I promised I would have some news about what the Serengeti team has been up to recently in the field. Our beloved camera-trap grid is still being cared for, cards downloaded, batteries replaced and cameras given the once over. So all is well on that front but what is the latest question being asked by the team.
Well thanks to the spatial occupancy modelling of the Snapshot Serengeti camera-trap grid we have learned a lot about how the animals share the environment. What we can’t derive from the camera trap images is the details of what the different species are doing when they are in those spaces and how so many large herbivores can exist together. It could be that they simply facilitate each others foraging or maybe they are using different resources. Scientists have identified what is known as niche partitioning, a mechanism that sees different species specialising in eating different proportions of grasses verses non-grasses; pure grazers and pure browsers and a sliding scale between the two. A second mechanism sees different species eating different parts of the same plant.
These two mechanisms seem to make perfect sense but it is not understood to what extent these two truly affect coexistence of large herbivores. This is where the Snapshot Serengeti team research comes in.
Under our own Dr Michael Anderson they have teamed up with Dr Rob Pringle and researchers at Princeton University in using a revolutionary new analysis method known as DNA metabarcoding to see what exactly each animal is eating.
Up until recently scientists studying herbivore diet had two choices, they could watch their subjects and try to identify what they were eating or they could use microhistology, whereby plant parts in faeces are visually identified. As you can imagine these methods are fine for differentiating between, say, grasses and trees but don’t allow scientists to classify down to individual plant species. With DNA metabarcoding they now have that ability and it should tell us a whole lot more about how the animals divide their resources in space and time.
So that’s the science but how does the team collect this data. Well as with microhistology it involves dung. Our intrepid scientists are roaming the Serengeti collecting poop from as many different herbivores as they can and then it all has to be shipped back to the labs for analysis.
If you are thinking that our team must be highly skilled detectives able to identify a wide variety of brown pellets in the savannah grasses then think again. That’s not to say they can’t but this work relies on 100% knowing which species produced said dung its sex and age as well as a sample that has not been contaminated in anyway. The method of collection relies then, on stealthy observation waiting for an individual to lift its tail and sprinkle the ground with brown pellets before running in with your sample jar at the ready to collect the freshly deposited “clean” offerings. I have some experience with this work and believe me it does feel slightly odd to be observing animals in this way, willing them on to have a bowel movement so you can move on to the next species. It is also a little risky as you can get so engrossed at watching your target animal that you forget there are predators there watching and waiting. At least in this project it is only herbivores the team are interested in, to do the same with predator’s faeces, that’s a whole lot more smelly.
The study is still in its early stages but the team reports they are already seeing some noteworthy things.
Spoiler alert, early results suggest that there are only two ‘pure’ grazers in Serengeti (zebra and warthog) and lots of variation between wet and dry season.
We will bring you further updates once the team has finished their analysis work and have the full results. It promises to be exciting stuff. In the meantime you can think on the glamorous job a field scientist has whilst you stay clean at home helping with the job of classification.
Recently the science team behind Snapshot Serengeti, lead by Dr Michael Anderson, were wandering around the plains going about their latest research (more about that soon) when they got to witness a sight of high intensity, namely a bit of large predator interaction.
The drama occurred around an area known as the Maasi Kopjes. The team at this stage were in their vehicle, as a lioness was nearby, when they noticed a lone cheetah wandering into the lioness’s territory.
The cheetah is obviously anxious as can be seen in this image.
The lioness quickly picks up the intruders scent and as Michael tells me used their vehicle as cover to stalk closer to the cheetah.
Initially the cheetah was unaware of its impending doom but the lioness’s indignation at the intrusion possibly affected her stealth and the cheetah finally noticed her approach.
The race was on. The big cat race.
From these shots you can see the sudden acceleration of the cheetah and yes, it got away, living to see another day and the lioness happily securing her domain on her territory.
Perhaps you will be lucky enough to see both these animals on our camera-traps!
Thanks to Dr Michael Anderson for sharing his Photo’s with us.
