Rising stress from walkers and dogs linked to declining fertility in Veluwe’s red deer

Stress caused by human presence is significantly affecting the fertility of red deer on the Veluwe, with researchers warning that increased recreational activity is disrupting the animals’ reproductive health, as reported by Omroep Gelderlander. A new study reveals that female red deer, known as hindes, are producing higher levels of stress hormones, leading to a sharp decline in their fertility and overall health.

Between 1985 and 2015, the number of pregnant hindes dropped by over 10 percent, according to the study conducted by researchers Estella Ebbinge and Beau Strijker. "We didn’t anticipate that stress would have such a profound effect on red deer fertility," the researchers said.

Surprisingly, the study found that walkers and free-roaming dogs cause more stress to the deer than cars or hunters. The unpredictable nature of hikers emerging suddenly from unexpected places creates heightened anxiety for the animals. In contrast, cars, though noisy, are predictable and allow the deer to anticipate their approach.

Over the past three decades, hindes have lost an average of 8 kilograms, a consequence of the stress caused by human activity. Previous research has also shown that animals often experience more stress from humans than from predators, leading to reduced food intake and migration to areas with less suitable food. These disruptions hinder the deer’s ability to maintain necessary fat reserves for successful reproduction, putting their future fertility at risk.

Red deer on the Veluwe, a popular nature reserve, are increasingly exposed to human disturbance, particularly in open areas like heathlands. Research by predator expert Rob Bijlsma found that the number of visitors to the Veluwe has surged 19 times since 1968, with many people wandering off designated trails, further disturbing wildlife.

The consequences of increased human activity extend beyond red deer. Hares and ground-nesting birds, already vulnerable to disturbances, are also suffering from heightened stress. In hares, this stress is linked to fewer offspring. Researchers stress the need for better management of recreational activities in these sensitive habitats to prevent further harm to the wildlife.

To protect the red deer and other vulnerable species, experts are calling for stricter regulation of human activity in fragile nature areas. They suggest establishing designated zones with varying levels of allowed recreation to give animals the opportunity to rest and reduce stress. Visitors must also be better informed about the impact their presence has on wildlife. Although dogs are allowed in many Staatsbosbeheer nature reserves, they must be kept on a leash to prevent them from disturbing animals.