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Patron bonus episode, May 1, 2017: Blue tigers

In this episode I try to keep to the topic of unusually colored tigers (like the infamous blue tigers of China and Korea), but am incapable of staying on topic so we'll learn about all sorts of big cats with strange markings and coat colors!

Welcome to the Patreon bonus episode of Strange Animals Podcast for May 1, 2017.

As you may know from our regular episode this week, my new microphone only lasted two and a half episodes before it stopped working. This is the half episode. I decided to keep the audio from the first half rather than re-record it, and it’s going to be totally obvious exactly where the mic died. Sorry about that. I have a brand new microphone on order that should be here soon (I hope).

Anyway, this week we’re looking at tigers, but I kept chasing off into the weeds while doing research so we’ll touch on other big cats too. One of my main references for this episode is zoologist Karl Shuker’s research into the topic of mystery cats. It’s probably obvious by now that I really enjoy Shuker’s writing. I think I mention him in every other episode. I’ll link to his book in Cats of Magic, Mythology & Mystery in the show notes, although I don’t actually own that book yet.

The tiger is a big cat—literally. While individuals vary a lot in size, and some subspecies are bigger than others, overall the tiger is the biggest of the felines. Yes, bigger than lions. A big male Siberian tiger can be eleven feet long [3.3 m] including the tail and stand 4 feet [1.2 m] at the shoulder.

Tigers used to live throughout eastern Eurasia, from Siberia right down to the Indian Ocean. These days, fewer than 4,000 tigers remain in the wild, and their range has been reduced by 90% due to habitat loss.

Unlike most cats, tigers like water. They swim well and they spend a lot of time playing in the water, especially on hot days. While tigers do stake out territories and are usually solitary animals, they can be surprisingly social. Sometimes they even share kills. One tiger was observed with her cubs feeding on a big antelope she’d killed, and during the day she was visited by five other adult tigers who joined her to eat. Female tigers usually raise cubs alone, but one male adopted and raised two orphaned cubs, including feeding them, protecting them, and teaching them to hunt.

All that sounds adorable, but tigers are dangerous to humans. Even tigers raised in captivity and raised by human handlers aren’t safe to be around. Occasionally a wild tiger will prey on humans, usually if it’s injured or debilitated in some way that stops it from effectively hunting other animals. Sometimes a tiger with cubs will kill a human who comes too close.

A tiger’s roar can carry two miles [3.2 km] and has infrasound elements that sometimes cause prey to freeze in terror. Even human handlers who are used to being around tigers can be affected.

Tiger coloration varies by subspecies, region, and individual. The tiger normally has a background coat color that is orange, although the shade can vary from brownish to yellowish. It has white on the belly and some areas of the face, and its stripes are black, sometimes dark brown. The stripe pattern shows faintly on the tiger’s skin too.

But there are other, rarer coat types that show up sometimes. That’s mostly what we’re talking about today. The golden tiger is a pale gold with stripes a shade darker. The background coat shades into white on the lower sides, belly, tail, and much of the face. Unfortunately, in this case the coat color is genetically linked to a weak pelvic girdle, so while the tiger looks lovely, it’s not as robust as its normal colored siblings.

Rarely, a tiger may have stripes so broad that at first it appears to be a black animal with narrow orange stripes. The term for this is abundism and it’s sometimes called pseudo-melanistic, where melanistic means all black. There are also reports from eastern India of tigers with stripes barely darker than the orange of their coats, so that they appear completely orange at a distance.

Historical records of white Bengal tigers date back to 1561 in India, but none have been spotted in the wild since 1958, and that individual was shot. White tigers are striking, which naturally made them a target for big game hunters. The white tiger population found in zoos almost all descend from a single male named Mohan, captured in 1951, but occasionally a white tiger cub not related to Mohan is born in captivity.

In 2013, geneticists determined that the white coloration in tigers is due to a single gene change. It stops the synthesis of red and yellow pigments but doesn’t affect black, which is why white tigers still have dark stripes. Occasionally a white tiger is born with a further variation that makes its stripes almost as pale as the rest of its coat. These are called snow tigers.

Snow tigers, like white tigers, have blue eyes. Albino tigers, which are incredibly rare, have no stripes, completely white fur, and pink eyes, the same as other albino mammals. White coloration doesn’t seem to make a difference to wild tigers. The big game hunters killed healthy adults who clearly didn’t have any trouble stalking prey.

