Ecotourism is a popular emerging industry where vacationers can travel to relatively untouched natural environments to learn about and catch a glimpse of rare wildlife. Proceeds from ecotourism ventures generally go towards conservation efforts or bolstering local economies, and the practice has allowed remote areas in developing countries to attract tourists without the construction of fancy hotels and amenities.

According to a press release from the University of California, Los Angeles, however, ecotourism does little to benefit the wildlife in these areas, and in some cases can actually pose significant risks to threatened species.

A recent study, published in the October 9 edition of the journal Trends in Ecology and Evolution, shows that ecotourism can lead wild animals to alter their behavioral patterns in a manner that puts them at serious risk. The study reviewed the findings of more than 100 prior studies on specific ecotourism destinations.

More than 8 billion people visit protected areas around the world annually. According to the study’s lead author and professor and chair of ecology and evolutionary biology at UCLA, Daniel Blumstein, the presence of humans in wild environments can lead to rapid changes in the way species interact with each other. It may make some species more vulnerable to poachers or other predators.

When animals interact with humans, Blumstein wrote, they are likely to let down their guard and become more relaxed. This newfound confidence can have devastating results when these species run into a predator or a dangerous situation. Humans are likely to “spoil” animals into thinking that they don’t need to work hard to survive.

Humans can also scare off predators, which can lead to the propagation of huge numbers of smaller prey species. This can result in extreme resource competition, and in some cases can collapse entire ecosystems. For example, vervet monkeys tend to congregate around humans because they know the predatory leopards are scared away. Similarly, elk and pronghorns in Grand Teton National Park spend more time grazing when they know humans are present.

As species become accustomed to human presence, they begin to shift the patterns of natural selection. Traits that would otherwise be useless suddenly become beneficial, and this can drastically alter the role a species plays in a given ecosystem. The increased risk of predation is one of the most salient examples.

Ecotourism can have similar results on animals to domestication and urbanization. Whether intentional or otherwise, human presence has a “taming” effect on animals, who look to us for protection and often food. Feeding wild animals can quickly shift their preferences for finding food, and is strongly discouraged in nearly every possible circumstance.

The study offers new insights into the ecological effects of ecotourism, revealing that it’s not a perfect alternative to a traditional vacation in terms of impact on the environment. Humans can pose risks to wildlife wherever they go, especially if that wildlife isn’t used to human presence.