The film about the ringing of the falcon chicks in Uccle.

The first 2022 falcons were ringed this weekend in Brussels. It is again the family of Uccle which is the most precocious.

So why band falcons? Very clearly, in order to have data that will make it possible to “monitor” the evolution of the population. And what is the point of monitoring the population? This makes it possible to sound the alarm bell in time, this time, if the trend would again be negative. Or to rejoice, as it is now, if the population dynamic is positive.

When Peregrine Falcons declined in Europe (and North America) during the 1950s and 1960s, the causes of the decline were unknown. There was no precise and continuous information about what is called the survival rate, in other words the proportion of falcons that survive each year. Or if we turn it around, the proportion of the number of falcons that die each year. That falcons die is not a problem, it is obviously a natural phenomenon. But the important thing is that this individual mortality does not lead to collective mortality! A population collapse. And if this happens, it is necessary, as soon as possible, to determine this and its causes. It is absolutely essential to fight the causes and avoid a potential extinction. We lost them once, we won't lose them twice!

Ringing also makes it possible, classically, to study, understand and observe the movements of birds. We love birds, we admire them, among other things for their exceptional ability to move, whether to migrate to the other side of the planet or more simply to go hunting at 400 km/h. Understanding and following the migration strategies of the Peregrine falcons is important in order to know how well they adapt to the environment which has changed so much and so quickly in recent years. What are the (re)colonization capacities of the Peregrines? How far do they settle to nest from the place they were born? This is important to know and especially to observe the evolution of these behaviors in order to carry out a useful monitoring.

The ringing operation is both simple and special. It can only be carried out by people certified* by the Royal Belgian Institute of Natural Sciences (RBINS).

The film appended to this blog presents each step:

1) an official scientific ring, engraved with a unique code and the abbreviated address of the RBINS, is positioned on the right paw,

2) a "coloured" ring, engraved with a simplified code, is positioned on the left leg in order to allow remote identification (at the telescope or on photo),

3) the falcon is weighed to the nearest gram, which makes it possible to assess its state of growth, its physical condition and to determine the sex (in combination with the next step),

4) wing length is measured, to determine growth stage and sex (in combination with weight),

5) a sample of feathers is collected in order to have genetic information but also to determine possible contamination by pollutants or other pesticides (not shown),

6) a sample of cloacal fluid is collected in order to study the circulation of influenza viruses (not shown).

The operation takes 2-3 minutes per falcon. As soon as the work is over, which therefore lasts a total of 10-15 minutes, the falcons are put back in their nest. Parent birds do not recognize their young by smell, unlike mammals, they never reject their chicks that have been handled.

The 2022 clutch of the couple of Peregrines from Uccle Saint Job includes one female and three males. The female weighs 1005 g; the code of her black colored ring is CRD. The males weigh 661, 702 and 642 g. Their ring code is respectively CRC, CRE and CRG. At just 3 weeks old, the chicks have already reached their adult weight! Until fledging, so over the next three weeks, all their acquired energy will be invested in the formation and growth of the plumage!

*To be certified collaborator-ringer of the Royal Belgian Institute of Natural Sciences, and therefore to be authorized to ring wild birds, you must have completed at least 4 years of training and passed two theoretical exams and then be legally authorized by the competent regional authority.

Video 1. The ringing film of Uccle

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