Turnaround at the ULB!

Since yesterday, and this is unprecedented, the nesting of 4 pairs of Peregrine Falcons settled in Brussels can be observed in detail. A quarter of the number of falcon pairs nesting in the city are thus connected to the Internet. Being able to observe hour by hour, day after day, the behavior, the individual characteristics of these magnificent birds is exceptional. It's even probably unique in the world and it's in Belgium that it happens!

But what happened at the ULB? Let’s go back a few years. In the spring of 2019, a pair of Peregrine Falcons was discovered on the belfry of the historic University building along Franklin Roosevelt Avenue. Both partners are ringed, which allows us to know their place of birth and their age. The male was hatched in April 2012 at the Church of Our Lady of Laeken, north of Brussels. The female was born in the spring of 2014, on a factory building that builds Minis and BMWs, near to Sittard, along the Meuse, downstream from Maastricht. The distance between Sittard and Brussels is 106 km. They reared two young. The same Peregrine pair is rearing three young in 2020 and two young in 2021. Still in their "eagle's nest" located at the very top of the Solbosch belfry.

And then comes the spring of 2022. The camera system shows that the same pair frequently visits the bell tower until mid-February. And then, nothing. They disappeared! But in mid-March, they were found again! 650 m away, on the church of Saint Adrian in Ixelles. Parades, cries, visits of the cavities behinds the abat-sons of the belfry. No doubt they moved! As a result, the camera is not connected to the web. Hence, significant work to improve the transmission system was carried out by the team of the ULB. Frustration!

But Nature is always in motion. Nothing is taken for granted, nothing is fixed. Phenomena, life histories are dynamic. Suddenly, the Peregrine pair reappears at Solbosch! The same two falcons are filmed regularly from April 4. They frequently visit their “historic” nest so regularly that… they have been incubating 3 eggs for 3 days! Incredible! But no, that's nature.

What happened? We are confined to hypotheses, but the most likely is that the pair decided, for some reason or another, to change nest location. This is totally exceptional, but it can happen, the proof. The observed behaviors of the Peregrines at the Saint Adrian church indicate that the pair began to nest on the building. But it should not have been profitable because the falcons finally returned to the ULB! This can only be because incubation in the church of Saint Adrian has failed! And therefore, no litter for this pair in 2022? And no, because many species of birds, including Peregrines, have the ability to lay a second clutch of eggs in the case the first one fails. And that is clearly what we are observing today! And this is what allows us to simultaneously observe 4 pairs of Peregrines living in Brussels. Let us take advantage!

Video 1 The ULB pair is back at Solbosch!