The phrase “urban jungle” gets thrown around a lot, but we don’t usually think of cities as places where rare or threatened species live.
Our research, published today in Frontiers in Ecology and the Environment, shows some of Australia’s most endangered plants and animals live entirely within cities and towns.
Stuck in the city with you
Australia is home to 39 urban-restricted threatened species, from giant gum trees, to ornate orchids, wonderful wattles, and even a tortoise. Many of these species are critically endangered, right on the brink of extinction. And cities are our last chance to preserve them within their natural range.
Urban environments offer a golden opportunity to preserve species under threat and engage people with nature. But that means we might need to think a little differently about how and where we do conservation, embrace the weird and wonderful spaces that these species call home, and involve urban communities in the process.
Roads to the left of them, houses to the right
When you picture city animals you might think of pigeons, sparrows or rats that like to hang out with humans, or the flying foxes and parrots that are attracted to our flowering gardens.
But that’s not the case here. The threatened species identified in our research didn’t choose the city life, the city life chose them. They’re living where they’ve always lived. As urban areas expand, it just so happens that we now live there too.
The first hurdle that springs to mind when it comes to keeping nature in cities is space: there’s not a lot of it, and it’s quickly disappearing. For example, the magnificent Caley’s Grevillea has lost more than 85% of its habitat in Sydney to urban growth, and many of its remaining haunts are earmarked for future development. Around half of the urban-restricted species on our list are in the same predicament.
It’s especially tough to protect land for conservation in urban environments, where development potential means high competition for valuable land. So when protected land is a luxury that few species can afford, we need to work out other ways to look after species in the city.
Not living where you’d expect
Precious endangered species aren’t all tucked away in national parks and conservation reserves. These little battlers are more often found hiding in plain sight, amid the urban hustle and bustle.
Our research found them living along railway lines and roadsides, sewerage treatment plants and cemeteries, schools, airports, and even a hospital garden. While these aren’t the typical places you’d expect to find threatened species, they’re fantastic opportunities for conservation.
The spiked rice flower is a great example. Its largest population is on a golf course in New South Wales, where local managers work to enhance its habitat between the greens, and raise awareness among residents and local golfers. These kinds of good partnerships between local landowners and conservation can find “win-win” situations that benefit people and nature.
A series of unfortunate events
It’s no secret that living in the ‘burbs can be risky: a fact best illustrated in the cautionary tale of a roadside population of the endangered Angus’s onion orchid. Construction workers once unwittingly dumped ten tonnes of sand over the patch in the late 1980s, then quickly attempted to fix the problem using a bulldozer and a high-pressure hose. Later, a portaloo was plonked on top of it.
Examples like this show just how important it is for policy makers, land managers and the community to know that these species are there in the first place, and are aware that even scrappy-looking habitats can be important to their survival. Otherwise, species are just one stroke of bad luck away from extinction.
It’s common to think if you want to conserve nature, you need to get as far away from people as you can. After all, we can be a dangerous lot (just ask Angus’s onion orchid). But we also have extraordinary potential to create positive change – and it’s much easier for us to do this if we only have to travel as far as our backyard or a local park.
Many urban-restricted species get support by their local communities. Examples from our research showed communities across Melbourne raising thousands of dollars in conservation crowdfunding, dedicating countless volunteer hours to caring for local habitats, and even setting up neighbourhood watches to combat vandals. This shows a huge opportunity for urban residents to be on the conservation frontline.
Our research focused on 39 species that are restricted to Australian cities and towns today. But that’s not where the opportunity for urban conservation ends.
There are about another 370 threatened species that share their range with urban areas across Australia, as well as countless “common” native species that call cities home. And as cities continue to expand, many other threatened species stand to become urban dwellers. It’s clear that if we only focus conservation efforts in areas far from humans, species like these will be lost forever.
For time immemorial, many wildlife species have survived by undertaking heroic long-distance migrations. But many of these great migrations are collapsing right before our eyes.
Perhaps the biggest peril to migrations is so common that we often fail to notice them: fences. Australia has the longest fences on Earth. The 5,600-kilometre “Dingo Fence” separates southeastern Australia from the rest of the country, whereas the “Rabbit-Proof Fence” stretches for almost 3,300 kilometres across Western Australia.
