Archive | July 2017

How Termites Shape the Serengeti

ser haartebeest.JPG

 

The Serengeti is one of the best examples of a fully functioning grazing ecosystem. It is home to the world’s largest body of free roaming herbivores. If you have helped classify snapshot Serengeti’s millions of camera-trap images you will know that wildebeest, zebra, topi, hartebeest, and gazelle to name a few are far more common than lion, cheetah and leopard.

Most people are aware of the millions of antelope that, along with the grasses themselves, shape this environment but they are not the only herbivores out there. There is a micro world down at ground level that is often forgotten about but which plays an enormous role in the functioning ecosystem; herbivorous insects such as grasshoppers, beetles ants and termites.

I want to take a look at termites. When most people imagine an African savannah they think of an endless vista of gently swaying grasses interspersed with the odd umbrella shaped tree and termite mounds. Termites are an integral part of the ecosystem here and it is thought that in terms of biomass they exceed the combined weight of the Serengeti’s mammals. They consume dead plant matter above ground (often during the night) then retreat underground where anaerobic bacteria in their stomach gets to work on breaking it down into a useable form, this is very similar to the process in ruminant herbivores.

Why are termites so important to savannah ecosystems? Well they serve multiple functions such as nutrient cycler’s, habitat architects and as food for other animals.

The daily activity of millions of tiny termites who bring dead vegetation into their underground homes helps to circulate nutrients with in the soil layer as well as aerating the soils themselves. If you ever get to look at a termite mound you will see that the grasses on them are often cropped short were as the surrounding area is full of long grass. This is because the grasses growing on the termite mound are particularly nutrient rich, thanks to the termites having created a nutrient hotspot and wildebeest, topi and zebras all know this and preferentially munch this grass.

Termite mounds shape the plains around them giving a relief to the flatness. Other animals such as topi, hartebeest and cheetah will use these small hills to climb onto to get a better view of their surroundings. In this flatness even a few inches of elevation could give an advantage. Many animals use termite mounds to create their own burrows.  Hyena, warthog and jackal will use them as dens but the master creator is the aardvark who does most of the excavating. Snakes, lizards and mongoose readily take to old mounds too.

Termites are nutritious critters themselves and almost any omnivorous animal will make a meal of them when the chance is offered. I remember seeing about twenty large raptors walking around on a dirt road in the Kruger Park looking like a flock of chickens gobbling up termites after an eruption.

Then there are the termite specialists, aardwolf can consume around a kilogram of termites in a night. Another predator is the ant, whispering ants will raid termite mounds grabbing worker termites, carrying two or three each at a time back to their own nests.

All in all termites are a hugely important part of the Serengeti ecosystem playing a vital role in so many lives be it nutrient provider, habitat provider or as food themselves. You will probably never classify a termite on snapshot Serengeti but it’s worth remembering just how important they are.

Advertisements

The Serengeti Plains

50c214218a607540b90367f2_0

 

Here on the Snapshot blogs we seem to concentrate on talking about the animals that populate the Serengeti. Of course these are the subjects of our many camera-trap images (oh, apart from those annoying over grown vegetation ones) and they are loved by us all but for once I thought I would talk about the Serengeti itself. Monitoring the animals that live in the Serengeti is a valuable way to assess the health of the landscape but to get a true idea of the state of play the whole ecosystem needs to be looked at. More and more scientists are realising that a holistic approach is needed to truly understand what makes an ecosystem tick and how to preserve it. Studying lion without looking at their connection to wildebeest and grass is like studying maths by looking at the numbers without the plus or minus signs.

So we have all heard of the Serengeti but what do we really know. It surprises me how many friends don’t actually know what country it is in. The Serengeti National park, where our 225 camera-traps are located is in Northern Tanzania bordering Kenya’s Maasai Mara National park. The two together with the Ngorongoro Conservation Area and other private game reserves make up the Greater Serengeti Ecosystem which protects the area of the great migration. It is easy to see where the confusion comes from.

Everyone has heard of the wildebeest migration but did you know that it is one of the largest animal migrations in the world that has not been drastically altered by humans, there are no barriers to impede the movement of the millions of animals that seek fresh grazing and water. The 1000km circular migration route sees around 500 000 zebra, over 1 million wildebeest followed by hundreds of thousands of other ungulates annually. All this is still able to happen thanks to the protected status of the entire ecosystem.

The Serengeti National Park itself is made up of around 1.5 million hectares of savannah. Flat or undulating plains covered in grasses which are nourished with ashy soils derived from nearby volcanoes dominate the landscape. Rocky out crops known as kopjes punctuate the flatness with infrequent river courses and their riverine habitat easing the monotypic view.

So what triggers the massive ungulate migration and all the inherent predator action? At the onset of the dry season grasses begin to dry out and water becomes scarce, ungulates are forced to follow their nose to find food and water. Luckily nature is well designed and there is a well defined gradient across the migratory path that sees differences in place and time for abiotic factors such as rainfall, temperature and soil type. It is these factors that govern what vegetation grows where and how available water is and of course where the millions of hungry herbivores can move to next to satisfy their needs. Once settled across the Mara River they can last out the dry season in the mixed savannah woodlands where food is not so scarce. But the pull of the plains is always there and with the onset of the rains back they go thundering towards the Serengeti once more in a tradition that has possibly been around for over a million years.

The area is the last remaining example of a large mammal dominated ecosystem that existed across much of Africa during the last 1.8 million years. With its relatively intact biodiversity and sheer size it is easy to see why scientists flock to study both the individual species that occur here and functioning of the ecosystem as a whole. Sadly there are not many places like it left on Earth.

