Providing evidence to improve practice

Individual study: Survival of reintroduced pygmy slow loris Nycticebus pygmaeus in South Vietnam

Published source details

Kenyon M., Streicher U., Loung H., Tran T., Tran M., Vo B. & Cronin A. (2014) Survival of reintroduced pygmy slow loris Nycticebus pygmaeus in South Vietnam. Endangered Species Research, 25, 85-95


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Detect & report dead primates and clinically determine their cause of death to avoid disease transmission Primate Conservation

A site comparison study 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, survived reintroduction while dead individuals were examined to determine their cause of death alongside eight other interventions. Four out of eight lorises survived for at least two months post-release. One individual died due to assumed hyperthermia, a predator killed another and the remaining two lost their collar soon after release. Lorises were released as multiple individuals during the wet season after a 6-week quarantine, veterinary screens and treatment for parasites. Both release sites were protected, no wild resident lorises occurred there and predators were present. Lorises were kept in an in situ cage between <2 months and two days, and were subsequently supplemented with food for 7-30 days in DTI and DNBR, respectively. The study does not distinguish between the effects of the different interventions mentioned above.

Remove/treat external/internal parasites to increase reproductive success/survival Primate Conservation

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 were treated for parasites prior to their release alongside eight other interventions, survived for at least two months. Four out of eight lorises survived for at least two months post-release, whereas the remaining individuals either died or their radio-collar signal was lost. Lorises were released in groups during the wet season after a 6-week quarantine, veterinary screens and oral treatment for parasites. Both release sites were protected, no wild resident lorises occurred there and predators were present. Lorises were kept in a cage at the release site between <2 months and two days, and were subsequently supplemented with food for 7-30 days in DTI and DNBR, respectively. Dead lorises were detected and examined. The study does not distinguish between the effects of the different interventions mentioned above.

Implement quarantine for primates before reintroduction/translocation Primate Conservation

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.

Detect & report dead primates and clinically determine their cause of death to avoid disease transmission Primate Conservation

A site comparison in 2008-2012 in mosaic forest at two sites in Cat Tien National Park, South Vietnam found that all reintroduced pygmy slow lorises Nycticebus pygmaeus either died or disappeared; dead individuals were examined to determine their cause of death along with other interventions. Three individuals were killed by predators and two others disappeared and were assumed dead. All individuals underwent a 6-week quarantine, veterinary screens and treatment for parasites. Lorises were released as multiple individuals during the dry season into habitat with no wild resident lorises but with predators. Another 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. The study does not distinguish between the effects of the different interventions mentioned above.

Remove/treat external/internal parasites to increase reproductive success/survival Primate Conservation

A site comparison study 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 treated for parasites prior to their release alongside other interventions either died or disappeared. All five lorises died or their radio-collar signal was lost soon after release. Lorises underwent a 6-week quarantine, veterinary screens and oral treatment for parasites. They were released in groups into habitat with no wild resident lorises but with predators. Three lorises were released at Cat Tien National Park during the dry season. Another 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 animals were examined to determine the cause of death. The study does not distinguish between the effects of the different interventions mentioned above.

Implement quarantine for primates before reintroduction/translocation Primate Conservation

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.

Fostering appropriate behaviour to facilitate rehabilitation Primate Conservation

A site comparison in 2008-2012 in mosaic forest at two sites in Cat Tien National Park, South Vietnam (8) found that all pygmy slow lorises Nycticebus pygmaeus that were allowed to learn natural behaviours prior to release alongside other interventions, either died or disappeared. All five lorises that were reintroduced died or their radio collar signal was lost at an early stage after release. Two individuals were held in a semi-wild enclosure for one month to foster behaviour aimed at facilitating survival in the wild. The latter were released during the wet season. Three other lorises were released at Cat Tien National Park during the dry season. Monkeys underwent a 6-week quarantine, veterinary screens, and parasite treatment. Lorises were released as multiple individuals into habitat with no resident lorises but with predators. Bodies of dead animals were examined. The study does not distinguish between the effects of the different interventions mentioned above.

