Update on the situation at the Cathedral of Saints Michael and Gudula
The situation in the centre of Brussels has become clear: the peregrine falcons will not nest this spring at the Cathedral of Saints Michael and Gudula. A visit at the top of the North Tower found that the peregrine’s perfectly bowl-shaped nest in the substrate of early April had been trampled on in every direction. And that there were no eggs.
That was what we already knew. Regular observations on the ground indicated that the falcons were not breeding there. Yet, they are very present! Three individuals are very regularly posed on the building. It are still the same ones we had seen at the beginning of April: a male hatched and ringed at the Saint Guido Collegiate Church of Anderlecht in spring 2017, a female hatched and ringed in Germany in 2016, and a female hybrid escaped from captivity who was already observed at the cathedral in the spring of 2018 but also at the basilica of Koekelberg. Very surprisingly, these three birds seem to get along well. Nevertheless, Peregrines are reputed to be very territorial. Fatal battles between females are observed almost every year in Belgium.
A few times during the past month, mating has been observed between the Anderlecht male and the German female. Never with the hybrid female. The female poses very high on a gargoyle. She then positions herself horizontally. The male arrives quickly and lands directly on her back! She puts her tail up, he puts his tail down, so that their cloacae touch allowing fertilisation. A sign to announce nesting! And yet. So why are the Peregrines this spring not nesting at the cathedral? Two hypotheses. The first is that the partners are not accomplices enough. Indeed, Peregrines are faithful in couples, although some cases of divorce are known. They take turns to hatch, feed their chicks together, hunt regularly in concert - one chasing a prey in a visible way while the other catches it by surprise, and defend their territory all year long. It is therefore that the communication passes perfectly between the two birds. According to the information available, they met for the first time at the beginning of March at the cathedral. A bit short for nesting a few weeks later? Very probable.
The second hypothesis is that of the disruptive element: the hybrid female. Peregrines are monogamous. It is not in their genes to conclude a threesome. On the other hand, this hybrid female, fruit of an artificial fertilisation, must very probably be disturbing for the pure "couple". It is larger than normal, has unusual plumage for a Peregrine falcon and probably vocalises pure Peregrines differently. So we could think that they tolerate one another - which is already exceptional - but from that to nesting is an impassable step.
One can even propose a third hypothesis. The combination of the two previous ones. Recent union + disruptive element = too much is too much!
The morality, the Peregrines did not desert the cathedral of Saints Michael and Gudula! They are there. They perfectly spotted the nest. They have identified the best perches and benefit from them. They know the hiding places where to store prey for bad weather days. They permanently fly over the center of Brussels, land at the top of the tower of the Town Hall on the Grand Place. No doubt, they have claimed the heart of Brussels!
Come and see them in real life by the temporary observation post we organise from noon to 6 pm every Wednesday and Saturday until the end of May. With a little patience, it will be possible to observe them with the telescope and even to photograph them with your smartphone! Come to ask your questions and get your poster "Falcons for Everyone 2019"!
Photo 1: The new Peregrine pair of the cathedral on the cathedral's cross (photo Thibaut Van Tomme).
Photo 2: The new German female on the balcony of the nest (photo DV).
Photo 3: The temporary observation post is organised every Wednesday and Saturday in May from 12:00 to 18:00 (photo DV).