Do koalas need better protected traditional habitat, or more new growth?
BRISBANE, SYDNEY, Australia––Can a newly made $34 million commitment by the Australian government save koalas?
Or are koalas already doomed by the deadly combination of global warming and development?
Jeopardized by bushfires, dogs (especially pit bulls), disease, deforestation, and drivers speeding through fragmented habitat, koalas have already declined to as few as 43,000, according to the most pessimistic projection by the Australian Koala Foundation, whose high population estimate is only 88,000.
Down from 10 million
Officially, the Australian government believes there are two to three times as many koalas as the Australian Koala Foundation believes. But the Australian Koala Foundation estimates are based on comprehensive habitat mapping, while the official estimates are widely suspected of being based on little more than political and economic convenience.
Either way, koala numbers are precipitously down from the estimated 10 million koalas distributed throughout the coastal forests rimming Australia when the First Fleet introduced European colonization in 1788.
Widely regarded as one of the world’s cutest and happiest animals, beatifically blessing the Australian coastal forests from high amid eucalyptus trees, koalas have few predators and fewer habitat rivals either native to Australia or introduced. Nothing else bigger than insects lives almost exclusively on eucalyptus leaves.
Koalas can’t jump
In theory, at least, koalas could thrive in the eucalyptus canopy above wooded suburbs. Some do. But because mature eucalyptus trees are quick to ignite, with tindery bark and easily flammable oily wood, Australians are increasingly anxious to clear them out of developed areas.
Koalas themselves, though presumed to favor tall old eucalyptus trees, tending to stand some distance apart from each other with relatively little cover in between, actually seem better adapted in some respects to low second growth.
Since koalas can neither jump nor swing easily from tree to tree, a koala wanting to feed from a different tree, or socialize with koalas in other trees, must descend, risk exposure while running to the other tree, and must then climb.
Slow afoot, koalas are easily vulnerable to cars.
Vulnerable to dog attack
And having evolved with little need to fend off attackers, with long claws better adapted to climbing than to slashing foes, koalas are shockingly vulnerable to dog attack.
The threat of dog attack has been exacerbated by the explosive growth in recent years of the Australian pit bull population, despite lightly enforced laws meant to discourage pit bull acquisition.
The Koala Hospital in Moggill, Queensland, managed by the state Department of Environment & Heritage Protection, and the Australian Wildlife Hospital at Beerwah, Queensland, together admitted 1,306 koalas who had suffered dog attacks between 1997 and 2009. Of these koalas, 954––73%––died or were euthanized due to their injuries.
More killed than found alive
Hospital personnel told media that far more koalas were known to have been killed than were brought in alive.
Located about 60 miles apart, on opposite sides of Brisbane, the Moggill and Beerwah hospitals serve at most about half of the koala habitat in Queensland.
Staff estimated as of 2008 that dog attacks had become the third most common cause of koala death after disease and roadkills.
More recently, Queensland veterinarian Jon Hanger and University of Queensland koala ecologist Sean FitzGibbon undertook the largest and most comprehensive koala tracking program to date. Outfitting more than 400 koalas with radio collars, Hanger and FitzGibbon followed them for two years in bushland habitat at the northern edge of Brisbane.
Among the 130 koalas who died during the study, the majority were killed by dogs.
Bushfires are double threat
“We’re down to about 2,000 koalas in that koala coast area. That’s about a 68% decline from the late 1990s” Hanger told Australian Broadcasting Corporation reporter Peter McCutcheon.
Bushfires, however, may kill even more koalas than dogs, as well as destroying koala habitat. Global warming is making the Australian eucalyptus forests hotter and drier, and therefore more vulnerable to fire.
Development––and well-intended habitat conservation projects, to some extent––have pushed back the kangaroos, wallabies, feral camels and horses, and even the sheep and cattle who formerly browsed and trampled fresh green understory before it became dry tinder.
Climbing doesn’t help
Year by year, bushfires devastate koala habitat. And koala behavior in fires makes matters worse.
Because koalas can only travel from tree to tree by descending, and tend to try to avoid threats from below by climbing, they respond to bushfires by scrambling higher and higher, until branches break and the koalas fall, or their trees become wholly engulfed.
Some koalas do survive bushfires, for a time. The most popular animal survivor of wildfires that burned a region of northeastern Victoria state larger than Luxembourg in early 2009, for instance, was Sam, a female koala with burnt paws who was found by firefighter David Tree during a backburning operation near Mirboo North.
“Drank three bottles”
“I could see she had sore feet and was in trouble, so I pulled over the fire truck,” recounted Tree to McNaught of the Herald Sun and Rohan Sullivan of Associated Press.
“She plonked herself down on her bum and looked at me like ‘put me out of my misery,'” Tree said. “I yelled for a bottle of water. I unscrewed the cap, tipped it up on her lips, and she just took it naturally. She kept reaching for the bottle, almost like a baby. She drank three bottles. The most amazing part was when she grabbed my hand.”
Another firefighter videotaped the incident on a cell telephone. The video became a worldwide hit.
Taken to the Mountain Ash Wildlife Shelter, Sam was put on an intravenous drip and given antibiotics and pain relief.
Unfortunately, while Sam survived her fire injuries, she was euthanized on August 6, 2009 due to incurably painful cysts caused by urogenital chlamydiosis.
The disease afflicts as much as half of the koala population.
Recently explained Live Science senior writer Mindy Weisberger, “Scientists suspect that a virus in the same family as the human immunodeficiency virus (HIV) could be the culprit, according to a study published online in the March issue of the Journal of Virology.
