Monday, March 24, 2014

Statistics for the Rest of Us

By: Elise Gilchrist

            There are a lot of facts, statistics, and measurements that get thrown around in the science world. Many of them are impressive or strange or even counter-intuitive, but the majority of them are (for me) incomprehensible. The units are non-relatable, the scale is too large or too small, or the statistic itself does not convey the magnitude of the issue at hand.
            This week, I decided to write about elephant statistics, but put them in terms that are easy to realize. I’ll put in a disclaimer: if you are a math whizz or have a brain (very different from my own) that easily envisions estimates and measures, this may not be the most engaging article. But for any like-minded reader who has no real concept of what 5,000 hectares of forest actually means then stay tuned for some relatable statistics.
            Word on the street is that elephants are big, but how big are they? Full-grown Asian elephants can be anywhere from 2 to 3 meters tall at the shoulder (or for my American readers 6.6 – 9.8 feet). If you know anyone who is 6 feet tall (1.8 meters) you can estimate the height of a smaller elephant. Elephants that land on the taller side of this statistic however, are the same height as a basketball hoop. Lebron James might not score too high in a one on one game against the bull male named, Phuki!
          Elephants are not just incredibly tall, but also overwhelmingly heavy. Asian elephants weigh 2.25 – 5.5 tons or 2,000 – 5,500 kg. This means that smaller elephants are similar to the weight of two Mini Coopers. An elephant that falls on the heavy side, however, has a weight comparable to two limousines or a small helicopter! Can you imagine pulling up with an elephant to take your date to the prom?
            With an animal this large, one can assume that they need to eat and drink a lot to maintain their body size. An elephant on average eats about 150 kg (330 pounds) per day, but larger individuals have been known to eat upwards of 300 kg (660 pounds). When you think about that in terms of salad (elephants are herbivores) that is a LOT of food! An average elephant, eating 150 kg of food per day, is eating the equivalent to 110 pizzas or 1,100 McDonalds cheeseburgers! That means that those hungry individuals who eat 300 kg are eating the equivalent of 660 loaves of bread, in one day! Of course, elephants drink a lot as well. They can hold 4 liters of water in a single trunkful (imagine four liters of Coca-Cola fitting up your nose!). Over the course of a single day elephants can drink 100 – 200 liters of water--that would be like you drinking 281 cans of Sprite or as much as 53 gallons of milk in one day!

Elephant salad bar.

            Speaking of trunks, did you know that an elephant’s trunk can have as many as 60,000 muscles in it? That number certainly sounds like a lot, but how does that compare to the muscles in, say, a human’s body? Our closest trunk-like appendage is probably our arms: humans have just 24 muscles in each arm. The entire human body contains between 650 and 850 muscles. That means that elephants have 70 times as many muscles in their trunk alone compared to the entire human body.  And what about their skin? The average skin thickness on an elephant is 18 mm (0.71 inches) but can be 30 mm (1.2 in) thick in some areas. Most human skin is only 2-3 mm thick. Elephant skin is up to ten times thicker than our own!
            Beyond body statistics, what other elephant measurements are of most concern to conservationists? Asian elephants used to roam over three and a half million square miles. That is slightly less than the total area of the United States of America. It is difficult to determine exactly how much land is suitable to elephant habitat today, but estimates put it around 190,000 square miles. This is just a little more than the area of the state of California. Imagine the population of the United States suddenly losing the land of 49 states, and trying to take up residence within California state lines. This is the harsh reality that Asian elephants are living.
            There are fewer than 40,000 Asian elephants left in the wild today. Oftentimes people hear this statistic and assume that this is a perfectly stable, healthy population size.  Indeed, 40,000 does seem like a big number, but what about if we compare it to human populations in different parts of the world? Shanghai, China has over 17 million people, New York and Bangkok each contain over 8 million, and Madrid, Spain boasts over 3 million residents. It is not until you start looking at the 500th largest cities in the United States that you even come close to populations of 40,000 people. So when we compare the numbers of elephants to the number of city-dwelling humans the statistics take on a new meaning.
            Finally, how many elephants are we losing as humans continue to eat up land and resources?  This is a scary statistic: we have lost about half the population of wild Asian elephants in just fifty years, about 800 individuals every single year. That would be the same as 3.5 billion humans losing their homes, livelihoods and lives since 1964. In Africa these numbers are even more shocking. In 2012 we lost 30,000 elephants to the ivory trade, which is close to the same as the number of elephants that live in all of Asia. It is estimated that we lose one African elephant every 15 minutes, due to an ever-growing demand for elephant tusks.
            Statistics can help strengthen arguments and offer hard evidence for a cause, but too often the statistics do not convey the full weight of the measurements at hand. We are losing elephants from this world at an alarming rate. Without a serious change in the way we use our planet’s resources and teach our children about the natural world, elephants will likely be extinct in the wild within the next 100 years. The question is, as David Attenborough put it, “… are we happy to suppose that our grandchildren may never be able to see an elephant except in a picture book?”
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Monday, March 17, 2014