Reintroduce primates into habitat where the species is absent Primate Conservation

A site comparison in 2008–2012 in two forest sites in South Vietnam found that several pygmy slow lorises Nycticebus pygmaeus that were released into habitat where the species was absent, along with eight other interventions, survived for at least two months. Four of eight lorises survived for at least two months after release, whereas the remaining lorises either died or their radio-collar signal was lost at an early stage after release. Both release sites were protected and predators were present. Lorises were released during the wet season after they had undergone a 6-week quarantine, veterinary screens and treatment for parasites. Lorises were kept in a cage for between two days and 2 months, and were supplemented with food for between seven and 30 days. Bodies of dead animals were examined to determine the cause of death. The study does not distinguish between the effects of the different interventions mentioned above.

Reintroduce primates as single/multiple individuals Primate Conservation

A site comparison in 2008-2012 in two forests in South Vietnam found that several pygmy slow lorises Nycticebus pygmaeus that were reintroduced as multiple individuals, along with eight other interventions, survived for at least two months. Four out of eight lorises survived for at least two months after release, whereas the remaining animals either died or their radio collar signal was lost at an early stage after release. Lorises were released during the wet season after all animals had undergone a 6-week quarantine, veterinary screens, and treatment for parasites. Both release sites were protected and no wild resident lorises occurred there, but predators were present. Lorises were kept in a cage for between two days and two months and were subsequently supplemented with food for between seven and 30 days. Bodies of dead animals were examined to determine the cause of death. The study does not distinguish between the effects of the different interventions mentioned above.

Reintroduce primates into habitat with predators Primate Conservation

A site comparison in 2008–2012 in two forests in Dao Tien Island (DTI) and mixed forest in Dong Nai Biosphere Reserve (DNBR), south Vietnam found that hyalf of pygmy slow lorises Nycticebus pygmaeus that were released into habitat with predators, along with eight other interventions, survived for at least two months. Four out of eight lorises survived for at least two months after release, whereas the remaining lorises died or their radio-collar signal was lost. Both release sites were protected and no wild resident lorises occurred there. Lorises were released during the wet season after all of them had undergone a 6-week quarantine, veterinary screens and treatment for parasites. Lorises were kept in a cage for between two days and two months, and were fed supplementary food for seven or 30 days. Bodies of dead animals were examined to determine their cause of death. The study does not distinguish between the effects of the different interventions mentioned above.

Reintroduce primates into habitat where the species is absent Primate Conservation

A site comparison in 2008–2012 in mosaic forest at two sites in South Vietnam found that all pygmy slow lorises Nycticebus pygmaeus that were released into habitat where the species was absent along with other interventions, either died or disappeared. All five lorises either died or their radio-collar signal was lost soon after release. Wild lorises were absent or had very low numbers at the sites. All lorises were quarantined for 6-weeks, were screened by vets and treated for parasites. Individual lorises were released alone. Three lorises were released during the dry season. Another two individuals were held in a semi-wild enclosure for one month to foster behaviour that would aid their survival in the wild. The latter were released during the wet season. Bodies of dead animals were examined to determine their cause of death. The study does not distinguish between the effects of the different interventions mentioned above.

Provide supplementary food for a certain period of time only Primate Conservation

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 half of reintroduced pygmy slow lorises Nycticebus pygmaeus that were supplemented with food for a certain period of time along with eight other interventions, survived for over two months. Four out of eight lorises survived at least two months after release, whereas others either died or their radio-collar signal was lost. Lorises were kept in a cage for between two days and 2 months and were subsequently supplemented with food for 7-30 days. Lorises were released during the wet season after a 6-week quarantine, veterinary screens and parasite treatment. Both release sites were protected, no wild resident lorises occurred there and predators were present. Bodies of dead animals were investigated to determine the cause of death. The study does not distinguish between the effects of the different interventions mentioned above.

