Hooded grebe | © Francisco González Táboas, Wikimedia Commons

Five Weird, Wonderful and Endangered Species on the EDGE

Natural World Safaris

Josh Wright

13 Mar 2019

A look at the conservation challenges facing the world's lesser-known wildlife

The EDGE of Existence programme highlights and protects some of the most unique species on the planet, which are on the verge of extinction. The programme gets its name from the traits that qualify these weird and wonderful species for inclusion on the EDGE list: each must be Evolutionarily Distinct and Globally Endangered. Representing a unique and irreplaceable part of our world’s biodiversity, many EDGE species have been overlooked by conservationists – until now.

The plight of so-called “charismatic megafauna” like the lion, elephant, orangutan and giant panda is often headline news – and rightly so – but in this blog, we’ve chosen to feature a quintet of lesser-known creatures from the EDGE list, the members of which are in many cases in even more dire straits than the picturebook animals we’ve known and loved since childhood. Read on to find out about a “four-eyed” antelope, a river-dwelling dolphin, a headbanging bird, a tortoise with stars on its shell and a fish that electrocutes its prey, with further information on how to see these unusual animals in the wild for yourself.

Hirola | © James Probert, Wikimedia Commons

The Hirola

Of all the 91 species of antelope alive today, the hirola is arguably the rarest and most endangered. The few hundred that remain in eastern Kenya are the sole surviving members of their genus, Beatragus. Hirola can be easily identified by the dark preorbital glands that can be seen below each eye, which has given rise to the nickname “four-eyed antelope”. These glands occur in many species of hoofed animals and produce pheromone-laden secretions that are used to mark territories. They serve the same function in hirola, but are especially large and distinctive in this species.

The hirola has suffered a sharp decline since the 1980s, when rinderpest, a viral disease transmitted by domestic cattle, wreaked havoc on the population which then stood at 14,000. Rinderpest has since been eradicated, but today the small number of surviving hirola are threatened by drought, poaching and habitat loss. As a grassland species, the hirola’s diet relies heavily on adequate grass cover. Over the years, their habitat has been restricted by overgrazing from livestock; the lack of manmade bushfires, which locals once set to ensure a balance between tree cover and grassland but have since become suppressed by government policy; and the poaching of elephants, who also played a part in regulating the forestation of the hirola’s habitat by feeding on and uprooting trees.

Hirola | © James Probert, Wikimedia Commons

The survival prospects for the hirola are, in a sense, tied to its name. The word itself derives from the Somali pastoral community who have lived and worked alongside the hirola for generations, and who consider the species to have a spiritual significance. Abdullahi Ali, who is leading an EDGE project to protect the species, explains: “My fellow Somalis have a reverence for hirola. They are indicators of good grazing areas for cattle and other livestock.” This particular antelope has been considered a good omen for many generations, but the once common sight of a hirola on the plains of eastern Kenya may soon become nothing but a memory for the herders here.

Just as controlled fires set by local communities once provided ample habitat for the hirola, local communities now hold the key to the survival of the species. Ali notes that voluntary reduction in livestock numbers will minimise overgrazing and open up new areas for the hirola population to expand into, while manual tree removal, grass seeding and community-based protection of elephants – in the form of anti-poaching squads and enhanced communication between villages – will protect said areas from becoming overforested. Of course, sustained conservation efforts require sustained funding as well, and for a species like the hirola that is on the brink of extinction, the situation is critical.

With his Hirola Conservation Programme, Ali is working to implement the aforementioned rangeland restoration efforts in eastern Kenya. The hirola’s range is restricted to a relatively small region here, which includes the Arawale Nature Reserve. A translocated population has also been established in the eastern section of Tsavo National Park

Ganges river dolphin| © National Oceanic and Atmospheric Administration, Wikimedia Commons

The Ganges River Dolphin

Dolphins are usually thought of as ocean-dwelling mammals that leap and frolic in the wake of boats in the open ocean, but a number of species make their home in river systems in parts of Asia and South America. A life in waters made murky by mud and silt means that river dolphins have evolved very small eyes for their size, and poor eyesight to go with them. Ganges river dolphins in fact have eyes that lack lenses, rendering them effectively blind, but their ability to echolocate means they can navigate waterways with ease.

