Place orphaned or abandoned wild young with wild foster parents

Overall effectiveness category Likely to be beneficial
Number of studies: 3
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How is the evidence assessed?

Effectiveness

52%
Certainty

42%
Harms

10%

Calculating overall effectiveness category

Background information and definitions

Young mammals believed to be orphaned or abandoned are sometimes taken in by wildlife rehabilitators, to be reared and released back into the wild. Often, this is done more for animal welfare reasons than for species conservation though for rare species, release of such animals may provide opportunities for choosing where to augment populations. An alternative to captive rearing may be to attempt to foster young into existing wild families. If this can be achieved, it may improve their ability to find food in the wild and reduce the extent to which they become imprinted on humans and could, thus, improve the prospects of longer-term survival in the wild. However, the success of such programmes can be difficult to judge, without benchmark data for survival of wild-reared mammals.

Study locations

Key messages

Three studies evaluated the effects of placing orphaned or abandoned wild young with wild foster parents. One study was in the USA, one was in South Africa and one was in Botswana.

COMMUNITY RESPONSE (0 STUDIES)

POPULATION RESPONSE (3 STUDIES)

Survival (3 studies): Two studies (one controlled) in the USA and Botswana, found that orphaned young black bears and African wild dogs had greater or equal survival compared to animals released alone or young of wild mammals with their biological parents. A study in South Africa found that an orphaned cheetah cub was not accepted by a family of cheetahs.

BEHAVIOUR (0 STUDIES)

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

A controlled study in 1973–1983 in temperate forests in Idaho and Pennsylvania, USA (Alt et al. 1984) found that orphaned black bears Ursus americanus released to wild females with cubs had higher short-term survival than did orphaned bears released alone. Ten days after release, 23 of 45 (51%) orphaned bears placed with females with cubs were seen to be in good condition, but only five of 39 (13%) cases in which orphans were released in the wild alone were deemed successful. In 1973–1983, twenty-nine cubs were released directly into dens of females with young, 11 cubs were released after chasing females and causing their young to climb trees and five cubs were placed with female bears and their young that were caught in culvert traps and then released. In seven cases, females were immobilized while the cubs were introduced. Thirty-nine orphaned bear cubs were held in captivity before being release alone into the wild. Reintroductions were regarded as successful if orphaned bears were observed with the foster mother at least 10 days after reintroduction or, for solo introductions, if animals survived for at least 30 days and did not become a nuisance to humans. Survey methods were unclear.
Study and other actions tested
Referenced paper
Alt G.L. & Beecham J.J. (1984) Reintroduction of orphaned black bear cubs into the wild. Wildlife Society Bulletin, 12, 169-174.
A study in 1994-1998 in a savannah reserve in North West province, South Africa (Hofmeyr & van Dyk 1998) found that when an orphaned female cheetah Acinonyx jubatus cub was put in a holding pen with a family of cheetahs, the orphaned female was not accepted by the group and was removed after two weeks. The orphaned female was prevented from accessing food by male cubs and the adult female was hostile towards her, although did not cause physical harm. The orphaned female cub was fed separately as a result and was relocated to a captive breeding facility after two weeks. An 8-month-old orphaned female cub was placed in a holding pen with one adult female and three 18-month-old dependent male cubs in a 60,000 ha game reserve. The orphaned female cheetah had been captured on a farm, the family group were from a rehabilitation facility.
Study and other actions tested
Referenced paper
Hofmeyr M. & van Dyk G. (1998) Cheetah introductions to two north west parks: case studies from Pilanesberg National Park and Madikwe Game Reserve. Proceedings of a Symposium on Cheetahs as Game Ranch Animals, Onderstepoort, 60-71.
A study in 2000 and 2003 at three savannah sites in Botsawana (Mcnutt et al. 2008) found that orphaned African wild dog Lycaon pictus pups released in the vicinity of wild dog packs were readily adopted into the pack and had survival rates similar to those of wild pups. A six-week-old pup was adopted into a pack of 24 adults and yearlings in August, and survived to at least October, but not to the year end. Four 10-week-old pups were adopted into a pack of seven adults and eight pups in August. Two pups survived at least to the year end. Three 10-week-old pups were adopted into a pack of three adults and four pups in August but did not survive to the year end. Where pups died before the year end, no pups born into those packs survived either. One orphaned pup was adopted within 24 hours of capture, the others after three weeks of quarantine. Four pups required moving to re-join their adoptive pack, which moved 7 km during the first night following interactions with lions Panthera leo.
Study and other actions tested
Referenced paper
McNutt J.W., Parker M.N., Swarner M.J. & Gusset M. (2008) Adoption as a conservation tool for endangered African wild dogs (Lycaon pictus). South African Journal of Wildlife Research, 38, 109-112.

Please cite as:

Littlewood, N.A., Rocha, R., Smith, R.K., Martin, P.A., Lockhart, S.L., Schoonover, R.F., Wilman, E., Bladon, A.J., Sainsbury, K.A., Pimm S. and Sutherland, W.J. (2020) Terrestrial Mammal Conservation: Global Evidence for the Effects of Interventions for terrestrial mammals excluding bats and primates. Synopses of Conservation Evidence Series. University of Cambridge, Cambridge, UK.

Where has this evidence come from?

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This Action forms part of the Action Synopsis:

Terrestrial Mammal Conservation

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Graze herbivores on pasture, instead of sustaining with artificial foods Action Link	Unknown effectiveness (limited evidence)	1	Synopsis Link
Hand-rear orphaned or abandoned young in captivity Action Link	Trade-off between benefit and harms	6	Synopsis Link
Temporarily hold females and offspring in fenced area to increase survival of young Action Link	No evidence found (no assessment)	0	Synopsis Link