The Royal Society for the Protection of Birds (RSPB) is a conservation charity based in the UK.
The Big Garden Bird Watch is the world's biggest citizen based wildlife survey.
Over the course of one weekend over half a million people spent an hour observing the number and different types of bird species in their backgarden.
This scatter plot shows the mean number of species spotted at any one time against the percentage of gardens in which they were spotted in.
Source: RSPB, 2015