River dolphins around the world are extremely vulnerable to habitat destruction, with pollution and the damming of rivers for irrigation and hydroelectric projects serving to degrade their habitat, isolate populations and prevent seasonal migration. The Ganges river dolphin, living in one of the most densely populated regions in the world, is particularly threatened by urban development. The pollution of the Ganges is no secret, and as the largest and most sacred river in India, the health hazards it poses are a danger not just to the Ganges river dolphin but to hundreds of millions of people as well.

River dolphins act as indicators of river health in the freshwater basins where they live. This places even more importance on the survival of the Ganges river dolphin, but population estimates are tricky, with the International Union for the Conservation of Nature (IUCN) rating the current population trend as ‘Unknown’. EDGE estimates that somewhere between 965 and 1,800 individuals remain in the Ganges-Brahmaputra-Meghna and Karnaphuli-Sangu river systems of Bangladesh and India, as well as the Karnali River and possibly the Sapta Kosi River in Nepal.

Ganges river dolphin | © Aafi Ali, Wikimedia Commons

The Ganges river dolphin was recognised as the national aquatic animal of India in 2010, but Conservation India has warned that “poor awareness”, among the other threats facing the dolphin, “are driving them to extinction” despite this title. Throughout the dolphin’s range, the species is threatened by accidental bycatch as well as the influx of fertilisers, pesticides, industrial effluents and domestic waste into river systems, which can poison not only the dolphins but also the fish which they feed upon.

In the Sundarbans, an area of mangroves on the coastal border between India and Bangladesh where the Ganges, Brahmaputra and Meghna Rivers meet, another problem facing the species is the increasing salinity of their environment. Upstream dams, barrages and water-intensive agriculture have decreased the flow of freshwater to the Sundarbans, while at the same time seawater ingression has increased due to a rise in sea levels attributed to climate change. Today only certain pockets of the Sundarbans can sustain Ganges river dolphins.

Aside from the Sundarbans, Ganges river dolphins may be seen by NWS clients along the Ganges and Brahmaputra Rivers and their tributaries in northern India, which snake their way through a number of protected areas, including Kaziranga National Park Cetacean aficionados may also choose to visit the Vikramshila Gangetic Dolphin Sanctuary in the state of Bihar, which was established in 1991 for the sole purpose of protecting this disappearing icon of India’s riverine ecosystems.

Hooded grebe | © Juan Maria Raggio, Wikimedia Commons

The Hooded Grebe

There are only around 1,000 hooded grebes left in existence, making them one of the world’s most endangered bird species. Podiceps gallardoi was only added to the scientific nomenclature in 1974, meaning that before then most people were sadly ignorant of this bird’s exquisitely choreographed courtship ritual, which has been likened to the tango (a dance that originated, aptly enough, in the hooded grebe’s homeland of Argentina). Filmmakers Michael and Paula Webster, whose footage from the documentary Tango in the Wind, describe the ritual of the hooded grebe as “a thing of beauty”. And if the birds’ amorous dance and dapper plumage wasn’t enough to endear you to the species, hooded grebe parents also have a heartwarming habit of carrying their chicks on their back!

The hooded grebe went undiscovered for so long due to its extremely remote habitat, centred on a few isolated lakes in the high plateaus of Patagonia (although they winter on estuaries on the Atlantic coast). Unfortunately, since becoming known to science, the population of the species has fallen significantly, perhaps by as much as 80%. A significant factor in this decline has been an invasive species, the American mink, which was introduced to Patagonia for commercial fur production in the 1930s – decades before the world even know of the hooded grebe’s existence.

