The Snapshot team have written another paper using the Snapshot data we all help to classify. The paper A ‘dynamic’ landscape of fear: prey responses to spatiotemporal variations in predation risk across the lunar cycle can be found at http://onlinelibrary.wiley.com/doi/10.1111/ele.12832/full for those of you interested in reading the original.
Lead by Meredith Palmer the paper explores how four ungulate species, buffalo, gazelle, zebra and wildebeest respond to predation risk during differing stages of the lunar cycle. These four make up the bulk of the African lion’s diet in the Serengeti along with warthog. Of course warthog are strictly diurnal so are not affected by the lunar cycle as they are tucked up nice and snug in a burrow.
For the other four night time can be a stressful time. None of these animals sleep all night, they snatch rest here and there, keep grazing and most importantly of all keep a watchful eye or ear out for possible attack.
It has long been thought that prey species territory is shaped by fear and that animals have safe areas (where they rest, give birth, etc) and risky areas where they instinctively know predators may be lurking. These areas trigger a risk versus reward response as they often contain better forage/water etc.
What Meredith and the team argue is that this landscape of fear is very much dynamic changing not only with seasons and night and day but on a very much finer scale as influenced by light availability through the moon.
Lions find it so much easier to hunt during nights where the moon gives of least light. It gives them a great advantage to stalking close to their prey using the dark as a kind of camouflage. The prey species, on the other hand, are at a distinct disadvantage, they can’t see the stalker and even if they sense its presence they are reluctant to flee as this presents a great risk in itself if they can’t see.
Meredith and her colleagues took the data from Snapshot Serengeti to quantify nocturnal behaviour of the key species using the presence or absence of relaxed behaviour (defined when we classify a species as resting or eating.) They then overlapped this with data collected through Serengeti Lion Project on lion density and hunting success. This data enabled them to work out what areas where high or low risk to the prey species. Using a clever statistical program, R, the data was analysed to see if lunar cycle had any bearing on animal behaviour, in particular, predator avoidance.
They found that moonlight significantly affected the behaviour of all four species but in a variety of ways. As we mentioned before there is often a good reason to venture into the high risk areas and the trade off in increased risk of predation is a really good feed. Buffalo for instance don’t change their use of space so much but were found to form more herds on dark nights. It seems safety in numbers works well for buffalo. Zebra react similarly in their herding activity but are much more erratic when it comes to space use, moving around a lot more randomly keeping potential predators on their toes.
Each species showed an aversion to using high risk areas at night but, particularly wildebeest and zebra, were found to increase their use of these areas when the moons luminosity was higher and safety increased. It was noted that high risk areas where avoided more frequently in the wet season than the dry. The thought being that there is increased hours of moonlight during the dry season that the animals take advantage of. Perhaps too the drive to find enough good food is a factor.
This paper serves to remind us that although what we do at Snapshot Serengeti is fun it is more than just a way for us classifiers to pass the time. It really has a very significant role in science and that role is ever increasing.
World lion day was set up to raise awareness of the conservation issues facing lions today. The African lion, listed by the IUCN as vulnerable, and the Asiatic lion listed as endangered are facing the triumvirate threats of habitat loss, human conflict and poaching.
Most of you who read my blogs will probably be aware of the threats and today there will be some really informative media pieces out there on the web if you are not penned by the world’s leading lion conservation organisations.
I thought instead that I would concentrate on the other side of World Lion Day, which is the celebration of the animal itself.
The first time I saw lion in the flesh was in South Africa’s, Kruger National Park. A car was stopped seemingly watching two tawny eagles perched in a tree. Now being a bird lover I couldn’t pass up this opportunity to get a good close look at these birds so I stopped too. Gazing up admiring the birds I became aware of the occupants of the other car waving at me, trying to get my attention. They were frantically pointing down under the bushes, following their jabbing fingers I found what they wanted me to see, four tawny legs poking out from under the bush, as if she heard me, up came a head, gave my presence a fleeting thought then slumped back down to sleep. My heart ready to burst with joy I grinned back at the car opposite then as I turned my glance back to the sleeping lion I caught a glimpse in my wing mirror that sent my heart racing. Two huge lions filled the mirror walking down the side of the car towards me. For an instant I forgot I was inside and a bolt of primal fear shot through me. But the lion were not interested in me, just the shade of the nice bush.