 

The sound of silence?

Laying in my tent last night listening to nightjars whirring and barn owls screeching I was reminded of the sounds of Africa. As I am away this week with little internet time I thought I would repost this blog I wrote a few years back.

African sunset 1

What does silence mean to you? Maybe it’s that moment at the end of the day when the telephones stop ringing and the office hubbub finally stops and you can hear yourself think. Maybe sitting in your garden listening to the insects and aeroplanes pass overhead. Or maybe it’s that first 5 minutes of waking before the baby starts howling. Whatever it means to you the point is silence isn’t really silent. Something is always making a sound even if it’s a leaf rustling in the wind or a cricket singing.

In the African bush night time silence is deafening.  Just before sunset there is a rush of activity. The day shift starts looking for a place to spend the night whilst frantically searching out that last mouthful of food. Young banded mongoose are scolded into their burrows by older siblings. Antelope take a drink before heading to thicker cover. Francolins are calling out their staccato calls whilst sandgrouse flock to drink. As the sun sets and darkness looms everything quietens down, the last to make a noise are the guinea fowl who wait till it is just dark to, one by one, barrel up to adorn their favourite roosting trees like giant Christmas baubles. They finally settle down, and the nearby baboons stop squabbling and there is a moment’s peace before the night shift takes over.

African sunset 2

The Scops owl is first with its ‘poop poop poop’ call sounding almost like an insect.  Then the night-jars join in. A distant rasping bark and the jackal are off calling ownership of their territory. They stop suddenly and a moment later there it is, the slow wo-oop! Woo-ooop! and the hyena clan are declaring they are up for business.

There has been no respite to the constant noise of the African bush during this transition between day and night; a seamless mix between the two sound tracks. As the evening wears on and the night shift are out hunting in earnest it gets quieter.  If you are lucky enough to experience this it is unforgettable. The silence is thick, it hurts your ears and you want to shake your head to clear it. You are straining to hear anything out there in the blackness and your senses have you on high alert, never mind that you are in a vehicle your primal instinct knows this is Africa and beasts roam that want to eat you.

The only sound is a cacophony of insects and it is this that gets in your head, it is a relief when a spotted eagle owl calls breaking the pitch and giving you perspective again. Staring into the blackness you see a shape move , you can’t make out what it is, then comes a noise that goes right through you, a guttural, low sawing sound, a leopard is calling broadcasting its presence using the ground as a sounding board. He walks out in front of you, pauses for a moment, then strides off purposefully into the night.

The silence of the African night is palpable. You could slice it with a knife. It is so full of promises of wonderful animal encounters that I never want to sleep. It’s my favourite sound of silence; what’s yours?

Guinea-fowl flying to roost

Antelope Versus Oxen- The Case of the Eland

 

ser eland pair

 

Of all the antelope that we classify on snapshot Serengeti the eland is one of the most distinct. Its massive size, heavy set horns and swinging dewlap lends it a bovine appearance yet it is an antelope – all be it Africa’s largest. A member of the Tragelaphini family or spiral horned antelope the eland is closely related to kudu, nyala and bushbucks.

There are two species, the common eland (Taurotragus oryx) we are familiar with in the Serengeti and the giant eland (Taurotragus derbianus) found sporadically in woodland savannah across Central and West Africa. One thing to get straight is that giant eland are on average less bulky than their common cousins, the ‘giant’ refers to their horns.

At close to a thousand kilograms in weight a fully grown male eland equipped with a fortified neck and viscous hefty horns could prove a lethal adversary. Perhaps it is unsurprising then that most male interactions are highly ritualised and the real fighting only really occurs between males of near equal stature. It is an unusual trait in male eland that the neck, shoulders and dewlap continue to enlarge as the animal ages. They develop tufts of wiry hair on their foreheads and noses and a strange clicking in their knees develops that is audible quite some distance away. I remember once sitting in a clearing in the bush and hearing what sounded like multiple people cracking their knuckles whilst moving closer towards me. I could not even begin to imagine what was fast approaching me and began to get a little nervous, looking around for a tree to climb. I heard nothing else but the odd branch moving until out from the edge of the bush appeared a small group of eland. Much to my relief it was precisely these knee clicks that I had heard.

Although not a particularly fast running antelope eland are noted to be extreme jumpers. They are capable of leaping over three meters high from a standstill which to me puts to bed any lingering doubts that they are antelope not oxen.

As many of our snapshot images attest to they are often found in quite large herds, congregations 100’s strong are not unheard of. But all the same there is no real structure to the group. Herds can comprise all males, all females or mixed sexes and ages. They are highly interchangeable and very few bonds are formed. Even the sacred mother and calf bond is tenuous in eland society. Calves form crèches when they are a few days old and prefer to hang out away from the adults. They only suckle once or so a day and that can be the only time spent with mum.  Female eland will band together in defence of their young but as they are often out of sight of the youngsters this doesn’t happen too often. Instead young eland grow fast attaining 450kg in their first year.

Young eland creche

Although life seems good in these juvenile gangs and generally eland are long lived, mortality can be high in youngsters. Whilst studying leopard in South Africa we found eland was a common prey item, in fact we discovered three kills within a month of eland less than six months old and those were just the ones we found. Lion and hyena are also known to take their toll. There is no real synchronised birthing in eland herds with young born at anytime. I guess this means there is always a slightly younger, less savvy, youngster in the crèche that is easy prey for predators.

 

leopard with eland kill

Leopard with eland kill

 

Next time you find an image of an eland herd have a close look to see if you can work out if they are females (smaller with more slender horns), males or if perhaps it is a crèche.