After my latest field trip to Namibia I was fortunate enough to spend a few weeks visiting some old haunts in South Africa. Even though I had very little time and no real scientific purpose other than curiosity I could not help but put out my camera traps whilst I was there. It was after all a nature reserve and surprises can happen.
One of the camera traps was located on a well used animal track that lead from the bush down to the river. The rains had not thus far been kind in that part of Africa and the bush was rather dry with little standing water so I was confident the track would offer some interesting images. As expected I had lots of images of vervet monkey, warthog, impala, nyala and waterbuck. Imagine my surprise then when I scrolled through 20 or so images of a small herd of waterbuck does with young to find this fluffy looking white thing that looked more like a sheep!
In fact it was a leucisitic waterbuck. Not to be confused with albinism, which is a condition caused by absence of melanin leading to pale skin, hair, feathers and eyes, leucism is defined as a partial loss of pigmentation that leads to an animal appearing pale or patchy but often with patterns still showing. The eyes in animals with leucism are normally coloured never the red that can occur in albinism. So albinism is a lack of melanin and leucism is a partial lack of melanin.
You can see this little waterbuck still has the distinctive bulls eye target ring around its rump that distinguish the common water buck from the Defassa waterbuck we are used to in the Serengeti proving it is leucistic not albino.
Regardless of which of the two conditions it has the young animal will have a tough time. The pale colour makes it stand out as a target to predators and it is thought that survival rates for leucistic animals are low. That’s not to say it won’t make it to adult hood, in fact the white lions of the Timbavati are a well followed case of leucism in a population that every now and then throws up a white cub or two, they are so well watched that it is known that some do survive into adult hood. From those few individuals stem most of the white lions that can be seen in captivity in zoos all be it showing all kinds of horrible traits of constant inbreeding.
After finding these images I was lucky enough to spot the herd with my own eyes. I watched the little leucistic waterbuck playing and frolicking with a like aged normal waterbuck and for all the world you wouldn’t know what all the fuss was about. The two were identical in every way except the pure chance of a mutated gene governing colour. Good luck to the pair of them.
Symbiotic relationships are common in the Serengeti. They fall into two main types, mutualism, whereby both partners benefit from one another and commensalism, whereby one partner benefits from the actions of the other but the other partner is largely unaffected or unharmed. I wrote recently of oxpeckers and large herbivores, large herbivores provide food in the form of ticks for the oxpeckers and oxpeckers provide a cleaning service for the large herbivores, a good example of mutualism. Birds such as cattle egrets that follow buffalo around to catch the invertebrates the buffalo disturb as they graze is an example of commensalism. Of course it is not just animals that have symbiotic relationships; my blog last week on termites and mushrooms was another example of mutualism.
So what about zebras and wildebeests? We see them all the time on Snapshot Serengeti in mixed herds, grazing peaceably with one another. Is this just coincidence or is this a form of symbiosis?
It is actually hard to say and of course that is why labelling things, especially behaviour is often tricky.
Zebra and wildebeest are both grazers meaning they mostly eat grasses but that doesn’t mean they share the same diet. They preferentially eat different parts of the plants that they consume. Zebras are quite content chewing longer tougher grasses where as wildebeest prefer shorter, more tender shoots. This partition of resources means they can quite happily graze side by side with out exerting pressure on each other.
Another good reason to team up is the extra safety that numbers provide. Not only do more ears and eyes provide better early warning systems but the odds of the individual being targeted by a predator are reduced when there are greater numbers to choose from. Apparently zebra have better eyesight but wildebeest have better hearing so the two complement each other.
There could be another reason. Our very own Meredith Palmer just published a paper about interspecies reaction to each other’s alarm calls, you can read it here: https://www.sciencedirect.com/science/article/pii/S0003347217304207
She found that zebra, wildebeest and impala recognise each other’s alarm calls but that they did not always respond in the same manner. When zebra sounded the alarm all three herbivores reacted strongly but when impala gave the alarm zebra where likely to ignore it, or assess the relative danger themselves. It seems that this varied response is down to predator size. Impala are prey to a wide range of smaller predators that would not be able to handle a mammal the size of a zebra, so when impala give the call it doesn’t always signal danger for the zebra. However when a zebra, the largest of the three herbivores sounds the alarm, whatever it has seen will probably be able to take down the wildebeest or the impala too so it’s prudent that all three scarper.
