Where’s Martin?

Dr. Martin Gilbert, Wildlife Health Cornell Carnivore Specialist

The fate of our wildlife lies at the hands of our policy makers – an obvious statement perhaps, but sometimes these forces work in unexpected ways.

Here in Tajikistan, on a beautiful day in Dushanbe, the sun filters down through an arbor hanging thick with grapes, flashing a glare across my computer screen. I am in the midst of a welcome few days of respite, snatching time to write up my research on health and it’s impact on Russia’s Amur tigers. I’m a slow writer, but gradually my manuscript begins to take shape – the culmination of seven years of work. My story traces 25 years of tiger history, using telltale antibodies in the blood of captured tigers to explain their changing fortunes and their exposure to the often lethal canine distemper virus. A key riddle is this…

Amur tiger in winter. Photo by John Goodrich/WCS

Amur tiger in winter. Photo by John Goodrich/WCS

Our detection of infections in a bear and a leopard in the early 1990s confirm that distemper has a long history in Russia’s Far East. Yet despite this, tigers showed no sign of exposure until the 2000s, after which the virus has become an important threat with over a third of their population now showing signs of exposure, and deaths recorded periodically since. The question is why didn’t tiger infections happen earlier….?

Pausing to mull on the wording of another sentence, my eyes are drawn to the cold metallic stare of a bronze ashtray on my table, fashioned in the shape of an Arabian horse’s head. Far from a mere kitsch trinket, this equine bust represents a little nugget of history. I’d been told that years earlier this modest artefact had housed the butts of none other than Russian Presidents Mikhail Gorbachev and Boris Yeltsin! …Considering that my host is the nephew of Tajikistan’s first premier this is quite believable. An old faded photograph shows him as a three-year old at a picnic with the architect of glasnost, during which he is reputed to have likened the Soviet leader’s bald pate to the hairless dome of his pet tortoise!

Gorbachev's Ashtray

A slice of history - an ashtray once used by Russian presidents Gorbachev and Yeltsin. Photo by Martin Gilbert/Cornell

In many ways the story of my tigers and the illustrious history of this truncated horse are intertwined, for both tell of the political winds of change and the fate of the Soviet Union….

Despite its name, canine distemper virus has more cosmopolitan tastes than man’s best friend and I now know that infection of wildlife is far more important than of dogs for transmission to tigers in the Russian Far East. Among the affected species the marten-like sable is king, for these feisty and abundant small carnivores act as a reservoir of infection driving the epidemiology of the virus in wild Russian ecosystems.

Sable (Martes zibellina)

Sable (Martes zibellina). This abundant wild carnivore is an important reservoir of distemper. Photo by Е.Медведева - zapbureya.ru

Economics may lie at the heart of the tiger’s distemper story, which is driven by the unlucky sable’s one valuable resource: its luxuriant fur pelt. Viruses like distemper need a steady supply of naïve animals to infect. An infected young sable might die, but survivors become immune for life. In heavily hunted populations fewer sable survive to old age, reducing numbers of immune adults (i.e. decreasing the herd immunity), and increasing the likelihood that distemper will encounter a naïve youngster. Although difficult to prove, my research suggests that hunting may be the catalyst that has allowed distemper to flourish in the tiger’s forest. Let me explain…

Returning to history, in the late days of the Soviet Union, fur trappers plied the forest, harvesting up to 20% of the local sable population each year. Then in the dark economic days following the Soviet collapse, as Gorbachev gave way to Yeltsin, the demand for luxurious sable fur crashed, and hunting declined as trappers looked elsewhere to make their living.  The respite from hunting was a boon for sable but brought hard times for distemper as immunity increased across the aging sable population, robbing the virus of naïve hosts. In these conditions, the exposure of tigers also slowed, as revealed by our blood samples from the 1990s. But the effect was short-lived.

By the close of the decade a new more outward looking Russian state and burgeoning international trade opened new markets for fur, leading to a return to hunting. By 2000 fur trapping had reached pre-Glasnost levels and has intensified since, with as many as 40 or 50% of sable hunted each year in 2013 and 2014.

