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Providing evidence to improve practice

Action: Implement quarantine for primates before reintroduction/translocation Primate Conservation

Key messages

  • One before-and-after study in Brazil found that most reintroduced golden lion tamarins did not survive over seven years despite being quarantined before release, alongside other interventions.
  • One before-and-after study in Uganda found that a reintroduced chimpanzee repeatedly returned to human settlements after being quarantined before release, alongside other interventions.
  • One before-and-after study in Madagascar found that most reintroduced black-and-white ruffed lemurs did not survive over five years despite being quarantined before release, alongside other interventions.
  • One before-and-after study in Malaysia found that a population of reintroduced orangutans decreased by 33% over 40 years despite individuals being quarantined before release, alongside other interventions. A controlled study in Indonesia found that all orangutans that underwent quarantine prior to release, alongside other interventions, survived over three months.
  • One before-and-after, site comparison study in the Republic of Congo and Gabon found that more than 80% of the reintroduced gorillas that underwent quarantine, alongside other interventions, survived over a ten year period.
  • Two site comparison studies in Vietnam and a before-and-after study in Indonesia found that most reintroduced lorises either died or their radio signal was lost despite being quarantined before release, alongside other interventions.

Supporting evidence from individual studies

1 

A before-and-after trial in 1984-1991 in coastal forest in Poço das Antas Reserve, Brazil found that the majority of reintroduced golden lion tamarins Leontopithecus rosalia that were quarantined before release alongside 14 other interventions, did not survive over seven years. Fifty-eight out of 91 (64%) reintroduced tamarins did not survive in the wild. However, 57 infants were born (reproductive rate=63%) during the study period, of which 38 (67%) survived. Tamarins were quarantined for six months before they would qualify for reintroduction. During quarantine their health was monitored continuously. Different groups of captive-bred or orphaned tamarins were introduced in different years into habitat already occupied by the species and predators. Groups were provided with supplementary food, water and nesting boxes, and allowed to adapt to local habitat conditions before release. Tamarins underwent veterinary checks and were treated for parasites before release. Sick or injured reintroduced tamarins were captured, treated and re-released. The reserve became officially protected in 1983 when a long-term research study was implemented. The study does not distinguish between the effects of the different interventions mentioned above.

2 

A before-and-after-trial in 1995 in Kibale National Park, Uganda found that a female captive, 4-6 year old wild-born chimpanzee Pan troglodytes schweinfurthii that was quarantined before reintroduction into a human-habituated community of wild chimpanzees alongside other interventions, repeatedly returned to human settlements post-release and was subsequently returned to captivity. Eight days after the initial release, she left the forest for the first time and was brought back into the forest. For the following ten days, she travelled, fed, nested and engaged in social activities with the wild chimpanzees. During this time, she increased ranging distance to humans and use of height, and visually monitored humans less regularly. However, the proportion of adult males in her vicinity decreased and she increasingly spent time alone. She was returned to captivity six weeks after her release. She was quarantined from humans, other than her caretakers, and wild chimpanzees and underwent a tuberculosis test. During this time, she also underwent pre-release training for three weeks before reintroduction into habitat with a resident wild community. At least ten community members worked on the project. The study does not distinguish between the effects of the different interventions mentioned above

3 

A before-and-after trial in 1997-2002 in primary forest in Betampona Reserve, Madagascar found that less than half of all captive-bred, parent-reared reintroduced black-and-white ruffed lemurs Varecia variegata variegata that were quarantined before release alongside ten other interventions, survived until the end of the study period of five years. Over five years, five of 13 individuals (38.5%) survived in the wild and six individuals were born, of which four survived. One female and one male of the group reproduced with wild resident lemurs and the male became fully integrated into the wild group. The on-site quarantine period combined with the pre-shipment quarantine period totalled 30 days. All released animals were radio-collared for post-release monitoring. Captive lemurs had limited semi-free-ranging experience and underwent veterinary screens before their reintroduction in groups into habitat with predators and wild resident lemurs. They were recaptured and treated when sick and provided with supplementary food and water for a certain period. They were allowed to adapt to local habitat conditions before release. Dead lemurs were clinically examined. The study does not distinguish between the effects of the different interventions mentioned above.

4 

A controlled study in 1964-2004 in tropical forest in Kabili-Sepilok Forest Reserve, Malaysia found that rehabilitated orangutans Pongo pygmaeus morio that were kept in quarantine for 90 days before their reintroduction along with eight other interventions, decreased in numbers by 33% over 33 years (1964-1997). Infant mortality (57%) was higher than in other wild and captive populations, and the sex ratio at birth was strongly biased towards females (proportion males=0.11) compared to wild and captive populations. Orangutans were daily provided with supplementary food from 2-7 feeding platforms. Inter-birth-interval (6.1 years) was similar to wild populations of the same subspecies. Mean age at first reproduction (11.6 years) was lower than in other wild and captive populations. Individuals underwent in-depth veterinary checks before release into the reserve, where other rehabilitated orangutans lived. Individuals were captured and treated when injured or sick. Staff and volunteers received medical checks and tourists had to keep safety distances (>5 m) at all times. The study does not distinguish between the effects of the different interventions mentioned above.