Reintroduce primates as single/multiple individuals Primate Conservation

A site comparison in 2008-2012 in two forest sites in South Vietnam found that all pygmy slow lorises Nycticebus pygmaeus that were reintroduced as individuals, along with other interventions either died or disappeared. All five lorises died or their radio collar signal was lost at an early stage after release. Before release, lorises were quarantined for six weeks, screened by vets, and treated for parasites. No wild resident lorises occurred at either of the release sites, but predators did. Three lorises were released at one site during the dry season. Another two individuals were held in a semi-wild enclosure for one month to allow them to learn natural behaviour that would aid their survival in the wild. The latter were released during the wet season. Bodies of dead animals were examined to determine the cause of death. The study does not distinguish between the effects of the different interventions mentioned above.

Reintroduce primates into habitat with predators Primate Conservation

A site comparison in 2008–2012 in two forest sites in Cat Tien National Park, Vietnam found that all pygmy slow lorises Nycticebus pygmaeus that were released into habitat with predators along with other interventions either died or disappeared. Three of five reintroduced lorises were killed by predators and the radio collar signal of two lorises was lost at an early stage after release. Before release all lorises underwent a 6-week quarantine, veterinary screens, and treatment for parasites. Lorises were released into habitat with no resident wild lorises. Three lorises were released during the dry season. Another two individuals were held in a semi-wild enclosure for one month to foster behaviour that would facilitate their survival in the wild, and then released during the wet season. Bodies of dead animals were examined to determine the cause of death. The study does not distinguish between the effects of the different interventions mentioned above.

Conduct veterinary screens of animals before reintroducing/translocating them Primate Conservation

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 half of the pygmy slow lorises Nycticebus pygmaeus that were screened for diseases before translocation alongside eight other interventions, survived for at least two months. Four out of eight lorises survived for at least two months post-release, whereas remaining individuals either died or their radio-collar signal was lost at an early stage. Lorises were released in groups during the wet season after all monkeys had undergone a 6-week quarantine, veterinary screens and treatment for parasites. Both release sites were protected, no wild resident lorises occurred there and predators were present. Lorises were kept in an in situ cage for between < 2 months or two days, and were subsequently supplemented with food for 7-30 days in DTI and DNBR, respectively. Bodies of dead animals were examined to determine the cause of death. The study does not distinguish between the effects of the different interventions mentioned above.

Allow primates to adapt to local habitat conditions for some time before introduction to the wild Primate Conservation

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), Vietnam found that several reintroduced pygmy slow lorises Nycticebus pygmaeus that were allowed to acclimatize to local the environment before release along with eight other interventions, survived over two months. Four out of eight lorises survived for at least two months after release, whereas the remaining lorises either died or their radio-collar signal was lost soon after release. Lorises were kept in an in situ cage for <2 months and for two days, and were subsequently supplemented with food for 7-30 days in DTI and DNBR, respectively. Lorises were released during the wet season after a 6-week quarantine, veterinary screens and treatment for parasites. Both release sites were officially protected, no resident lorises occurred there, but predators were present. Bodies of dead lorises were examined. The study does not distinguish between the effects of the different interventions mentioned above.

Conduct veterinary screens of animals before reintroducing/translocating them Primate Conservation

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 their translocation alongside other interventions either died or disappeared. All five lorises died or their radio collar signal was lost at an early stage after release. Each loris was examined under anaesthesia and an intradermal tuberculosis test was conducted. All monkeys underwent a 6-week quarantine and treatment for parasites. Lorises were released in groups into habitat with no wild resident lorises. Three lorises were released at Cat Tien National Park during the dry season. Two other individuals were held in a semi-wild enclosure for one month to foster behaviour that would facilitate their survival in the wild. The latter were released during the wet season. Bodies of dead animals were detected and examined to determine the cause of death. The study does not distinguish between the effects of the different interventions mentioned above.