New York, Oct 10 (IANS): Ecotourism, in which travelers visit natural environments with an eye toward funding conservation efforts or boosting local economies, can actually be harmful for wild animals, a study says.

The presence of humans changes the way animals behave, and those changes may make them more vulnerable -- to poachers, for one, but also in less obvious ways, said the study's senior author Daniel Blumstein, professor and chair of ecology and evolutionary biology at University of California, Los Angeles, in the US.

When animals interact in seemingly benign ways with humans, they may let down their guard, Blumstein said.

The life scientists analysed more than 100 research studies on how ecotourism affects wild animals.

As animals learn to relax in the presence of humans, they may become bolder in other situations and if this transfers to their interactions with predators, they are more likely to be injured or killed.

The presence of humans can also discourage natural predators, creating a kind of safe haven for smaller animals that may make them bolder, the study said.

Interacting with people can cause significant change in the characteristics of various species over time.

"If individuals selectively habituate to humans -- particularly tourists -- and if invasive tourism practices enhance this habituation, we might be selecting for or creating traits or syndromes that have unintended consequences, such as increased predation risk," the researchers wrote.

Ecotourism has effects similar to those of animal domestication and urbanisation, the researchers said.

The research was published in the journal Trends in Ecology and Evolution.