Necropsies: a scientist's chore (Warning: This blog contains pictures of blood and guts)

First, a little background:

I am a field scientist, but sometimes I am a wussy field scientist. I find bugs fascinating but, spiders terrify me. I’ll bathe in a crocodile infested river if I have to, but only if the water is clear enough to see the crocs coming. Perhaps my strangest “atypical for a scientist” trait is the fact that I passionately dislike doing necropsies. I am enthralled by the inner workings and details of the animal body, no matter the species, because they all have unique adaptations. I love reading about those adaptations in books and seeing diagrams and even pictures but, when it comes to cutting open an animal and seeing it all for myself, I can’t handle it. It’s not the blood and guts; those don’t bother me. Somehow I manage to freak myself out with the idea that this was once a living breathing animate creature, and now it’s not. I get light headed and nauseous and I am deeply affected by the “smell of death” (whether it’s real or imagined, I’m not sure).

I learned this lesson early on when I had an unexpectedly difficult time dissecting a fetal pig in my high school biology class. That knocked veterinarian off my list of possible “things I want to be when I grow up” and made room for research biologist.

Next, to the story:

On obs one day in December we came across one of our collared females who had been wounded by lions. She was in very bad shape, so bad that she didn’t move when we drove right up to her or when we got out of the car. Unfortunately, in this situation, even if there had been anything we could have done, it would have inappropriate to do so and interfere in the natural process. We resumed obs and by the time we came back to check on her an hour later, she had passed away.

For me, this experience was sobering enough without having to also load her into the car and take her back to camp for a necropsy. As a scientist I completely understand and appreciate the wealth of data that we collect during a necropsy but, I just can’t get excited about helping to perform one. I was in a state of utter dread the entire ride back to camp. I was convinced I was going to throw up, pass out, or both in quick succession. I quickly made my case to Sean and Kasaine and allowed them to take on the jobs of flensing the skull and cutting so that I could maintain my distance from the specimen by doing the paperwork and sample labeling.

Part of the necropsy involves determining the cause of death. That was easy: lions. Lions are the number one cause of death of hyenas and the lions hadn’t left much to the imagination. Our poor females had puncture wounds from claws and teeth in her neck, chest stomach, and inner back leg. One particularly nasty wound on her neck was the probable cause of death and seemed to have been bleeding the most.

Next, we had to take body measurements such as body length, height at the shoulder, leg lengths, and head circumference. Then, Sean cut off the hyena’s head and began flensing the skull. At this point, I mentally checked out. Our last task was to take organ and tissue samples. I focused on labeling my vials for the samples and recording how many of each we collected. After about an hour or so, I was so busy that I forgot to feel sick and light headed. By the end, I was surprised to find that the collection of our last few samples was captivating.

Kasaine had done a fine job locating all the vital organs that we needed to collect samples from, until we reached the sex organs. This is where my junior high and high school sex ed classes, and mammology class came in handy and gave me the advantage. I knew generally where the uterus and ovaries should be and what they should look like, while Kasaine was completely clueless. We located both, dissected the uterus and found a fetus! I realize how strange it is that this was the most exciting part for me and I can’t really explain why I didn’t find it even more depressing to find the fetus. I think it was the exploration of finding the correct organs and confirming our suspicion by finding the fetus itself.

I doubt I’ve completely cured myself of my necropsy handicap but at least I know I can survive them and find something positive in the experience.

One-eyed wonder

About a month ago, we noticed that Quark, a 5-month old Happy Zebra cub, had a very swollen right eye. The swelling has finally gone down, and now we realize the eye isn’t just damaged…it’s completely gone.


I know what you’re thinking: are you guys really geeky enough to name a lineage of hyenas after subatomic particles?

Um, yes we are. But perhaps you’re also thinking: yikes…what’s it like being a hyena with only one eye?

Hyenas have what we call “binocular vision,” meaning that their vision is a result of two overlapping images – one from each eye – that the brain puts together. This allows for several fantastic advantages, such as depth perception and increased detection. Animals such as predators (which rely on particular visual cues to hunt moving prey) and primates (which need to find and select particular fruits from the surrounding vegetation) often have binocular vision. Their eyes are usually placed closely together on the head and oriented forward.

