Koenig, now a science advisor on the GROVER Project, asked Hans-Peter Marshall, a glaciologist at Boise State University to bring in his expertise in small, low-power, autonomous radars that could be mounted on GROVER.

ENGADGET: NASA's GROVER eco-rover to examine Greenland's ice sheet (video)

Project leader Dr Rupert Marshall explained how the city bird song was captured.

BBC: Birds in cities 'singing louder'

Dr James Marshall, a computer scientist at the University of Sheffield co-ordinating the project, said simulating a brain was one of the "major challenges" of artificial intelligence.

BBC: Bee brains help to make robots smarter