Both of these enormous fences were intended to repel rabbits and other “vermin” such emus, kangaroos and dingoes that were considered threats to crops or livestock. Built over a century ago, their environmental impacts were poorly understood or disregarded at the time.
Since construction these fences have caused recurring ecosystem catastrophes, such as mass die-offs of emus and other species trying to find food and water in a land notorious for the unpredictability of its rainfall, vegetation growth and fruit production.
The same thing is happening across much of the planet. While a nemesis for larger wildlife, nobody knows how many fences exist today or where they’re located. A study that mapped all the fences in southern Alberta, Canada, found there were 16 times more fences than paved roads.
Scientists are waking up to the peril of fences, realising that from an environmental perspective they’re grossly understudied — “largely overlooked and essentially invisible,” according to a recent global review.
In Africa, home to some of the most spectacular wildlife migrations, scientists found that of 14 large-mammal species known to migrate en masse, five migrations were already extinct. Proliferating fences, along with habitat loss and wildlife poaching, has sent ecosystems such as the Greater Mara in Kenya crashing into ecological turmoil.
And a 2009 audit of Earth’s greatest terrestrial-mammal movements showed that of 24 large species that once migrated in their hundreds to thousands, six migrations have vanished entirely.
Many remaining migrations are mere shards of their former glory. For instance, Indochina once had mass migrations of elephants and other large mammals, big cats, monkeys and birds — often called the “Serengeti of Southeast Asia”.
The thundering herds of American bison – some numbering up to 4 million animals – which once dominated the plains of North America have all but vanished today.
How to save mass migration
There are two main ways to destroy mass migrations: killing the animals outright by hunting and over-harvesting, or stopping the animals from accessing food or water, typically by fencing them out or clearing and fragmenting their habitat.
As the human footprint rapidly expands, scary things for wildlife are happening all over. Research that one of us (Bill Laurance) led revealed that 33 African “development corridors” would, if completed, exceed 50,000 kilometres in length and crisscross the continent, chopping its ecosystems into scores of smaller pieces.
Beyond this, over 2,000 parks and protected areas in Africa would be degraded or cut apart by the massive developments.
Migrations are vulnerable even in the seas. Recent research shows that growing shipping traffic is an increasing danger to migratory great whales, basking sharks, and giant whale-sharks – all highly vulnerable to collisions with fast-moving ships, as well as disruption of their sensitive hearing and vocal communications by shipping noise and sonar, and pollutants from vessels.
But the inspiring news is that, if you remove barriers such as fences, animal migrations can spontaneously resume – like a phoenix rising from the ashes.
In 2004, a fence that had blocked a former zebra migration in Botswana was removed. By 2007 it was one of the longest animal-migration routes in the world.
And a few places on Earth are still free from fencing and fragmentation. The world-famous Seregeti ecosystem of Tanzania is an iconic example. In war-torn South Sudan, a spectacular mass migration of a million antelope — known as white-eared kob — is still intact because there are no fences.
And caribou still migrate in great herds across large expanses of northern Canada and Alaska.
Alarming news for Botswana
Collapsing migrations are a global concern, but right now conservationists are most worried about Botswana.
This mega-diverse nation in southern Africa is considering profoundly changing its wildlife management by expanding fences and cutting off wildlife migrations not considered beneficial to the country’s current priorities.
This would be a shocking decision, because Botswana’s wildlife conservation is almost entirely dependent on its mass migrations.
For wildebeest, zebra, eland, impala, kob, hartebeest, springbok and many other large migrants, isolation is a killer – destroying their capacity to track the shifting patterns of greening vegetation and water availability they need to survive.
And it’s not just grazing and browsing animals that are affected: entire suites of large and small predators, scavengers, commensal and migratory bird species, grazing-adapted plants and other species are integrally tied to these great migrations.
Botswana is already sliced into 17 giant “islands” by fences, erected in colonial times to protect the livestock of European farmers from foot-and-mouth disease.
