Unleashed: walking dogs off the lead greatly increases habitat disturbance in UK lowland heathlands

Human population growth is associated with increased disturbance to wildlife. This effect is particularly acute in urban and periurban areas, where the area of effective disturbance extends beyond that of human presence by the roaming behaviour of pet dogs. Dogs are globally the dominant companion animal, with a population of ~ 12 million in the UK. As urban areas extend, dogs are exercised in green space close to housing. In southeast and southern England these areas include lowland heath, a habitat of high conservation value. To quantify disturbance caused by dog walkers and their dogs, we used GPS units to track the movement of people and their dogs across four lowland heath sites, used a questionnaire to ask about dog walking habits, and mapped potential areas of disturbance caused by dog walkers. Questionnaires were completed by 798 dog walkers and the walks of 162 owners and their 185 dogs were recorded. Mean (± SE) walk time was 56 ± 23 min, walk distance 3.75 ± 1.68 km and dogs were a median distance of 20 m from the owner during walks. Dogs were walked once (44%) or twice (56%) a day. Most (always: 85%; always or occasionally: 95%) dogs were walked off the lead even when signs were present requesting that dogs were kept on a lead. This resulted in up to a 21% increase in reserve area disturbed. In one reserve (Snelsmore Common), > 90% of the area was disturbed by dogs, greatly eroding its conservation value. This work highlights the importance of considering how dog ownership can exacerbate levels of disturbance in sensitive periurban habitats when housing developments are planned.