To bring myself up to speed with the fundamentals of lion research in the Serengeti, I have spent the last week or so reading through the classic work The Serengeti Lion: A Study of Predator-Prey Relations, by the reputable George B. Schaller. For a collection of field notes, the book it quite a page-turner. The work covers everything remotely relating to lion biology, from social systems to predation patterns, and manages to capture both the drama of the dynamic Serengeti system and the dusty, hot, sweaty reality of watching big cats sleep for 18 hours a day.
Although the focus of the book is the life of lions, the life of George B. Schaller himself turns out to be just as intriguing. Digging a little into his background, I discovered that Schaller, dubbed the “Megafauna Man” by National Geographic, has undertaken a 50-year career in field biology studying some of the most iconic systems in the world.
Schaller had moved to the Serengeti with his wife and two sons for two years in 1966 to uncover the intricacies of the lives of big cats and their prey. This, however, was not the start of his field career. Back in 1959, when he was a mere 26 years old, Schaller packed up and headed off to Central Africa to study the mountain gorilla. For two years, amidst dodging poachers and eluding Watusi invaders, he uncovered facts about these great apes which helped to dispel common notions about their brutishness and revealed them to be gentle and intelligent animals. His work paved the way for other naturalists, including the well-known Dian Fossey, and led to the creation of Virunga National Park.
In the ‘70s, Schaller worked in both South Asia and South America, studying large mammals including the blue sheep and snow leopards of Nepal and the jaguars, capybaras, and caimans of Brazil. The American novelist and naturalist Peter Matthiessen accompanied Schaller to Nepal and wrote a travelogue on their exploits (The Snow Leopard) that went on to win the 1979 National Book Award. Matthiessen describes Schaller as “one of the finest field biologists of our time. He pioneered the practice of turning regions of field research into wildlife parks and preserves,” a epithet that held true yet again when five years later, the Nepalese government used Schaller’s research to form Shey-Phoksundo National Park.
Following these adventures, Schaller and his wife were given the distinction of being the first westerners invited by China to enter the remote southwest Asian wilderness and research the Giant Panda in its native habitat. As part of this work, Schaller focused on understanding threats to the diminishing panda population and discovered that the primary culprits in their demise were poaching and logging. In his book, The Last Panda, Schaller writes “The panda has no history, only a past. It has come to us in a fragile moment from another time, its obscure life illuminated through the years we tracked it in the forests.” Despite this foreboding prophesy, since Schaller’s work on panda biology, the number of panda in the wild has increased by 45%.
In the 1990s, Schaller worked in Laos, Vietnam, and Tibet studying antelope and in the process discovering and rediscovering several species of mammals including a bovine, a pig, and a type of deer. More recently, he has been collaborating with agencies in Pakistan, Afghanistan, Tajikistan, and China to develop a 20,000-square mile “Peace Park” for the protection of the world’s largest wild sheep species, the Marco Polo sheep.
Over the span of his career, Schaller has made profound contributions to our knowledge about large mammals, both their biology and ecology, and has greatly furthered species conservation in the creation of over 20 parks and preserves throughout the globe. I can highly recommend his writings on the Serengeti Lion, and if you want to delve further into his life and career, his other authored books (there are over 30) include The Year of the Gorilla, The Last Panda, Tibet Wild, and A Naturalist and Other Beasts.
Most of you have probably seen this picture:
As well as the ones after it:
This series of photos was taken at site H11 along the Loyangalani river and remains, to me, one of the most amazing accomplishments of our camera trap survey to date.
First, seeing a kill is rare. In the 47 years that the Lion Project has been watching Serengeti’s lions, we’ve only seen lions with about 4,000 carcasses; of those, we’ve only actually seen them in the act of killing 1,100 animals. That might sound like a lot, but with one or two people on the ground, almost every day of the year, racking up nearly 50,000 sightings, that’s not that often.
