Ex-Situ conservation Zoos and gardens Chapter 14
Summary What is ex-situ conservation? Why do we need ex-situ conservation programs? Ex-situ programs: objectives, design and management Costs and benefits
What is ex-situ conservation? In-situ conservation: conservation management of species within their natural habitat Ex-situ conservation: species conservation initiatives outside the species’ natural habitat Ex-situ conservation involves maintaining individuals in “unnatural” environments under close supervision, i.e. zoos and gardens
Shifting priorities of zoos and gardens
Why ex-situ conservation? Many populations of endangered species (e.g. all five extant rhinoceros species, giant panda) in natural habitats are so small that extinction risk is very high.. …so establishment of off-site populations reduces extinction risk
Why ex-situ conservation? Some species (e.g. Père David’s deer, Przewalski’s horse, Franklin tree) no longer exist in the wild… …so maintenance of “captive” populations essential to prevent extinction
Extinct or near extinct species
Extinct species in captivity
Martha
Ex-situ care: the institutions Major institutions include zoos and zoological gardens, aquaria and herbaria Most of these institutions are now actively in on-going conservation efforts both in-situ and ex-situ
How do ex-situ conservation strategies help maintain wild populations? Individuals from ex-situ populations can be periodically released to augment existing wild populations, maintain genetic variability and reduce inbreeding Research on captive populations can suggest new conservation strategies or identify potential problems with existing in-situ strategies How do ex-situ conservation strategies help maintain wild populations? Self-maintaining ex-situ populations can reduce need to collect wild individuals for display or research purposes Ex-situ populations can enhance public awareness, which translates into increased support for in-situ conservation programs
Establishing a captive breeding program Decline in wild population to “critical” threshold results in attempts (sometimes unsuccessful) to establish one or more captive populations While captive population is being built up, factors responsible for decline in the wild are determined and mitigated (where possible) Once captive population is well established, wild reintroductions and monitoring begin
Establishing a captive breeding program: management tasks
Limitations/problems of ex-situ conservation While some rare of endangered species do breed successfully in captivity (e.g. Golden lion tamarin, Père David’s deer), others (e.g. Panda. rhinoceros) do not For species which do not breed in captivity, ex-situ conservation is difficult, if not impossible
Problems/limitations of ex-situ conservation Small population size due to restrictions on space, resources, and technical expertise Hence, captive populations often have low genetic variability and great pains are taken to try and maintain existing variability and reduce inbreeding through “stud” books and zoological exchange
Tracking breeding 1. Short-term propagation and re-introduction Breeding endangered/extirpated species in captivity and releasing them into an area within the species original range Implies reasonably healthy captive populations and sufficient quantity/quality of natural habitat
The California condor (Gymnogyps californicus) Population declined beginning in middle 19th and 20th century due to shooting, habitat loss and pollution (DDT, lead shot in carcasses) Captive population begun in mid 1940s By 1985, only 6 adults in wild, 21 in captivity All wild adults captured in 1986 (amid much controversy!) The California condor : a 3-pronged conservation approach “In-situ” conservation: purchase of Hudson Ranch (5300 ha) and creation of Bitter Creek National Wildlife Refuge by U.S. Fish and Wildlife Service in 1987 Enhancement of captive flock through successful breeding Release of female condors into wild; learned to nest in artificial structures and take contaminant-free food from feeding stations
Why the flap over the 1986 decision? Until that time, no successful breeding in captivity Would captivity and exposure to people alter behavior? Cost: as of 1992, $20 million had been spent on a single rare species which, in the view of many, was unlikely to ever be reestablished in the wild
Prerequisites for successful short-term propagation and reintroduction Self-sustaining captive population with reasonable level of genetic variability, of sufficient size to overcome ongoing losses from reintroduction programs Elimination or mitigation of factor(s) causing species decline in the wild
Prerequisites for successful short-term propagation and reintroduction Habitat of sufficient quantity and quality to sustain growth of reintroduced population Adequate feasibility studies of species needs; requires knowledge of species reproductive biology, ecology and behavior
Pre-requisites for short-term propagation and reintroduction Choice of release site: sites should generally have low abundance of wild population to minimize potential behavioral conflicts, spread of disease, etc. Adequate pre-release training, socialization, etc.