Animals with “monocular vision” (like the rhino below) have eyes that are on opposite sides of their head, rather than in front. These animals use each eye separately, but the big advantage here is an increased field of view – sometimes nearly 360 degrees. If you’re a tasty Mara antelope and the biggest problem in your life is some scary carnivore creeping up on you while you’re chowing down on grass, you’re going to want to see as much as the world around you as possible. For most prey species, accuracy and depth perception probably aren’t quite as important as knowing what's around you at all times.


OK, enough biology lessons. The point is that, since hyenas need abilities such as depth perception, poor one-eyed Quark is probably at a real disadvantage. Try closing one eye and trying to play darts (first, please make sure nobody else is within striking distance)…it’s not easy. Now, imagine losing an eye and trying to catch a gazelle zipping around at 50 miles per hour.

But, Quark still has one good eye, and we aren’t counting her out quite yet. After all, our resident rebel Moss is likely blind in one eye, and she continues to kick some serious butt. Plus, Quark is pretty high-ranking, so, in theory, she doesn’t need to hunt at all to survive…she just needs to take advantage of others’ success. In any case, life probably isn't going to be easy for Quark.

Another death in the Happy Zebra Clan

It's sad when any hyena dies.
It's even worse when it's a hyena you're particularly fond of.
It's hardest of all when it's a tiny cub.

Last night, we came upon what originally seemed like an idyllic scene at the Happy Zebra den. Sawtooth - one of my favorite hyenas - was grooming her tiny black cub Neverland, who was born fewer than 20 days ago. The cub, however, wasn’t moving. We could see that his head was covered in blood.


After the vigorous bath didn’t breathe life into Neverland, Sawtooth stood over her motionless cub, looking confused. Several minutes later, she lay down in the denhole, just a meter or so from Neverland's body.

None of the other hyenas at the den seemed to understand why the cub was so very still. Over the next hour, several of them came over to sniff and prod the dead cub. Snapper, a Happy Zebra subadult, even picked Neverland up and carried him around for a while before she lost interest, placing him carefully back where she had found him.


Our necropsy showed that Neverland had died from massive head trauma just an hour or two before we arrived at the den. His entire skull and jaw had been crushed. While adult hyenas have extremely robust skulls, a young cub's skull still has a lot of developing left to do, and is surprisingly fragile.

The most likely scenario? Infanticide by another hyena. It’s brutal, but it happens in many species. When food is a limited resource, any extra mouths to feed mean less nourishment for you and your offspring. One way to deal with such competition is to kill it. It’s hard to know how often infanticide happens among hyenas, and we’ll never find out all the details surrounding Neverland's death.

The sad truth is that fewer than half of all hyena cubs survive to adulthood. We’ve got over fifty cubs here at Serena…let’s hope they can beat those tough odds.

It's only natural

When I posted the photo of the obese hyena on Halloween, an astute reader posed the question of if she might get diabetes from being so fat. An excellent question!

The short answer is no, probably not. First of all, hyenas can go from "fat" to "normal" and back pretty quickly...they are capable of gaining an astounding 20kg in a single meal (that's 44 lbs. for those not metrically-minded). To give you some perspective (if you still need any after reading "44 lbs."), that's about 130 hamburgers, and at least three times as much as I can eat at Thanksgiving. Obviously that's not all retained as fat, although after such a gorging they will stay fat for days (Navajo, the hyena in the picture, is just now starting to return to her normal, albeit heavy, weight).

But back to the question—can hyenas get diabetes from being so fat, even if they're only fat sometimes? Well, I'm sure it's possible, but the truth is that most wild animals don't contract diseases like diabetes or cancer. That's because the selection pressures (yes, selection as in natural selection) are too strong. In other words, if there were a hyena that got diabetes from obesity—let's call him Carl—it would probably be because Carl had a genetic mutation predisposing him to the disease. Well, Carl certainly wouldn't fare very well against the other hyenas in The Game of Life, since he would be too busy trying not to keel over in a diabetic coma. Carl probably wouldn't produce as many offspring as other hyenas. In fact, maybe Carl would die before he had a chance to produce any. Bummer for Diabetic Carl, but less of a bummer for the hyena population's next generation, because now those genes for diabetes have gone with Carl, without getting passed on. In other words, they've been selected out. This is also why animals don't typically get diseases like cancer.

