The family of Woluwe-Saint-Pierre is growing!

The couple installed at the top of the tower of the town hall in Woluwe-Saint-Pierre has been brooding since March 17, and yesterday morning the two first falcons hatched. The male and the female Peregrine had been taking turns day and night, brooding their 4 eggs since March 17, to ensure they maintained a near constant temperature of 37.7 ° C. Thirty-two days of incubation is exactly the norm for the Peregrine Falcons!

The first falcon appeared as the day dawned. At 07:39, his down just dried, he already received his first meal. The male arrived with a half-plucked Song Thrush. The female took three steps outside the nest box, grabbed the prey from her partner's beak and returned to give the prey to her first hatchling of 2018. A few hours later, in the late morning, a second falcon came out of her egg.

This morning: the hatching of a third falcon. Such a short time lapse in between hatchings is normal since the Peregrines' strategy is to start brooding only once the penultimate egg has been laid, in order to avoid precisely a large gap between the hatching of the first and the last chick. If this is not the case, considering that the female lays 2 days apart, there would be a difference in age (and size!) Of 6 days between the eldest and youngest. The falcons are not particularly aggressive to each other, but their diet, and especially the size of the prey, differs according to age. Having a brood of chicks of the same age thus provides an advantage to the species. The disadvantage is that the eggs are not brooded and therefore kept for several days, with the risk of being swept away by a predator or killed by frost. Life is a matter of compromises!

There is still one egg that remains to hatch, patience!

This is the fifth year that a couple of Peregrines is nesting in Woluwe-Saint-Pierre. We know the male has been coming back each year: the code on his ring indicates that he hatched in the spring of 2012 at the church of Saint Antoine d'Etterbeek, another Brussels municipality, a few kilometers way. And it is he who has been nesting on the site since 2014. The Peregrine Falcons are mature at 2 years old, so he is quite the ambitious fellow! This male is now 6 years old. His partner is not ringed, and hasn’t been since the first nesting. However, because it was never a ringed female, it is not possible to know her origin or to know if she is the same bird as that of previous years.

In 2014, the female laid 2 eggs. This small a brood is exceptional for Peregrine Falcons. Was the female, like the male, in her first year of reproduction, which would explain this modest fertility rate? Perhaps. Be that as it may, two magnificent falcons, a male and a female, took flight at the end of May. A first for this Brussels municipality! In 2015, the female laid 3 eggs, total success again with 2 female falcons and 1 male falcon hatched. In 2016, she outdoes herself and lays 4 eggs, which is considered the "normal" maximum for the Peregrine Falcon. Three falcons hatch: again 2 females and 1 male. The female laid 4 eggs last year, but the nesting fails : two falcons hatch but one dies after a few hours, the other after a couple of days. The causes remain unknown but, it very plausible it was  poisoning. Two eggs did not hatch.

The 2018 brood of Peregrines in Woluwe-Saint-Pierre is therefore eagerly awaited!

 

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