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Henri Weimerskirch and his
"marine birds and mammals" team at the CNRS1
have been studying how birds and mammals use the sea's resources and investigating
the consequences of environmental changes on predator populations for
many years. In the February 15 issue of Science, Weimerskirch published
the results of a study that equipped the albatross with miniature GPS2
transmitters. By virtue of their accuracy and light weight, the latest
generation of GPS transmitters offers many advantages. The transmitted
data (retrieved every second) allow researchers to track "to within
one meter" the birds' movement in their natural habitat, giving them
valuable information for research into the ecology of marine wildlife.
Thanks to these miniature GPS transmitters, which weigh between 50 and
100 grams and are attached to the birds, it is now possible to accurately
track the movements of large albatrosses in the Austral Ocean. By taking
into account the speed of the wind and the bird's direction, researchers
can determine the trajectory and record the bird's speed (up to 135 kilometers
per hour) in real time. The albatross adjusts its path to locate sectors
of the ocean the bird is familiar with, seeking the shorelines of the
continental plateaus where squid thrive, thereby increasing its chances
of finding food. The accuracy of the GPS system is such that scientists
can measure the speed and direction of the ocean's currents by tracking
the drift pattern of the bird once it has landed on the water.
Henri Weimerskirch's team, with the assistance of the "Institut Polaire,"3
uses telemetry techniques or remote tracking and data acquisition to understand
the behavior of predators in their habitat: since 1989, satellite telemetry
using miniature Argos transmitters4 have made
it possible to track the movements of Antarctic marine wildlife, such
as petrels, penguins, sea-lions, and particularly albatrosses which are
capable of covering enormous distances (up to 2,000 km) when foraging
to feed their fledglings. By coupling the Argos tracking transmitters
with other data recording devices, researchers were also able to study
the animal's behavior and collect physiological data pertaining to the
amount of food ingested, the depth of a bird's dive, its heart rate, etc.
The team could also identify where squid or other fish were plentiful
and record various physical characteristics of the bird's habitat. However,
such telemetry techniques only enabled sporadic tracking transmissions
(one per hour in good conditions) with limited accuracy (within one kilometer,
on average) and a relatively limited battery life.
To overcome these difficulties, the CNRS team and the University of Zurich
worked together to develop a miniature GPS transmitter5
and high-capacity disk recorder. Once attached to the bird, the GPS system
relays information to the satellite: the data received by the ARGOS system
is analyzed by the disk recorder, stored, and then recovered by the researchers.
Analysis of the database compiled from all the data collected from the
readings will help researchers answer specific questions, particularly
in the field of aerodynamics. This new telemetry technique has enormous
potential for ecology research applications and will no doubt become an
indispensable technique in the years to come.
Reference:
Weimerskirch H., Bonadonna F., Bailleul F., Mabille G., Dell'Omo G. and
Lipp H.P., GPS tracking of foraging albatrosses. Science, February
15, 2002.
(1)The
Chizé Center of Biological Studies is a CNRS laboratory located
in the Chizé forest (in the Deux-Sevres department). The center
is a field station for conducting interdisciplinary research on the ecology
and evolution of vertebrates in their natural and modified habitats.
http://www.cebc.cnrs.fr
The “marine birds and mammals” team is a non-profit organization
for scientific purposes devoted to the ecology of marine wildlife affiliated
with the "Centre de Recherche sur les Mammifères Marins"
and the higher marine predators team of the University of La Rochelle.
http://www.cebc.cnrs.fr/Fr_taaf/taaf.htm
Henri Weimerskrich is a member of the French delegation to SCAR (Scientific
Committee for Antarctic Research) and CCAMLR ("Convention pour la
Conservation des Ressources Marines Antarctiques").
(2)Global Positioning System.
(3)French institute for polar research and technology
http://www.ifremer.fr/ifrtp/
(4)Satellite tracking and data transmission system
(5)This includes the antenna and the electronic
GPS satellite data retrieval system coupled with a data processing and
storage unit.
Researcher
contact:
Henri Weimerskirch
Tel: +33 5 49 09 78 15
Fax: +33 5 49 65 26
E-mail: henriw@cebc.cnrs.fr
CNRS Department of Life Sciences, Communications contact:
Marie-Pascale Corneloup-Brossollet
Tel: +33 1 44 96 46 48
Fax: +33 1 44 96 49 19
E-mail: marie.corneloup@cnrs-dir.fr
CNRS press contact:
Magali Sarazin
Tel: +33 1 44 96 46 06
E-mail: magali.sarazin@cnrs-dir.fr
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