Numerous observers have noted this month that Arthur (F12), our four-year-old male with a territory at Hagneck on the Lake of Bienne, has been having increasing bouts of “building frenzy”. He has been showing off his acrobatic flying skills by diving into trees to break off a dead branch and carry it to one of his nests, at times making typical territorial calls.

This is classic behaviour at this time of year for a single male of his age. Even without a female around, Arthur is busy getting ready for when one comes along, in order to provide her with a nice choice of nests. In addition to bringing more branches to the platform installed for him last year, he has started building not just one (already mentioned in July), but two “secondary residences”. Since they are both on dead trees, it remains to be seen if they will resist autumn and winter storms. But one thing is certain: Arthur is very motivated!

There are now not many days left before Arthur and our other four males identified this year start heading south. Then a stressful six-month count-down will start, until hopefully all of them make it back from their wintering grounds in West Africa.