But foot-and-mouth disease is far more likely to be spread by cattle, not wildlife. Fence-free strategies for managing disease risk also have have great potential.
And nature tourism in Botswana is a large, vibrant, and growing part of the national economy. Ecotourists will continue to favour the nation so long as it maintains untrammelled areas and spectacular animal migrations.
But you can kiss a lot of those tourism revenues goodbye if Botswana shatters its great migrations – killing off the spectacular living panoramas that are a magnet for the world’s nature lovers.
If we can avoid fencing and bulldozing critical parts of the Earth, we could hugely increase the chances that our most vibrant wildlife and ecosystems have a fighting chance to survive.
Bill Laurance, Distinguished Research Professor and Australian Laureate, James Cook University and Penny van Oosterzee, Adjunct Associate Professor James Cook University and University Fellow Charles Darwin University, James Cook University
Like something out of a zombie movie, species that were once thought extinct seem to be rising from the dead. Between February 21 and March 4 2019, three notable rediscoveries were announced – the Fernandina Island Galápagos tortoise (Chelonoidis phantasticus), which was last seen in 1906; Wallace’s giant bee (Megachile pluto), which had supposedly disappeared in 1980; and the Formosan clouded leopard (Neofelis nebulosa brachyura), which disappeared after the last sighting in 1983 and was officially declared extinct in 2013.
These rediscoveries suggest we may know very little about some of the world’s rarest species, but they also raise the question of how species are declared extinct in the first place. The IUCN Red List collates a global register of threatened species and measures their relative risks of extinction. The Red List has a set of criteria to determine the threat status of a species, which are only listed as “Extinct” when…
… there is no reasonable doubt that the last individual has died.
According to the Red List, this requires…
… exhaustive surveys in known and/or expected habitat, at appropriate times… throughout its historic range [which] have failed to record an individual. Surveys should be over a time frame appropriate to the taxon’s life cycle and life form.
Given all the evidence – or rather, lack of evidence – that’s needed, it’s surprising that any species is ever declared extinct. The criteria show that to understand whether a species is extinct, we need to know what it was doing in the past.
Sightings at a certain time and in a certain place make up our knowledge of a species’ survival, but when a species becomes rare, sightings are increasingly infrequent so that people start to wonder whether the species still exists.
People often use the time since the last sighting as a measure of likelihood when deciding if a species has died out, but the last sighting is rarely the last individual of the species or the actual date of extinction.
Instead, the species may persist for years without being seen, but the length of time since the last sighting strongly influences assumptions as to whether a species has gone extinct or not.
But what is a sighting? It can come in a variety of forms, from direct observation of a live individual in the flesh or in photographs, indirect evidence such as foot prints, scratches and faeces, and oral accounts from interviews with eyewitnesses.
But these different lines of evidence aren’t all worth the same – a bird in the hand is worth more than a roomful of recollections from people who saw it in the past. Trying to determine what are true sightings and what are false complicates the declaration of extinction.
The idea of a species being “rediscovered” can confuse things further. Rediscovery implies that something was lost or forgotten but the term often gives the impression that a species has returned from the dead – hence the term “lazarus species”. This misinterpretation of lost or forgotten species means the default assumption is extinction for any species that hasn’t been seen for a number of years.
So, what does this mean for the three recently “rediscovered” species?
While a living specimen of the Fernandina Island Galápagos tortoise had not been seen since 1906, indirect observations of tortoise faeces, footprints and tortoise-like bite marks out of prickly pear cacti had been made as recently as 2013.
The uncertainty around the quality of these later observations and the long time since the last living sighting probably contributed to it being declared “Critically Endangered (Possibly Extinct)” in 2015. In the natural world, a species is presumed extinct until proven living.
Wallace’s giant bee may not have been recorded in the last 38 years but it was never actually declared extinct according to the IUCN Red List. In fact, for many years it languished under the criteria of Data Deficient and was only recently assessed as Vulnerable.
So, while this is an exciting find for something that hadn’t been seen for so long, its rediscovery shows how little is known about many rare species in the wild, rather than how scarce they are.
