Whether it's due to climate change, population growth or conservation, contact between wild animals and humans in the United States are on the rise.

Nowhere is this more so than in communities throughout the Rocky Mountains. In the area around Durango, in south-western Colorado, there were more than 1,500 reported sightings of black bears last year - with almost two-thirds of respondents reporting bears digging into their rubbish bins.

Are the increased sightings due to more bears or bolder bears?

In an effort to understand why such contacts are becoming more frequent, a team of researchers from Colorado's Parks and Wildlife service is in the middle of a five-year study tracking the movement of Durango's bears.

The BBC's Paul Adams travelled with the team as it checks up on one female black bear, known simply as Bear 57.

Produced by Robert Brown. Filmed by David Eckenrode. Edited by William McKenna.