Biologists at Bielefeld University make new discovery in zebra finches

The behavioural scientists Dr. Tobias Krause and Dr. Barbara Caspers from Bielefeld University have discovered that songbirds use their sense of smell for social communication and can apply this to distinguish relatives from non-relatives. The scientists' study is being published today (4 January) in the online version of the journal Biology Letters published by the renowned British Royal Society. Only recently, the two biologists were able to confirm that songbirds – in contrast to previous claims in the textbooks – have a sense of smell.

Animals need to be able to distinguish their relatives – be it to help each other search for food or build nests, or be it to avoid incest and prevent having deformed offspring. Previously, research had assumed that songbirds can certainly distinguish their relatives – but nobody was sure how.

The behavioural scientists at Bielefeld carried out experiments in order to find out whether songbirds can smell out their relatives. In one experiment, they placed zebra finches in a nest with unrelated chicks a few days after they had been hatched and let them grow up in these nests. About three weeks later, they placed these 'foster children' in front of two different nesting boxes. One of these contained material (coconut fibres and droppings) from the nest in which each chick had been hatched. Hence, it smelled like the chick's original home. The other nest was marked with material from the nest in which the chick had been reared with non-relatives. The result: The test chicks spent markedly more time close to the nesting box that smelt of its parents and siblings.

In another experiment, the researchers found that the chicks' preference for a home nest with a familiar smell was even stronger when more siblings had lived in it. 'Both experiments clearly show that zebra finches are able to recognize the smell of relatives', says Professor Dr. Oliver Krüger from Bielefeld University's Faculty of Biology.
The researchers consider that their findings can be transferred to other songbirds. Krause says: 'Because zebra finches – as representatives of the songbirds – can recognize their relatives by smell, we can assume that other songbirds possess the same or similar abilities to recognize relatives.' Moreover, other studies have shown that the genetic mechanisms for the perception of smells are also to be found in other types of songbird.

Krause and Caspers set up the experiments forming the basis for the new set of trials in September 2010. They had shown that songbirds have a sense of smell. Until then, the established belief had been that the "nostrils" in a bird's beak have no particular function. The researchers at Bielefeld found out that zebra finches use their olfactory organs to find their way back to their own nesting sites within their breeding colonies. This is particularly helpful to young fledglings, because when they fly for the first time, they still do not know how the breeding colony is organized and where to find their own nest in it. Hence, they are unable to orient themselves by sight. With their experiments, the two biologists confirmed that zebra finches prefer nesting sites that smell like their habitual nest.

The study is published in:
Biology Letters online on 04.01.2011 http://dx.doi.org/doi:10.1098/rsbl.2011.1093

Contact:
Dr. Barbara Caspers,
Faculty of Biology
Telephone: 0521 106-2825
Email: barbara.caspers@uni-bielefeld.de

Dr. Tobias Krause, Bielefeld University
Faculty of Biology
Telephone 0521 106-2841
Email: tobias.krause@uni-bielefeld.de

Prof. Dr. Oliver Krüger, Bielefeld University
Faculty of Biology
Telephone 0521 106-2842
Email: oliver.krueger@uni-bielefeld.de