http://www.nature.com/nsu/040517/040517-5.html
ID bands may harm penguins
Research tool impedes birds' activities.
19 May 2004
MICHAEL HOPKIN
Researchers who study penguins could be unwittingly harming them by
attaching permanent identification bands to their flippers. The metal
bands, fitted to thousands of penguins each year, seem to adversely
affect their swimming and fishing.
Many bird species are monitored using metal bands around their legs.
Researchers use information on individuals to deduce the birds'
breeding and migration patterns. But penguins' legs are the wrong shape
for bands, so the devices have to be attached to their flippers instead.
This is a significant hindrance to the birds, say Michel Gauthier-Clerc
of the Station Biologique de la Tour du Valat in Arles, France, and his
colleagues. They suspect that aluminium or stainless-steel bands may
hinder the penguins as they glide through the water.
Gauthier-Clerc's team compared 50 banded and 50 non-banded king
penguins (Aptenodytes patagonicus) from a colony that breeds on
Possession Island in the Indian Ocean during the Southern Hemisphere's
summer. All were implanted with tiny electronic tags under their skin
so that even unbanded birds could be recognized.
Contra band
Over the course of four breeding seasons, banded penguins generally
arrived at the breeding grounds later than unbanded birds, the
researchers report in Biology Letters1. Over the course of the study,
the banded birds produced a total of just 28 chicks, compared with 54
for unbanded penguins.
If bands do indeed hinder penguins, they could also skew researchers'
data. Besides being used to track penguin movements, the information
has been used as an indicator of the climate effects that drive these
migrations.
Despite their widespread use, it is not surprising that the bands seem
to impede penguins, says Keith Reid, a penguin biologist with the
Cambridge-based British Antarctic Survey. The survey's researchers
stopped using bands during the mid-1990s.
Gauthier-Clerc and his colleagues argue that electronic tags should be
used in place of bands. The devices weigh just 0.8 g and emit a signal
that is picked up by receivers along the penguins' migration route.
Others argue that bands made out of alternative materials are the way
forward. Metal bands tend to rub feathers away, creating a small bald
patch that leaks body heat, says Duncan Bolton, a penguin expert at
Bristol Zoo Gardens, UK. Whether or not they have difficulty swimming,
penguins losing energy in this way would take longer to make an
Antarctic migration because they would need to collect more food.
Bolton and his colleagues are testing a synthetic rubber band that he
hopes will replace metal ones. Bands are desirable because they allow
researchers thousands of kilometres apart to observe the same birds
without expensive electrical equipment, he says.
The next step is to ensure that the rubber bands are as hardy as their
metal counterparts, says Bolton. "Once we've shown that they're durable
over two or three years, I would push for them to be used more widely,"
he says.
References
Gauthier-Clerc, M. et al. Proc. R. Soc. Lond. B (suppl.), published
online, doi:10.1098/rsbl.2004.0201, (2004).
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