The Formosan clouded leopard, meanwhile, was actually listed as Extinct. The last sighting of the species was in 1983, based on interviews with 70 hunters, and extensive camera trapping during the 2000s failed to detect its presence. It was officially declared extinct in 2013.
While the giant tortoise and bee were proclaimed alive after living specimens were found, the clouded leopard’s rediscovery is more uncertain. Based on sightings on two separate occasions by two sets of wildlife rangers, the evidence is compelling. But whether the Formosan Clouded Leopard has really risen from the dead will require considerably more effort to prove.
The biggest killers of wildlife globally are unsustainable hunting and harvesting, and the conversion of huge swathes of natural habitat into farms, housing estates, roads and other industrial activities. There is little doubt that these threats are driving the current mass extinction crisis.
Yet our understanding of where these threats overlap with the locations of sensitive species has been poor. This limits our ability to target conservation efforts to the most important places.
In our new study, published today in Plos Biology, we mapped 15 of the most harmful human threats – including hunting and land clearing – within the locations of 5,457 threatened mammals, birds and amphibians globally.
We found that 1,237 species – a quarter of those assessed – are impacted by threats that cover more than 90% of their distributions. These species include many large, charismatic mammals such as lions and elephants. Most concerningly of all, we identified 395 species that are impacted by threats across 100% of their range.
Mapping the risks
We only mapped threats within a species location if those threats are known to specifically endanger that species. For example, the African lion is threatened by urbanisation, hunting and trapping, so we only quantified the overlap of those specific hazards for this species.
This allowed us to determine the parts of a species’ home range that are impacted by threats and, conversely, the parts that are free of threats and therefore serve as refuges.
We could then identify global hotspots of human impacts on threatened species, as well as “coolspots” where species are largely threat-free.
The fact that so many species face threats across almost all of their range has grave consequences. These species are likely to continue to decline and possibly die out in the impacted parts of their ranges. Completely impacted species certainly face extinction without targeted conservation action.
Conversely, we found more than 1,000 species that were not impacted by human threats at all. Although this is positive news, it is important to note that we have not mapped every possible threat, so our results likely underestimate the true impact. For example, we didn’t account for diseases, which are a major threat to amphibians, or climate change, which is a major threat to virtually all species.
Hotspots and coolspots
We produced the first global map of human impacts on threatened species by combining the parts of each species range that are exposed to threats.
The overwhelmingly dominant global hotspot for human impacts on threatened species is Southeast Asia.
This region contains the top five countries with the most threats to species.
These include Malaysia, Brunei, Singapore, Indonesia and Myanmar.
The most impacted ecosystems include mangroves and tropical forests, which concerningly are home to the greatest diversity of life on Earth.
We also created a global map of coolspots by combining the parts of species ranges that are free from human threats. This map identifies the last vestiges of wild places where threatened species have shelter from the ravages of guns, snares and bulldozers. As such, these are crucial conservation strongholds.
Coolspots include parts of the Amazon rainforest, the Andes, the eastern Himalayas, and the forests of Liberia in West Africa.
In many places, coolspots are located near hotspots. This makes sense because in species-rich areas it is likely that many animals are impacted whereas many others are not, due to their varying sensitivity to different threats.
There is room for optimism because all the threats we map can be stopped by conservation action. But we need to make sure this action is directed to priority areas, and that it has enough financial and political support.
An obvious first step is to secure threat-free refuges for particular species, via actions such as protected areas, which are paramount for their survival.
To ensure the survival of highly impacted species with little or no access to refuges, “active threat management” is needed to open enough viable habitat for them to survive. For example, tiger numbers in Nepal have doubled since 2009, mainly as a result of targeted anti-poaching efforts.
Tackling threats and protecting refuges are complementary approaches that will be most effective if carried out simultaneously. Our study provides information that can help guide these efforts and help to make national and global conservation plans as successful as possible.
James Allan, Postdoctoral research fellow, School of Biological Sciences, The University of Queensland; Christopher O’Bryan, PhD Candidate, School of Earth and Environmental Sciences, The University of Queensland, and James Watson, Professor, The University of Queensland
The link below is to an article reporting on how plastic is leading to reproductive problems for marine wildlife.