The human-led migration of the Northern bald ibis led by the Waldrappteam has taken place and with it also my data collection. The preparation for this data collection was a long process, mainly because in my case there is no second chance: the migration is only once a year and there is little room for mistakes.
The migration was really fast, from the 14th to the 26th of August. This year it went from Heiligenberg, in Baden-Württemberg (DE) to the WWF Oasis of Orbetello, in Tuscany (IT). It was divided into six bouts, four of which were also suitable for data collection.
Data on V-formation flights
My work consisted in equipping all the 29 hand-raised juveniles of Northern bald ibis with GNSS receivers to study how they fly in a V-formation. Many of you may ask, what are GNSS receivers? Well, basically these loggers are able to receive the signal from different satellite constellations, which in my case were GPS, Galileo, and GLONASS. The benefit of using different satellites systems is to be able to calculate the position with higher accuracy. However, the true speciality of these loggers stays in other two features:
- They collect and store raw satellite data: this means that the loggers themselves do not calculate the position of the bird (as any receivers would do, think about when you navigate with your smartphone and Maps), but collect and store the stream of information coming from the satellites. The data can then be downloaded and post-processed to calculate the position. This type of data collection is surely more complicated and time-spending, however, it allows to reach cm-level accuracy in the calculation of the position. This is fundamental in my project, as birds fly quite close to each other in a formation and normal accuracy (1-3 m) is not enough.
- They are small and light-weighted: all my loggers weight on average 20 g and their design was a real challenge. Such “GNSS loggers that collect raw data” are already existing on the market but usually, they are big and too heavy to be carried by a bird. Therefore, we had to create our own. In collaboration with the company RTK Consultants LLC, we came up with these receivers, which suited all my purposes.
All the birds in the group have to be equipped with a receiver to have a comprehensive view of the V-formation. Juveniles carried the loggers on the back by means of a leg-loop harness and 3D-printed plastic housing.
My data collection does not only consists of raw satellite data, but I also carry on behavioural observation. In particular, I am interested in seeing whether the social dynamics in the group are reflected in the flight formation or vice-versa. To achieve this, I conducted affiliative and aggressive behaviour observations before, during and after the migration.
Data collection went pretty good and the amount of data is huge. Now it is time to start with the data analysis!
Photo credits: Anne-Gabriela Schmalstieg. Waldrappteam, LIFE Northern Bald Ibis.