I don’t love this series simply because this random, stationary, complacently-stuck-to-a-tree camera trap caught this rather rare event – but because it goes on to document the story that follows: A single lioness takes down a zebra much bigger than herself. Within minutes, her sister joins her (free meal!). Note how big their bellies already are though, when they begin to eat. These aren’t particularly hungry lions to begin with. About 45 minutes later, they are staring out of view of the camera, and then comes a group of hyenas. The carcass goes back and forth between them throughout the night, with a jackal darting in to sneak a nibble.
Food stealing, or kleptoparasitism, is a major part of life for Serengeti carnivores. Contrary to long-standing popular belief (reinforced by the Lion King), hyenas are not skulking scavengers living only off others’ leftovers. Hyenas are quite adept predators and scavenge only about 40% of their diet; lions scavenge at least 30% of theirs. And, in fact, lions steal a lot more food from hyenas than is apparent at first glance. More often than not, when we see hyenas lurking anxiously around a pride of lions demolishing a carcass, it’s because hyenas made the kill, and lions stole it away. Research from Kenya suggests lions might actually suppress hyena populations simply by stealing their food.
On the flip side, work from Botswana suggests that hyenas are able to steal food from lions if and only if hyenas outnumber lions by at least 4 to one, and there are no adult male lions present. (Remember, males are half again as big as females: hyenas don’t stand a chance.) But observations that Craig and a former graduate student made from the Ngorongoro Crater further revealed that even when lions do give up a kill, they are so full they can barely move – it’s simply not worth the effort to fend off hyenas any more.
So, kleptoparasitism is a part of life if you are a Serengeti carnivore, but it’s not always as simple as the movies make it out to be. It’s a pretty cool mechanism that might be driving predator dynamics though – I just wish it weren’t so hard to test!!
### Today we’ve got a guest post by our very own Daniel Rosengren, lion tracker (& photographer) extraordinaire. ###
It started with some mysterious footprints around the Loliondo Kopjes. There were a lot of fresh paw marks in the mud following the road. I could tell it was a big pride but the only big pride with a territory nearby was the Young Transects. But I could not hear their collar. Neither could I hear any of our other prides. I drove around for a while looking for lions, especially on the rocks and under trees. I didn’t find any and guessed it could have been the Young Transect lions anyway, only without the collared female.
A couple of weeks later I was headed out east when I soon caught eye on a big group of lions. As I drove closer I realized they weren’t any lions I knew. I tried to get photos of all of them but it wasn’t easy knowing who you’d already got in a group of 17 lions. Luckily they all started walking along the track. All I had to do was park ahead of them and take photos as they passed one by one. Once I had photos of all their left sides I went home to try to figure out who they were.
I concentrated on the older females as the youngster probably never had been seen before by the Lion Project. After a while I found a couple of matches. It was TR86 and TSF from the Transect Steady pride, not seen since December 2009, almost three and a half years earlier. But the last time they were seen regularly in our study area was in 2008.
Now I contacted TANAPA and the vets to organize a collaring of one of the females. They were coming. I drove back to the place where I’d seen the lions and hoped they hadn’t walked too far. I found them in the shade of a tree. Then a long wait started for the vets to organize themselves and drive all the way from Fort Ikoma. Once they came, the collaring went smoothly, the rest of the pride watching from a distance.
About a week later I found the pride just outside the northern edge of our study area along the Pipeline track. Two more old females known since before had joined them, TR93 and TR106. Then they disappeared. So two weeks later I decided to search for them and drove along the Pipeline track north. But instead of driving on the actual track, which in many places was disappearing because of little use, I drove parallel to it, hitting all hilltops to be able to pick up the radio signal from a greater distance. The drive was terrible as the hills in the area are specked with large rocks and I had to drive dead slow. I held on the the steering wheel as little as possible. Having no power steering means that every time I hit a rock I risk breaking thumbs or worse.
I picked up the signal after a while but I still had to pass several hills before finally finding them, right by the track at a river confluence. That was quite far north of our study area and too far to go and see them on a weekly basis. The future will have to show where they finally settle.