It is an interesting reaction and maybe wildebeest hang out with zebra because they are more trustworthy alarmists. I am not sure that the companionship of zebra and wildebeest can be classed as symbiotic I think it is more of an interaction due to a shared habitat but it seems that on some level they can benefit each other.
Whilst we wait for the next batch of Snapshot Serengeti images to be processed and posted up for us to classify I thought I would regale you with a short tail from my recent field work in Namibia. I was based on a cattle farm near to the small town of Otjiwarongo. One of the highlights, apart from the wealth of wildlife living alongside the cattle came as a total surprise. Mushrooms, giant, dinner plate sized tasty mushrooms.
Who would have thought to discover such a delicacy in the thorny scrubby bush of north eastern Namibia, a place normally thought of as desert.
I was out driving the boundaries of the farm with the owners one Saturday morning when they came to an abrupt stop and started reversing backwards. When we stopped they jumped out as if for action crying Omajowa! Thinking this was some Herero word for poacher or something similar I prepared myself for action too following them towards a very tall termite mound.
Omajowa were no poachers, they were giant mushrooms growing all around the base of the termite mound and according to my hosts, delicious. They expertly plucked a few out to take home for dinner and to share amongst the staff. We ate them cut into large chunks, breaded then fried like a schnitzel. Yes they were a taste to behold I can tell you.
The Ejova (singular, Herero name) or termitenpilz (German Namibian name) is the mushroom species Termitomyces schimperi. Termitomyces species are found over much of West, East and Southern Africa and live in association with various termite species.
In Namibia omajowa are found on the mounds of the termite Macrotermes michaelseni that build very tall mounds reaching heights of 5 meters tall. It has been noted that these often incline to the north.
The termites cultivate the fungus by providing a perfect substrate and perfect microclimate for the fungus to grow whist eliminating any competitors to the fungus. In return the fungus helps break down plant material aiding the efficient uptake of nutrients for the termites as well as providing additional food sources from its own body that are rich in nitrogen.
The omajowa, like most fungus is for the most part concealed away below ground but when conditions are right, in this case after a good rainfall between December and March the more familiar fruiting body emerges from the base of the termite mound growing on a stalk up to 50cm high with a cap that can reach 40cm diameter. Usually in groups of 5 to 10 up to 50 on one termite mound have been recorded in Namibia. They are really quite a sight.
From a cultural perspective they are seen by Namibians as a symbol of growth and prosperity and they are eagerly sought out. It is not unusual to see someone standing on the road side hefting one of these giants up in the air in an invitation to stop and buy from him.
Once pulled from the ground they have a strangely alien appearance with the dangling pseudorhiza (root like structure) still attached, though it is probably more ecologically sound to leave most of the pseudorhiza behind. The termites will feed on this and the remaining fungus will carry on growing to pop up another year. Like everything in nature, sustainable thoughtful use should be practiced in order preserve the delicate balance of life.
Camera-trapping has vastly opened up the possibilities of studying animals in the field in a relatively unobtrusive manner. Leaving a bunch of camera-traps clicking away 24/7 over a long period is generally cheaper than employing researchers to stay in the field providing them with accommodation, food and vehicles.
However it has its drawbacks. Good field skills are only learned over time spent in the field and although field researchers cannot operate 24/7 like the camera-traps they are less impartial observers noticing all kinds of fine details surrounding that which they study.
It is these observations that stimulate and inform new scientific questions and drives the understanding of the world around us. I am not suggesting that the results of camera-trap studies can’t also do this but since the days of the first naturalists it is being in the field that nurtures the very interest in studying wildlife in the first place.
