At Kibale National Park in Uganda–a protected rainforest home to chimpanzees, leopards, and the occasional lion–rangers often can’t connect to the internet when they’re on patrol. But a new app called Forest Watcher is helping connect them to near real-time satellite data on illegal logging, mining, or forest fires to help alert them to incidents they need to inspect.

The app is an extension of Global Forest Watch, a project that maps deforestation around the world. “We monitor forests from space, and we can see deforestation happening every single week using satellite data and algorithms,” says Rachael Petersen, acting director of Global Forest Watch at World Resources Institute, the organization that runs the program. “But the reality is that many of the people who are on the front lines of deforestation, whether those are park rangers in national parks or indigenous people who live in the forest, don’t have access to internet connections or desktop computers to be able to utilize this wealth of information that we’re producing.”

With the new tool, if someone has a smartphone and enough internet access to download the app and the latest data, they can then take it offline. Using GPS, which doesn’t require an internet connection, the app can guide rangers to an area that is being deforested. From a remote area of a forest, a ranger can also add photos, video, text, and mark points with GPS, all of which could later be uploaded to the cloud when they later go online. A later feature may send text alerts when users walk near an area being illegally logged.

Rangers in Kibale who work with the Jane Goodall Institute have been beta testing the app for the last several months, and were able to use it to discover a part of the park that was being cleared by tea producers, far from their usual patrol routes. “I’ve seen forest rangers using these alerts to navigate to areas and identify an illegal clearing that they wouldn’t have known about otherwise,” says Peterson. “I think it’s really critical in very large forested areas, where you can’t possibly physically know what’s going on.”

The satellite data, she says, can’t stop deforestation without strong governance and enforcement. But as people chopping down trees begin to realize that technology can catch them more quickly, behaviors may change. “In Uganda, we heard stories that the rangers in the park had special powers because they seemed to just know where deforestation was taking place,” she says. In Brazil, a 2015 study found that illegal loggers are clearing smaller areas to try to avoid detection from space.

Change needs to happen quickly to keep up with deforestation; in Brazil, for example, the deforestation rate last year was 29% higher than it was the year before.

Correction: This article misstated what year the study about illegal loggers in Brazil was published, it was 2015, not 2016.