In 1994, a terrible disease ripped through the Serengeti, killing lion after lion. By the end of the year, a third of the lions in the Serengeti were dead. The culprit was a virus known as canine distemper, and lions that died of the disease did not die quietly. The symptoms were clear to any observer: facial twitching, disorientation, and eventually convulsive seizures.
The lions in Craig’s study area were not spared, but the data he had been collecting over the previous decades proved invaluable in understanding what happened in 1994.
Using archived blood samples that had originally been taken for genetic analysis, Craig and his colleagues were able to go back and test for a number of viruses. The earliest year blood had been sampled was 1984, but because some of the lions sampled had been ten years old or older, he was able to infer information about when lions had been exposed to viruses as early as 1970.
They found that there had been previous outbreaks of canine distemper in the lions in 1977 and 1981. Because the lions had been studied then, he knew that these outbreaks had not caused large die-offs like the one that occurred in 1994. Instead, he found that by 1994, essentially all lions in Serengeti were free from canine distemper antibodies, meaning that none of the lions had any immunity to the disease. This widespread lack of immunity and a mutation in the virus were thought to have caused so many deaths.
The lion population recovered after the 1994 outbreak. Just years later, though, two “silent” outbreaks hit the population in 1999 and 2006. Unlike the 1994 outbreak, these ones were not noticed at the time because few lions died. They were only detected through blood sample testing. An analysis of the archived blood samples finally revealed the major difference between the canine distemper outbreak that led to massive death and those that did not. High death rates in the 1994 outbreak were due to the simultaneous infection with another disease — a protozoan parasite known as Babesia — that becomes increasingly common during and after major droughts. When Babesia is absent, lions contract canine distemper, but their immune systems fight it and they become immune. When lions are also infected with Babesia, they cannot fight off the canine distemper virus as easily, and more of them get sick and die.
The long-term lion data was also instrumental in understanding the spread of canine distemper in the 1994 outbreak. The disease showed up sporadically in the study area prides, suggesting that lions acquired the disease from an outside source, rather than spreading it from one lion to another. Sophisticated analyses revealed that the origin of the outbreak was likely in domesticated dogs in the human settlements around the Serengeti ecosystem. Further, it is likely that lions acquired the disease repeatedly from hyenas. Hyenas move great distances, use human-inhabited areas around the Serengeti more than lions do, and interact with lions at kills.
Scientists cannot predict major droughts. Nor can they predict wildlife disease outbreaks. It isn’t possible to recreate major droughts with experiments in vast wilderness areas. Nor is it ethical to introduce novel diseases into natural areas in order to understand more about the disease. It is ONLY through long-term research projects like the Serengeti Lion Project that we acquire the data necessary to understand what happens in nature during disease outbreaks, droughts, and other rare, but important events.
Ideally we would like to run Snapshot Serengeti for at least a decade. We want to be able to capture some drought years in our data set, and some years with unusually wet dry seasons. We want our cameras to be running when the next unexpected disease outbreak occurs — in lions or in other species. To those of you have already contributed to our crowd-funding campaign, a heartfelt thank you. If you haven’t yet, and are able, please consider a donation.
To read more about canine distemper, Babesia, and Serengeti lions, check out:
Munson, L., K.A. Terio, R. Kock, T. Mlengeya, M.E. Roelke, E. Dubovi, B. Summers, A.R.E. Sinclair & C. Packer. 2008. Climate extremes and co-infections determine mortality during epidemics in African lions. PLoS-One 3, e2545.
Hopefully you’ve been enjoying the adventures of the lions that David Quammen has been writing about in this month’s National Geographic. David writes about the dramatic lives of C-boy and Hildur, two very good-looking male lions that roam the Serengeti, and the challenges that they face as male lions trying to survive in the Serengeti. I was in the car with Ingela that day that the Killers nearly destroyed C-boy — it was one of my first days in Serengeti, and one of the many moments that I fell in love with the dramatic lives of the animals there.
There’s a good chance you’ve seen C-boy and Hildur and Killers, as well as all the ladies they’ve been fighting over, in the camera traps. Below is a map of the pride territories overlaid on the Snapshot Serengeti cameras. There are a lot more prides than this, but these are the ones that Nick Nichols and Davide Quammen followed.
