When the nest box smelled of ferrets, the blue tits hesitated on entering. Image: Gustavo Tomás
Reading Birds, like other animals, are able to detect potential dangers of the smell: they can identify various attackers by their smell and change their behavior depending on the risk situation, researchers have discovered Luisa Amo de Paz of the Netherlands Institute of Ecology. In their experiments, the scientists placed various odors in the nests of blue tits and then examined the behavior of the parent birds. Many animals perceive enemies via the sense of smell, but in birds, this ability has hardly been studied. It is especially for those species that like blue tits nest their nests in poorly visible tree holes, a good sense of smell of advantage: they can determine whether martens or weasels, their main enemies, have come into the nest or approach from the outside.

To test to what extent the smell is important to the birds, the researchers around Amo de Paz prepared the nest boxes of blue tits with the exhalations of ferrets. Through a video camera placed a few yards away from the nest, they monitored the parent birds feeding the cubs. When the nest smelt of ferrets, the blue tits flew up the nest more often, without going in, the scientists observed. Although the parents fed their offspring as often as before, they spent less time overall in the nest. This reduced the risk of being attacked while feeding. The growth of the chicks was not affected.

In further experiments, the researchers used the smell of quail to find out how the birds reacted to unknown odors. In these experiments, the birds did not wait as long to enter the nest as they did to weather the ferrets, the researchers discovered.

Little was known about the sense of smell of birds for a long time. There is increasing evidence that the animals use it in many situations, such as foraging, orientation and individual identification of conspecifics. With the current study, the researchers now show for the first time that the smell also plays a major role in the perception of natural enemies. This discovery may help in understanding many aspects of the bird's life cycle, researchers conclude. display

Luisa Amo de Paz (Dutch Institute of Ecology) et al .: Functional Ecology, Vol. 22, p. 289 ddp / science.de? Michael Böddeker

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