These carnivorous mammals prey on hooded grebes at every stage of their life – from egg to chick to adult – a diet which, when combined with the hooded grebe’s low reproductive rate (an individual rears just one chick per breeding season), has devastated the population. The IUCN reported that in 2010-2011 a single mink killed more than half the adults in a breeding colony of two dozen nests. Climate change has also played a role, with warming temperatures in Patagonia contributing to lower levels of winter snowfall, which in turn reduces the size of the lakes in which the hooded grebe’s main food source, the milfoil plant, grows.

Hooded grebe | © Franalverja, Wikimedia Commons

The hooded grebe may not be in danger of the poacher’s rifle, but their plight is a good example of indirect consequences of human activity causing big problems for a species. In addition to the threats of climate change and invasive minks, hooded grebes must compete for the milfoil plant with invasive salmonid fish (notably rainbow trout) which also deplete the quality of the lake water itself. Not only that, but a native bird species, the kelp gull, which preys on hooded grebe chicks, has enjoyed a population explosion thanks in large part to the waste from human settlements that it feeds on.

Thankfully, all is not lost for the hooded grebe. Minks are being controlled; steel grills are being placed on tributaries which block troublesome fish from making their way to the lakes where hooded grebes live and breed during the summer; kelp gulls are being deterred from breeding near hooded grebe colonies; fishing activities are being shifted away from grebe sites (meaning there’s less danger of the birds drowning in fishing nets); and a regulation forbidding the introduction of trout on the Buenos Aires plateau has now been passed. Concerted conservation efforts like these have stabilised the bird’s population trend, yet with so few birds remaining, their situation remains precarious.

The hooded grebe can be found in small interior lakes in remote Patagonia, predominantly in the Argentinian province of Santa Cruz, but possibly also in Chile Speak to one of our Destination Specialists to discuss your best chance of spotting this rare bird in the wild.

Radiated tortoise | © Bernard Dupont, Flickr

The Radiated Tortoise

In the short list of EDGE species described in this blog, the radiated tortoise of Madagascar is the unfortunate ambassador for the devastating effects the illegal wildlife trade is having on our endangered species. The species is prized in the exotic pet trade thanks to its eye-catching shells, characterised by radiating “stars” that dot the carapace. Juveniles are favoured by wildlife traffickers for this purpose and are exported in large numbers, mainly to Asia and often through Thailand and China, and thence to the rest of the continent. Meanwhile (and closer to home), adult specimens are targeted for their meat, which is then sold in Madagascan markets.

An unbelievable 10,000 radiated tortoises were discovered in a single house in the town of Toliara in April 2018, while just a few months later, more than 7,000 were confiscated from wildlife traffickers in the very same town that the previous bust occurred. Although the scale of these illegal operations are unprecedented, seizures of tortoise specimens are by no means uncommon. Asia is the usual destination for smuggled tortoises, with seizures in both India and Thailand making the news in recent years. Radiated tortoises are a very long-lived species, with recorded lifespans of at least 188 years, and their long generation length (40 years) makes them particularly susceptible to rapid population declines, such as the one currently being brought about by this considerable surge in unwanted attention from traffickers.

In a 2018 report, the NGO Traffic, which works towards the eradication of the illegal wildlife trade, identified a spike in the number of endangered tortoise species being sold in Indonesian markets. Many species, like the radiated tortoise, had been transported thousands of miles from their homeland, with the journey itself resulting in the deaths of many individuals. 486 radiated tortoises were discovered in Traffic’s survey, with some specimens on sale for over $7,000. The radiated tortoise is listed on Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), meaning commercial trade in wild-caught specimens is illegal. Trade is permitted only in exceptional licensed circumstances, e.g. for scientific research.

Radiated tortoise | © Charles J. Sharp, Wikimedia Commons

Wildlife poaching in Madagascar has been on the rise in recent years, as the country’s economy continues its downward spiral set in motion by the 2009 political coup, which has weakened environmental protection efforts. The United Nations Development Programme has identified that 86% of the population subsist on less than $3.10 a day, with widespread poverty driving people to make a profit from their natural environment in unsustainable ways. In addition to its CITES listing, the radiated tortoise is protected by law in Madagascar and can be found in four protected areas in the country, yet exploitation is rife. Traditional cultural beliefs around the radiated tortoise have been slowly eroded, leading local tribes that once protected the tortoises to now turn to them for survival.

