SOUNDS OF KENYA: Vulture Scramble

In this line of work we see a lot of hyenas on carcasses.  If you stick around long enough, this leads to seeing a TON of vultures on carcasses.  Vultures here have amazing eyesight and are quickly clued in to a carcass by feeding carnivores, loping hyenas, and other vultures.  I have seen over thirty vultures arrive at a hyena den where there is only a small, meatless scrap.  They seemed to appear from out of nowhere, seemingly because they happened to sight other vultures swooping in.  They all waddled around very disappointed in the lack of available meat, but that didn't stop the bravest ones from approaching the den hole and trying to scare the cubs off of their carcass scrap toy.

At most kills, the vultures will fly in and wait patiently on the outskirts for the hyenas to finish.  Once enough hyenas move away from the kill though, they begin sneaking in to grab mouthfuls of meat.  A lone hyena on a kill will futilely attempt to chase the vultures off now and then, but its never long before they are sneaking back in.  Once the last hyena decides they've had their fill (either of meat or chasing vultures) and abandons the carcass, the vultures swarm over it, stripping every last bit of edible meat, tendon, and connective tissue from the carcass bones.

It looks a lot like this, but more frenetic:

And it sounds exactly like this:

Migration!

The migration finally came (on the 23rd of July) to my side of the Mara, and given how high the Mara River was at the time, there were some pretty dramatic crossings and subsequent die offs. Chris Dutton and Amanda Subalusky who study the river (maraadventure.blogspot.com) said that in the first crossing, they counted over 3,000 carcasses just below the crossing point. As I’m sure you can guess, that made for a pretty stinky river, but for some very happy vultures, crocs, and hyenas!

Wait your turn

Pecking orders exist in many aspects of life. Never is this clearer than when a large animal is killed in the Mara. While waiting at the Keekorok airstrip for a flight to take a friend back to Nairobi, a ranger in the Mara told me there were hyenas feeding on a giraffe that had been killed by lions a day or two earlier.

When I arrived on the scene I found about 10 hyenas coming and going from the carcass. At least 50 vultures were hanging around patiently, and at times impatiently, waiting for their chance to stick out their neck and grab a chunk of the recently departed. The hyenas at the scene were not from a clan that we study, but it was clear which hyenas were dominant. Despite the fact there were probably hundreds of kilograms of meat and bones remaining, some of the hyenas were intent on not letting their fellow hyenas get a bite or meat, or even snap off a bone. This is one of the reasons it is important for hyenas to be able to eat large amounts very quickly, you don't know who is going to chase you away before you are full.

When a low ranking hyena is attacked or chased by higher ranking hyena, the lower ranking hyenas will many times displace the aggression onto the nearby vultures. In our regular hyena observations we call this scapegoating.





Whenever I see a hyena, whether it is on TV or standing next to my car, I always think, "Do I recognize this hyena?" I didn't immediately recognize any, but I did find one hyena with an ear tag. I was unable to read the ear tag, but I am hoping a former resident of Fisi Camp may recognize the hyena picture here.




After about 20 minutes of the semi-relaxed feeding scene, a male lion came trotting in and scattered the hyenas and vultures. This male was very fat and had probably been feeding on this carcass for the past day or two. Yet, he was unwilling to let anyone else near the carcass while he stuffed the last open pocket in his vast stomach. Truly a glutton. At one point he even picked up the entire carcass and dragged it about a meter. I am not sure if this was to reinforce to all present that he was at the top of the pecking order or if he may have been showing off, just because he could. Either way, I was impressed.

Happy Valentine's Day...

...from Mama Fisis in the lab to Mama and Bwana Fisis in the Mara. Hope everyone finds as much love as these animals!

A new day dawns on the hippo...

Here's the hippo, day 2. A LOT of meat is gone, in a bit over 24 hours! You can see the ribs are exposed, so just the meat along the backbone, as well as some scraps near the head, are left.


The lions, completely stuffed after collectively consuming several thousand pounds of meat, were lying in the bushes nearby. One greedy lioness didn't like the vultures feeding on "her" carcass. Every time the vultures wound descend, she would drag her painfully fat body up, and chase them off. She'd then return immediately to the shade to sleep off the indigestion from which she must have been suffering. You can see her in the corner of this picture, just after she scared all the vultures away.


This jackal was a bit luckier than the vultures, and somehow managed to snag an entire hippo leg for himself. Despite the leg being bigger than he is, he tried valiantly to drag it away from the scene to keep it safe from other scavengers. Needless to say, he didn't make much progress.


Our hyenas have been lurking around, waiting for a good opportunity to make a move, but the lions' presence hasn't given them their chance...yet.