The researcher who knows their study area well will be at an advantage to one who has planned from afar after using GIS. I know because I have been both. My first camera-trap project was on a reserve where I had lived for three years and that helped me know intuitively where I should place my camera-traps. On the other hand my latest project involved a very fine time window and I had to set up camera-traps on an unknown farm within two days of arriving. By the end of the 8 week period I was just starting to get a better feel for the place and could have kicked myself for not placing my cameras in the optimum places. When I went back to collect the cameras I found myself wading thigh high through a carpet of small yellow daisy-like flowers that left me coated waist down in a yellow stain. Had I have known the farm better realised this plant grew only in a few areas and could have avoided it entirely and saved myself the turmeric skin wash and a lot of miss-triggers.
My latest trip to Africa reminded me of why living in the field is so rewarding. Whilst the camera-traps are diligently collecting your data it gives you the chance to observe without frantically thinking of your research question, you can take time to take inspiration from the broader environment.
Near my tent was an old dead knob thorn tree that had five white-browed sparrow-weaver nests hanging like straw balls from it. Each night at dusk a pair of sparrow weavers would fly into the tree, call loudly as if claiming the spot and the female would dive into her preferred nest. The male would remain up high above waiting. Just as the last light was fading 3 or 4 small dark shapes would arrive and the sparrow weaver would chase after them squawking disapproval. Having seen them off he would come back and settle himself into the nest of his choice retiring for the night. Watching closely revealed, a few minutes later, the return of the invaders; two pairs of black-faced waxbills. They alighted at the top of the tree and cautiously made their way down towards the remaining nests finally one by one slipping quietly into the unused nests one couple per nest.
The thing about this little drama was that it was played out every night for over two months. None of the birds seemed to alter their routine and none where actively breeding at the time, they just had their bed time ritual. This was the kind of observation that the camera-traps will never quite capture as well as a human. In just the same way, although Snapshot Serengeti would not exist without the cameras it would be nothing without the human, citizen scientists behind the scenes sorting out the images. Even with computer recognition programs on the horizon I believe it would be foolish not to still use humans who’s innate sense of life will always pick up on something that is slightly odd, unusual or different about an image.
You are probably aware that the 225 camera traps of Snapshot Serengeti are set out in a grid pattern, spaced every 1km over a part of the Serengeti National Park. It sounds relatively simple but actually there is a lot of painstaking scientific pondering as to how exactly to set out your camera traps.
Over the last couple of decades there has been much debate as to the best way to design a camera trap study. The main choice, in terms of placement pattern, is whether to place your camera traps randomly or selectively and what kind of spacing/density to use.
Truly random is to grid your study site and then let a computer randomly choose which grid squares to place the cameras. Alternately you can choose a line or grid and place your camera trap at regular intervals regardless of where that may fall, still a random point. With selective placement each site is carefully chosen for a specific feature.
In reality most projects use a mixture of the above methods and the best method is really determined by what your scientific question is. For instance, if you where trying to acess the number of leopards in a given area it is better to place your camera traps strategically in places you know or guess leopards are most likely to pass rather than using a randomised method. However if you are carrying out a census of an area and wish to know what species are present then a randomised grid is ideal.
As I said a mix of methods is often used. Imagine setting out a grid in the comfort of your office on your computer. It looks good, covers a large area and promises good results. Once out in the field you navigate to your carefully worked out GPS reference point only to discover it is slap bang in the middle of a marsh or in a thick overgrown patch of thorn trees. This is where the scientists allow themselves a little leeway. Often they will take the GPS point as home base but choose an ideal spot within a certain radius of this point where perhaps there is a game trail or some other sign of animals passing, thus allowing them to select a good site within the vicinity.
I have recently had experience of this type of placement and I can say the work done in selecting your study site and then laying out your grid onto a map is laborious but not nearly as much as stomping through the bush keeping your fingers crossed that your next randomly selected site will be perfect. Turning up to emplacement three to find a thick tangle of vegetation is a little soul destroying, mostly you wonder if any animal is likely to bother to pass that way. The reality is that you normally find a spot that is better within 10 meters and with some slight pruning of the vegetation the sites can often turn out remarkably productive.
