Mapping the Flickr of night lights

“Take nothing but pictures, leave nothing but footprints” goes the old saying. Scientists looking to better conserve the natural values of our planet are now using the information on where these pictures were taken to prioritise our conservation efforts.

As human populations grow, our impact on natural areas beyond urban centers is rapidly increasing. There’s a need to estimate not only where people live and work but also where humans are found in the more remote and natural areas, which are often the targets of protection efforts.

“Apart from a few well-monitored national parks, spatial patterns of human recreational activity remain largely unknown,” explains Associate Professor Noam Levin from CEED and the University of Queensland. “And we need accurate data about human presence in remote areas to help guide our conservation efforts.”

Levin and colleagues developed an innovative analysis that combines information from social media with remote sensing (Levin et al 2015).

“We combined an analysis of ‘big data’ coming out of Flickr, a social media site where people load up their geo-tagged photos, with remote sensing data that records artificial night lights,” says Levin. “We used data from the Flickr photo-sharing website as a surrogate for identifying spatial variation in global visitation, and complemented this estimate with spatially explicit information on stable night lights between 2004 and 2012. The night lights help us identify urban centers.”

Natural regions attracting visitors were defined as areas both highly photographed and non-lit. The researchers confirmed that the number of Flickr photographers within protected areas was a reliable surrogate for estimating visitor numbers by comparing the information with local authority censuses.

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While most photos are taken by people outside protected areas, the millions of Flickr photos uploaded to the internet combined with night-light imagery allowed the researchers to map and quantify, for the first time, worldwide visitation of both protected and unprotected areas. This enables the identification of visitation hotspots (and coldspots) for multiple countries and ecoregions across the world.

“The technique we have developed has many applications,” says Levin. “It can be useful for assessing the gaps of future protected area, help in devising strategies, and enhance the effectiveness of protected area management in relation to visitor pressure.”

More info: Noam Levin


Levin N, S Kark & D Crandall (2015). Where have all the people gone? Enhancing global conservation using night lights and social media. Ecological Applications 25: 2153–2167.

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