White tigers are relatively common and well-known, thanks to Mohan’s best efforts with the ladies. White lions are something else entirely. Stories of white lions have long been known among the natives of South Africa, but until 1977 scientists didn’t believe white lions were anything but stories. Then a zoologist discovered three of them on a private game reserve.

The lions were pure white with blue eyes. They were siblings, with a fourth cub showing normal coloration. After one of the white lions was killed by poachers, the remaining two, and their normal-colored brother, were captured and moved to the national zoo in Pretoria, where they grew up and became the founding members of a white lion breeding program.

In 2009, a pride of white lions from the program was introduced into the wild. Like white tigers, they don’t seem to have any problem hunting.

2013 genetic research into white lions points to variants in the TYR gene as causing the coloration. This same gene in other animals is related to white coat color and a form of albinism in humans.

I’m not going to go into the genetic details, because I don’t understand them and as a result I think they’re boring. I start reading about them and lose focus, and catch myself thinking about whether I should make that lime cookie recipe I’ve been wanting to try…

But some of the genetic research is really interesting, specifically that genetic diversity in lions and tigers is about the same as in humans. 73,000 years ago, the Toba volcano in Sumatra erupted. It was an incredibly eruption, the largest known to science so far. I recently read a book by William K. Klingaman called The Year Without Summer, about the 1815 Mount Tambora eruption in Indonesia and its aftermath, which led to widespread famine—not just in that region but throughout the world. That eruption literally changed the course of history. Well, the Toba eruption was 100 times larger.

There’s a theory, proposed in 1993 and still very controversial, that the Toba eruption may have caused a genetic bottleneck in humans and other species. According to the theory, the eruption and its resulting years or even decades of climate change wiped out almost all of our ancestors. No more than about 10,000 survived, possibly a lot fewer. Some researchers also think all modern tigers may have descended from a single population in south China after the eruption.

This bottleneck is supported by genetic evidence, but the evidence that it was caused by the Toba eruption is much weaker. Whatever happened, though, humans and tigers both managed to survive. So did many other species that show similar bottlenecks, including cheetahs.

Cheetahs, in fact, show so little genetic variation that individuals are practically identical—and yet, they manage to have an interesting coat variation of their own. Cheetahs with stripes along their spines, thick fur, and blotchy spots instead of the small, neat spots of ordinary cheetahs were long thought to belong to a different species, called the king cheetah. It was rarely seen, although known to actually exist since individuals had been shot and examined, and in 1975 one was photographed.

Then, in 1981, two cheetahs in a wildlife center in South Africa gave birth to litters that each contained a king cheetah’s markings. The father of both litters was a wild cheetah from the same region where king cheetahs had long been reported. Genetic studies have determined that the king cheetah is just a variant coat marking of an ordinary cheetah. Because cheetahs are so genetically similar to start with, a careful breeding program is now in place to produce more king cheetahs to be released back into the wild, to help preserve that genetic variant.

But let’s get back to tigers. In September 1910, American big game hunter Harry R. Caldwell was in the Fujian Province in southeastern China when he spotted an extraordinary tiger. Instead of the ordinary orange coat with black stripes, this tiger was blue with black stripes.

Caldwell intended to shoot it, of course, but to do so without putting some nearby children in danger he had to move first. When he moved to get a clean shot, the tiger vanished into the forest. Caldwell searched for it, but never saw it again.

This is Caldwell’s description, taken from Karl Shuker’s blog and originally appearing in Caldwell’s book Blue Tiger, published in 1925:

“Now focusing upon what I had altogether overlooked in my previous hurried glances, I saw the huge head of the tiger above the blue which had appeared to me to be the clothes of a man. What I had been looking at was the chest and belly of the beast.

“The markings of the animal were marvelously beautiful. The ground color seemed to be a deep shade of maltese, changing into almost deep blue on the under parts. The stripes were well defined, and so far as I was able to make out similar to those of a tiger of the regular type.”

Blue tigers have been reported in southeastern China and Korea for centuries. It’s easy to dismiss these stories as fanciful, except that other blue cats definitely exist. We’re not talking bright blue like the sky or a robin’s egg. It’s a color more akin to slate gray, but in the right light it definitely looks blue. The shade is sometimes called maltese and there are a couple of domestic cat breeds, British blue and Russian blue, of that color. Blue bobcats, lynxes, and even cheetahs have been documented. It’s a rare genetic mutation, but that much rarer than melanistic felines like black panthers.

So what about black tigers? Rumors of black tigers have persisted for centuries, but no skins exist and no black tiger has ever been born in captivity or photographed in the wild. The black tiger pictures you find online are all fakes.