“Adult koalas catch chlamydia just as people do — through sexual transmission,” Weisberger continued, “but young koalas can also become infected by eating pap, a nutritious type of feces, when it is excreted by infected mothers.”
Why koalas eat @#$%
Eating pap is how baby koalas acquire the microbes that enable them to digest eucalyptus leaves.
“Eucalyptus leaves, which provide much of adult koalas’ nutrition in the wild, contain a compound called tannin that can be highly toxic if it isn’t broken down by certain types of gut bacteria,” Weisberger elaborated. “If those microbes are absent, koalas might be unable to process their eucalyptus meals.”
Deforestation that causes koalas to live at greater densities in the remaining habitat is believed to have contributed to the spread of chlamydia.
Bushfires are one major cause of deforestation. Urban sprawl is another, and forest conversions to crop and grazing land are yet another.
Development not the biggest threat
“Development, and the loss of koala habitat for housing and infrastructure, was considered a key reason why the koala was added to the ‘vulnerable’ species list in 2012,” wrote Ben Smee of The Guardian in April 2018. “But analysis by World Wildlife Fund conservation scientist Martin Taylor challenges the idea. Taylor concludes,” said Smee, “that of more than 5,000 estimated koala deaths due to loss of habitat in Queensland from 2012 to 2016, almost 94% occurred outside the heavily developed southeast.
“Taylor said once thriving populations of koalas in the south-east corridor had ‘collapsed’ over several decades,” Smee continued. “But he said the scale of that problem is now dwarfed by the clearing of agricultural land, putting the species under further threat.”
Said Taylor, “There’s this illusion out there that somehow koalas only occur in southeast Queensland and that’s just not the case. Koalas occur broadly throughout the state, and if you bulldoze koala habitat you’re pushing them closer towards extinction.”
Is old growth the best koala habitat?
But is the remnant tall eucalyptus habitat where koalas visibly find refuge, to which they have been pushed by development of surrounding areas, really the best habitat for the species?
Wrote Smee, “Taylor’s study, which he said was ‘deliberately conservative,’ estimated koala deaths across the state by mapping the marsupials’ habitat,” the traditional approach. The study assumed that when habitat was bulldozed, the animals there mostly died.”
The same presumption prevails about koalas in New South Wales.
EPA study says yes
Wrote Michael Slezak for The Guardian, “Between 1990 and 2010, koala populations in New South Wales were estimated by the federal government to have declined by 30%. And a report released in May 2018 by the New South Wales Environmental Protection Agency found that all koala populations in New South Wales, with one possible exception, have continued to decline, with at least one population now considered endangered.
“That EPA report,” Slezak summarized, “also found there were more koalas in forests that were more mature. It therefore concluded that logging was bad for koalas, since even if the forests are replaced, logging reduces the maturity of the forests.”
The Australian National Parks Association, Australian Koala Foundation, and Friends of the Koala are accordingly furiously opposed to a new draft Integrated Forestry Operations Approvals protocol released by the New South Wales government in mid-May 2018.
“Refuges for threatened species”
The new protocol would allow increased logging throughout public native forests, permit logging in stream buffer zones that are currently protected, open previously protected old-growth forest to logging, and “replace the need to look for koalas with a habitat model that will require the retention of a maximum of 10 feed trees in mapped koala habitat,” Friends of the Koala summarized in a May 25, 2018 alert to supporters.
The areas newly opened to logging, Friends of the Koala charged, include “the most important refuges for threatened species, including gliders and quolls [as well as koalas], left in many forests.
The New South Wales government, Friends of the Koala alleged, “is abandoning any pretense of sustainable logging by proposing dramatic erosions of environmental protection to meet timber supply shortfalls resulting from historic mismanagement.”
But maybe dispersal helps
Asked the New South Wales National Parks Association: “Do we want to protect koalas, or do we want to allow logging and land-clearing to drive them to extinction?”
There are, however, some hints that loss of old growth might help koalas by forcing them to colonize habitat less likely to burn, at densities less congenial to the spread of chlamydia––if they can get there without being hit by cars or mauled by dogs.
After the New South Wales Blue Mountains fires of October 2012, for instance, “a koala was spotted in the upper reaches of the mountains for the first time in 70 years,” reported Oliver Milman of The Guardian. “It is thought that the koala, and others, managed to escape the fierce bushfires, which burned through about 140,000 hectares (346,000 acres), by fleeing to areas they usually don’t inhabit,” Milman wrote.
“Told us not to look”
Said University of Sydney faculty member Kellie Leigh, founder of the Blue Mountains Koala Project, “People told us not to bother looking up there, but we’ve had eight or nine sightings of koalas in unusual areas, probably due to the fire forcing them away from the valleys. The general thinking was that they just didn’t exist in this area, but we are getting reports that a lot of koalas are out there,” especially in “some places there wasn’t massively intense burning and the canopy still has green patches.”
Altogether, Milman wrote, based on Leigh’s report, “There could be several hundred koalas in Blue Mountains National park, fragmented into two or three populations.”
“Sightings where they haven’t been seen for years”
Pro-logging spokesperson Andrew Freeman of AgForce Queensland told Smee of The Guardian in April 2018 that, “Landholders across the state are reporting sightings and a return of koalas to some areas where they haven’t been seen for many years.”
Calling itself “The unifying voice for Queensland’s beef, sheep and grain producers since 1999,” AgForce Queensland certainly is not a pro-animal organization, let alone pro-koala.
Yet what if what koalas need most is not more population density in protected old growth, but instead broader distribution in less flammable habitat, farther from cars and dogs?