Why satellite tracking?

Background

During the translocation stages of the project, the young Ospreys released at Rutland Water were fitted with small tail-mounted radio transmitters and this proved most valuable for studying the birds during the period they spent around Rutland Water prior to migrating. These transmitters have an effective range of only a few miles. Some adult and young Ospreys had also been fitted with similar radios in Scotland to study fishing activities and breeding ecology.

In 1997 members of the project team visited Southern Spain and Gibraltar during September at a time when radio-tagged bird may have been passing. Not surprisingly, they and radio operators of the RAF were unable to pick up any signals from the Rutland Water Ospreys. In fact very few Ospreys are observed by raptor migration watchers in that area because Ospreys, unlike other migrants, do not tend to cross the sea at narrow points such as the Straits of Gibraltar.

So, once the birds had left their breeding area, we lost contact with them and could learn no more about their movements except possibily from colour-ringing sightings and ringing recoveries. However, in North America and Sweden satellite radios had been fitted to Ospreys and had given researchers considerable insights of the migration and wintering behaviour of the birds.

What could we hope to learn from satellite tracking?

We hoped it would provide answers to some of the following questions.

What routes are used during the autumn migration?
How long does Osprey migration take?
Are there particular stopping-off sites used during migration?
Where do the birds spend the winter?
How much wandering takes place during the winter?
What return routes are used by adults during the spring migration?
Where do first-year birds spend the second summer of their life?
How do sub-adults join the breeding population?
Do family groups stay together during migration and the wintering periods?
If birds die, where and under what circumstances does it occur?

The tracking carried out from 1999 to 2001 provided some answers but we are still some way from providing definitive statements. In most cases, we originally had no idea what the satellite tracking would reveal. This was real live research and, by making the data freely available on the world-wide web, many people were able to share in the excitement. Some have commented, others have pointed out patterns and suggested ideas.

To see some of this debate click here. Why not join the debate by sending us an email? If you think you can contribute please contact us. All contributions will be acknowledged and any that are published will be attributed. We look forward to hearing from you!