16.09.21 – Concluding remarks
Reality check: the initial phase of our Yelkouan program is now drawing to a close … due to the natural ‘death’ of our transmitters which survived anyway much beyond our wildest expectations.
Here are some key findings that clearly make a success of our eleven-week investigation. Some were totally unsuspected.
We have identified for the first time a seasonal axis of connectivity between the Adriatic and Black seas via a seabird species that leaves its nest in the central Mediterranean to travel as far as the northeastern corner of the Black Sea. The migratory flights of our tagged individuals were all distinct in time (asynchronous) but very similar in their trajectories, with the added discovery that they never flew overland, even avoiding the major shortcut offered by the Canal of Corinth. What are their main navigational tools ? The triggers for their individual departure ?
Expending such massive energetic costs (flying over 3,000 km a few meters above the waves !) is more than compensated by reaching the spawning grounds for millions of anchovies – the main staple food of the Shearwater – near the Azov Sea.
The individuals found migrating in our study did not exclude juveniles, born a few weeks previously. Are they travelling with parents ? With other elders ? With other juveniles? Other individuals studied were still flying in the north Adriatic when we lost, one by one, their signal. Distinct migration strategies ? Or just a delay in taking off for the Black Sea?
MIGRATORY MAPS OF ADULTS (A) & JUVENILES (J) YELKOUAN SHEARWATERS
[the sequence of the 15 maps below is based on the longest flight achieved so far]
• Species: Yelkouan shearwater (Puffinus yelkouan)
• Colony site: Zaklopatica (Lastovo Archipelago) – Partnership with Udruga BIOM
• 11 adults and 4 juveniles tracked with GPS/GSM since 29/06/21 (end of breeding season)