So that is the placement sorted but there is a long list of other agonising variables to consider, what settings to use on the camera trap itself, how many to use and how long to keep them up. Believe me every scientist designing studies deliberates the pros and cons of these factors and worries incessantly about if they have made the right choice. You don’t want to set up all you camera traps and leave them for a few months only to find your set up was not great, something which happened to me recently when I chose to set the camera trap on high sensitivity to make sure I had every chance of capturing the small, fast critters. The problem was it was so hot, 40°c plus, that the ambient waves of heat set the camera trap off almost permanently between 12pm and 5pm leaving me with 2000 images of nothing. I have had to compromise and reduce the sensitivity to avoid all the miss triggers; hopefully it won’t miss too many small things.
Snapshots camera traps have now been up for over 7 years so most of these teething problems have been ironed out. But as with the best laid plan you cannot control everything, the odd camera still malfunctions as I am sure that our regular classifiers can attest to!
When living in the bush in Africa your life becomes attuned to the rhythms of nature. Up with the sunrise, the spurfowl, guinea fowl and francolins won’t have it any other way, their raucous calls start well before the sun is actually visible. Physical work can be done until about mid day and then if possible its best to seek shelter till around 4pm when the sun is at least not high enough to cook you yet still pretty hot. By 8pm its dark so there is nothing else to do but sit back around a fire and let the night envelope you.
I am living so basically at the moment, my clothes are starting to look shabby after two weeks of hand washing in minimal water. I am however improving my skills daily at cooking on an open fire. It is amazing what you can do with a skillet, a pot and bits of old rebar and wire. I may have invented a new dish last night, Christmas Eve, when I conjured up a gemsbok stir fry.
The wood here gives new meaning to the term hard wood. Luckily for me there is a ready supply of wood due to the need for bush clearing on this cattle farm. Just a few pieces are enough to get really good coals glowing to cook over. They use a deep three legged cast iron pot in Africa for cooking stews, known as a potjie here in Southern Africa. I might even try my hand at bread next.
So last night after a good feed, Trev and I sat contemplating the embers whilst watching nightjars and bats hawking what looked like flying termites. It has rained recently triggering the eruption, earlier we watched guinea-fowl, hornbills, starlings, drongos and a whole host of other small birds running back and forth slurping them up straight from the holes before they could even get airborne. There is a constant suzzz of insect noise interrupted by the screech of barn owls and the odd jackal.
Then there is a deathly screech to rival that of the barn owl, what is it you ask? well it’s me. Something has just ran up my leg across my back up on to my head and then dropped down again to the ground between my feet. I am not usually given to screaming like a girl and creepy crawlies don’t usually bother me, but there is nothing quite like the dark to bring out the pathetic in us. So a quick scrabble for flash lights ensues and the culprit is spotted.
It’s a solifuge, otherwise known as a sun spider. Not actually a spider, though belonging to the same class, arachnida, they form an order by themselves, solifugae. They differ from spiders in not having silk glands and therefore do not spin webs. They appear to possess 10 legs but in fact the front most pair are actually pedipalps that act as sensors and aid in feeding. They are voracious predators and will eat anything they can overpower such as spiders, scorpions, insects and invertebrates.
Totally harmless to humans they do however install a lot of fear. This is partly due to two behavioural traits. If disturbed in the day the solifuge will head for the nearest dark place, often the very shadow cast by the human that caused the disturbance in the first place, giving the false impression that the solifuge is running at you in attack mode. Similarly at night they will follow a light source, again, often that of a human with a flash light.
The second trait is that they move like greased lightning. They are constantly zipping from here to there in a frantic search for prey to keep their high metabolism ticking over. They have also been known to take human hair to make their nests.
You are not likely to pick one of these up on Snapshot Serengeti’s camera-traps but if you ever get the chance to observe one of these arachnids going about its daily business it is really very fascinating, if of course you can get over your human fear.
You know you are in Africa when you wake up at the airport lodge on the edge of a capital city and stepping out from your room you come face to face with a bird that towers above you. Ostrich aside the dry heat of the Kalahari leaves you in no doubt you are in Africa.
I am in Namibia where I will be for the next two months. I am working on a cattle farm in the Waterberg plateau that is part of a greater nature conservancy. I have already got my camera-traps out, hopefully snapping away as I write. The idea is to look at how camera-trap spacing affects the chances of recording smaller mammals. There are plenty of those here, bat-eared fox, jackal, caracal, mongoose, pangolin, hare and aardwolf to name but a few.