Okay, so why do we get cancer? By now you have probably caught on and guessed, because if you're reading a blog about hyenas you're most likely in touch with your Inner Science Nerd, but I'll elaborate nonetheless.

Humans are subject to natural selection just like any other species, but we have a special knack for relaxing (weakening) it. We have developed a million different medicines, medical treatments, and other life-saving and life-prolonging tactics to help us overcome things that would have surely done us in a couple hundred years ago. Think about it—a few hundred years ago, if you got the flu, things didn't look good for you. If you had a difficult childbirth, you and your child were in serious danger. And if your body stopped producing insulin, well, you were pretty much out of luck. It's therefore no surprise that life expectancies were half what they are today.

Today, thanks to technological advances, we're able to look natural selection in the eye and say "Pfff! Bite me!" Okay, it's not exactly like that, but the selection that operates on us now is so weak that it can be almost impossible to detect. I've had the flu, as have most of you, and I'm confident that if I can't pop a baby out naturally, my obstetrician can come up with some kind of a solution. And although diabetes is a very serious health condition, it is now something that people can commonly live with if they take proper precautions (and live in a country that doesn't mind insuring all its citizens...whoops, sorry, slip of the tongue). As for cancer, most wild animals—like humans not that long ago—never live long enough for cancer to get them. Those that do get it die pretty quickly, so the ones that are less likely to get cancer are the lucky ones who get to pass on their genes.

I don't mean to imply that natural selection doesn't act on humans at all any more, because it certainly does. It can just be a lot slower and a lot more subtle than it used to be. This is why human overpopulation is such a problem—we've removed many of the natural population controls. But that's a story for another day.

**Special thanks to Andrew S. Flies for his input on this matter.

Tragedy strikes

NOTE: The sentiment among the bloggers at FisiCamp is that we really want to give you an accurate depiction of what happens out here, and that means writing about both the highs and the lows that we experience. While I’ve tried to spare you most of the gory details, just be advised that this entry does illustrate the harsh realities of life out here. It redeems itself somewhat at the end, I promise…
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The hardest part about studying animals occurs when, all of a sudden, you’re reminded that they aren’t invincible. Despite the fact that hyenas are amazingly feisty and resilient animals, they live difficult lives.

When we spotted Geezer, we immediately knew something was wrong. He was trying to walk into a shallow water hole, but he could barely move. He was moving slowly and laboriously, and it took a long time for him to reach the edge of the pool. As he bent down to drink, blood ran down his neck from several puncture wounds, and the water around him turned red. Geezer drank laboriously for several minutes, which wasn’t a good sign - healthy hyenas don’t tend to drink much.


From the size and shape of the punctures on his neck, as well as other wounds on his back and hindquarters, we could tell that the poor guy had been attacked by lions. He’s from the Happy Zebra Clan, whose den was visited by lions not long ago. Recently, we’ve repeatedly seen a group of five large male lions in the heart of the clan's territory.


To make a sad story short, Geezer didn’t make it through the night.

Out here, we walk a thin line between being animal enthusiasts and scientists. As animal lovers, we inevitably grieve when a hyena dies. These hyenas become our family and our closest friends. We know their favorite hangouts, their friends and foes, and their funny quirks. We see them day after day, carrying on with their lives, and it’s impossible not to get attached.

Unfortunately, rule #1 in research is “don’t get attached,” because our jobs don’t just end when a hyena dies. We can learn invaluable information post-mortem, so we have to retrieve the body, perform a necropsy, and prepare the skull to be sent back to the US. As scientists, we have to (at least attempt to) distance ourselves from the situation; it’s a strange and difficult balancing act between emotion and obligation.

But, all is not lost. In an ironic twist of fate, the same day Geezer died, we had our first sighting of Quark, the newest cub in the Happy Zebra Clan. The coincidental timing of Geezer’s death and Quark’s birth was a perfect reminder that, while nature can be harsh, new life is just around the corner.

Maasai Medicine

Doctor “Action” Jackson (shown below, with the BEAM 2008 class) runs the local medical clinic in Talek, and has been a good friend to the residents of FisiCamp for many years (it’s nice to be on good terms with a doctor when you work with bone-crushing predators). While the basic principles are the same, third-world medicine is a world away from the health care system with which we are so familiar.


