Hyaena research in Masai Mara, Kenya

Hans's picture
Fri, 2008-06-06 16:43 by Hans

This year I had the opportunity to visit the hyaena research camp near Fig Tree, Masai Mara. This is an illustrated report of some of the research work I could observe and a brief introduction into the life of the spotted hyaena. My thanks go to Dr. Kay E. Holekamp, the leader of the research project, and to her assistants Danielle and Eli.

2008-05-26 – To Masai Mara

Early in the morning I drove to Masai Mara. The road is good to Mai Mahiu, but then it is mostly bad to very bad, up to Narok.

Nairobi – Masai Mara
Nairobi – Masai Mara

I arrived in Masai Mara in the late afternoon and parked the car at a river crossing. The water was low, so it was easily possible to cross the water on dry foot at a place where there are large stone plates.

On the other side is the hyaena research camp, my destination and temporary home for a few days. I met its current inhabitants, settled into the camp and into my tent and slept very well.

2008-05-27 – Hyaena research

At 5 am we all met in the dinner tent for an early morning tea, then set out, while it was still dark, to look for the hyaenas. We found several, and the scientists went about their work and recorded their findings.

Hyaena tracking in Masai Mara
Hyaena tracking in Masai Mara

After our return a group of students from St. Lawrence University came visit and was given a lecture about the camp, conservation, and the hyaenas.

Later, back in the camp, I pulled my mobile phone high up into a tree to get an internet connection, so I could update this web page.

My bush Internet
My bush Internet

The mobile phone connection is still not very good around here, but it helps.

2008-05-28 – More on hyaenas

I'll try to explain some of the many things I have already learned about them. More information can be found on the IUCN Hyaena Specialist Group website and in the MSU hyenas blog.

Hyaenas may well be the most successful large mammalian predators of Africa. Their family went through a long and winding evolution, and only four different species of hyaena remain alive today, the spotted hyaena, the striped hyaena, the brown hyaena, and the aardwolf. The latter is a most peculiar and highly specialized animal that eats only termites.

The species with which we are dealing here is the spotted hyaena, a social hunter. The following text relates only to this particular species.

Hyaenas are built similar to a big, sturdy dog with a back that is sloping downward, leaving the impression that the hind legs are shorter. It is not precisely known what advantage this stature conveys, but other endurance runners, like the gnu or wildebeest, also has this sloping-down back. Hyaenas are also amblers, which is probably necessary because of the length of their legs in relation to the relatively short length of their rump.

Tracy walking - video (WMV,  20 s, 1.2 MB)
Tracy walking - video (WMV,  20 s, 1.2 MB)

Compared to a similar-sized dog, two differences are most conspicuous:

  1. The hyaena's heart is about three times as big.
  2. The hyaena's jawbones and supporting skull parts are much more strongly built.

The latter enables the hyaena to crack all known prey bones, which results in their ability to eat their prey whole, leaving behind only horns, hooves, and teeth.

Their big heart is related to their ability to run long distances, some kilometers, at a fairly high speed. Their maximum speed is around 55 km/h. (They could be fined for speeding when running through a city.)

They are also built such that they can cope with the problem of overheating. While other runners, like cheetahs and lions, often lie down and pant for minutes after a chase, before they can even start eating their prey, hyaenas don't seem to have this problem.

Gucci Fozzy
Gucci; Fozzy

Females are generally larger, more aggressive, and higher in rank than males. The external genitalia of females and males look very similar, which makes it very difficult for a casual observer to determine their sex.

Hyaenas live in clans of up to 100, sometimes even 120 animals. The size of the clans depends on food availability. If there is plenty of prey, they form larger clans. All members of a clan know and recognize each other individually and also from far by their call. The most common call, that you can hear over much of Africa at night, is the whooping call, through which hyaenas announce their identity, presence, location, and likely a lot more information. The clan occupies a large territory and defends it against neighboring clans.

Hyaena society is ordered strictly by rank. The highest-ranking one is the alpha female. The next lower ranks are occupied by her youngest offspring, then her older offspring, followed by the next-in-rank female, etc. The characteristic of children assuming their mother's rank is somewhat unusual among social animals.

Hyaenas can generally recognize their kin, often merely by call. They can even recognize relations as distant as great-aunts and cousins and behave less aggressively and more cooperatively towards them. Similarly to baboons, fathers can recognize their offspring and, even more surprising, spotted hyaenas can even recognize their fathers.

Detailed information: Social intelligence in the spotted hyena (Crocuta crocuta)

After puberty, at 2 to 5 years of age, males migrate to another clan, which is a common behavior type in social mammals to avoid inbreeding. In the new clan the entering male assumes the lowest rank.

Hyaenas build common dens, where they commonly raise and protect their young. The mother first builds her own natal den, where she bears her young. After three weeks they move into the communal den, where each mother nurses her own young and where they all live and play.