Don't Sweat It: How elephants beat the heat

by Rebecca Shoer

A common question people ask us about elephants (aside from
"Do they ever stop eating?") is whether or not elephants sweat.  All three species of elephants (savannah, forest,
and Asian) live in hot and even tropical climates, ones in which humans
definitely sweat a lot.  This means that,
for humans at least, we need to drink extra water to stay hydrated; as the days
warm up here in Thailand, I find myself drinking two or three liters of water a
day.  But what about elephants?  They drink around two hundred liters of a water a day, and this is just on an average day!  Do they sweat to beat the heat?  And if they do, just how much more water do
they need to be drinking to stay hydrated?

Water is one of the most important limiting factors in an
elephant's environment.  This is because an
elephant will much more quickly deplete a water source than a food source, and
like most animals she can survive longer without food than water.  In fact, one of the main roles of an elephant
matriarch is to lead her herd annually from watering hole to watering hole.  If they arrive at a known watering hole and
find that it's dry, the elephants will dig in the soil to access the water
trapped below.  And they don't just use
this water for drinking: elephants use water to cool off, and mixed with dirt
they can cover themselves with a protective mud coat.  Of course, elephants also love the water for
fun and play: just watch this clip of Lamyai playing in the water in the grasslands!

Elephants need a lot of water, and they need it every day--the elephants here get two to three baths a day.  Because of this, it would be unreasonable and unfeasible for an elephant to sweat extra during the hot season--she would not be able to drink enough water to make up for the loss of moisture through her skin.  Perhaps, as elephant ancestors moved and their habitats warmed, individuals that sweat less survived and reproduced more than their sweatier cousins.  This process continued over centuries and millennia until the arrival of the modern Elephas maximus.  Now, even on a hot day, you will find that a toasty elephant doesn't have a sweaty brow to match your own.  In fact, there is only one place on an elephant's body that she can sweat from, and it's a tricky place to spot!  Looking at this picture, can you see her sweat?

Photo by Elise Gilchrist

If you guessed her toenails, you were right!  Elephants do possess sweat gland tissue equivalent to that of humans in the cuticles of their toe nails (Lamps et al. 2001).  Why did they retain these miniscule glands, if they most likely do little to cool them off?  Well, it all has to do with natural selection: so long as a trait isn't harmful, or doesn't reduce an individual's ability to reproduce, it will persist through the generations.  Even thousands of years from now, elephants may still have these small glands between their toes.

So if they can't sweat, how do elephants cool off?  Well, we already mentioned one method: a good dip in the pond and a nice mud pack can keep an elephant nice and cool.  They also use their amply-sized ears to keep cool: not only do they flap like giant fans, but the skin on their ears is so thin that the blood itself is cooled by this flapping motion.  Indeed, elephants' blood may be cooled anywhere from 2 to 8 degrees centigrade, which then circulates throughout the rest of their body. 

Picture by Rebecca Shoer

Finally, three recent studies have revealed previously undiscovered thermoregulation strategies of both Asian and African elephants.  First, Asian elephants have been shown to allow their internal body temperature to fluctuate significantly during hot days (Weissenbock et al., 2011).  This may sound like an odd strategy to keep cool, but the true benefit of this strategy becomes apparent over night: Asian elephants allow their body temperature to dip much lower than other animals, and this gives them a sort of internal shield against the heat during the day.  Second, the same research group found that African elephant have "thermal windows," or areas around their bodies where the skin is thin and there is a large concentration of blood vessels (Weissenbock et al., 2010).  These "windows" give the elephants even more areas from which to cool off their blood, and thus keep their body temperature cool.  Lastly, a third study found that elephants' sparse body hair is actually used to dissipate heat from their bodies (Myhrvold et al., 2012).  The hairs allow elephants to increase body heat loss (and thus decrease body temperature) up to 20%.  It may seem counterintuitive, but this is the first documented example of hair being used to cool off an animal instead of keeping it warm!