The clinic consists of a waiting area, two tiny examining rooms, and a storage room that doubles as a treatment area (shown below). With no access to the expensive hospital equipment on which American hospitals rely, Jackson’s shelves are stocked instead with cotton balls, alcohol swabs, and painkillers. However, his knowledge of medicine is impressive and he relies on common sense and resourcefulness rather than high-tech treatments. He has even fashioned a simple, solar-powered centrifuge from a Tupperware container and a tiny electric motor.


Jackson sees dozens, and sometimes hundreds, of patients each day. On the busiest days, there’s a line way out the door of the clinic, and patients must wait for hours to be examined. In order to make medical care widely available, he keeps his rates very low; adults pay 300-400 shillings (about five dollars), and children are usually charged just 100 shillings (less than two dollars). If a family can’t afford treatment, he often pays out of his own pocket. Livestock is the major form of currency among the Maasai, so Jackson sells cattle in order to fund his work and keep the clinic running. Here's two Maasai "mamas" waiting to be seen by Jackson.


According to Jackson, malaria and pneumonia are the top two causes of death of Talek residents. However, Jackson also has lots of experience with conditions that are less familiar to us Westerners. Obviously, life in the bush can be dangerous, and Jackson treats more than a few animal attack victims per month. Lion and buffalo are the biggest problem animals; however, a few days ago when I dropped by to see Jackson, he was treating a man who had just been mauled by a leopard. Deep, bloody gashes covered the man’s arms, hands, and head. What amazed me most, however, was that the man was walking, talking, and able to return home the very next day.

While his knowledge, generosity, and passion have been embraced by most locals, Jackson has also made some controversial moves. By speaking out against female circumcision, as well as against some cultural beliefs regarding HIV and other STDs, he has made some enemies who condemn his disregard for valued Maasai customs. Despite these adversaries, however, Jackson continues to provide low-cost, innovative care to the residents of Talek.

How to handle a hyena (don't try this at home...)

In order to collect some kinds of data, we have to get up close and personal with the hyenas. Since none of us are willing to lose a limb (or our lives!) to those strong jaws, we dart the animals in order to work on them. Here's the process, with some pictures from the darting that Audrey and I did this morning...

First, we identify a target hyena, which is more complicated than it sounds. The animal has to be alone, because lions and other hyenas may attack a vulnerable hyena while the drug is taking effect. We also don’t want the hyena to get lost in the bushes or fall into water before we can get to it, so we only dart in open areas where we can keep an eye on the hyena as it goes down.

If we’ve found a good darting situation, we fill a dart with a drug called Telazol and load it into our CO2 rifle. As soon as the hyena turns away from us (we don’t want it to associate our vehicles with the experience of being darted), we aim for the hindquarters and shoot. Hyenas generally start to act “drunk” quite quickly, and they’re usually down just less than ten minutes after they’re darted.


Once it’s safe to get our hands dirty, we work as quickly as possible. First, we cover its eyes because, although the animal is immobilized, it’s not unconscious; bright colors and fast movements can disturb hyenas while they’re down. Then, we draw several vials of blood to look at hormone levels, immune function, and DNA.


We take many different tooth measurements (by the way, since hyenas chew on so much bone, their teeth are surprisingly clean and their breath doesn’t stink nearly as much as you’d expect!), and several body measurements as well. This morphological data helps us understand how hyenas’ teeth, skulls, and bodies change with age. It also shows us the physical differences between males and females, and high- and low-rankers.


To identify the individual again in the future, we often ear-tag hyenas when they are darted. If this hyena is seen again (or found dead) many miles away or several years later, eartags can give us important information on movement, dispersal, and mortality.


Finally, we drive the hyena to a safe place in the bushes to wake up and cover it with water to keep it cool while the drug wears off. This can take anywhere from a few minutes to an hour or more, depending on the individual (the hyena in the picture is already raising its head and starting to come around).


While that’s the end of the actual darting, we still have work to do! We go back to camp to do all the bloodwork so that the samples can be sent back to the US. Fisi Camp may be in the middle of nowhere, but we’ve got plenty of sophisticated lab equipment (which we run off solar power and car batteries) to help us get the job done.

All in all, darting is a lengthy and complicated process, but it’s also unbelievably exhilarating to work, hands-on, with such an amazing predator.