A scavenging saga

Who doesn’t like freebies? As we've said, it's a pretty good strategy to get a meal without having to expend any energy hunting or waste any time ambushing. Therefore, many carnivores in the Mara scavenge at least some of the time, and there’s a lot of competition for free meals out here. This morning, we watched a fascinating drama unfold between several scavengers.

We happened upon a freshly-dead male impala that must have succumbed to starvation or disease. A lucky black-blacked jackal had been among the first to find the carcass, and it was hungrily feasting on the impala’s hindquarters when we arrived.


Soon, two species of vulture (White-backed and Rüppell’s Griffon) began to arrive from all directions, and within minutes, over 40 vultures had descended upon the impala. The jackal was clearly outnumbered and was driven away after just a few minutes of feeding. The frenzied vultures mobbed the carcass immediately, fighting like crazy for access to the meat.


There’s a specific hierarchy among vulture species, and here in the Mara, the Lappet-faced Vulture is king. With its large body, short muscular neck, and strong bill, this vulture can dominate the other species. When two of these bullies arrived on the scene, they swooped down and attacked the other vultures, who quickly gave way. The carcass had changed hands again, and the Lappet-faced were now in control.


But the saga wasn’t over yet. Three lions came trotting over the hill towards us, probably attracted by the vultures’ hysterical vocalizations. The largest lioness strode confidently to the carcass, and the vultures scattered. She began to drag the impala away and finally settled down in the tall grass about 80 meters away, in sole possession of the carcass. She ate quietly as the jackal, the vultures, and the two other lions watched from a distance.


What’s the moral of the story? Take whatever you can out here, but eat fast and stay vigilant. That carcass may seem like an easy meal, but there are formidable scavengers everywhere, thinking the very same thing about that very same carcass.

Are you going to eat that?

We humans usually think of ourselves as pretty smart. One of the intelligent ideas ourancestors happened upon long ago, was the concept of cooking our food before we eat it. Many modern cultures place a good deal emphasis on cooking as a means to enrich the taste of the food. However, the overriding reason that cooking food has spread throughout human societies is that it is still the most effective way of killing microbes (bacteria, viruses, fungi, and protists) that would otherwise make us ill.

For those of us that love a good steak, we often prepare the steak rare or medium rare, meaning the steak is not cooked all the way through. This is a risk we are willing to take, since not cooking the meat completely leaves the door open for microbes that are able to tolerate high temperatures. Spicing up your favorite dish adds flavor that not only enhances dining experience, but is some cases may also provide antimicrobial activity. Wild animals do not have the option of cooking or adding antimicrobial spices to their meal. As a result, animals have evolved other means of dealing with potential pathogenic (disease causing) organisms.

Spotted hyenas seem to be particularly adept at dealing with microbes that would make you or I extremely sick. This is one of the main reasons I am interested in studying hyenas. Hyenas will eat just about anything, plants being a major exception. Members of the hyena research team have witnessed hyenas eat rotting carcasses that other animals refuse to eat. Many animals will routinely pass up a meal that is decaying, most likely because the risk of infection from the consumption of the decaying meat is high. This widespread behavioral adaptation is an effective method of avoiding dangerous infections. This behavior is so pervasive that some animals have actually developed an anti-predator strategy that includes playing dead, also know as "playing possum." The logic behind this is that if an animal keels over and dies right in front of you, it must be very sick, and thus would probably make you sick if you ate it.

If the behavior of avoiding rotting meat is an effective way of avoiding infection, why are hyenas so willing to eat it? The simplest answer, is that it provides them with an advantage over other animals when prey animals are in short supply. The wildebeest migration is currently in the Mara and food is plentiful. However, the wildebeests will soon migrate back to Tanzania and prey will become more scarce. As the food becomes more difficult to obtain, being able to eat leftovers can be very important for survival. Of course hyenas are not the only animals to take advantage of carcasses, vultures have nearly perfected the art of locating and consuming rotting meat. Hyenas have an additional trick up their sleeve to get nutrients out of a carcass that vultures do not. I will write about this in a future post. If anyone knows what this behavior may be, please feel free to post a comment or email me what you think it is.

Hyenas are one of the most effecient hunters on the African savanna, but they also take advantage of kills made by other animals and animals that have died of disease and/or starvation. This food source can mean the difference between life and death for an animal that cannot go to the grocery store or McDonald's when it is hungry. The drawback of taking advantage of this food source is that hyenas must be able to fend off harmful microbes in the food they eat. This can be done in many ways. I am particularly interested in finding out how the hyena immune system is able to withstand the inexhaustible onslaught of microbes that seeks to exploit them. Over the next 6 months I will continue to write about this topic. I hope some of the readers of this blog will contribute their own ideas as to why hyenas are so resilient to disease.

Important life lesson:

It's nice to have a friend with whom to watch the sunset.










Even if you're a vulture.