The great thing about using camera-traps is that now they are up I have some weeks to wait before moving them so I have plenty of time to immerse myself in the African bush. I have already clocked up over 100 bird species in less than a week, its taking a while to get my ear back in gear, I keep hearing tantalisingly familiar calls but can’t quite remember who they belong to. It is the start of the rainy season and subsequently the breeding season so there is an awful lot of activity. The binoculars are back living on my shoulder and in use every few minutes.
The bush here consists of a lot of small bushes and trees interspersed with small open grass patches. Plenty of sickle bush, raisin bush and buffalo thorn. I forgot how hard it is to walk through, constantly getting hooked up on vicious thorns that grab at you as you pass.
The best bit of the trip is living in a tent, ok afternoon naps are impossible in the heat but you get to wake up early to the birds calling. The francolins and spurfowl are calling before the sun even rises. There are white browed sparrow weavers building nests in a tree near the tent that have the loveliest melodies. Then there is the night shift. It is pretty hard to fall asleep sometimes when the noises just make you want to get up and investigate. So far I have come face to face with a honey badger sniffing around our fire and several genets. The jackal’s shrill call is omnipresent but the one I listen out for is the rasping call of the leopard. I haven’t been disappointed, every other night that sound rumbles through me.
My internet connection is not so great but I should still be making regular posts for Snapshot Serengeti and there are still plenty of images to classify. We would like to run season 11 in the New Year if we can get season 10 completed. I may even have the odd camera-trap image from my Namibia project to share. Watch this space.
One of the groups of animals that seem to prove quite tricky to tell apart on Snapshot Serengeti are the small carnivores that belong to the canid and hyenid family. That is to say the jackals, black-backed and side-striped, the bat-eared fox and the aardwolf.
There are good reasons for this. Firstly they are predominantly nocturnal, though the jackals can often be seen in day light hours. Secondly they are small and constantly on the watch for larger predators. Studies have even shown that similar species such as coyotes are rather camera-trap shy so it could be possible these African cousins are avoiding the cameras. I noticed when looking for bat-eared fox images particularly that there are very few close up images, the foxes always seem to be in the distance. Something to maybe study?
So back to classifying, what’s the best way to tell these species apart?
Let’s start with the jackals, the most dog–like of the Serengeti’s small carnivores.
The first thing to note is there are actually three possible jackals to be found in the Serengeti but I will stick here to the side-striped and black-backed as the most common, the golden jackal doesn’t come up so often on our cameras but looks broadly the same as the other two with slightly more uniform colouring.
Jackals have dog like proportions with the shoulders and hind end approximately the same height. They have very pointed muzzles and large pointed ears. The black-backed can be distinguished by its black saddle running from the back of the neck through the shoulders up to a point at the top of the tail. It is flecked with white hairs giving a grizzled appearance. The rest of the body is a sandy colour. The side-striped is more uniform grey brown with a flash down its side both light and dark but lacking the saddle. The tip of the tail is often white. Their ears are smaller than black-backed jackal.
The bat-eared fox meanwhile is a strange looking creature. All three of these carnivores have large ears to help them locate prey but the bat-eared fox wins the prize. Its ears dwarf its little face which is very small. They need these huge ears to locate their insect prey. Over all bat-eared foxes are the smallest of the three and have a rather plain silver/grey coat with dark legs, ears and upper parts of its thick bushy tail. If you are not sure look at the over all posture. The jackals hold their head high on a strong neck but the little bat-eared fox often has his head down and appears to have no neck.
Aardwolf, although not canids, are included here because in size and shape they are very similar to the other two. Fortunately these guys have distinctive striped coats which help separate them from all but the much larger and very rare (in Snapshot Serengeti) striped hyena. The aardwolf seems to have a rather thick long neck and a much more hyena shaped heavy muzzle.
So the tip here is to look closely at body form as well as colour, hopefully seeing these images of the three together will be helpful next time you get stuck classifying.