Encountering humans can reduce animals’ fear of natural predators thereby impeding their security.

A new study reveals that eco-tourism is exposing wild animals to danger because encountering humans reduces their fear of natural predators.

Human encounter with mammals and birds alters their ‘anti-predator’ reactions and impedes their survival in the wild when they encounter predators.

Biologists conducted about 200 scientific studies to analyze alterations in several ‘anti-predator’ traits after human encounter.

Anti-predator traits are traits that enables an animal outwit a predator and survive.

It was discovered that encounters with humans in places like zoos and tourist centers reduces the natural ‘anti-predator’ impulses in multiple species.

Animals in the wild that live near cities and new urban developments are not left out.

Anti-predators reactions in animals includes : stunning the predator, mimicry – acting like another organism, hiding, disguise/camouflage, distraction – mostly by emitting chemicals, playing dead.

Anti-predator techniques differ between different species – from altering colour as a means of camouflage, to hiding in a hole, only coming out of their habitats at night, playing dead or running.

‘While it is well known that the fact of being protected by humans decreases anti-predator capacities in animals, we did not know how fast this occurs and to what extent this is comparable between contexts,’ explained Benjamin Geffroy from the Institute of Marine Biodiversity, Exploitation and Conservation in France.

‘We believe they should be systematically investigated to draw a global pattern of what is happening at the individual level.

‘We need more data to understand whether this occurs also with the mere presence of tourists.’

The researchers examined the results of 173 peer-reviewed researches analyzing anti-predator traits in 102 species of mammals, birds, reptiles, fish and molluscs.

The researchers observed the change in anti-predator reactions during encounter with humans under three varied contexts – urbanisation, captivity and domestication.


Here are animals that will possibly lose their anti-predator reactions after encountering humans, in three varied contexts.

– Domestication:

European sea bass, fox, chicken

– Captivity:

Atlantic silverside (fish), Vancouver Island marmot (rodent), red rock lobster

– Urbanisation

Common pigeon, Carrion crow, black-tailed prairie dog.

Animals demonstrated rapid alterations in anti-predator reactions in the initial generation after encountering humans.

This initial reaction is due to behavioural flexibility, which might then be supported by genetic modifications if human encounter is continued over many generations.

It was also discovered that domestication changed animals’ anti-predator reactions three times sooner than urbanisation, but changes in captivity was the slowest.

It’s possible that animals retained in captivity – like tigers and elephants in Africa – have less direct encounter with humans than those in domestic or urban environments.

It was also discovered that herbivores altered behaviour faster than carnivores and that lonely species were more inclined to change than those that live in groups.

‘Conserving the variety of anti-predator responses that exist within a population will ultimately help sustain it,’ the researchers say in their research paper.

‘This might involve intentionally exposing animals to predators or to predator-related cues for conservation purposes to prevent the loss of necessary anti-predator traits.’


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