I have had a few questions about why I need sightings of my study birds when they are being tracked by satellite so I thought I'd explain.
The tracking devices are tiny weighing only 17g so they have limited battery life. They are programmed to switch on for only a few hours at a time. There are also gaps in when satellites are overhead to be able to receive the signal and tell me where they are. Sightings help fill in the gaps.
The tracking devices will stop transmitting well before the marking on their tails fade or the feathers are moulted early next year so sightings will extend the time over which the study birds are followed.
Sightings also provide the opportunity to make other observations such as what they are feeding on, flock size and direction of travel. These observations help explain why they might be in a particular location.
