The title of world's smallest owl belongs to the elf owl (Micrathene whitneyi). This minute owl is about 12-14cm long (the size of a tin of beans) and weighs between 35-55g. It lives in the dry thorny deserts of the US and Mexico.
They are compact little birds, with yellow eyes, short tails, no ear tufts and larger-than-usual heads for their body size.
The elf owl likes to nest in old woodpecker holes and similar cavities in trees and cacti.
Its diet consists of insects such as crickets, beetles, moths, grasshoppers, cicadas, stick insects, wasps, spiders, small lizards, rodents and scorpions. Not bad for a little raptor.
Like most birds, the male attracts the female at the start of the breeding season by demonstratively singing to mark its territory. It sings from inside its nesting hole and feeds the female to show what a great father it will be.
Once coupled up, elf owls are known to nest together for survival in order to mob any potential predators such as snakes, mammals and bigger owls. They have one brood every breeding season.
Elf owls are known for their unique take on housekeeping: they will capture a thread snake (Leptotyphlops) and bring it back to the nest so that it can eat the parasites that could otherwise harm its tiny owlets. Tree ants are also welcomed into the nest to perform the same task.
When an elf owl captures a stinging creature such as a scorpion or wasp, it will manipulate its prey in its beak to remove unwanted body parts such as the sting or wings and neutralise the prey before offering it up to its chicks.
The the elf owl is also the smallest raptor in the world.