Archive | Camera Trapping RSS for this section

Happy Birthday To Us

Camera-trap

 

Snapshot Serengeti has around 225 camera-traps laid out in a grid in the heart of the Serengeti National Park. They have been there for around 7 years and make up one of the longest running camera-trap monitoring projects in the world. Snapshot was launched on the Zooniverse portal in December 2012 and has inspired many more similar camera-trap projects from around the world. So Happy 5th Birthday to us, may there be many more to come.

There is no doubt that camera-trapping has gripped the hearts and imagination of both scientists and the public. Eight years ago when I first used camera-traps I had to explain them very carefully to friends and family as they had never encountered them, these days references to camera-traps appear in popular press articles and  wildlife documentaries and most people have a basic idea of their use in conservation.

It was K. Ullas Karanth, an Indian wildlife zoologist, who is credited with pioneering the use of camera-traps as scientific tools in his study of tigers in the 1990’s. In the last two decades the technique has advanced at a hugely fast pace and has revolutionised the study of elusive and seemingly well known species alike. It is a scientists dream to observe animals without being present yourself to influence their behaviour.

But looking at the history of the discipline I can across many references to much earlier work using camera-traps. Back in 1927 National Geographic published an article by Frank M Chapman titled delightfully “Who Treads Our Trails”. The piece opens with this amazing paragraph

“If there be any sport in which the joys of anticipation are more prolonged, the pleasures of realisation more enduring, than that of camera trapping in the Tropics I have yet to find it!”

This guy would have loved Snapshot Serengeti. This is most likely the very first scientific paper to report on using camera-traps all be it very different cameras. His rig involved a tripwire the animal steps on rigged up to the camera shutter and bowls of magnesium that will explode and create the flash needed to illuminate the animal at night time. It seems incredible now that this would be allowed considering today’s ethically minded ethos but the author himself points out that the alternatives to studying animals could include using dogs or trappers to catch an animal or even poison bait. He decides he wants a census of the living not a record of the dead and so the idea of camera-traps for scientific study are born. He drew heavily from the work of George Shiras who published the first pictures taken by remote camera back in 1906 (also in National Geographic). George Shiras took the pictures for the pictures sake only later becoming involved with conservation but Frank Chapman was a true scientist.

Obviously the technology has changed a lot and the loud noisy explosions that accompanied Franks work have been replaced by covert black IR where even the glow of the infra-red flash is almost invisible. He would marvel at the amount of pictures that can be stored on an average SD card and that camera-traps are being used from the tropics to the snowfields of Antarctica.

You can look for the original article with this reference:

Chapman, F.M., September 1927. “Who Treads Our Trails?“, National Geographic, 52(3), 331-345

Or visit this site to see some of Frank Chapman’s images: http://www.naturespy.org/2014/03/camera-traps-science/

Advertisements

Unusual Critters

There is a small mammal that is found in the Serengeti which I am not sure we have ever captured on camera-trap or if we have most of you won’t have got the chance to classify them as the capture rate will be very low.

It is not because they are rare or even that elusive, visit the Serengeti or any number of suitable reserves across Africa and you will bump into these odd little creatures. It is just that they are very restricted by their habitat which is rocky outcrops.

The mammal I am talking about is a relative of the elephant, yes that’s right, the largest land mammal is cousin to this rabbit sized African curiosity, the hyrax otherwise known as rock rabbits or dassies. It seems that the two species split some 70 odd million years ago so plenty of time to both specialise in their own way. However one odd trait the hyrax retained was a long gestation period (7 months) more similar to larger mammals. Compare this to scrub hares that have a gestation period of around 42 days. New born hyraxes are extremely well developed and commence eating grass within a few days of birth. Unusually for a small mammal life expectancy is long, up to 12 years.

 

Rock Hyrax  Procavia Capensis

Rock Hyrax

 

Photo Credit: Max Pixel; creative commons zero- cco

 

There are two species of hyrax we could encounter in the Serengeti, the rock hyrax (Procavia sp) and the bush hyrax (Heterohyrax brucei). In fact they can even be seen side by side sunning themselves on rocks. Although they both make their homes in rocky outcrops the two have decidedly different life styles. The rock hyrax eats predominantly grasses and rarely strays far from rocky out crops, conversely the bush hyrax eats mainly leaves, twigs and bark which it climbs trees to eat. The two species however live in colonies in rocks and in the Serengeti at least these colonies can be a mix of both species. The rocky retreats act not only as safety from the many predators that eat hyrax but also offer a way to thermo-regulate.