US Presidents Ronald Reagan and George HW Bush with Mikhail Gorbachev in NYC 1988

U.S. presidents Ronald Reagan and George HW Bush with Mikhail Gorbachev in NYC, 1988

With hunting at these scales few sable survive into adulthood, and the younger naïve population is for distemper what a tinder-dry forest is for wildfire. As distemper flares-up, spread to tigers is inevitable, and although infrequent, can be enough to threaten their rare and fragile populations.

Back at my computer in Dushanbe and grappling with my writer’s block I look across at Gorbachev’s horsehead gazing back from his perspective of history. Time moves on and the changes he’s seen bring hope. While today he sees a world full of challenges for tigers, he also sees a society becoming more urbanized and abandoning their rural ways. Looking ahead, perhaps he sees a future with society reshaped by the forces of policy and economics, and a time when the interplay of hunting and disease becomes kinder on the lives of the sable and the tiger.

Martin Gilbert is actively fundraising to support field studies to address gaps in our understanding of wild carnivore ecology and disease threats, which are critical to effective conservation.

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Dr. Martin Gilbert, Wildlife Health Cornell Carnivore Specialist

While sitting in a café contemplating the surrounding forested hills, it struck me that there is something unique about the city of Thimphu in Bhutan. What other country can boast the presence of tigers in forests that lie within sight of their capital? And Bhutanese anomalies don’t stop there. Elsewhere tigers are a lowland species, prowling the forest glades and valley bottoms across their Asian refuges. But here, a population of at least 100 tigers roams unimpeded from the low edges of the Brahmaputra floodplain to the lofty Himalayan ridges as high as 11,000 feet above sea level.

Prayer flags at Chelela, high above Paro.

It was a pursuit of the truth about one of these tigers that had brought me to this enigmatic Himalayan Kingdom. In March 2018, an adult tiger emerged from the forest on the outskirts of Thimphu. This impressive nine-year-old male was well known to researchers from camera trap images captured around the hills ringing the city. But from his most recent appearance, he was clearly in trouble. In scenes reminiscent of sick tigers observed in Russia, he walked as if in a trance in the daylight, unconcerned by the approach of people, and displaying nothing of the fearsome energy of a tiger in distress. This now familiar scenario has been seen repeatedly in Russian tigers infected with canine distemper virus, and it was this concern that brought me into contact with veterinarians with Bhutan’s Ministry of Agriculture and Forests.

Team tiger. From left to right: Dr. Yoenten Phuentshok (veterinarian, National Centre for Animal Health), Dr. Kinley Choden (veterinarian, Nature Conservation Division), Dr. Tempa Tshering (National Tiger Center), the author (Wildlife Health Cornell Carnivore Specialist), and Sonam Wangdi (Chief Forestry Officer, Nature Conservation Division).

As we learn more about distemper in tigers, the threat it represents to wild populations is becoming clearer. The virus circulates widely among unvaccinated dogs as well as populations of common wild carnivores. As many as one in three tigers in Russia have been infected, and mortality is common. Even small increases in mortality rates can spell extinction for small tiger populations. But we still have much to learn, in particular the extent of the problem across the tiger’s distribution: at this time, the threat distemper poses outside of Russia is unknown, as potential cases elsewhere have not been thoroughly investigated.

Just as we’ve seen in Russia, the Bhutanese tiger’s condition declined despite several weeks of care in captivity, and then he succumbed. So far, this really sounded like distemper. Thinking this might at last be our opportunity to learn more about the disease in non-Russian tigers, and with an invitation from Bhutan’s Nature Conservation Division, I boarded a plane for the Himalayas to help with the diagnosis.

Tiger facade. Representations of tigers are a common sight on the walls of traditional buildings in Thimphu.

The approach into Paro International Airport is not for the faint-hearted. Located on the closest piece of flat land to Thimphu that is big enough to accommodate a landing strip (40 km away!), the descent into Paro takes you weaving up steep terrace-walled valleys and forested hillsides that flash past on both sides of the plane!

At first glance, Bhutan certainly seemed to bear the hallmarks of a country where distemper might be an issue. Nurtured by compassionate Buddhist traditions, the city of Thimphu teems with street dogs – packs of them, lying in doorways, across sidewalks and retreating into the shade under parked cars. At night they come alive, with residents lying sleepless in their beds thanks to a cacophony of howling and yammering canines!

Morning feed. Empathic Buddhists bring food for the street dogs of Thimphu to get them started on their day.