The juvenile da Gama
The juvenile da Gama

Young hyaenas are incapable of supporting themselves by hunting for several years. Their bones, muscles, and experience are not suffiently developed for hunting, before they are several years old. Their mothers and later the entire clan have to provide for them until they are fully grown and developed.

Contrary to public preconception, hyaenas do not normally hunt in packs like wolves, lions, or African hunting dogs. Instead they mostly hunt alone or with just two individuals. The reason seems to be that that gives them a chance to eat a much larger share of their prey before the others find them, if they find them at all. This is particularly important for low-ranking hyaenas, who would be driven from their own prey.

Of course there are exceptions, and a larger group of hyaenas can occasionally hunt and bring down a large animal, even a buffalo.

A typical hunt evolves as follows. The hyaena or two hyaenas walk around at night, dawn, or dusk, looking for prey. When they find typical prey animals, particularly Thompson or sometimes larger gazelles, they probe by running into the herd and checking for any animal that is slow and promises to be easy to catch. Examples would be a limping gazelle or a heavily pregnant zebra.

If such an animal can be identified, the hyaena or hyaenas will chase it to exhaustion, then begin to eat from it. The prey soon dies of blood loss.

During the hunt the hyaenas are quiet to avoid the attention of other predators, including other hyaenas. Only after other hyaenas arrive at the prey, there will be noise of hyaenas squabbling over the food.

Typical average hyaena meat intake can vary roughly between 2.5 kg and 7 kg. They gladly eat more, if more prey is available. They normally have to eat every four days, but they hunt and eat every day, as long as they can find enough suitable prey.

2008-05-29 – Den and dart

As every day we drove out still in the dark, looking for the hyaenas. At night the radio equipment shows its strength. Without it, it would be quite difficult to find the hyaenas and, even if they can be found, to identify them. Of course I have no night photos.

Subadult male lion
Subadult male lion

In the first morning light we passed by a pride of young lions. Hyaenas and lions are not the best of friends, so it is no surprise that we have to drive away some distance to find the hyaenas.

We went to the communal den and watched the always interesting interactions there.

Communal den Juvenile hyaena
At the communal den

Hyaena babies are born black and stay black for their first five weeks. Then they begin to develop white, more precisely, light grey, eyebrows, and during the following weeks this color spreads over their head and further back, when the characteristic spots develop that give this hyaena species its name, "spotted hyaena".

At the den there is often a lot of interaction between mothers and kids, playing between the kids, and interaction with other visiting hyaenas. Males also visit the den, particularly those, whose kids are being brought up there. I'm not sure though whether or how well they can recognize their own offspring.

At the communal den - video (WMV, 12:36 min, 22.5 MB)
At the communal den - video (WMV, 12:36 min, 22.5 MB)

After a long den observation session we drove on to see what the other hyaenas were up to. We could observe a hunt, as a group of hyaenas, including several relative youngsters, began to investigate a family group of zebras.

As described above, this is not their most common hunting configuration, but particularly the youngsters seemed to get excited about the zebras and liked to chase them around a bit. The method to get the potential prey to react and run is quite typical though. The hyaenas test the reaction of their potential prey and check particularly whether any of the possible victims shows signs of weakness, slowness, or makes some other mistake.

Hunting zebras
Hunting zebras

The stallion of the zebra group turned back and attacked the hyaenas several times, giving a really good performance and showing that zebras are by no means defenseless. A well-placed zebra kick can kill a hyaena.

At one time he stumbled and fell, and we thought that the hyaenas would instantly use the opportunity to keep him down and kill him, but he jumped back up again very quickly and escaped the hyaenas.

Hunting zebras - video (WMV, 16 s, 199 KB)
Hunting zebras - video (WMV, 16 s, 199 KB)

After chasing the zebras for a few hundred meters, the hyaenas gave up on them. Most had apparently eaten already at night, and so their interest was not big enough to perform an expensive chase of a group of strong and healthy zebras. It seemed to me that the hyaenas had spent fairly little energy on this chase, nowhere near exhaustion. They certainly spent much less energy than the zebras. It looked almost playful, like an enjoyable game they played with the zebras.

Roosevelt and Morpheus
Roosevelt and Morpheus

Research work is rewarding, but tedious. The researchers were continuously busy observing and recording, whenever hyaenas were in sight.

Binoculars Radio scanner headset Dashboard of a research vehicle with GPS and radio scanner
Research tools

Standard field research tools are a well-equipped off-road car, binoculars, a radio scanner that scans the frequency ranges of the hyaenas' radio collars, a GPS to record the precise position for every observation, and a small dictation device. In addition the researchers carry lots of information, particularly one file of hyaena pictures for each clan for identification and various maps.