It’s a wonder that these closely related species don’t hybridise but it seems they have extremely different genital structures as well as the differing dental work needed to cope with the different diets. All species have long sharp upper incisors that are often used in dominance scuffles, hyrax can be very bad tempered and those incisors can inflict serious damage.

 

Bush Hyrax showing incisors

 

Photo Credit: Peter Steward, Flickr CC-BY-NC2.0

 

Living in a relatively small area and in colonies has lead to some interesting behaviour amongst hyrax. They use latrines which are thought to be centuries old. In fact you can often spot the white stains on the rocks of an active colony.

All in all a fascinating little creature, if you are ever faced with a snapshot image with rocks in, take a good look to see if you can’t see a hyrax sitting there.

Wonderful Wildebeests

Wildebeest

 

I thought I would write about wildebeest this week, it seems we take them for granted a bit. Certainly on Snapshot Serengeti they generate about the most images and it has been commented in the past “No, not another wildebeest”. The Serengeti is after all world famous for its wildebeest.

But what do you know about them, other than the roam around in large herds and get eaten by lions, leopards, hyenas and crocs?

Well ecologically they have evolved in a fascinating way. They are heavily dependent on water, never straying more than 20km or so from it. However, their square looking lips are designed for nibbling at short grass swards that are found in drier, fire maintained grasslands like that of the Serengeti and they are unsuited to wetter areas of equatorial Africa where grasses become tall and rank. They are bulk grazers that operate in large herds. Wildebeest are not especially fast runners having a body shape that favours their digestive tract, instead they rely on the size of the herd for protection. Unlike their close cousins, the hartebeest who are designed to outpace predators, wildebeest have proportionately shorter legs and males develop sturdy thick necks.

We have all seen footage of the migration with nervous looking wildebeest stampeding along, hell bent on reaching their destination. What you may not know is that this mass getting together stimulates the rutting state in both sexes. In amongst the moving herds males try desperately to mark out and keep a small territory from which he cavorts around noisily evicting other males and trying to impress a few females to mate with. The problem is he has to keep moving with the herd so these territories are very temperal and really only exist in his mind and he has to move on every day or so in order to keep up with the ladies. There are always a few males left in the wake of the procession that get caught up with fighting each other and trying to hold territories without realising the females have all gone. Once the migration has reached its destination everything calms down a bit and things get back to normal, breaking up into smaller groups until it’s time to do it all again.

Wildebeest no longer exist in their historic numbers. They are particularly affected by land use changes, susceptible to domestic live stock diseases and are targeted by poachers. Their dependence on water, quality short grasslands and large herd size means they don’t fare well on marginal land. However it’s not all bad news. Wildebeest are well represented in national parks across their range in Africa.

 

Leopards; Most catty of cats?

This week I posted a great image of an elusive leopard on the Snapshot Serengeti facebook page. I have a real soft spot for these large cats that stems from my first foray into the world of camera-trap studies. Back then I lived on a small nature reserve in South Africa where leopards were the top predator. Without lion present and an abundance of prey the leopards thrived there and our study looked at the population density on the reserve. The interesting thing with the study was that we almost never physically saw a leopard on the reserve yet we were able to get heaps of camera-trap photos. It was although these leopards had learned that yes this was a great place to live, just keep your head down when one of those humans comes by.

I have been thinking about what draws me to leopards more than the other big cats of Africa and decided it’s the catty-ness of them. Now don’t get me wrong, lion and cheetah are definitely cat like too but somehow they are out done by the leopard.

Let’s take the lion. King of beasts they may be but really, hanging out in prides, what’s that all about. That’s what dogs do right? And cheetah, well with those only semi retractable claws and that speed over the plains, well, it could almost be a greyhound.

