Urban ecology The cities where the wild things thrive alongside humans

In the Sapzurro bay on the Colombia-Panama border, the blue land crab can be found scuttling below concrete structures, burrowing in the nooks and crannies of the coastal settlement.

- Sofia Quaglia

The species, which can grow up to 15cm and range in colour from violet to bright cerulean blue, is considered critically endangered or vulnerable in this region. It traditionally lived in the region's rich mangrove forests, many of which have now been urbanised - habitat loss that scientists have blamed for the crab's decline.

But when scientists studied the distribution of the species around Sapzurro bay, they were surprised to find it was still thriving in sections of the bay where vegetation had been eliminated. While burrows in urban areas were fewer and smaller, it had successfully built homes along sewage canals and among houses.

A growing body of research is collecting data on species like this crustacean - threatened wildlife learning to thrive in urban spaces alongside humans.

"We often forget that we are dealing with living animals," said José Marin Riascos, a marine ecologist at the Corporation Centre of Excellence in Marine Sciences of Colombia, who published the study on the blue land crab in April this year. "They are not passive, they are active. If you change something, then they answer with another change."

These findings also complicate the long-held idea that cities cannot be hotspots for animals and plants. "We are assuming that when humans modify an ecosystem, the habitat for the biodiversity is lost," said Riascos. "That is not always the case."