2. Long-term propagation Maintenance of captive populations over many generations For some species that are extinct in the wild, captive populations are too small or reintroduction is not immediately possible because insufficient natural habitat currently exists (e.g. Père David’s deer, European bison)
3. Fostering & cross-fostering In some birds, if the clutch is removed, a second clutch is produced The first clutch can then be raised by another set of parents of the same species (fostering) or of another species (cross-fostering)… …resulting in a doubling of reproductive output In many birds of prey, several eggs are produced by only one nesting survives, so removal and fostering of other eggs increases reproductive output Mixed success: the slow recovery of the whooping crane Grus americana Never abundant, declined dramatically in 19th and 20th centuries due to hunting, habitat loss By 1942, only 15 birds remained in the wild; one remaining nesting area (Wood Buffalo National Park) one remaining wintering area (Aransas national Refuge, TX)
The slow recovery of the whooping crane Lays 2 eggs, but only 1 chick survives, so extra eggs removed and cross-fostered to Sandhill crane (Grus canadiensis) nests Chick survival high but… …cross-fostered chicks did not learn species-specific behaviors needed to form mating pairs with wild whooping cranes
Mixed success: the recovery of the whooping crane Despite tremendous conservation efforts, Whooping crane recovery has been very slow… …unlike the Sandhill crane, which has recovered nicely Nonetheless, conservation efforts have thus far saved the Whooping crane from certain extinction
4. Augmentation, translocation, reintroduction and introduction Augmentation: addition of captive bred or wild-caught individuals to an existing population Translocation: transferal of individuals from one wild population to another 4. Augmentation, translocation, reintroduction and introduction Reintroduction: captive-bred or wild individuals released into an area within the species original range Introduction: captive bred or wild-caught individuals released into an area outside the species original range
Correlates of reintroduction/translocation success Release area habitat: success rate increases dramatically with quality and quantity of available habitat Release location: success rate higher for areas at “core” of historic range, versus periphery or outside
Correlates of reintroduction/translocation success Success rate is higher for wild-caught reintroductions than for captive-reared Success rate is also higher for herbivore species than carnivore species
Correlates of reintroduction/translocation success For birds, data suggests that success rate increases with the number of individuals released, up to about 100 animals… …after which there is little increase in success with increasing release numbers Issues in translocation/reintroduction: selecting donor populations In general, the closer donor populations are (geographically) to the site, the better, as this minimizes risks of outbreeding depression… …but must also try and avoid inbreeding, so reintroductions from several donor populations are preferable
The reintroduction of the gray wolf (Canis lupus) to the Greater Yellowstone Ecosystem (GYE) Once widespread throughout North America, buts systematically exterminated throughout the U.S. as a matter of federal policy since late 1800s By mid 1980s, small relict populations remained only in Minnesota… …but is still relatively common in Canada and Russia
Wolf reintroduction to GYE: rationale Previously present but extirpated due to perceived threat to ungulate populations Single major missing biotic element of historical GYE Evidence of ungulate overgrazing, in part due to lack of predator control
Wolf reintroduction to GYE: some players Ranchers: feared livestock losses Mining industry: saw presence of (yet another) VTE species as restricting public lands available for mineral development Hunters: wolves eat deer & elk; therefore fewer for hunters to shoot. U.S.F&WS - legally mandated to institute wolf recovery since C. lupus is listed under U.S. ESA. Parks Canada, provincial (Alberta and B.C.) F&W authorities: wolf donors Conservationists, U.S. P.S.: want GYE rehabilitated to something closer to original state.
Wolf reintroduction to GYE: the operation Wolves (family groups) captured in several Canadian national parks 14 released into Yellowstone National Park in January 1995, 17 in 1996 Now over 300 in Yellowstone
Wolf reintroduction to GYE: current management issues Problem: antipathy of ranchers Solutions: reward for landowners on whose lands wolves successfully reproduced; compensation for livestock losses; culling of problem animals Problem: wolf movement outside park boundaries Solution: relocation of family groups inside park 5. Artificial incubation Collection of eggs from wild populations during egg laying Incubation under artificial conditions and care of juveniles, followed by… …release into the wild Usually done only for reptile, amphibian, fish and (more rare) bird species with little parental care
6. Artificial insemination Used when only one or a few individuals are present Females in breeding condition are impregnated with sperm collected from suitable (usually captive) Costly and with a low success rate, this is usually attempted only for very rare species which tend not to breed in captivity (e.g. Javan rhino, giant panda)
7. Embryo transfer Used when only one or a few individuals are present Involves transfer of an embryo from an endangered species to a more common species, sometimes even a domesticated species Very costly, technically demanding and with a low success rate, this is usually attempted only for very rare species which tend not to breed in captivity (e.g. Bongo, guar)