Nong Sam is extra hairy to help him cool off while he's growing. 
Picture by Rebecca Shoer

No matter how much we think we may know about elephants, they are still full of mystery, from their intelligence and behavior to even their most basic biology.  As the population of all elephants continues to decline, and with so few labs in the world researching these incredible individuals, we are in a race against time to try to discover the secrets of these spectacular species.

Lamps, L.W., Smoller, B.R., Rasmussen, L.E., Slade, B.E., Fritsch, G., Goodwin, T.E.. 2001. "Characterization of interdigital glands in the Asian elephant (Elephas maximus)." Research in Veterinary Science. 71(3):197-200.
Myhrvold, C.L., Stone, H.A., and Bou-Zeid, E. 2012. "What is the use of elephant hair?" PLoS ONE. 7(10)e47018.
Weisseböck, N. M., Arnold, W., and Ruf, T. 2011. "Taking the heat: thermoregulation in Asian elephants under different climatic conditions." Journal of Comparative Physiology. 182(2):311-9.

Weissenböck, N. M., Weiss, C. M., Schwammer, H. M., Kratochvill, H. 2010. "Thermal windows on the body surface of African elephants (Loxodonta africana) studied by infared thermography." Journal of Thermal Biology. 35(4):182-188.

Wednesday, March 12, 2014

It's a Boy!

By Sophie Wasserman

We are so excited to share that on March 3rd the Golden Triangle Asian Elephant Foundation welcomed their newest elephant into the world! 

Sahm, a few hours old
Photo: Rebecca Shoer

Nicknamed Sahm (Thai for “three” since he was born on the third day of the third month), the healthy baby boy was estimated to weigh in at a hefty 200 lbs (90 kg), on the larger end of the normal range of 70-100 kgs for newborns. Though elephants typically give birth during the night, Sahm was born at approximately 11:15 AM and within a few hours was walking about and attempting to nurse (it took him a few tries to get it right). Like most ungulates, a baby elephant is called a calf and Sahm will probably continue to nurse from his mother for another 2-3 years, though in the wild some calves aren’t weaned until age 5.

Sahm nursing from his mother

Mother Boonjan arrived pregnant to GTAEF in 2013 and has been on maternity leave since last fall, spending the last months of her almost 2 years of pregnancy relaxing in the grasslands. Sahm is her fifth calf and also fifth son. Females usually only give birth to 4-5 calves throughout their lifetime, almost always one at a time, though there have been rare cases of twins. 

Sahm, a week old, and mother Boonjan
Photo: Rebecca Shoer

Sahm’s older brother Somjai also lives in the GTAEF camp, where he continues to excel at our research tasks, so we have high hopes for his new baby brother. Like most very intelligent species, elephant calves are born with only a fraction (about 35-50%) of their adult brain weight. Although Sahm may be able to nurse by instinct, he still has a lot to learn about being an elephant by observing his mother and other elephants as well as his own trial and error throughout the first ten years of his life.

Photo: Rebecca Shoer
At a week old, Sahm is still a little shaky on his feet and hasn’t quite mastered stepping over, rather than on, his own trunk. His control improves every day, and by the end of the first month he should be able to pick up and hold objects with his tiny trunk. He won’t be able to use it to hold water, however, until a few months down the road. Sahm is reluctant to stray far from the safety of his mother’s legs and Boonjan is even more hesitant to let him go, gently but firmly herding him close with her trunk. In the wild, calves are the center of herd attention and are taken care of not only by their mother, but also older sisters, cousins and aunts, a behavior known as alloparenting.

To stay updated on Sahm’s most recent accomplishments, follow ThinkElephants on Facebook and Twitter. Got a question about young Sahm, animal intelligence, elephant conservation or something “irrelephant”? Ask a Research Assistant by emailing