The rehabilitated chimpanzees of Rubondo Island

Published source details Borner M. (1985) The rehabilitated chimpanzees of Rubondo Island. Oryx, 19, 151-154.
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This study is summarised as evidence for the following.

	Action	Category
	Reintroduce primates into habitat without predators Action Link
	Provide supplementary food for a certain period of time only Action Link
	Reintroduce primates as single/multiple individuals Action Link

Reintroduce primates into habitat without predators

A study in 1966–1985 on a forested island in Rubondo National Park, Tanzania found that eastern chimpanzees Pan troglodytes schweinfurthii reintroduced into habitat devoid of predators along with other interventions, bred and increased in numbers from 17 to at least 20 individuals over 16 years. No statistical tests were carried out to determine whether this increase was significant. At least two males were shot after attacking game scouts. Two new-born infants were observed in 1968 and in 1985. All of the 17 reintroduced chimpanzees had been born in the wild and had spent time in captivity. Their age at the time of release varied from four to 12 years. Chimpanzees were released in four lots (from 1966 to 1969). Chimpanzees in the first release group were provided with supplementary food for two months. The study does not distinguish between the effects of the different interventions mentioned above.
Provide supplementary food for a certain period of time only

A study in 1966-1985 in Rubondo National Park, a forested island in Lake Victoria, Tanzania found that reintroduced eastern chimpanzees Pan troglodytes schweinfurthii that were supplemented with food for two months after the first release along with other interventions, bred and increased in numbers from 17 to at least 20 individuals over a 16-year time period. However, no statistical tests were carried out to determine whether this increase was significant. Only the first out of four release groups received supplementary food. At least two males were shot after attacking game scouts. Two new-born infants were observed in 1968 and in 1985. All of the 17 reintroduced chimpanzees were wild-born and spent various amounts of time in captivity. Their age at the time of release ranged from 4-12 years and their health from good to poor. Chimpanzees were released in four lots in 1966-1969) with considerable time intervals in between release events, and only a few had met before. The island was free of predators. The study does not distinguish between the effects of the different interventions mentioned above.
Reintroduce primates as single/multiple individuals

A study in 1966–1985 on, a forested island in Tanzania found that reintroduced eastern chimpanzees Pan troglodytes schweinfurthii that were released as multiple individuals during four reintroduction events (from 1966 to 1969) alongside other interventions, bred and increased in numbers from 17 to at least 20 individuals over a 16-year time period. No statistical tests were carried out to determine whether this increase was significant. At least two males were shot after attacking game scouts. Two new-born infants were seen in 1968 and in 1985. Male-to-female ratios in the four release groups differed (4.7, 1.0, 1.0, 2.2) and few individuals within each group had met before. All 17 reintroduced chimpanzees had been born in the wild and spent various amounts of time in captivity. Their age at the time of release varied from four to 12. The island was free of predators and chimpanzees. The first release group was provided with supplementary food for two months. The study does not distinguish between the effects of the different interventions mentioned above.