Lion have long been revered by man. The Eurasian cave lion has been immortalised by Palaeolithic man in cave art such as that found in Frances Lascaux and Chauvet caves. The Chauvet caves are thought to be the oldest rock art in the world dated at over 30 000 years old. Our very own Dr Craig Packer had the privilege to go into the caves to analyse these lion images. Only a handful of people have ever been inside the caves in an effort to preserve them.
Modern lions probably originated in eastern and southern Africa around 120 000 years ago where they then spread across Africa, south -eastern Europe, the Middle East, South Caucasus and into India. Ancient Greek writers suggest they were still present as recently as 100 BC in Greece and the Balkans. Lions survived in parts of Mesopotamia and Syria into the 19th century when the proliferation of guns saw their demise.
Their image, even today, is commonly used in heraldry as a symbol of strength, nobility, bravery or royalty. The ancient Greeks had many myths and stories of lion and their buildings and statues are resplendent with lions. It is easy to see why they are the most commonly used animal in heraldry. Even today in our jaded world lion are loved by many and as the example of Cecil the lion shows can elicit a huge emotional response from people the world over.
Let’s hope that on this World Lion Day that the tide can start to turn on the conservation fight for these glorious animals and we don’t lose that long history we have with the King of Beasts.
This summer in South West France has not been its usual hot balmy self. In fact as I look out the window now the overriding colour is a deep lush green. Normally by July it is turning a straw yellow colour but this year we have had plenty of rain. In contrast, to the south of us, fires have been raging through Portugal, Spain and South Eastern France. Who knows if this is a taste of what’s to come or a one year glitch in the system but one thing is for sure climate change is going to affect life on this planet in both subtle and not so subtle ways.
I wrote about termites last week and their importance in the ecosystem. This week I read a disturbing news article about aardvark, who of course survives on eating termites and ants.
A group of scientists in South Africa were studying aardvarks in the Kalahari. They had inserted biologgers into several aardvarks in order to follow their activity and body temperature. It turned out that the year of their study was an exceptional year of draught and all but one of the study animals along with others in the area died. They unexpectedly recorded a phenomenon not seen before that should be an eye opener to the ways in which future climate could affect not only individual species but whole ecosystems.
The aardvark themselves can withstand high temperatures but the termites on which they rely for food and water cannot. With the information provided by the biologgers the scientific team where able to see that the aardvark were not finding enough termites or ants to keep their energy levels up. Night times can be pretty cold in the Kalahari and the team found that the starving aardvark even swapped their usual night time foraging behaviour to day time in order to conserve body energy. They were even seen sunbathing in a bid to save energy. It seems that none of this adaptive behaviour was enough. There simply was not enough food for their needs and they slowly starved to death. At an average weight of 60 to 80 kg an aardvark is a large animal and needs to eat around 50 000 termites or ants a night.
One or two bad years will always happen but if climate change shifts as it is predicted many areas of Africa will become drier and hotter creating an aridity that most of the native termites and ants cannot tolerate. True, given time, more tolerant species may take over but in the meantime the much loved aardvark may become a creature of the past. But that is not the end of the story. The aardvark is more than just a curiously put together animal, it is the architect of large burrow systems that many other mammals, birds and reptiles are reliant on to escape extremes of hot and cold weather, to bring up their young and escape from predators. Most cannot excavate the hard earth themselves so with the possible demise of aardvark life would get a whole lot tougher for many many more animals.
If you want to read more about the study have a look at this link https://africageographic.com/blog/aardvarks-beating-climate-change/
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.
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.
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.
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.