But it is here that our story takes an unexpected turn, as the tiger’s post mortem examination revealed something quite distinct from previous distemper cases. Within the confines of his skull, two coin-sized, fluid-filled cysts emerging from the surface of the brain, where they had been exerting pressure, were found: that could plausibly explain the tiger’s unusual behaviour. Closer examination, and further laboratory testing, revealed these cysts to be the refuges of the larval stage of the human tapeworm! Like many parasites, tapeworms have a complex life cycle, with time spent in at least two different animal host species. The adult stage of human tapeworms inhabit the intestines of infected people, laying eggs that are dispersed with their daily defecation. Where sanitation is poor, the peculiar appetite of pigs invites the second, and intermediate life stage, with eggs hatching in the porcine intestine, and the larvae burrowing their way into the tissues. Here they form a cyst and await ingestion by humans with a penchant for undercooked meat, and their life cycle repeats from there.

Bhutan is home to an estimated 100 Bengal tigers, which occur in one continuous population from approximately 600 feet to 11,000 feet above sea level. Photo by R. Gilbert.

Considering the series of chance events that a tapeworm follows through its life, it is perhaps not surprising that they sometimes happen to find the ‘wrong’ host… but it isn’t common! There have been just a handful of reports of domestic cats infected with human tapeworms, and never a case in a tiger (or indeed any other wild felid as far as we are aware).

This bizarre and possibly unique case, while devastating for the tiger, serves as a lesson for the rest of us. It illustrates the wonderful complexity of nature, and warns us to avoid making assumptions.

Canine companion at Chelela.

But the case also speaks to the intimate association between people, domestic animals and wildlife that dominates the modern world. With a human population approaching eight billion, we can expect more and more of these unusual events to occur, with infections moving between each point of the One Health triangle that connects humans, domestic animals and wildlife.

Meanwhile, our investigation into this case is ongoing. With the help of our Bhutanese colleagues, tissue samples from the tiger have now been brought to Cornell for a range of diagnostic tests. Our question is now whether there were other health-related factors that might have predisposed this unfortunate tiger to this most unusual of parasitisms. Most importantly, we must determine if this was a one-off case, or a sign of something more important for Bhutan’s precious tiger population.

Martin Gilbert is actively fundraising to support field studies to address gaps in our understanding of wild carnivore ecology and disease threats, which are critical to effective conservation.

Dr. Martin Gilbert, Wildlife Health Cornell Carnivore Specialist

On a sweltering monsoon afternoon in September 1994, I stepped out from a garish-painted bus in western Nepal, the driver pointing me south along a rough track threading off between vibrant green rice fields. At twenty years old, and on my summer break from veterinary school, I’d opted to backpack my way across the Indian subcontinent looking for adventure. With my fixation for wildlife, and tigers in particular, I’d been undeterred by the news that the great Indian tiger reserves were closed for the wet season, heading instead for a newly-opened border post in remote western Nepal. Established just six years earlier, Nepal’s Bardia National Park warranted just a few lines in my guidebook, but crucially mentioned that access was possible even during the high waters of the monsoon.

The lush green rice fields in Thakurdwara, some moody skies and a rainbow against a backdrop of the Himalayan midhills. Photo from 1994, by author.

After several miles walk I reached the sleepy village of Thakurdwara and was pointed to a basic mud brick building that served as the only budget accommodation for the rare visitor to the park. Several hours later, in the darkness of the early hours, I awoke to an urgent chorus from the black looming forest that ringed the village. Sharp barks of alarm from hidden spotted deer, or chital, that intensified to a crescendo – only to be cowed by the victorious bellow of a baying tiger.

By dawn I was electric with excitement! Together with my guide (a young lad of the same age as me), we waded across the chest-high river that bounded the park and set out into the forest. With the first rays of sun the shadows retreated to a chorus of birdsong. Vivid green parakeets cannoned overhead, and small groups of deer stepped nervously through the undergrowth. I barely knew where to look first, I was so distracted by the sights and the sounds. But my guide knew better, and his senses prickled knowing that something else was on the move.

Dawn stakeout along the river - sometimes it is best to wait for the wildlife to come to you, or just sit back and enjoy the day slide past.