Now back to the catty-ness of leopards. Well they slink about, pounce on anything they can get away with, shoot up trees at the drop of a hat and generally act aloof just like you average house moggy. One more thing they share with their diminutive house cousins, they love to sit in boxes. Ok maybe not boxes but I have seen leopard tucked up all cosy in various natural alternatives. The picture below I took in the Kgalagadi where this leopard was sound asleep on top of a giant sociable weaver nest.

 

Leopard in weaver nest

 

 

The beautiful cryptic pattern of the leopard is one of its best adaptations that allow it to thrive in all kinds of habitats across Africa and Asia. Their coat pattern helps to break down their overall shape and they use broken terrain and vegetation to conceal their presence as they stalk close to prey and then ambush. More than capable of taking large prey leopards will happily snack on rodents, insects and small mammals if the opportunity presents itself. This camera-trap image shows a leopard with a zebra kill. The actual event was witnessed by a colleague who confirms that the leopard came out of nowhere and caught the zebra totally by surprise.

 

Leopard with zebra kill

 

Despite this seemingly remarkable ability to blend into the background leopard do not go unnoticed by man and recent studies have highlighted that leopard numbers too have plummeted as they are targeted for their skins, as trophies and just killed as pests. They seem to be declining in the same way they thrived, quietly and out of sight.

Wildlife Photographer of the Year

Well it is that time of year again when the winners of the prestigious wildlife photographer of the year awards are announced.

Having a browse through this year’s winners I notice with a touch of sadness but a good dose of hope just how many of the photos touch on the demise of wildlife and have a conservation message. Brent Stirton’s moving image of a poached black rhino although tragic is a strong weapon in itself in the fight to change the hearts and minds of those people that covet rhino horn.

One of my favourite images is in the bird behaviour category. The much maligned marabou stork is the subject and the shot was taken in the one spot on this planet that Snapshot Serengeti fans know so well, yes the Serengeti.

But the story doesn’t end there. The photographer who was awarded finalist in the bird behaviour category is well known to us. Daniel Rosengren worked for the Serengeti Lion project for 5 years in the field with the most enviable job going. He spent every day following the study lions getting to know them intimately and generally building up the rich source of study data that this 30 year+ project has gained.

Of course when Dr Ali Swanson came up with her wonderful idea of seeding the area with 200 odd camera traps and the Snapshot Serengeti project was born it was Daniel who looked after our precious cameras for several years. So we have a lot to thank him for.

Daniel moved on from the project in 2015 to pursue a career as a professional wildlife photographer and we congratulate him on his achievement this year in the wildlife photographer of the year award. Well done!

If you want to learn more about the story behind his image or just want to see some stunning wildlife images visit his website here http://danielrosengren.se/wpy-awardee/

And to see all the other winners from this year’s wpy 2017 visit

http://www.nhm.ac.uk/visit/wpy.html

 

Weekly Round-up

This week we have had a lot of great images that our community of classifiers have flagged up for discussion. Numbers seems to have been the theme, with unusual sightings of two aardvark stepping out together, elephant herds and lion prides.

My favourite is the unusual grouping of three dikdik, almost certainly a family unit, all looking behind as a bushbuck saunters past.

So here is a taste of the action:

 

 

 

Hot air balloon

 

Zebra

 

Lion pride

 

What will you find this coming week? Don’t forget to share the best or the unusual with the rest of the community. Head over to https://www.snapshotserengeti.org/

 

Celebrating Owls

Sotted eagle-owl

Spotted eagle-owl

 

Although mammals are the target for the Snapshot Serengeti camera-trap project we do on occasion capture other things, humans, vehicles, reptiles and birds. The most common of the birds is probably the larger ground patrolling species like kori bustard, secretary bird, guinea-fowl or the birds that are attracted to mammals like oxpeckers, egrets. It is actually surprising just how many species we have picked up over the years.

One of my favourites though has to be the owls. Always such fascinating creatures they are often loved but often feared too. Their nocturnal, silent flight lends to the mystery but anyone who has been around owls much will know that they can be noisy birds when it comes to calls.