The radiated tortoise once numbered in the millions and was abundant in the spiny forests and dry shrublands of southern Madagascar, but is now much rarer. It was historically a “symbol of Madagascar’s south”, says the IUCN, but no longer. In addition to exploitation by humans, the species is also threatened by the loss and degradation of their native habitat to farming and ranching.

Sightings can still be had in Madagascar’s southwest in a roughly crescent-shaped area that swings between Ifaty in the west and the Berenty Reserve in the east. In addition to the aforementioned spiny forests and dry shrublands, the species also makes it home on high inland plateaus and the sand dunes of the coast. Additional reserves in the region that may produce sightings are Tsimanampetsotsa, Beza Mahafaly and Cape Sainte Marie.

Caribbean electric ray | © National Oceanic and Atmospheric Administration, Wikimedia Commons

The Caribbean Electric Ray

One of 69 species of electric ray, this fish is capable of producing an electric shock ranging from 14 to 37 volts using specialised organs that run along each side of its body, which can be used to stun prey or defend itself against attackers. It can even produce electrical charges from the moment it's born! The species has been known to knock humans down with such shocks, and care should be taken to avoid touching or disturbing the species, but aside from pain and discomfort the shocks should not have any lasting ill effects.

Although the Caribbean electric ray is not of commercial importance to humans, they are regularly caught as bycatch in coastal shrimp fisheries and seine net fisheries, which has driven their population down significantly throughout their range. As a result they are now considered Critically Endangered by the IUCN. In the Gulf of Mexico, it is estimated that the population has fallen by 98% since 1972. The introduction of bycatch reduction devices in the Gulf has lowered overall bycatch rates for marine species here, but as the Caribbean electric ray is a relatively small and slow-swimming species, such mitigation measures are not as effective. The survival rate of those that are caught remains low, while pregnant females tend to abort as a result of the stress.

Caribbean electric rays have an ovoviviparous mode of reproduction, meaning the embryos develop inside eggs which are retained within the mother’s body until they are ready to hatch. Despite being inside the mother, the young rays (known as pups) are nourished not by the mother’s placenta but by the egg yolk that surrounds them, supplemented by a protein-rich liquid known as histotroph that is secreted by the mother’s uterine lining. Caribbean electric ray females reach maturity at just two years old, an unusually young age for sharks and rays.

True to its name, this ray can be found offshore of a number of locations in the Caribbean, but undoubtedly some of the best diving can be had off Belize, whose tropical waters are home to a profusion of marine life, a network of over 450 cayes and atolls, and the world’s second-largest barrier reef. Caribbean electric rays can usually be found in shallow coastal waters buried beneath the sand or swimming among beds of seagrass, but are generally nocturnal.

Caribbean electric ray | © Tam Warner Minton, Wikimedia Commons

Unlike the rest of the species on this list, there are currently no conservation measures in place to protect the Caribbean electric ray. While initiatives like EDGE are making great strides in raising awareness of many lesser-known species under threat, and organisations like the Hirola Conservation Programme are involved in projects on the ground that contribute directly to the survival of such species, the fact remains that many animals are suffering a silent extinction outside of the headlines.

There are currently 26,500 species threatened with extinction on the IUCN Red List of Threatened Species. We are currently in the midst of the Earth’s sixth mass extinction event, termed by some as the Anthropocene extinction due to its source: us. The current species extinction rate is estimated by some scientists to be 100 to 1,000 times higher than natural background rates; while the number of species lost per day is up for speculation (estimates vary wildly between 24 and 150), the reality of human-driven extinction is inescapable.

If adequate conservation efforts are not implemented and the effects of climate change curbed in time, the fascinating species described in this blog (and their fellow members of the EDGE list) will go the way of the dodo (and the passenger pigeon, and the Tasmanian tiger, and the Spix’s macaw, and the northern white rhino, and the Bramble Cay melomys...)

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Kyle crocker

20/3/2019 3:19 AM

good job

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