Abstract

Great apes are the most intelligent animals in zoologic institutions. Due to their intelligence and strength, apes pose significant risks to employees, themselves, and the public when escapes occur. In some instances, dramatic action is necessary to resolve dangerous situations.

Three cases of great ape escapes are presented here which all occurred at the Kansas City Zoological Park (KCZP). All three were resolved without injury to the animal, public, or staff. Animal escape protocols were generally followed and successful. With each escape, revision of these protocols influenced the successful resolution of future escapes.

Case 1

In 1995, a 31-year-old female chimpanzee (Pan troglodytes) escaped over a 4.5-meter wall and into the public area 12 days after introduction into the new three-acre chimpanzee exhibit at the KCZP. A call from a keeper in an adjacent area alerted the primate keeper that a chimpanzee had escaped onto a boardwalk adjacent to the exhibit. A small crowd of patrons took pictures of her sitting within two meters of children and adults. The chimpanzee was calm and made no aggressive movements until she saw the keeper approach, whereupon she charged the keeper. The keeper struck the chimpanzee and escaped into an adjacent brush pile. The keeper radioed the staff, which descended upon the enclosure. Patrons were locked in the closest restrooms and security guards protected entrances. Patrons in the rest of the zoo were escorted out of the zoo. Upon seeing zoo staff approaching, the chimpanzee jumped back into the exhibit. The chimpanzee troop was taken off exhibit and an inspection of the outdoor facility revealed that the escaped chimpanzee had climbed a pole supporting hot-wires, sat on top of the pole, and jumped approximately 4.6 meters to the top of the wall, whereupon she pulled herself over. A piece of acrylic was subsequently bolted to the wall and no further escapes have occurred.

In this case, an exhibit design flaw was corrected. This incident also prompted the purchase and usage of deterrent sprays carried by all animal staff. In addition, all staff is required to respond to any animal escape with appropriate poles, etc., as self-protection to distance or help fend off an attack. Stockpiles of adequate poles are located in strategic locations in the zoo for use during animal escapes.

Case 2

In 1997, a 14-year-old lowland gorilla (Gorilla gorilla) escaped into the keeper area of the gorilla building. The keeper had forgotten to secure an overhead door and while working in one empty stall, saw a shadow pass by, whereupon the keeper looked out of the stall and witnessed the kitchen door close. The next set of doors at the time was not secure from the inside, but the gorilla proceeded to explore the kitchen area instead. The keeper opened the nearest stall door and threw the kitchen door open, whereupon the gorilla rushed down the hallway. The keeper ran from the stall, past the kitchen door, and manually held the door closed while the gorilla attempted to open the doors. The keeper subsequently called for help. Patrons were escorted from the forest exhibit, and the rest of the zoo. Veterinary staff immobilized the gorilla by darting him in the hallway through a darting portal. All controls to hydraulic doorways, exhibit, etc., were located in the same hallway the gorilla escaped into. The gorilla ran into the exhibit, whereupon he became immobile. The building was secured while additional staff monitored the anesthetized animal with binoculars. The gorilla was tuberculin tested, blood drawn, and placed in a stall to recover. Since that time, the doors have been reinforced, the outside doors must be key-locked, and expanded metal grates have been installed across windows. The controls to doorways, exhibit, etc., are still located in the hallway.

In this case, keeper error led to the escape. However, the escape pointed out several design flaws with the holding area, security doors, darting portals, and windows. Staff response was immediate. Firearms and deterrent spray were available. Most of the staff responded with some type of pole, etc. Two perimeters, one inside the building and one outside, were established prior to immobilization. The resolution of this escape was an entire success.

Case 3

In 1998, a 12-year-old male Bornean orangutan (Pongo pygmaeus pygmaeus) escaped from his outdoor enclosure by leaning a tire against a wall, reaching and subsequently grounding the hot-wire, and pulling himself over the wall. A zoo-grounds worker radioed staff that a member of the public reported being chased by an orangutan. When asked to confirm what the public was seeing, the grounds worker stated it was a large, orange-colored animal which was sitting in a chair when the visitor opened an exhibit door. The orangutan chased the visitor, who ducked inside the door of the exhibit and waited until the orangutan stopped pounding upon the door, whereupon they contacted the grounds person. The keeper confirmed the escape, and staff responded immediately, forming a double-staff perimeter in constant visual contact with the animal. The ARCS committee, which maintains firearms in cases of animal escapes, was properly positioned and in constant visual and radio contact should lethal force have been necessary. The animal health staff drove by the orangutan and darted him, whereupon the orangutan chased the vehicle, climbed across the windshield, and subsequently became recumbent in the farm garden of the zoo. The orangutan was physically examined and returned to the inside holding area.

In this case, staff responding to the escape were prepared with poles, deterrent spray, and visual and radio communication. Staff did not predict the risks associated with the growth of this young orangutan to adult size, which contributed to his escape. The dry moated area was deepened, and tires were removed.

Conclusions

In none of the cases were the staff, public, or animal injured. Immediate response by security staff, animal response team, and veterinary staff resolved all three cases without incident. In these cases, human error and design flaws contributed to the escapes.

In conclusion, great ape escapes, as with all animal escapes, can be effectively resolved. A calm, logical approach to each situation is mandatory for successful resolution of a great ape escape. Every effort to prevent escape is an obvious, but not always predictable, goal.

Acknowledgments

The author would like to thank all of the Kansas City Zoological Park staff that has participated in animal escapes without injury to the animals, visitors, or employees.