Across the African Savannahs many different birds can be seen strutting around on long legs, a perfect adaptation, often coupled with long necks, to give them a higher vantage point to see over the long grasses. We are talking about ostrich, korhaan, ground hornbill and storks to name a few. All these birds use the same method of steadily walking through the grass picking of preferred prey items; grass itself in the case of the ostrich.
One of the most fascinating to me is the secretarybird (Sagittarius serpentarius). Reportedly named for its resemblance to a medieval scribe with a quill behind his ear other sources suggest the name is a Francophile corruption of the Arab word saqr et-tair which translates to hunter-bird. Whatever the origins of its name the frond of spatulate nape feathers and the elongated central tail feathers easily distinguish this bird.
It is something of an enigma taxonomically speaking, making up its own unique family, Sagittariidae. It seems secretarybirds are related to eagles sharing skull structure and a type of feather lice. Currently aligned to diurnal birds of prey it has previously been thought of as a relative of storks and cranes. Indeed its breeding behaviour is very similar to that of storks, which to make things more complicated are also share a close affinity to birds of prey.
Taxonomic complexities aside secretarybirds do look like elongated hawks, they share that hooked bill and yellow cere common in birds of prey, they also possess a large gape which allows them to open the bill wide enough to swallow large prey whole. But it’s their feet that do all the work.
The modus operandi for a secretary bird is to stalk along quietly and stomp its prey with a torrent of fast powerful kicks to dispatch it. This method is used for a number of prey items such as arthropods, rodents, amphibians, game birds even mongooses. In fact anything, really, that can be subdued and killed by its deadly kicks is fair game. That said it is the secretarybird’s ability to despatch snakes that has endeared it to most Africans.
To sneak up on a snake and then kill it quickly takes a lot of skill and you best not make a mistake otherwise in the African bush you may end up the one dying.
A study led by Dr. Steven Portugal, from Royal Holloway, University of London found that although other birds of prey strike their prey with far more force this is enhanced by the momentum of their entire bodies plunging down from flight. The secretarybird is able to exert a force 5 times greater than its own body weight from standstill and can repeat this accurately with multiple kicks being delivered at a speed of 15 milliseconds each. Fast and furious, that’s how this bird tackles deadly snakes and biting mongoose.
If you are interested you can read the paper here. http://www.sciencedirect.com/science/article/pii/S0960982215014839
June through August is a busy time for scientific researchers. They get to leave their desks and all that computer stuff and go visit their study area. Snapshot Serengeti’s resident researcher Meredith is lucky enough to be in the Serengeti as I write and she has shared a few recent experiences with me.
She is currently setting up a new camera-trap array in Grumeti Reserve which borders the Serengeti National Park in the north west. This area was created as a buffer zone to the Serengeti National Park to help protect the western corridors of the famous wildebeest migration of the Serengeti/Mara ecosystem. Grumeti in turn is bordered by villages and has one of the fastest growing human populations around the Serengeti Park. Traditionally these communities hunted for bushmeat to supplement their diets but with the rise in population it is doubtful if this is still sustainable.
Meredith has been out this week following the migration as it moves along Grumeti’s northern border. As well as setting camera-traps and marvelling at the numbers of wildebeest she has also seen the darker side of conservation that almost anyone working in protected wildlife areas in Africa is familiar with; poaching. She reports that they have been removing snares daily and that distressingly they found 4 snared wildebeest within a half hour, two were dead, one had a broken leg and had to be killed but miraculously they were able to release one. Whilst trying to select camera-trap spots Meredith and her team encountered poachers butchering a fresh caught wildebeest, they were able to give chase, alas to no avail.
In areas like this the locals know well the movements of the animals and they will seed the area with thousands of wire snares. Anti poaching teams are kept even busier during migration time knowing this too. The anti poaching team, well trained as they are, have had more luck than Meredith and her team. This week they set up an ambush and took out a biltong (dried meat) camp. Their efforts on the front line destroying snares and apprehending poachers as well as the community liaison work that goes on at Grumeti has reaped rewards. Animal numbers are on the rise, the elephant population has quadrupled in the last 11 years and giraffe and topi numbers have tripled.
