Humans use lavender to keep moths from destroying woolen garments. Now it appears birds resort to similar tactics. A new study reveals that tiny birds on the French island of Corsica may decorate their nests with sweet-smelling herbs to keep them free of pests.
Many ecologists think that smell plays little role in birds' lives, says Marcel Lambrechts of the Functional and Evolutionary Ecology Center in Montpellier, France. Birds that add aromatic material to their nests, some scientists argued, do it for visual effect, to attract mates.
Now, in the July issue of Ecology Letters, Lambrechts and his colleagues report that Corsican blue tits (Parus caeruleus) deck out their nests with fragments of 10 or more fragrant plants including yarrow, lavender, mint, and lemon balm. While the parents were out shopping, the scientists experimentally removed all fresh plant material from 64 nest boxes, which were home to blue tits and their chicks. They then hid aromatic plant material--which could be smelt but not seen--in half the nests. The birds coming home to herbless nests flew off to collect fresh material. However, those in nests with hidden herbs didn't react until the second day, when the aroma began to wane.
The scientists believe that the herbs are placed in the nests for protection, because many of those collected possess chemical properties that kill or repel mites, bacteria, and viruses.
"This study clearly demonstrates that blue tits can smell," comments Simon Griffith, a zoologist at the University of Oxford, United Kingdom. The innovative behavior may be unique to Corsican tits, adds Bart Kempenaers of the Max Planck Research Center for Ornithology in Seewiesen, Germany--perhaps because they face greater pest threats or because aromatic plants are more available there than in other parts of Europe.