A pair of wild Eurasian eagle-owls has hatched two owlets at Burgers’ Zoo for a second time. Early in the morning on Tuesday, 23 May, eagle-owl expert Gejo Wassink weighed and banded the hatchlings, after which they were returned to the nest immediately. Just like in 2016, one of the owlets was male and the other female. The female is estimated to be 4 days old, and is slightly heavier than the male. That is normal among eagle-owls, as the female must guard the nest during the incubation while the male does the hunting. The male is around 40 days old, so they would have hatched in early April. They will leave the nest in three to four weeks. There are only a few experts in the Netherlands with a permit to catch, measure, and band these endangered birds. The zoo in Arnhem was pleasantly surprised by the spontaneous breeding success of two wild owls in 2016. Plant care staff discovered two oversized owlets by accident during routine pruning work; the birds were just about ready to fly out. The Eurasian eagle-owl is the largest species of owl in Europe, and is relatively rare in the Netherlands. In 2015, a total of 21 breeding pairs were identified here: the highest count to date. In 2016, the counter reached 17 breeding pairs, and we are headed towards 20 territories in 2017.
The Eurasian eagle-owl prefers to breed in mountainous areas. The breeding pairs counted in the Netherlands are primarily found in Limburg (near places such as the Pietersberg) and in quarries (such as in Winterswijk). The owls also chose an elevated area to breed at Burgers’ Zoo. Wild eagle-owls prefer rather large prey animals, such as crows, pigeons, rats, rabbits, hedgehogs, and even other species of owl. A variety of animal remains were found near the nest last year, including a long-eared owl, various species of duck, rats, a crow, and a hedgehog. Eagle-owls have excellent night vision and fly silently, making them excellent hunters at night and at dusk.
Burgers’ Zoo maintains close contact with Sovon, the Dutch Centre for Field Ornithology. Joost van Bruggen from Sovon put Burgers’ Zoo in touch with eagle-owl expert Gejo Wassink. Catching eagle-owls is not without danger, as the owls have extremely powerful claws and sharp beaks. The Eurasian eagle-owl is a protected species in the Netherlands. Banding the young birds helps accurately monitor the wild population in the Netherlands, both now and in the future. Valuable data is gathered during the banding process, such as size and weight.