since approximately 1984 animals, including large birds have
been fitted with small transmitters, which emit a radio signal
at regular intervals. These signals are picked up by the ARGOS
satellite system, relayed to the central receiving station
in Toulouse, South France, and forwarded from there to the
The ARGOS system is currently made up of 4 satellites operated
by a US-French company. The original applications included
functions like locating ships. Later, areas such as ecology
and animal migration were added, eg. observing the migration
routes of migratory birds.
Thanks to this technology approx 80 white storks (Ciconia
ciconia) have been equipped with transmitters since 1992
and precise data about the birds’ migration routes
including the time taken have been obtained as a result.
Up until then for example, it was not known that the eastern
and western Stork populations had an overlapping wintering
ground in Africa (Chad).
Equally, in the case of the highly endangered western population
of the Siberian Crane (Grus leucogeranus), satellite telemetry
provided the key to discovering the exact route taken by
the birds when migrating (1996-97).
The first transmitters suitable for birds were developed
in the early ‘80s in Baltimore, USA. To start with
they were quite heavy (180-200g, later reduced to 55-60g).
Mr Howay later founded a company, which produces transmitters
in small quantities to order.
Transmitters are also produced in Japan. This is not the
place to enter a comparison of quality or prices.
Transmitters are constantly being refined. As opposed to
earlier, today they have a more aerodynamic design and weigh
only (25-35g), depending on the required capacity. The latest,
which comes from Japan , weighs less than 20g, but these
are still undergoing trials.
These transmitters do not appear to be technically fully
developed, since the failure rate is relatively high. Besides,
they are produced in such small numbers that it is almost
impossible to undertake projects at short notice.
The smaller the transmitters become, the greater the number
of possible applications. There are birds for which a transmitter
of 25-30g is still too heavy and whose migration routes
are still completely unresearched. The Slender-billed curlew
(Numenius tenuirostris) is among the most threatened species
of birds in the world. It breeds somewhere in Siberia and
its migration range stretches across the whole Middle East
and the Mediterranean basin to the Atlantic coast of Morocco.
Successfully protecting this species will only be possible
if the breeding , resting and wintering grounds, as well
as the migration routes, are definitively identified. Science
is therefore waiting urgently for a further miniaturisation
of the transmitters, so that the migration routes of smaller
birds can also be researched using satellite telemetry.