The World’s Remaining 3,200 Tigers Face a New Foe
Between habitat loss and poaching, you’d think the 3,200 tigers left in the wild had enough to worry about.
The latest threat to big cats: dogs.
A recent study published in the journal PLOS One investigated the impact of canine distemper virus—a disease common in domestic dogs—on tiger populations.
Highly contagious, CDV is fatal in 50 percent of cases and is the leading cause of infectious disease death in dogs. It targets an animal’s lungs, digestive system, and brain. While the disease does not infect domestic cats, big felines such as lions and tigers can contract the virus—especially if they’re preying on sick dogs or wild carnivores, such as foxes, raccoons, and badgers, that are susceptible to CDV.
Wildlife Conservation Society veterinarian Martin Gilbert said that while the researchers knew individual tigers had died from CDV in the wild, they wanted to understand the risk the virus presents to whole populations.
"Our model, based on tiger ecology data collected over 20 years, explored the different ways that tigers might be exposed to the virus and how these impact the extinction risk to tiger populations over the long term,” he said in a statement.
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The results? Isolated or small populations of tigers, like the Amur tigers in Russia's Sikhote-Alin Biosphere Zapovednik, are at a severe disadvantage if CDV is present.
Researchers from the conservation groups Panthera and WCS and other scientists focused on the SABZ population because the population had dwindled from 38 tigers to nine between 2007 and 2012. Two tigers found dead had contracted CDV.
They ran models of various tiger population sizes and the likelihood of population extinction over a 50-year period if CDV was present in the area. The scientists determined that the SABZ population was 56 percent more likely to be extinct in 50 years than a CDV-free population of a similar size.
That’s bad news for tiger enclaves around the world—many of which contain populations of fewer than 25 adult breeding individuals.
Tiger populations worldwide have dipped 97 percent over the past century, according to the World Wildlife Fund.
The main culprits in the tiger decline? Loggers who are slicing and dicing tiger habitat and poachers who kill the animals for body parts used in traditional Asian medicines.
"Tigers face an array of threats throughout their range, from poaching to competition with humans for space and for food,” Dale Miquelle, WCS’s Russia program director, said in a statement. “Consequently, many tiger populations have become smaller and more fragmented, making them much more susceptible to diseases such as CDV.”
“While we must continue to focus on the primary threats of poaching and habitat destruction,” he added, “we now must also be prepared to deal with the appearance of such diseases in the future.”