Birds identify eggs by 'colour'

Melbourne, July 5 (PTI) Avians are more intelligent
than you ever thought -- they use colour to identify eggs of
'parasite' birds, such as cuckoos, from their own and eject
them from their nests, a new study has revealed.

Researchers in Australia have found that birds have
the ability to recognise small changes, particularly in the
ultraviolet wavelengths, which helps them in distinguishing
between their own eggs and eggs of other birds.

According to lead researcher Dr Mark Hauber of
the University of Auckland, "Birds have very different visual
senses to humans, for example they can see ultraviolet
wavelengths where we cannot.

"Those birds which parasitically introduce their eggs
into the nest of other birds dramatically increase the amount
of time and energy needed to provision the nest.

"Our research shows that the peculiar abilities of
birds to perceive broad-spectrum colour is vital to recognise
their own eggs, and can identify small differences as well as
wavelengths that humans wouldn't be able to distinguish."

In their study, the researchers introduced eggs into
the nests of song thrushes in Australia and New Zealand,
painted in a range of colours close to the birds' own eggs.

They found that the birds ejected eggs of different
colours from their nests, particularly those with differences
in reflecting ultraviolet or short (blue) wavelength light,
the 'Biology Letters' journal reported.

The research was conducted in collaboration with the
University of Birmingham in Britain and Palacky University in
the Czech Republic. PTI