Jua Kali, where Hildur and C-boy resided in 2009, control just a tiny patch of land in the center of the study area where the Seronera river begins. They spend most of their time in a marshy lowland where those two small tributaries, converge. The marsh has lush grass and standing water, but is just a tiny oasis in the otherwise dry and desolate grassland. It is not the best territory that a lion can have.
After C-boy and Hildure were deposed from Jua Kali, they eventually took over the Vumbi pride. It worked out pretty well for them in the end – the Vumbi’s are not only a bigger pride, but maintain control over the Zebra Kopjes, a suite of rocky outcroppings that provide shade, water, and a vantage point to watch for prey across the open plains. Despite C-boy’s brush with death and his inelegant retreat from power, C-boy and Hildur really haven’t done too badly for themselves.
North of Vumbi, the Kibumbu pride ranges along the Ngare Nanyuki river. When David was writing about our lions, the Killers had recently taken over the Kibumbu pride. Unfortunately, the Kibumbu females had had young cubs fathered by the previous coalition; the Killers would have killed these cubs to bring the Kibumbu females into sexual receptivity. Infanticide is a brutal, but natural part of a lion’s life.
So there it is. The lions that are gracing the pages of this month’s National Geographic magazine are the same ones that you see yawning, sleeping, and stretching in front of the Snapshot Serengeti camera traps. David’s story, and Nick Nichols’ photos, provide an amazing and detailed dive into their lives.
We’re currently raising funds to keep Snapshot Serengeti and the long-term Lion Research Project afloat. Thanks to everyone who has donated so far!
In addition to the main feature story on the Serengeti lions that I wrote about on Wednesday, there are a number of lion extras at National Geographic Magazine, too.
There’s an interactive map, where you can see the fragmentation of wild lions. The Serengeti (‘C’ on the map) is one of only a handful of strongholds that contain at least 1,000 lions.
There’s a short interview with Michael Nichols, the photographer for the stories, and a fabulous slideshow of images that he took. (Although I have to say that I always think lions look very strange in black and white.)
And there’s a high-resolution download of this image of Serengeti lion cubs you could use for your desktop background if you wanted.
The August edition of National Geographic Magazine has a cover story on the Serengeti lions that Craig has been studying for decades. And because Ali set out the camera trap grid in the same place as Craig’s lion study area, you see the same lions (plus more) on Snapshot Serengeti as those featured in the article. In fact, photographer Michael Nichols was out in the Serengeti during Season 5, so his pictures are contemporaneous with the ones up on Snapshot Serengeti right now.
So if you have a moment, go check out “The Short Happy Life of a Serengeti Lion,” which is entertaining and gives a nice history of the foundational research on which the Snapshot Serengeti science rests. And take a gander at the editor’s note, which accompanies this picture.
Last week, we left off with this crazy biological paradox: lions kill cheetah cubs left and right, yet as the Serengeti lion population tripled over the last 40 years, cheetah numbers remained stable.
As crazy as it sounds, it seems that that even though lions kill cheetah cubs left and right, it doesn’t really matter for cheetah populations. There are a number of reasons this could be. For example, cheetahs are able to have cubs again really quickly after they lose a litter, so it doesn’t take long to “replace” those lost cubs. It’s also possible that lions might only be killing cubs that would probably die from another source – say, cubs that would otherwise have died from starvation, or cubs that might have been killed by hyenas. Whatever the reason, what we’re seeing is that lions killing cheetah cubs doesn’t have an effect on the total number of cheetahs in the area.
I think this might hold true for other animals, not just cheetahs. It’s a bit of a weird concept to wrap your head around – that being killed, which is really bad if you’re that individual cheetah, doesn’t actually matter as much for the larger population – but it’s one that seems to be gaining traction among ecologists who study how different species live together in the natural world. Specifically, ecologists are getting excited about the role that behavior plays in driving population dynamics.
