As an adult, his interest in the nocturnal mammals grew to the point of obsession.

Nocturnal mammals may have little or no color vision.

They can also be identified by their long whiskers, common to nocturnal mammals.

Most people recognise badgers by their black- and white striped head, but because they are nocturnal mammals, they are rarely seen.

Nests, including incubating adults, chicks and eggs, are vulnerable to predators, particularly snakes but also nocturnal mammals.