Zoo Basel's Owlets Stick Close to Home
April 26, 2017
A pair of Spectacled Owl chicks, at Zoo Basel, hatched at the beginning of February. Too big for their nest, they are now quite content to perch on branches and wait for Mama or Papa to bring them food!
The owlets are already as big as their parents. However, it will be two to three years before the siblings' snowy feathers change to the dark patterns of the adults.
Keepers at Zoo Basel utilized DNA samples and were able to determine that the chicks are male and female. Staff initially suspected as much by just examining the physical aspects of the chicks. Female eyebrows are usually slightly larger than the males, but otherwise look identical. To be quite sure, determination of the sex is made by means of a genetic examination. The Zoo’s veterinarian pulled out a small growing feather and sent it to the lab. The keeper’s speculations were confirmed: the bigger of the chicks is the female.
During examinations, veterinarians also applied a chip the size of a rice kernel under the skin. With this, the bird receives a lifelong identity. This is important for the conservation programs that guide zoological breeding and care of the Spectacled Owl.
The parents of the chicks are a well-established couple. In several breedings, the two have proved that they are very caring and attentive. This winter season, at Zoo Basel, was a bit turbulent. The birds were temporarily indoors, and the two proved to be completely stress-resistant and looked after their nestlings reliably.
The Spectacled Owl (Pulsatrix perspicillata) is a large tropical owl native to the neotropics. It is a resident breeder in forests from southern Mexico and Trinidad, through Central America, south to southern Brazil, Paraguay and northwestern Argentina.
This species is largely nocturnal. It is a solitary, unsocial bird, associating with others of their own species for reproductive purposes.
The Spectacled Owl is typically the largest and most dominant owl in its range, with the larger Great Horned Owl (Bubo virginianus) rarely venturing into true rainforest habitats.
It preys principally on a wide array of mammals, eating almost anything that is nocturnally active. Various rodents may be primary, but virtually any type of small mammal in its habitat is vulnerable.
In Costa Rica, eggs are laid variously in the dry season (November–May), or at the start of the wet season (June–July). This owl typically nests in an unlined tree cavity, but may also use the crutch of a large tree. Spectacled Owls typically lay one to two eggs, which are incubated almost entirely by the female for about five weeks. Chicks leave the nest for surrounding branches at about five to six weeks but cannot usually fly well at this stage. They tend to depend on their parents, for several months after leaving the nest, and may be cared for and fed for up to a year once fledged. Spectacled Owls have been known to breed while still in immature snowy plumage, since it may take up to five years before full adult plumage is obtained.
The Spectacled Owl occurs over a very large range and is still a resident in much of its native habitat. Due to this, it is currently classified as “Least Concern” by the IUCN. However, in areas where prey is hunted by people, and habitats are destroyed or compromised, their population may decrease.