What it takes
Something to whoop about
The whooping crane, a migratory species that traversed between sites in the US and Western Canada, had all but died out by the mid-1940s, with just 21 birds remaining. Habitat loss and indiscriminate hunting had just about done it in. Hunting the birds had been banned for over 20 years by then, but recovery from such small numbers was not guaranteed.
In the 1960s biologists embarked on a captive breeding programme to boost numbers. This involved getting the monogamous birds to produce more than one clutch of eggs every breeding season, by taking away the first eggs laid for artificial incubation, encouraging the couple to mate again and lay more. Chicks born from eggs left in the nest were raised by the adult birds, but those hatched in an incubator imprinted with their human keepers. In order to make these birds capable of being released in the wild, keepers dressed head to toe in white crane costumes and taught the hatchlings whooping crane behaviour.
By the early 1990s, the first chicks raised in this manner were reintroduced to central Florida, where they successfully mated and produced a wild whooping crane chick in 2000. Another hurdle successfully tackled was teaching these newly reintroduced chicks how to migrate from Florida to Wisconsin for the summer – a 1,900-kilometre journey.
For this the team partnered with Operation Migration, whose volunteers began training the chicks to follow an ultralight aircraft driven by a pilot dressed in full crane costume. Landowners along the way provided safe overnight rest stops. And so began the first human-led migrations of whooping cranes. The human effort involved – much of it voluntary – has been staggering. Today whooping crane numbers have risen to 826: still endangered but no longer critically. Whether theirs is a success story will depend on whether the next challenge is overcome – conserving their wetlands habitat.
This frog went to market
In 1998 Ivan Lonzano, then director of Bogotá’s wildlife rescue centre, was called to the city’s airport by Colombian police who had intercepted two boxes destined for Europe. Inside were crammed nearly 800 highly colourful poison dart frogs, many from critically endangered species, most either dead or dying. The shock of this encounter spurred Lonzano on a conservation journey that nearly ruined him financially and also almost ended his marriage.
Colombia has 734 frog species of which 160 are critically endangered. Unfortunately international frog collectors and unscrupulous traffickers paid little heed to that latter fact. Lonzano hit upon the controversial idea of creating a legal trade of captive bred poison frogs (which, incidentally, lose their poison but none of their exotic colouration in captivity), hoping this would drive down market prices and thus make it less attractive to lift specimens from the wild. It took him years building up the knowhow to breed the frogs and trying to convince the Colombian government of his good intentions so they would permit him to export them legally.
His efforts are now beginning to pay off – collectors are attracted by this legal channel for obtaining frogs and prices for specimens from the species he breeds have tumbled, pulling the rug from under the traffickers. Lonzano notes that many of the collectors have successfully bred frogs from specimens he has supplied and sold them on, further lowering prices. His next step is to breed frogs for reintroduction into the wild.
The shy rhino’s fertility experts
Desperate efforts have been underway for over three decades to prevent the shy Sumatran rhino from going extinct. A lonely species prone to emitting melodious squeals, the Sumatran has earned the nickname ‘the singing rhino’. Once ranging across an arc of Southeast Asia from Bhutan down to Indonesia, today the few that remain in the wild (numbers are estimated as anywhere between 30 to 80) are found in pockets of jungle in Sumatra and Borneo. As their habitat has dwindled and fragmented over time, the few that remain are further separated. Over the years this has led to inbreeding and shrinking genetic diversity.
While there is a renewed push towards habitat preservation (though recent road-building plans in Aceh province form yet another new threat), conservationists have long felt the only chance of survival rests in captive breeding. So, back in 1984, the decision was made to capture individuals in the wild, keep them safe in captivity and thus try to bring up numbers. Easier said than done. Of the 40 rhinos first captured, 13 had died by the end of the decade due to issues ranging from disease and injury to being fed the wrong diet (hay instead of the fresh vegetation they ate in the wild). There were also no calves. It looked like conservationists were helping this species to extinction.
Two Sumatran rhinos in the Cincinnati Zoo in the US developed eye problems which keepers discovered were due to too much time in the sun – in the wild they would have been shaded by the forest canopy. The zoo spent $500,000 for special awnings to provide shade.
The fertility problem was partly due to this species being induced ovulators; females only ovulate in the presence of males. Another problem was that if females didn’t mate regularly, they developed uterine cysts and growths and if they didn’t get pregnant and deliver babies often enough they rapidly became infertile. When natural mating was attempted, miscarriages were common. The first calf was not born until 2001 and so far only two captive females, one in the US and another in Sumatra, have produced babies. This does not augur well for the future as the small population in the wild continues to not produce enough offspring.
The race is now on to try IVF techniques using surrogate mothers. This means trying to capture yet more animals. Extracting eggs from rhinos is fraught with danger due to their anatomy – one wrong move and a major blood vessel could be punctured.
Even if the efforts succeed, it looks likely that the Sumatran rhino’s future could be as a captive species, as its wilderness home continues to shrink.
The recalcitrant tree
The Sicilian Zelkova (Zelkova sicula) was first discovered in 1991 in a single population of 230 in the Iblei Mountains, eastern Sicily. A second patch of about 1,000 trees was found within the same mountain range in 2009. Considered one of the most endangered tree species in the world, the hunt is on for further sites.
Due to a chromosomal irregularity, the Sicilian Zelkova produces sterile seeds and propagation is via root suckers. Scientific research has shown that the remaining populations could likely be traced back to a single ancestor. The two known sites have been fenced off to prevent grazing and afforestation activities are afoot in the region but the threat to the trees could come from climatic sources, with prolonged dry weather a particular enemy. So conservationists have decided that the best bet is to raise enough new saplings to be trialled in other locations where the environmental conditions might be more favourable.
That’s easier said than done, as scientists have discovered. While the team at the Conservatoire National Botanique of Brest has worked on obtaining new plants from root cuttings, scientists at the Institute of Biosciences and BioResources of Palermo have been trying in vitro techniques. After many years of trial and error, during which the species was described as ‘recalcitrant’ to in vitro culture, the researchers finally succeeded. But of all the saplings so far produced, only eight per cent managed to acclimatize outdoors. Reintroductions in the wild are underway and investigation into what role this rare species plays within the ecosystem is ongoing.
This article is from
the January-February 2021 issue
of New Internationalist.
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