Protecting habitats and biodiversity is one of the key objectives of the Deer Initiative. Ultimately, a healthy and diverse natural environment can maintain healthy and viable populations of deer. They are dependent on the habitat in which they live and at the same time they have variety of impacts upon it.
Deer at relatively low densities can be responsible for helping to create a variety of levels of open space in a habitat and this can have a positive influence on biodiversity, but where deer impacts are too intensive the effect is nearly always negative both for their habitat and ultimately their own health and wellbeing.
There are six species of deer (four are introduced, non-native) living wild in the UK, all are increasing their range, and deer numbers are known to have risen in many areas.
Deer have evolved as prey animals and prefer to spend their time in cover or where they feel secure. With a large rumen they can ingest large quantities of bulky plant food then return to safe areas to lie down (couch) and ruminate (chew the cud). Deer graze and browse, that is, taking ground-level plants as well as food from higher shrubby plants and trees. Each species has its own preferences which may vary according to habitat; some are especially selective in their feeding habits. In woodland habitats, succession and structure may be modified as a result of the activities of deer. Heavy browsing modifies the form of seedlings, often preventing a shrub layer developing and in old woodland creates a browse line beneath which no young living tree shoot survives. Selective browsing can radically alter the proportions of different plant species present and even eradicate some. Deer can also be very destructive to trees, damaging them by browsing and by debarking when they remove the velvet from their antlers by rubbing them against tree trunks.
Individual habitats can tolerate a certain number of deer without them being permanently harmed or changed. Unfortunately deer numbers, if not carefully managed, can easily exceed the "carrying capacity" of a habitat. The consequences vary but commonly those plants that can tolerate deer impacts may survive or even thrive while those that are vulnerable perform badly or may be greatly diminished or lost. The physical structure of woodland and its ability to regenerate naturally can also be affected. In addition, fauna such as birds and butterflies that are dependent on certain plants or on a particular woodland structure can be negatively affected by high deer numbers.
Even before habitats are seriously affected by high numbers of deer there may be other human interests that require that numbers are kept under control. Deer vehicle collisions, and damage to agricultural and forestry crops can all be significant, meaning that there may be a "cultural carrying capacity" above which deer numbers become harder to tolerate.
Increased fragmentation of available habitat from competing land-use and encroachment of urban development further into the countryside, can also bring deer into closer contact with humans. At present deer populations are not always so large in all parts of the country as to threaten established woodland and other ecosystems, but populations and distributions continue to change and under conditions that allow them to multiply rapidly, the outcome is often widespread ecological, economic and cultural damage. The Deer Initiative has focused much research on the problem of deer management from the point of view of maintaining a viable population of deer which is not too destructive. It has become clear that effective management needs to be considered (and integrated) within a wider framework of how deer themselves and their management relate to other land-management aims and objectives in more general terms. Similarly to be effective management must be carried out at the landscape scale, or at least at an equivalent geographical scale to that of the range of population to be managed. Management decisions must take into account both positive benefits and negative impacts of deer across the landscape mosaic and land-use objectives (agriculture, conservation habitats, as possible vectors of disease for humans or domestic livestock, deer-vehicle collisions etc) as well as within a purely woodland or forestry context.
The Deer Initiative is working with a wide range of stakeholders to tackle these diverse challenges, and we are helping our Partners in Government to develop the right framework to support and find solutions for the protection of biodiversity.