So who might we encounter in the snapshot Serengeti camera-trap images. Well there are 9 species that call the Serengeti home:

  1. Barn owl – Tyto alba
  2. African marsh owl – Asio capensis
  3. Spotted eagle owl – Bubo africanus
  4. Verreaux’s eagle owl –Bubo lacteus
  5. African wood owl – Strix woodfordii
  6. Pear-spotted owlet – Glaucidium perlatum
  7. Southern white-faced scops owl – Ptilopsis granti
  8. African barred owlet – Glaucidium capensis
  9. African scops owl – Otus senegalensis

The barn owl found on every continent except Antarctica is probably familiar to us all. The spotted eagle owl, a medium sized owl is just that, heavily spotted and barred overall greyish. The similar sized wood owl sticks to more densely wooded areas and is a darker chocolate brown. This is a rare bird for the snapshot habitat.

The largest owl we will encounter is the Verreaux’s eagle owl, pale grey the most obvious distinguishing feature is bizarrely its eye lids, they are bright pink. Unmistakeable if you get a good view.

As for the small owls two are actually reasonably active during the day, pearl-spotted and barred owlets. Quite hard to tell apart the pearl-spotted has white spotting on its back where as the barred has, you guessed it, a barred back. However if you are ever lucky enough to hear a pearl-spot in the wild they are unmistakable. It has a slow single note, rising pitch call that builds up to deflating drawn out descending notes. Hard to describe but its other name is the orgasm bird!

We would be lucky to pick up a scops owl, the smallest of all these owls. It remains hidden in trees all day and hunts insects at night.

African scops owl

The African marsh owl is unusual in that it roosts on the ground, tunnelling into long grass. Superficially it resembles a barn owl but the pale facial disc is rounder than the heart shape of a barn owl. They mostly eat rodents.

African marsh owl in flight

The white-faced scops owl has a very striking white face framed by black bands. The rest of its body is pale grey. Size wise it is slightly bigger than the two owlets.

If you want to see more snapshot images of birds follow this link where one of our moderaters has put together some great stuff:

https://talk.snapshotserengeti.org/#/boards/BSG0000008/discussions/DSG0000ek5

 

Dynamic Landscape of Fear

Lions with zebra kill

†

 

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.

 

Meet The Dikdik, Master Of Cool

 

Male dikdik

 

The Serengeti plains hold a wealth of wildlife familiar to us all. As long as our camera trap images are clear most people have no problem identifying wildebeest, zebra, giraffe and impala. It is some of the smaller antelope that prove a bit of a problem. The smallest of the Serengeti’s antelope, the dikdik is not so well known but what it lacks in size it makes up for in a fascinating life history.

So what makes this diminutive antelope so special and how does it survive living in the lion’s den, so to speak.

It is the antithesis of the wildebeest. Instead of running as a herd of thousands the dikdik live fairly sedentary lives, instead of a constant male battle for mating rights to a harem of females the dikdik forms pair bonds that last for life. Essentially it opts for a quite life under the radar. Living in bushy scrub and kopjes gives it plenty of places to stay hidden and its ability to reach up to 42km/hour enable it to escape even the swiftest of predators. Though of course dikdik do end up on the menu sometimes.

Dik dik are territorial and use dung, urine and scent to mark the boundaries. The scent comes from preorbital glands on the face which is rubbed on sticks. All members of the family will contribute to these markers but it is the male that does most of the work. The strange twist is that males are subordinate to females in the pair bond so really the male is marking and defending his mate’s territory for her. I guess it pays to keep your missus’ happy when you pair for life.

Obviously whilst holding a territory you will have neighbours and that is certainly the case for dikdik pairs but it seems that the peace is kept by making sure you only add more dung/urine/scent to your side of the heap. Dikdik must have the most defined territory of any antelope in the Serengeti. If there is a border dispute it can lead to mass pooping; as many as 10 dung piles per 100 meters which is three times as many as a normal border.

Traditionally there were thought to be 4 species of dikdik mostly restricted to East Africa with one, Damara dikdik, found in Namibia. New work suggests that the four subspecies of Kirk’s dikdik are actually full species making Cavandish’s dikdik (madoqua cavandishi) the species we are familiar with from the Serengeti. It’s hard to keep up with systematics.

