Pressures on UK wildlife

Each pressure on UK wildlife works through a different mechanism, and the mechanism decides what actually helps.

Habitat loss

A species that loses the place it feeds, breeds or shelters in has nowhere to move to if that place is not replaced elsewhere. Habitat loss happens through building, drainage, ploughing of previously uncultivated ground and the removal of features such as hedgerows and ponds, and its effect compounds where the remaining habitat is fragmented into patches too small or too isolated to support a breeding population.

Pollution

Pollution changes the chemistry of the water, soil or air a species depends on, often without killing anything outright. Nutrient runoff from farmland and sewage overflow into rivers feed excessive algal growth that starves the water of oxygen, while pesticide residue can affect the invertebrates that sit lower in the food chain, with effects that show up at a level most people never see.

A changing climate

A changing climate shifts the timing of seasonal events, such as when insects emerge or when migratory birds arrive, and moves the geographic range in which a species can survive. Where a species cannot move fast enough to track a shifting range, or where its food source and its own life cycle fall out of step, the mismatch shows up as a decline even where the habitat itself is untouched.

Invasive species

A non-native species becomes a pressure when it outcompetes, preys on or brings disease to species that have no defence against it, having arrived without the predators or competitors that kept it in check where it came from. The effect depends heavily on the species and the setting, from a plant that shades out native ground cover to an animal that displaces a native competitor from its own habitat.

Land-use change

Land-use change is close to habitat loss, but it looks at a whole region over time: the conversion of one type of land, such as unimproved grassland or wetland, into another, such as intensive arable farming or built development. It's worth treating on its own, because the direction of change across a whole region, not just the loss of one site, decides whether a species has anywhere left to go.

Wildlife crime

Wildlife crime covers offences against protected species and their habitats, including the illegal killing of birds of prey, the destruction of bat roosts and the disturbance of protected sites. It is a matter of enforcement, and its scale is harder to measure because much of it goes undetected or unreported.

Disease

Disease can spread through a wild population quickly where individuals live at high density or where a pathogen is new to a species that has no resistance to it. A disease introduced from outside the UK, or one that spreads from livestock into wild populations, can affect a species across its whole range in a way that no single local action can reverse.

The Joint Nature Conservation Committee (JNCC) publishes the UK Biodiversity Indicators, the UK-wide set of measures used to track how these pressures and their effects are changing over time.