Abstract

In November 2006, in a world first pilot project, a 14-year-old captive born Sumatran Orangutan from Perth Zoo was released into the protected Bukit Tigapuluh National Park in Sumatra as part of a reintroduction program.

Veterinary preparations for the release began approximately 12 months prior to her departure and included assessment of disease risk and general health, as well as dietary planning.

More specifically, a disease reference spreadsheet (Table 1) was developed and a risk analysis approach was taken to complete the table. Decisions as to what action was required for each disease was based upon specific criteria which included pathogenicity of disease versus risk of exposure; known effectiveness and/or safety of vaccine protocols in non-human primates (NHPs); interpretation of serology results and vaccination; and/or disease testing protocol for release site staff.

Table 1. Orangutan release - disease reference spreadsheet.^a

^aCategories modified using Munson L, Cook R. Monitoring, investigation, and surveillance of diseases in captive wildlife. J Zoo Wildl Med. 1993;24:281.
^bPathogenicity of Agent: 1=Infects immunosuppressed animals, 2=Infects some contact animals, 3=Infects all contact animals.
^cOutcome of disease: F=Usually fatal, PD=Causes permanent disability, SR=Serious but full recovery usual, TD=Temporary disability (mild disease), I=Usually inconsequential.
^dAvailability of prevention: 1=Effective, easily administered vaccine/treatment available, 2=Vaccine/treatment available but limited effectiveness/difficult to administer/not tested in NHP, 3=No vaccine or treatment available.

Health assessment indicators and monitoring sheets were developed by Perth Zoo for the staff tracking the orangutan post-release. These were designed to provide good consistency to the recording of observations.

The orangutan was placed on a dietary program which gradually reduced caloric intake while introducing a wide variety of tropical fruits into the diet. The nutrition plane was then stabilized and the orangutan was given access to a large fig tree to encourage climbing, foraging, and increased fitness.

At the date of writing this abstract, the released orangutan–who was born and raised naturally by her mother at Perth Zoo–was continuing to do well, adapting to the wild environment rapidly and successfully. Supplementary feeding was being provided in the forest once per week. Trackers continue to follow her progress.