He ate a Cuckoo - a Peregine’s menu.
The couple of Peregrines from the cathedral captured a gray Cuckoo and fed it to their hatchling!
The gray Cuckoo is well-known for its characteristic song and remarkable reproductive behaviour. He is also a great migrator. Cuckoos that nest here, and more widely in Western Europe, spend the winter in the rainforest in Central Africa. The species is very rarely seen in Brussels: only one or two couples nest in the area.
How did the Peregrines manage to capture this unfortunate bird? Peregrines are - almost solely – aerial hunters. These falcons don’t really catch their prey on the ground, unlike the Kestrel - the Peregrine’s smaller and more common cousin. Moreover, the Kestrel mainly captures small rodents. So, the Peregrines of the cathedral captured this cuckoo somewhere in the Brussels’ sky, obviously as the cuckoo flew over the city while migrating.
It’s rare for a peregrine to capture a gray cuckoo in Brussels and the surrounding areas. Since 2004, the beginning of systematic observations at the cathedral, this was the third time that the species has been spotted on the menu of Peregrines. But he is far from being the only prey!
So far, 62 bird species have been listed on the menu of the couple in the cathedral during the nesting season! The latest one was spotted on April 20th; a Siskin, a small granivorous passerine of fifteen grams. It has been identified, live, from the images transmitted by streaming from the nest. The complete list of identified prey is available here.
Most prey, however, has been identified by collecting fallen feathers at the base of the tower where the Peregrines have their nest. These feathers simply fell from the nest, or they were torn off by the Peregrines when they brought them back to the gargoyles.
Identifying a species from just one or a few feather(s) fallen on the ground is often a challenge! Exciting! Several websites allow us to compare our discoveries with collections of meticulously identified feathers. This one is probably the most remarkable one. Several books are also very useful, for example: Identifier les plumes des Oiseaux d’Europe occidentale (Delachaux and Niestlé), Vogelveren (Fontaine uitgeverij) and Feathers: Identification for bird conservation (Natura Publishing House).
Regarding the species on the menu of the Peregrines in the cathedral : waders dominate the list with a total of 18 species represented! Small passerines are the least represented, but maybe simply because it is more difficult to identify their feathers than those of larger species. The smallest species listed is the Lesser Whitethroat whose average weight is 12 g. The biggest is the common Buzzard with a weight of about 1 kg. However, the Buzzard wasn’t exactly prey: if one was killed by the Peregrines of the cathedral, it’s because she was considered a competitor. Remember that peregrines are very territorial (see blogpost of 26/04/2018). The biggest actual prey species are Feral Pigeons, Teals and Woodcocks weighing between 350 and 300 g. Very rarely, Wood Pigeons, whose weight reaches 450 g, have also been listed on the menu of the Peregrines in the cathedral. Wood pigeons are very common in Brussels. The fact that it is so rarely captured by Peregrines indicates that the weight limit of their prey during the nesting period is between 350 and 300 g.