One of the most amazing adaptations in dikdik’s is their central cooling system which allows them to live in arid, hot conditions. To cool down they increase their breathing rate from 1 to 8 breaths per minute. This passes over numerous blood vessels in the flexible proboscis (that oversized long snout that makes dikdik look so odd) cooling the blood. From here the cooled blood passes back to the heart through the cavernous sinus. Due to the large surface area in the sinus as hot blood is pumped to the brain a form of heat exchange takes place allowing cool blood to be pumped to the brain ensuring that brain function is not impaired by hot conditions even if body temperature is elevated. This is a trait that dikdik share with other dessert adapted animals such as oryx and camels.

So small it may be but the dikdik is not to be dismissed without some appreciation for its ability to survive in pretty harsh conditions.

Small Cats of the Serengeti

 

Whilst we all love to see lion, cheetah and leopard, the big cats of the Serengeti, their smaller cousins are fairly elusive. I am referring to caracal, serval and wildcat. These three small cats manage to slink around between the large carnivore guild keeping themselves to themselves. Lion cheetah and leopard not to mention hyena will all kill small cats. Despite their diminutive size their larger cousins still see them as competition and threat. All three are solitary cats and to survive in this very competitive world they each have their own niche.

 

Caracal

The largest of the small cats, females weigh in at around 10kg and males up to 19kg. They are found across Africa, Arabia and parts of India preferring drier habitats such as savannahs, steppes and dry woodland. The caracal is a magnificent hunter. It is extremely powerful for its size and is able to take down prey as large as small antelope like duiker and bushbuck. The bulk of their diet is made up of hares, rodents, hyraxes and antelope but they are renowned for their ability to leap into the air to catch flushed birds. Their back legs are longer than their front legs and are endowed with powerful muscles that enable them to burst upwards and snag flying birds.

This cat is uniformly coloured the bulk of its body ranging from a tawny grey to a brick red with some spotting restricted to its pale cream underbelly and chin. Its most distinguishing feature is its black tufted ears and black facial markings as well as a short stubby tail that put one in mind of a lynx. It is in fact not related to the lynx family at all.

 

Serval

Probably the most easily recognised of the three and the most commonly encountered of the cats on Snapshot Serengeti. These exquisite little animals are restricted to the African continent south of the Sahara across savannahs, marshes and forest edges particularly near water courses where tall grassy plants grow.

The serval weighs between 6 and 13 kg with males being larger than females. Proportionate to its size it has the longest legs of any cat species and along with its elongated neck and large pointy ears makes this cat unmistakeable. Its tawny coat is spotted black; these spots may run into bars on its neck, shoulders or legs. Melanistic (all black) morphs are known and we have been lucky enough to capture this rarer variation on Snapshot camera-traps.

Food wise these cats are small mammal specialists stalking prey through long grass locating their prey by sound and then using their long legs to leap into the air and strike prey in a fox like manner. They have very flexible toes and will hook fish and amphibians out of water as well as mammals from burrows. The bulk of their diet consists of small rodents under 200g but they will take reptiles, amphibians, birds and small antelope.

 

Wildcat

These cats are smaller than the other two, heavily resembling a domestic cat it is found throughout Africa, Asia and Europe. They weigh between 2 and 6kg and like the caracal and serval males are heavier than females. Apart from size the appearance of the sexes in all three cats is very similar and show little dimorphism.

Its coat is highly variable in colour and pattern ranging from grey brown to red. Dark spotting tends to appear towards the rump, down the tail and on the legs which often bleed into each other appearing more like dark stripes.

It is perhaps more of a generalist than the other two small cats and takes a wide variety of small prey with rodents making up the bulk of its diet. Birds are less frequently taken but insects have been identified as an important part of the diet. Its method for hunting is more familiar to us than the stalk and pounce of the caracal and serval. It will locate prey by sight or sound and then silently creep towards it by slinking belly to the ground before pouncing at the last minute. We have probably all witnessed a domestic cat stalking like this.

 

Of course once you are familiar with these three cats it is easy to tell them apart, that is if you are lucky enough to get a good daytime or colour image. Although serval are seen out in the day caracal and wildcat are less frequently active during daylight and all three mostly hunt at night. It can be harder to tell one from the other in a black and white night image but the trick is to concentrate on the shape. Does it have outsized ears, long legs and obvious spots (serval) or a rounded head on powerful shoulders and ears with tufts (caracal) or does it really remind you of the proportions of a domestic cat (wildcat). Like always make your best guess and perhaps post on the descussions page for more help.