contaminants pose major risks to wildlife and human populations. Although disease is a natural driver regulating the dynamics of wildlife populations, some diseases warrant particular attention because they:
- cause major mortalities that lead to population crashes of affected species and their predators, (e.g. myxamotosis in rabbits)
- threaten wildlife species of high conservation concern (e.g. squirrelpox virus in red squirrels)
- pose a potential threat to Man (e.g. rabies, avian influenza).
The risk that environmental contaminants can pose to wildlife populations has been repeatedly demonstrated, classic examples being the impact of organochlorine pesticides on predatory birds and mammals from which populations are still only recovering. Assessment of the risks posed by disease and contaminants to wild vertebrates (and through them to Man) typically involves monitoring occurrence and severity in key organisms.
Various monitoring schemes have been developed in the UK. They fall roughly into two categories:
- disease or contaminant-specific monitoring that is often focussed on a single disease/contaminant and sometimes a single species (e.g. TB in badgers (Meles meles))
- surveillance of one or more sentinel species, usually for multiple diseases and/or contaminants.