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Birds Can Detect Predators Using Smell

Birds Can Detect Predators Using Smell
http://tinyurl.com/5xnrvq

The use of smell to detect chemical signals can be useful for birds in
various situations, such as feeding and orientation. However, they can
greatly increase their chances of survival if they can tell whether or
not the smell they have detected is associated with a predator. Luisa
Amo de Paz, the study’s lead author, explained that: “Birds can detect
the presence of a predator� thanks to their sense of smell. Working as
a biologist at the Spanish National Research Council’s (CSIC) Natural
History Museum while the study was carried out, Ms. Amo de Paz is
currently working for the Netherlands Institute of Ecology
(NIOO-KNAW).

The research, published in the latest issue of Functional Ecology,
provides the first ever evidence to show that birds are able to
distinguish their predators using chemical signals. According to the
researchers at the CSIC’s Natural History Museum, this study “opens up
a new and promising area of research in understanding numerous aspects
of bird behaviour, which have been ignored until now.�

The sharpness of the sense of smell among certain birds, especially
those that raise their young in holes in trees, such as some of the
tit species, is essential for determining whether their major
predators, weasels or martens, have got into their nests or are
approaching, particularly because of the limited visibility inside
their nests.

Experiment with blue tits

The researchers carried out an experiment with a population of blue
tits that raise their young in nest boxes in Miraflores de la Sierra
in the Sierra de Guadarrama mountains, in Madrid province. The
researchers placed the scent of mustelids (ferrets) inside the nest
boxes when the chicks were eight days old, and “the parents took
longer to enter the boxes to feed their chicks, and they approached
the boxes more often without going inside,� Ms. Amo de Paz told SINC.

Thanks to the images captured by a video camera located several metres
from the nest box, the scientists were able to work out the number of
times the chicks were fed, and deduced that the birds did not feed
their chicks on fewer occasions, although “they spent less time inside
the nest while feeding their babies,� according to the biologist. By
spending less time in the nest box, the parents lessened the risk of
predator attack while still feeding their chicks.

The biologists added the scent of quail in other nest boxes in order
to monitor the effect of a new smell on the blue tits’ behaviour, and
water in others to monitor the effect caused by moisture. This
demonstrated that when the birds detected an unknown smell, such as
that of the quails, they did not wait such a long time before entering
their nests, and did not reduce the amount of time spent feeding their
chicks.

When the chicks were 13 days old, the scientists topped up the
corresponding scent for each nest box, and measured the results again.
Ms. Amo de Paz said this was to “see whether the ferret scent had had
an effect on the chicks’ physical condition�, given that their parents
had spent less time inside the nest. The conclusions show that the
chicks’ growth was not affected during the time they were exposed to
the supposed predator. The researcher thus concludes that “birds are
able to detect the chemical signals of predators and use these to
weigh up the risk of predator attack.�

Adapted from materials provided by PLATAFORMA SINC, via AlphaGalileo.

ScienceDaily. Retrieved April 29, 2008, from
http://www.sciencedaily.com­ /releases/2008/04/080427233813.htm

The experiment was carried out with a population of blue tits that
raise their young in nest boxes in Miraflores de la Sierra in the
Sierra de Guadarrama mountains, in Madrid province. The researchers
placed the scent of mustelids (ferrets) inside the nest boxes when the
chicks were eight days old.ScienceDaily (Apr. 28, 2008) — Many animal
species detect and avoid predators by smell, but this ability has
largely been ignored in the study of birds, since it was traditionally
thought that they did not make use of this sense. However, it has now
been discovered that birds are not only capable of discerning their
enemies through chemical signals, but that they also alter their
behaviour depending on the perceived level of risk of predation.