Reproducibility study disproves a
popular hypothesis about how pigeons successfully return home
Date: July 26, 2018
Source: Springer
Homing pigeons use familiar
smells to navigate their way across hundreds of kilometers of unfamiliar
territory. Researchers have now confirmed that artificial odors cannot be used
to stimulate or trigger a pigeon's navigation system. This means that the
so-called olfactory activation hypothesis -- which has been proposed by some
researchers -- should be disregarded, argues Anna Gagliardo of the University
of Pisa in Italy. Gagliardo and her colleagues have published their research in
Springer's Journal of Comparative Physiology A.
The researchers set out to test
the olfactory activation hypothesis proposed by a team of Portuguese and
American scientists in 2009 and 2010, by using similar steps and methods. In
order to replicate the study, Gagliardo and her colleagues used 63 adult
inexperienced pigeons that were allowed to perform spontaneous flights in their
home area. The birds were divided into three experimental groups then each
fitted with a GPS-tracking device, and released singly 53 kilometers from home.
The first group was transported
in open crates and released without manipulation. Pigeons in group two were
carried and kept at the release site in airtight containers ventilated with
natural air before they were released. The third group also travelled in an
airtight container, with the air filtered to remove most of the natural
odorants it might contain. During their travels and before their release, the
birds in this group were exposed to the scents of lavender, eucalyptus, rose
and thyme. Prior to their release, the nasal cavities of the birds in the
second and third groups were washed with a zinc sulphate solution in order to
make them temporarily unable to smell.
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