The ULB Peregrine falcons have been ringed

The ULB Peregrine brood was ringed this Wednesday. The falcons are 3 weeks old, the ideal age to carry out the process of ringing.

Each falcon chick was measured and weighed. The recorded weights are: 488 g, 547 g, 548 g and 574 g. After the 4 sisters at the Saint Antoine church in Etterbeek, these are 4 brothers!

The distribution of weights suggests that the heaviest is the one hatched on April 23, then followed by the two hatched on the 24th whose weights are almost identical and then, the youngest, which finally emerged from its shell on April 26. The difference in weight of around a hundred grams between the heaviest and the lightest is therefore nothing to worry about.

Each falcon is marked with an official ring from the Institute of Natural Sciences which, as part of the European EURING network, has organized the ringing of wild birds in Belgium since... 1929. The principle of such a ring is simple: a ring metal is engraved with a unique alphanumeric code (up to 7 characters) and the abbreviated address of the scientific institution of reference. If the size of the ring allows it, an email address is also engraved. The ring is closed around the leg with special pliers. But it is of course not tight around the leg, it must be able to turn freely and move up and down the leg so as not to interfere. Its diameter is of course adapted to each species. Ringing falcons, as is the case for all chicks, can only be carried out when the leg is sufficiently developed so that it does not fall off!

And it's not just Peregrine falcons that are ringed since, year after year, around 700.000 wild birds are ringed each year in Belgium by a network of 300 certified volunteer ringers. Certified means that each bander has completed at least two years of training and passed two assessments (practical and theoretical); in most cases, the duration of the internship is at least 4 years and the number of evaluations is 3. The ringing of wild birds therefore represents an enormous amount of work which constantly allows us to increase and update knowledge in matter of migration and demography of wild birds.

If you find a ringed bird, you can very usefully participate in this study by entering the data here (link to

As part of a particular study, and this is the case with the specific monitoring of Peregrine falcons initiated in Belgium in 1996, a second ring can be positioned. This will be coloured and engraved with a very simplified code. Why is that? In order to enable remote location, using a telescope for example. It is therefore possible to identify a bird without having to recapture it or without waiting for it to be found dead. In this case, the system allows us to know the origin of the Peregrine falcons which brood in Brussels and beyond in Belgium, but above all to have information about survival rates. This is crucial for monitoring the species! Thanks to this system, we know that the two partners of the ULB couple have been the same since their first brooding in 2019, that the male is 12 years old and the female 10 years.

The attached video illustrates the ringing of the 4 ULB falcons. The process takes place in 4 stages: positioning of the official ring of the Institute of Natural Sciences on the right leg, positioning of the coloured ring on the left leg, measurement of the wing, weighing. All data is scrupulously noted and will then be encoded in the Institute’s database. The operation takes 3-4 minutes per falcon.

Between their arrival on the Solbosch campus in spring 2019 and 2023, the Peregrine couple raised 17 falcons, 14 of which were ringed. What have they become? Read next blog !

video 1 blog 05/15/2024: The ringing film (DV video)