5 

A controlled study in 2004-2005 in secondary tropical forest in Bukit Tigapuluh National Park, Central Sumatra, Indonesia found that all reintroduced Sumatran orangutans Pongo abelii that underwent quarantine prior to release alongside other interventions, survived for at least three months. Al eight captive orphaned orangutans with largely unknown histories survived for at least three months post-release. Before transportation to the reintroduction centre, orangutans were quarantined and underwent medical screens and clearance at a quarantine centre. All activities and procedures at the quarantine and reintroduction centres followed national and international regulations and guidelines, including IUCN reintroduction guidelines. Orangutans were released into habitat where previously-released orangutans lived to re-establish populations. Supplementary food was provided regularly. One group was directly released into the forest after a 6-month acclimatization phase at a sanctuary. Another group was kept in semi-free conditions for 7-9 months prior to release and allowed to overnight in the enclosure. Staff members guided daily the latter group to the forest. The study does not distinguish between the effects of the different interventions mentioned above.

6 

A before-and-after, site comparison study in 1996-2006 in tropical forests of Lesio-Louna Wildlife Reserve, Republic of Congo (Congo) and Batéké Plateau National Park, Gabon found that the majority of reintroduced western lowland gorillas Gorilla gorilla gorilla that underwent quarantine prior to release alongside 14 other interventions, survived over four years. Twenty-one of 25 gorillas (84%) released in Congo and 22 of 26 gorillas (85%) released in Gabon survived at least four years. Nine females gave birth to 11 infants, of which nine survived. Before release, gorillas underwent disease screening and received preventative vaccinations. Gorillas were released in groups and allowed to adapt to local environment and supplemented with food prior to release. Gorillas were released into habitat with no resident gorillas to re-establish populations. Released gorillas were monitored frequently, treated for parasites, recaptured when sick, treated and released again. So-called ‘problem-animals’ were removed and relocated and dead gorillas were clinically examined. Forty-three individuals were rehabilitated wild-born orphaned gorillas and eight gorillas were ex-situ captive-borns. Both sites became protected areas before reintroduction commenced. The study does not distinguish between the effects of the different interventions mentioned above.

7 

A site comparison in 2008-2012 in bamboo thicket-dominated forest at Dao Tien Island (DTI) and mixed forest in Dong Nai Biosphere Reserve (DNBR), South Vietnam found that several pygmy slow lorises Nycticebus pygmaeus that underwent quarantine before release alongside eight other interventions, survived for at least two months. Four out of eight lorises survived for at least two months after release, whereas remaining ones died or their radio-collar signal was lost soon post-release. All lorises underwent a 6-week quarantine, veterinary screens and treatment for parasites and were released in groups during the wet season. Both release sites were protected, no wild resident lorises occurred there and predators were present. Lorises were kept in an in situ cage for either <2 months or two days, and were subsequently supplemented with food for 7-30 days in DTI and DNBR. Dead animals were detected and examined. The study does not distinguish between the effects of the different interventions mentioned above.

8 

A site comparison in 2008-2012 in mosaic forest at two sites in Cat Tien National Park, South Vietnam found that all pygmy slow lorises Nycticebus pygmaeus that were screened for diseases prior to translocation alongside other interventions either died or disappeared. All five lorises died or their radio-collar signal was lost soon post-release. Each loris was examined under anaesthesia and an intradermal tuberculosis test was conducted. All individuals underwent a 6-week quarantine and parasite treatment. Lorises were released as multiple individuals into habitat with no wild resident lorises present but with predators. Three lorises were released at Cat Tien National Park during the dry season. Two individuals were held in a semi-wild enclosure for one month to foster behaviour that would facilitate their survival in the wild and were released during the wet season. Dead lorises were detected and examined. The study does not distinguish between the effects of the different interventions mentioned above.

9 

A before-and-after trial in 2006-2011 in tropical forest at Gunung Halimun Salak National Park and Batutegi Nature Reserve, Indonesia found that only few reintroduced greater slow lorises Nycticebus coucang and Javan slow lorises N. javanicus that were quarantined prior to release alongside other interventions, survived for at least 146 and 22-382 days, respectively. Out of five reintroduced greater slow lorises, only one survived over 146 days and out of 18 reintroduced Javan slow lorises, only five individuals (28%) survived for at least 22-382 days. The study did not report more details about their fate. All lorises were quarantined for six weeks and underwent veterinary screens prior to single releases. Sick individuals were recaptured and treated. All but two lorises were held in enclosures at the release site to adapt to local habitat, where conspecifics and predators occurred. Dead lorises were examined to determine cause of death. The study does not distinguish between the effects of the different interventions mentioned above.

Referenced papers

Please cite as:

Junker, J., Kühl, H.S., Orth, L., Smith, R.K., Petrovan, S.O. & Sutherland, W.J. (2018) Primate conservation. Pages 393-445 in: W.J. Sutherland, L.V. Dicks, N. Ockendon, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2018. Open Book Publishers, Cambridge, UK.