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.