Abstract
In St. Louis Zoo first acquired Spectacled Owls in 1986 for a display in the Bird House. A commitment was made at the time to ultimately house two pairs of owls. Both pairs of birds produced offspring over a five year period. This paper reports on the captive management of Spectacled Owls and their reproductive efforts.
Two captive reared female owls were acquired from the Oklahoma City Zoo and a wild caught male was obtained from the Cheyenne Mountain Zoo in Boulder, Colorado. In 1989, a second male was purchased from the San Diego Zoo. This bird was handreared. None of the birds had a history of reproduction prior to arriving at St. Louis.
The first pair of owls was housed in an indoor enclosure at the Bird House. The exhibit is triangular in shape and measures 2.5 m x 2.5 m x 4 m. The two short walls are solid and the long side is of piano or harp wire. The height of the enclosure is 2.5 m. The ceiling has a skylight and incandescent lights provide a minimum daylength of 12 hours. Live plants decorate the exhibit and are planted in a soil substrate. Fresh water is provided daily in a small dish. The birds are fed dead mice once daily in the late afternoon.
The nest is a box made out of plywood which measures 50 cm x 50 cm x 75 cm. The entrance is a hole 25 cm in diameter near the top of the box. The nest is painted a dark brown and elevated so the hole is 1.2 m off the ground. Oak bark mulch is added to the box to a depth of 20 cm. The nest was put in the exhibit as soon as a pair was introduced together.
In February of 1988, a single egg was found on the floor of the exhibit and was removed for artificial incubation. The egg proved to be infertile. The next egg was laid in late February 1991 in the nest box. Egg laying was preceded by the male feeding the female and increased vocalizations between the pair. In late February, the birds began spending an average of four hours a day in the nest. The 30th of March was the first time one bird was constantly in the box. A single egg was pulled for artificial incubation on April 30 and the egg hatched on May 3. The estimated incubation period was 35 days. The chick was raised without difficulty by bird department keepers.
On June 6, 1991, an egg was seen in the nest box and a second egg was noticed in subsequent nest checks. A decision was made to leave these eggs in the nest to determine the adults' ability to rear their own offspring. The first chick was heard vocalizing on July 11 which was 36 days after the first egg was seen. A few weeks later a second chick was seen in the nest. During this period, the owls were...