It’s possible that some of the reports of black tigers were mistaken identity. Black panthers look similar to the untrained eye. Also, until about the mid-19th century, the word “tiger” was often used for both the actual tiger and for the leopard or other big cats.

But not all the accounts can be brushed aside this way. In 1846, the naturalist C.T. Buckland reported that a black tiger had been preying on cattle in a village near what is now Bangladesh. It also killed a local. When Buckland learned that the tiger had been killed by a poison arrow, he and a friend went to look at the corpse. This is his report, which I’ve taken from Shuker’s blog:

“It was a full-sized tiger, and the skin was black, or very dark brown, so that the stripes showed rather a darker black in the sunlight, just as the spots are visible on the skin of a black leopard...by the time that we arrived the carcase was swollen, the flies were buzzing about it, and decomposition had set in so that those of our party who knew best, decided that the skin could not be saved…”

So why aren’t there as many black tigers out there as white tigers—rare but not unknown? It might be due to the tiger’s ancestry. Unlike many big cats, which evolved in the tropics, tigers are originally from much colder areas. Black fur radiates heat much more readily than any other color, so would be a disadvantage in cold climates.

All the black lion pictures online are fakes too. There aren’t even all that many rumors of black lions. In 1975, a lion cub was born in a Scotland zoo that had a black splotched that covered his chest and one foreleg. The cub was otherwise normally colored. When the cub, named Ranger, grew up, he mated with a number of lionesses in hopes that his offspring would show melanism, but he turned out to be sterile.

Ranger wasn’t a melanistic lion anyway. Instead, he seemed to exhibit somatic mosaicism. Basically, this just refers to an animal with anomalous black spotches due to abnormal skin cells.

There’s a population of leopards in the Malay Peninsula where almost all individuals are melanistic. Leopards are the most common big cat in the world despite habitat loss and poaching, and melanistic leopards are the ones frequently referred to as black panthers. Scientists have no idea why the Malay Peninsula leopards are all black, but it’s clearly conveying some benefit or it wouldn’t be so widespread.

Conservationists use infrared flash photography in their tracking cameras to tell the individual leopards apart, so they can more easily determine population size. The spot pattern shows up in infrared when in ordinary light the leopards look plain black. Unfortunately, poachers also like shooting the leopards, and not with cameras.

Lions, by the way, are technically spotted animals although their spots mostly fade in adulthood. Some individuals retain their spots, though, and very rarely the spots align to form stripes. Maybe this explains the carving of a striped mystery cat on a 5th dynasty Egyptian tomb from about 2400 BCE. The limestone relief is beautifully carved with a number of animals, all so detailed it’s clear what they depict. There’s a leopard and a lion and a tiger...except that the tiger clearly has a tufted tail like a lion. The stripes don’t extend down the tail, either. Considering the wealth of detail in the other carved animals, maybe this animal isn’t a tiger at all but some other mystery big cat.

Lions and tigers are related so closely that they can interbreed, although resulting male cubs are almost all sterile and females may be infertile. It’s possible that the striped animal on the relief is a liger or tigon. I didn’t make up those names, which are stupid. That’s just what they’re called.

The offspring of a lion and a tiger may have spots or stripes on a tawny coat, and its tail may have a tuft like a lion. Males may grow a short mane, but not always. These days, lions and tigers only interbreed in captivity, since their ranges don’t overlap in the wild, but 4500 years ago the Asiatic lion’s population definitely overlapped that of the Bengal tiger, and there were occasional reports of hybrid cubs.

Tigers have never lived in South Africa as far as we know, but according to Nelson Mandela in his autobiography, Long Walk to Freedom, the Xhosa language of South Africa has a word for tiger that’s separate from the word for leopard. Here’s the quote from his book, taken again from Shuker’s blog, this entry a teaser post from Cats of Magic, Mythology, and Mystery:

“One subject we hearkened back to again and again was the question of whether there were tigers in Africa. Some argued that although it was popularly assumed that tigers lived in Africa, this was a myth and they were native to Asia and the Indian subcontinent. Africa had leopards in abundance, but no tigers. The other side argued that tigers were native to Africa and some still lived there. Some claimed to have seen with their own eyes this most powerful and beautiful of cats in the jungles of Africa. I maintained that while there were no tigers to be found in contemporary Africa, there was a Xhosa word for tiger, a word different from the one for leopard, and that if the word existed in our language, the creature must once have existed in Africa. Otherwise, why would there be a name for it?”

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