Still Dr Craig Packer and his colleagues have estimated that tens of thousands of wildebeest are poached each year…and this is not a problem that will go away. You can read more about the issue in this Africa Geographic article.
Poaching goes on all around the world, I have even found wire snares set in my own garden her in France (probably for badger). It is a senseless, lazy but effective way to catch animals. There are many reasons why people poach, when I lived in South Africa the local community would poach our animals not because they were poor and couldn’t afford meat but because warthog and impala meat could fetch higher prices than chicken, goat or pig. Christmas was a particularly bad time for poaching as local chiefs put in their orders. Bushmeat was a delicacy and poaching made good money. In Central African Republic the systematic stripping of wildlife by the Sudanese cattle herders has been stimulated by draught and poverty in Sudan, they dry most of the meat to take back and sell in the Darfur region. Utilising the natural world is deeply rooted in many cultures around the world and always has been. Opportunity is what fuels the practice but it is the rapidly rising human population that is causing this age old practice to become unsustainable in our shrinking world.
I hope Meredith doesn’t have to witness too much more wildlife destruction but all the same it is good for a scientist to get firsthand experience of one of the biggest issues facing wildlife today and for us to recognise it.
As some of you know, Snapshot Serengeti is not just about mammals. Their avian cousins also like to get in on the act especially the larger ones. Amongst the more common captures are kori bustards, secretary birds, korhaans, and storks. The one I like best though is the ground hornbill.
I fell in love with these birds many years ago when I helped hand raise southern ground hornbill chicks. Although wide spread and fairly common over most of southern and eastern Africa the southern ground hornbill has lost around 70% of its home range in South Africa. They are large birds and don’t do well outside of protected areas especially where human density is high.
Ground hornbills lay two eggs in, believe it or not, a cavity in a tree. The first chick to hatch will kill the second, which is really just an insurance policy in case the first egg doesn’t hatch or should die in the first few days. We were given permission to take the second egg once the first had hatched in order to hand rear then release the birds. The newly hatched chick has to be one of the ugliest babies I have seen. It is a charcoal grey naked greasy looking blob with a head so large it cannot lift it up. For the first day or so it just flops around barely able to raise its bill for food. When its feathers start growing it looks like a diminutive dinosaur. Eventually they do blossom into the splendid giants that strut across the savannahs in small family groups eating a range of food stuffs from insects, rodents and reptiles. They can kill efficiently with that heavy bill and will take anything up to the size of a hare.
Considering their size it is hard to believe that they can fly but fly they do and spend time perched in trees. In fact the loss of large trees is another reason behind their decline, as I said earlier they need trees to nest in. Ground hornbills are cooperative breeders with several family members helping to rear the single chick. This joint effort seems strange until you realise that although they breed once every three years the groups only manage to raise one chick to maturity every 8 to ten years. Once a chick has fledged it is dependent on its parents for two years, which is the longest span of any bird and makes reintroduction programs very hard. It only reaches maturity at 6 years old.
There are two species of ground hornbill, found only in Africa. The southern ground hornbill (Bucorvus leadbeateri) the species found in the Serengeti and the northern ground hornbill (Bucorvus abyssinicus) found across sub-Sahara from Mauritania to Uganda in suitable savannah habitat. The later is slightly smaller than the former and has some blue facial patches which distinguish it from the red of southern ground hornbills.
Such a large bird living mostly on the ground the ground hornbills have not escaped the attention of man. Although many tribes hold totemic beliefs about the birds that afford them some protection others are not so lucky. The Zulus and Xhosa of South Africa believe that to break a drought a dead ground hornbill must be tied down in a streambed to attract rainwater. In a more modern twist ground hornbills, ever territorial will smash windows and car windscreens with their powerful bills in a misguided attempt to evict intruders (namely their reflections) This has not endeared them to humans.
All in all the ground hornbills are magnificent birds, next time you spot one on Snapshot Serengeti take a moment to have a closer look.
