Official Magazine of the Nature Society (Singapore)
Tempting but Highly Dangerous
Main article | Lessons from failed reintroduction | Plans to reintroduce the Greater Mousedeer
Everyone knows the story of Noah's Ark. Anticipating a great flood that would cover much of the world thousands of years ago, Noah brought a pair of each animal (and probably many plant species) into the Ark. When the waters finally receded, the animals were released and with them, Noah repopulated the world. Man's attempt to reintroduce species that have gone extinct with habitat loss sounds like a grand idea, he is playing modern-day Noah. But Lim Kim Seng warns that failures outweigh successes.
Nature lovers everywhere are pained at the rate of species extinctions and reintroducing an animal or plant to a site where it was formerly found sounds like a beautiful, even grand idea. But it is one fraught with many dangers. Success stories such as the Red Kite and Osprey (bird) reintroduction programmes in Britain, the Peregrine (bird) reintroduction in Europe and the United States, Piere David's Deer in China and the Arabian Oryx (antelope) in Arabia get a lot of news coverage and cloud the fact that failures outweigh successes. (Piere David was a missionary-cum-naturalist who 'discovered' the deer named after him in eighteenth century China).
In Singapore we reintroduced the Oriental Magpie Robin in the early '80s and while it appeared initially promising, ultimately failed. On the surface it seems simple enough. Just list those animals and plants that previously thrived on the site, get stock/seeds from somewhere and let them loose. Or, in the case of plants/trees, sow the seeds.
Such a naive approach is sowing the seeds for certain failure. Here's why.
Firstly one has to study whether the factors that caused the extinction of the species at the selected site are still present. These factors are habitat loss and degradation, poaching, pollution including pesticide poisoning, competition and unviable population levels. Then one should study the ecosystem currently in place at the site. Questions one has to ask and answer include: Is the site still suitable for the species being considered for reintroduction? Is there sufficient prey and protection for them to survive and thrive? Would the reintroduction of the 'new' animals upset the existing ecological balance and cause further extinctions of the extant but rare animals there? Does the niche for the species still exist? There must be comprehensive studies done to ensure all these questions are answered satisfactorily before commencing a reintroduction programme.
Selecting which species not so simple
Does one introduce animal or plant, herbivore or carnivore, insect or mammal, 10 or 100 specimens, one or many species? How many males and how many females of each? As you can see, selecting which species to introduce is a mammoth undertaking. The usual step would be a "take one species at a time approach". While slow, it reduces risks. For example, it would minimise unanticipated interactions between speciesa potential problem.
Public sentiment can also dictate what is being introducedoften with undesirable consequences. For instance, the public would undoubtedly choose cute adorable animals over creepy crawlies. Dubbed the 'Bambi Syndrome', it means that eagles and even tigers get the nod while bugs, worms or snakes get nowhere. Then one has also got to decide on whether to reintroduce an animal that is already extinct or one that is on the verge of extinction? According to ecologists, the magic number for a sustainable population is 50 pairs. If the wild population of a species is below this number, it renders it very vulnerable to disease, predation and inbreeding.
What's more, even assuming that these native animals were from zoos and bird parks, here or in the region, and the reintroduction programme would not be inadvertently supporting the illegal wildlife trade, there are still ecological questions to answer.
Are the animals being considered of the same subspecies? There has to be some assurance that they are of the same subspecies and disease free.
Reintroduction committees everywhere have made many difficult decisions. Even so, failures outnumber successes.
Examples of Failures
Masked Bobwhite (Colinus virginianus)
The Masked Bobwhite occurs in southern USA (Arizona) and Mexico (Sonora). The US population was extirpated by about 1900 and the Mexican population almost crashed by 1985 because of drought and cattle grazing. Efforts at reintroduction in the US from 1937 to 1950 proved unsuccessful because the birds were introduced outside of their former range (New Mexico) and in the wrong habitat. Success was only assured in 1966 through an intensive captive-breeding programme and the restoration of its grassland habitat. It is still endangered.
Laysan Finch (Telespiza cantans)
Rabbits introduced in 1903-4 on Laysan Island, Hawaii, almost eliminated the Laysan Finch (through denudation of native plants). Only about 100 birds were left when the rabbits were finally eradicated in 1923. Attempts to introduce the Laysan Finch to Midway Island also failed due to the accidental introduction of Black Rats.
Bali Starling (Leucopsar rothschildi)
There are now less than 30 Bali Starlings, in the wild, all of them in Bali Barat National Park, and over 300 in captivity. Efforts at reintroduction of this rare and beautiful bird is being sabotaged by poaching within the park despite international conservation efforts.
Reintroduction and Monitoring
Where reintroduction programmes are in place, this is what normally happens. The animals have been obtained and a quarantine facility has been found and manned. Each animal has to be identified by tags, rings or other methods and monitored for its health. It has also got to be trained to feed itself (remember, it is being released back into the wild.) After a period of close monitoring, the animals are released in stages. This is when field monitoring begins and it is carried out with the aid of devices like telemetry and satellite tracking. Field monitoring is normally maintained for a few years to ensure that the animals are alive and coping well and hopefully breeding in their new home. At the same time, checks are made to ensure that they are not having a negative impact on their new environment. In the better run reintroduction programmes, there would be a contingency plan for evacuation or relocation of the animals should problems arise. Even after the animals have successfully adapted to their new home, monitoring continues in order to evaluate the status of the entire programme. This can take several years and a lot of manpower, time and money.
Reintroduction sounds seductively simple and attractive but like accidental introductions it is fraught with dangers and must be undertaken very cautiously. A far better thing would be to fiercely protect/conserve whatever natural habitats we have got left on the mainland and offshore islands and even start working at regenerating these habitats before we plunge into reintroducing animals. It is only when the habitats are flourishing, that mammals and bigger plants can thrive. Let's not get caught up with the Bambi syndrome.
This article is part 2 of a 2-part feature on Introductions and Re-introductions. The first part, entitled 'Of Aliens that Follow in Man's Footsteps' was published in Nature Watch Vol 6 No. 3 Sept-Dec 1998.
The writer Lim Kim Seng is a member of the NSS Conservation Sub-committee. He was the co-ordinator of a four-year bird survey of the nature reserves which was organised by the National Parks Board and conducted with the help of NSS volunteers. The survey was concluded in 1997.
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