Blue tits embrace 'aromatherapy'

Blue tits use medicinal plants to disinfect their nests, scientists have discovered.

The birds line their nests with aromatic plants such as mint or lavender, which kill bacteria.

That creates a more sterile environment for chicks, which in turn grow faster and have a better chance of survival.



However, individual blue tits are quite picky about which plants they use, and it is not clear how they pass their knowledge on to other birds. On Corsica, blue tits (Cyanistes caeruleus) also incorporate fresh fragments of aromatic plants including lavender, mint and curry plants into their nests.

"We hypothesised that aromatic plants used by blue tits had some anti-parasite properties, because most of these plants, or close species of the same genus, are traditional Mediterranean plants with well-known medicinal properties," says Adele Mennerat, a biologist now at the University of Bergen in Norway.

No other bird has yet been shown to use aromatherapy in the same way, while related species such as the great tit or coal tit do not even decorate their nests with such plants. So it is unclear how the behaviour originated in blue tits.