Mountain biking is increasing within protected areas worldwide with social and environmental impacts. Monitoring recreational activities can be difficult, but nowadays massification of GPS use and track's sharing can provide new tools to help do so, lower resource consumption. This study compares GPSies. com and Wikiloc.com to evaluate the similarity between both, as data sources' and if this information can be used to spatialize and measure use intensity of mountain biking in Sintra-Cascais Natural Park's (PNSC), Portugal. Virtually all mountain biking GPS tracks available for Sintra and Cascais area of PNSC were downloaded, rasterized and analyzed using GIS software. Although GPSies provided almost twice the amount of tracks and was proved to be the best webshare service for PNSC's mountain biking, overall results from using either one of those services were similar. Results and Conclusions reveal that voluntarily given data can be adequate and should be used to monitor recreational activities within recreational and protected areas, and webshare services are a valid data source for such studies. MANAGEMENT IMPLICATIONS The increasing use of protected areas for recreational activities requires better and faster monitoring technics to help park managers deal with, and avoid, unwanted impacts. Previous work showed that GPS tracks voluntarily uploaded or created in sport dedicated webshare services might be a good information source to spatialize recreational activities. This study compares data from two webshare services, GPSies. com and Wikiloc.com, regarding mountain biking in Sintra-Cascais Natural Park (PNSC). Although the amount of data for PNSC's from both services is different, similar results can be drawn, providing quality information for monitoring purposes, on a low human and time resources budget. Crossing that information with road networks, habitat charts, among others can help park managers to identify where unwanted conflicts and impacts are more likely to occur. This approach can provide support to park authorities' decisions and actions for the sustainable use of recreational activities within protected areas. (C) 2016 Elsevier Ltd. All rights reserved.