The 5th of June is world environment day. This event was created by the United Nations back in 1974 to promote awareness of our environment and to spur people globally to help protect it. Its celebration has never been more important than in today’s challenging times. All over the world people will be taking part in a host of events that celebrate our environment. Some have formed clean up events of local beaches or city parks. Others will be doing a bioblitz in their gardens or local reserves many will include children who will be inspired by searching out and identifying bugs. There will be events organised on the public scale such as awareness marches or environmental film screenings. Some folks will simply celebrate by stepping out in the open air to take a walk or picnic. Whatever the event you can be sure that a lot of people will be considering the environment this week and that can never be a bad thing.
Each year there is a theme, this year it is ‘connecting people to nature’ I thought this was particularly apt for us citizen scientists at Snapshot Serengeti. Through the millions of images we classify there is a strong connection to the rhythms of animals in the Serengeti. We get to appreciate the wide biodiversity of this immense ecosystem and for those of us unable to visit such a place it is a way to connect to a wild unspoilt place. It is a way to visit, virtually, leaving no carbon foot print as we would by flying there. I feel it is a privilege afforded us thanks to technology that I would not have even dreamed of 15 years ago.
Snapshot Serengeti is the perfect antidote to the doom and gloom decried each day by the newspapers. In a world where wildlife is dwindling and the finger is firmly pointed at us as the major cause of climate change Snapshot Serengeti feels like something positive and good. Something to give us hope that we might not have wrecked everything just yet. From our armchairs we not only experience the wonders of nature but at the same time we are actually benefiting science with our classifications. What can be better than that?
So if you have nothing else planned this #World Environment day why not jump on to Snapshot Serengeti and get classifying, better still see if you can recruit new classifiers, the more the merrier.
If you want to read more about world environment day visit this site.
The waterbuck just stood there, unfocused, staring at nothing. He didn’t move except for the gentle flare of nostrils and rise of ribs as he drew breath. About 8 to 10 minutes went by and still not even a twitch of an ear to dislodge an annoying fly. Then as if released from a spell his drooping head rose a little and he took a step or two towards the stone bird bath where he took a few long draughts of water. After that he slowly walked of through the bushes and out of sight.
I couldn’t quite understand his behaviour thinking perhaps that he was ill. Although he sported a magnificent set of horns his coat looked more than a little out of condition and he looked thin. For a waterbuck to be this close to the house in the middle of the day was unusual. He was less than a meter from me; if the glass window wasn’t there I could have reached out and touched him. I didn’t see him again after that encounter until about 5 days later. Sitting on my stoop I could smell a whiff of something dead, not an unusual smell when you live in the bush, so I went exploring following my nose. It didn’t take long to find him. He was tucked in, sitting down, between the banking and a large boulder. First I thought he had fallen but actually he looked so peaceful I think he lay down in a position that he felt protected in and let his life ebb away.
You see on closer inspection I found his teeth to be worn away to almost nothing. This is common in antelope, if they make it through life without being preyed upon or succumbing to disease then they often die from starvation when the teeth, worn down to nubs, are unable to cope with the tough vegetation it survives on through the dry season. That vacant stare I had seen is something I have witnessed in starving antelope before. So although I couldn’t rule out disease (I am no medical expert) my guess from his behaviour and condition was that he had passed away with old age.
My quandary now was what to do with him. I could leave him be and let nature take its decomposing course (and this is what I would normally do) but that would mean I was going to live with an ever more nauseating death smell for a few weeks which believe me is not good. On the other hand pulling a 200kg animal out from a snug hole was not going to be easy. To cut a long story short I called for backup and with ropes and much holding of noses we got the waterbuck out and dragged him down to the river side. I sat there all day waiting to see if a croc would come and take the waterbuck or perhaps a hyena or vulture. Disappointed that none of natures garbage collectors came I walked off home just before dark.
First light the next day off I went back to the scene. Nothing. Not even a drop of blood. I can only conclude that the crocs did indeed come under the cover of dark and dragged the carcass into the depths where nature’s great cycle of life and death continued to the crocs advantage.