Also, within the pen, young owls can learn to hunt. Unlike other hacking pens where rehabilitators use dead mice, Mark uses live mice and places them in the pen for the owls to naturally find on their own. The hacking pen used in this study was divided in half for breeding purposes. Mark acquired 13 barn owls (pairs and babies) from Flamingo Gardens in Florida, two from the Bronx Zoo, and one male from Elmwood Park Zoo in
Norristown, Pa. One breeding pair is housed on one end of the hacking pen, while one male occupies the other end awaiting a female. One pair was given to a private land
owner with a breeding facility, not far from the zoo. Another pair was given to The National Aviary in Pittsburgh, where the babies from that pair are destined to come back
to the zoo to be released. In early 2004, Mark did release four adult barn owls; one has been seen hunting on zoo grounds