Stepping out beyond the trees onto a road framed by towering elephant grass, two chital stood frozen barely fifty yards away. Their ears pivoting, they looked both toward us and back on down the trail, before taking their leave and stepping off into the grass. With that, time slipped as a familiar orange form emerged from cover, fixing us with a stare – irritated by a hunt interrupted. I couldn’t say how long it lasted – my first encounter with a tiger – but that image of her dark rimmed eyes framed in white left an indelible mark on me that remains to this day.

A pair of endangered swamp deer stags are on alert as we pass.

Nearly a quarter of a century later, it was with some trepidation that I returned to Bardia. That first trip had been so personal, such a mythical experience, that my thoughts had drifted back to it regularly over the years. My mental film reel included not just the tiger, but the rhino that chased me up a tree, and the encounter with an elephant in the forest at night. Surely a return risked breaking a spell, tarnishing an experience I have carried into a career with wildlife, a youthful adventure that ultimately brought me to work on the health of wild tigers themselves?

The intervening years had brought considerable change. Although still comparatively remote, Thakurdwara now bustles with life, its pulse now hitched to a knot of hotels and guided jungle walks. These days the roar of my midnight tiger had been usurped by a new generation, their village drum and bass pounding, speakers cranked-up to distortion.

It is best to give greater one-horned rhinos a wide berth - short-sighted and short-fused, these one ton hulks of armour-plated muscle can move surprisingly quickly!

But the forest was still there, and while I was no longer a solitary visitor, the park’s remoteness still deters the clamour of the selfie-snapping day-trippers that seem to converge on so many of the region’s reserves. The few visitors we encountered seemed content to soak up the scenery and wildlife in quiet appreciation. Together with some friends, I spent several pleasant days exploring the forest on foot along trails soft as flour pressed with the mark of the tiger’s pug. One of my companions got her own tiger initiation, with a tigress emerging from the midmorning heat to cool off in a riverine pool.

Relief in the heat of the day - a tigress emerges from the haze to take a cooling dip in the river.

That Bardia has changed in the quarter century since my first visit is no surprise. It never was the secret magical place of my memories, but a living breathing landscape, home both to the tigers and also a growing local population. Recent research has shown that Nepal’s parks are a net benefit for local people, adding wealth and opportunity to local economies. Inevitably society’s car horns and boom boxes invade the peace of a once tranquil forest. But who am I to dictate my own aesthetic? …These same people now recognise the value of the landscape and its wildlife, and feel benefits in their own lives. Surely these are the ingredients of wildlife’s future? In today’s Bardia, there are now twice as many tigers as when I visited 24 years ago, and there aren’t many places on Earth that can claim that!

Martin Gilbert is actively fundraising to support field studies to address gaps in our understanding of wild carnivore ecology and disease threats, which are critical to effective conservation.

Dr. Martin Gilbert, Wildlife Health Cornell Carnivore Specialist

Bogor

Given their near supernatural reputation, it can be hard to distinguish the truth of the tiger from its mythology. Across much of their remaining range, their invisible presence invites embellishment from those lucky (or sometimes unlucky) enough to encounter them. But hidden within these tales might there be a thread of truth that hints at a new threat to their survival? ...continue reading

Dr. Martin Gilbert, Wildlife Health Cornell Carnivore Specialist

Russian Far East

Photo-by-Nikolai-Zinovyev for the Far Eastern Leopard Programme

The Far Eastern or Amur leopard (Panthera pardus orientalis), already among rarest of the world’s big cats, has now been found to face another threat: infection with canine distemper virus (CDV). In spring 2015, a young female leopard was reported along a road that runs through the remaining habitat occupied by the last wild population, in the Russian Far East, along the border with China. ...continue reading

Dr. Martin Gilbert, Wildlife Health Cornell Carnivore Specialist

Victoria Falls

If you are a soccer fan you probably remember the penetrating drone of vuvuzelas that pervaded the stadiums of South Africa in the 2010 World Cup (listen here). Well it seems those overlong trumpets of torture live on, with a new, more harmonious role addressing conflict between humans and lions! ...continue reading

Dr. Martin Gilbert, Wildlife Health Cornell Carnivore Specialist

Baluran

Dawn breaks over a wide and acacia-studded savanna. In their wallows, the mud slathered buffalos blink sleepily at our passing, and the air is alive with the purr of zebra doves. Squint, and this could be a scene from East Africa, but the dawn-blushed slopes of the surrounding volcanos gaze down across a new day in Indonesia. ...continue reading