The next operation was one of the most complex and intense procedures the researchers have to do. From time to time a hyaena must get darted to get data from it that cannot otherwise be obtained, and to mark it or put a collar on it. The dart is an injection needle that can be shot from an pressurized air rifle, putting the hyaena into temporary sleep. The substance used for hyaenas, Telazol, is different from that used for elephants, M99, and is, fortunately, much more forgiving, as far as its dosage, normally 2.5 mg/kg of body weight) is concerned. There is no counteracting wake-up drug, however, so the hyaena just wakes up slowly after some 45 minutes, depending on the dose.

The researchers shown in the photos are Kay, the very experienced head of the project, and Danielle, who had trained shooting darts and learned the entire procedure, but had never darted a living hyaena before.

Darting a hyaena is much more difficult than darting an elephant, for a number of reasons.

  1. The hyaena is much smaller.
  2. The hyaena doesn't have a skin as thick and robust as an elephant. Therefore the air pressure for the dart rifle has to be lower to minimize the injury. This means that the dart does not fly as fast and far, and its flight path is distorted much more by gravity and wind.
  3. Hyaenas move quickly and are often very active, making it difficult to find a suitable moment to shoot the dart.
  4. Unlike elephants, hyaenas have excellent vision and can only be darted while they look away from the car, because if they see the rifle and grasp the correlation between rifle and shot, you can never dart them again.
  5. Other hyaenas might also see the rifle and understand what's happening. Therefore you can dart a hyaena only when no other hyaena is looking.

The individual to be darted was Kent, a young male. Two other hyaenas, who had been with him, had disappeared, leaving him alone. We got close enough to him for a dart shot, and Danielle took the rifle.

She was understandably nervous (she explained later, but I certainly didn't notice), but she aimed well and shot at the right moment. The dart hit Kent at approximately the best place near the upper hind leg, but hit a bone and fell off. However, enough of the sleeping drug was injected in that split second to slowly bring him down. The low dose took much longer than the usual two minutes, so it was obvious to the researchers that only a fraction of the dose had been injected.

When Kent was lying and no longer moving after about 10 minutes, Kay carefully walked up to him to inject a booster dose to make up for the incomplete first dose. This operation involves a certain risk, because the hyaena might not be fully asleep and might defend himself by biting or show other undesirable reactions. But Kay placed the injection successfully, and the two researchers could continue with their routine, which consists of a long work sequence that has to be done in the shortest possible time, but still very precisely.


Safeguarding and extracting blood

Among the tasks to be performed are safeguarding the hyaena, particularly the open eyes, extracting blood, doing an extensive range of measurements, including quite a few on the teeth and jaws, and marking and weighing the hyaena.

Teeth and jaw measures Body sizes Kent fast asleep
Measuring

A hole in the ear Earmark
Marking

Weighing
Weighing

While all this is done, and it can easily take up all of the available 45 minutes, the hyaena has to be watched for proper hartbeat and breathing, but also for signs of premature awakening. After all, a hyaena is a dangerous wild animal and has to be treated with a lot of respect.

Finally the hyaena is taken to a secluded, shady place, which has to be scoured for other predators, particularly lions, to allow it to wake up slowly and in peace.

Loading the hyaena into the car An unusual sleeping passenger
Loading the hyaena into the car

Resting the sleeping hyaena in a shady, secluded place Resting the sleeping hyaena in a shady, secluded place
Resting the sleeping hyaena in a shady, secluded place

Researcher etiquette requires that a photo be taken of the novice and her target after a first darting.

Danielle and her first real dart target Danielle and her first real dart target Danielle and her first real dart target
Danielle and her first real dart target

Finally Kay pours water over Kent to keep him cool while he slowly wakes up.

Keeping the hyaena cool during the wake-up phase
Keeping the hyaena cool during the wake-up phase

After this intense hour and after returning to camp, the lab work begins, which takes even longer and consists of even more steps. Among many others it involves a centrifuge, liquid nitrogen, several other substances for dilution and other reactions, lots of different and special containers, and glass slides for microscopy.

Tedious lab work Tedious lab work
Tedious lab work

Danielle at work Eli at work
Danielle and Eli at work

Blood samples on glass slides for microscopic analysis
Blood samples on glass slides for microscopic analysis

I learned once again that darting a hyaena and scientific field work in general are not just pure fun, as one may at first think, but entail lots of difficult work that has to be learned, performed accurately and without mistakes, and that takes lots of time and energy. Nonetheless it is one of the most interesting tasks I can imagine.

Later we went to the market in Talek village to go shopping to replenish the camp food resources. Here's one of the village pubs.

Pentagon Pub in Talek village
Pentagon Pub in Talek village

The evening observation led us to the den again and across the grass savannah of the eastern Masai Mara nature reserve, whose richness in wildlife makes it one of the great nature spectacles of our time.