Human activity ‘forces animals to move 70% further to survive’

Researchers analysed 208 separate studies of 167 animal species over 39 years to assess how human disturbance influences animal movement, writes Tom Batchelor

Badgers are on the move in response to UK cullings (PA)

Human activity such as farming and tourism forces animals to travel 70 per cent further to find food, shelter or a mate, the first study of its kind to consider the impact on global wildlife stocks over nearly four decades has found.

Australian researchers discovered that a wide range of animal species were negatively impacted by humans, from Swedish deer disturbed by skiers to spotted sand lizards in South Africa disrupted by intensive farming methods.

The research analysed 208 separate studies of 167 animal species over 39 years to assess how human disturbance influences animal movement.

They discovered that in more than one-third of cases, animals were forced into changes that saw movement increase by more than 50 per cent.

Across the study as a whole, the researchers noted an average increase in animal movement of 70 per cent where human activity was deemed to be a factor.

“Movement is critical to animal survival, but it can be disrupted by human disturbances,” said Tim Doherty, a wildlife ecologist at the University of Sydney, who led the study.

“Animals adopt behavioural mechanisms to adjust to human activity, such as by fleeing or avoiding humans, travelling further to find food or mates; or finding new shelter to avoid humans or predators.”

The study found that in some cases, human activity forced a reduction in animal movement, due to increased access to food near human settlements, a reduced ability to move from their human-modified habitat or restrictions to movement by physical barriers such as roads or railways.

“As well as the direct impact on animal species, there are knock-on effects,” Dr Doherty said.

“Animal movement is linked to important ecological processes such as pollination, seed dispersal and soil turnover, so disrupted animal movement can have negative impacts throughout ecosystems.”

The team led by scientists from the University of Sydney and Deakin University in Melbourne found that human activities such as hunting, aircraft, military activity and recreation were to blame for a much greater increase in distances animals moved than logging or farming.

This included badgers in the UK, which the study found increased their movements in response to the government’s culling programme.

Military manoeuvres in Norway triggered an increase of 84 per cent in the distances travelled by the local elk population, the study published in the journal Nature Ecology & Evolution found. 

Elsewhere, cross-country skiers in Sweden caused a 33-fold increase in movement speeds of elk in the first hour after a disturbance.

In South Africa, spotted sand lizards in overgrazed areas moved more frequently and over larger distances than those in less disturbed areas.

“In marine environments and landscapes relatively untouched by human impact, it is important that habitat modification is avoided,” Dr Doherty said.

“This could involve strengthening and supporting existing protected areas and securing more areas of wilderness for legal protection.”

He added: “Where habitat modification is unavoidable, we recommend that knowledge of animal movement behaviour informs landscape design and management to ensure animal movement is secured.”

Species covered in the study ranged from a sleepy orange butterfly weighing just 0.05 grams to the more than 2,000 kilogram great white shark. 

There were 37 bird species, 77 mammal species, 17 reptile species, 11 amphibian species, 13 fish species and 12 insect species covered.