Most scientists have studied this phenomenon in predator-prey systems – say, wolves and elk, or wolf spiders and “leaf bugs”.
What scientists are discovering is that predators can suppress prey populations not by eating lots of prey, but by causing the prey to change their behavior. Unlike many spiders, wolf spiders actively hunt their prey – sometimes lurking in ambush, other times chasing their prey for some distance. To avoid being eaten, leaf bugs may avoid areas where wolf spiders have lots of hiding places from which to stage an ambush, or leaf bugs may avoid entire patches of land that have lots of wolf spiders. If these areas are the same ones that have lots of mirid bug food, then they’ve effectively lost their habitat. Sound familiar?
Back to Africa – what does this mean for wild dogs and cheetahs? Interestingly enough, lions do not displace cheetahs from large areas of the Serengeti. We’ve discovered this in part from historic radio-collar data that was collected simultaneously on both species in the late 1980’s. Below is a map that shows average lion density across the study area. Green indicates areas with higher densities. The black “+” symbols show where cheetah were tracked within the same study area. They are overwhelmingly more likely to be found in areas with lots of lions. This is because that is where the food is – and cheetahs are following their prey, regardless of the risk of encountering a lion. The Snapshot Serengeti data confirm this – cheetahs are way more likely to be caught on cameras inside lion territories.
Unfortunately, we don’t have radio-collar data on the Serengeti wild dogs from the 1980’s. But we do have radio-collar data for the wild dogs that have been living in the larger Serengeti ecosystem for the past 8 years. As you can see in the map below, wild dogs regularly roam within just 30km of the lion study area. But they don’t settle there – instead, wild dogs remain in hills to the east of Serengeti – where there are local people (who kill wild dogs), but very few lions.
Other researchers in east and southern Africa are starting to pick up on the same patterns in their parks. From Tanzania, to Botswana, to South Africa, researchers are finding that wild dogs get kicked out of really large, prime areas by lions…but that cheetahs do not. What they’re finding (since they have all these animals GPS-collared) is that cheetahs are responding to lions at a very immediate scale. Instead of avoiding habitats that have lions, cheetahs maintain a “safe” distance from the lions – allowing them to use their preferred habitats, but still minimize their risk of getting attacked.
Carnivore researchers are only really just beginning to explore the role of behavior in driving population-level suppression, but I think that there’s good reason to believe that large scale displacement, or other behaviors, for that matter, have greater effects on population numbers of cheetahs and wild dogs, as well as other “subordinate” carnivores – not just in African ecosystems but in systems around the world. It’s a new way of thinking about how competing species all live together in one place, but it’s one that might change the way we approach carnivore conservation for threatened species.
By now it’s no secret that lions are kind of mean – and that if you are any other carnivore living in the Serengeti, you’d probably prefer a lion-less world. No tawny, muscle-bound foes to steal your food, kill your cubs, chase you around…life would be easy! You’d have plenty of food, your cubs would grow up strong, and your numbers would increase.
Or would they?
It certainly makes sense that all the nasty things that lions do to other carnivores should add up to limit their numbers. Lions are responsible for nearly 30% of wild dog deaths, and over 50% of cheetah deaths! On top of that, they steal food that cheetahs and wild dogs have worked hard to get – and might not have the energy to get again. Researchers are pretty sure that more lions means fewer wild dogs in two ways: 1) In reserves where there are more lions, there are fewer wild dogs, and 2) When lion numbers increase through time, wild dog populations decline.
The same has generally been believed about cheetahs, and some research from the 1990s suggested that reserves with more lions had fewer cheetahs. But as I started digging into the data from Serengeti, I saw a different, quite unexpected, story.
Lions, cheetahs, and wild dogs were all monitored by long-term projects for a number of years. This graph shows their population sizes since the 1960s. The increase in lions is pretty clear – lions have nearly tripled in the last 40 years, largely due to increases in wildebeest. Wild dogs disappeared from the study area. Now, their final disappearance was due in large part to disease, but it’s possible that lions didn’t help matters. In sharp contrast, the cheetah population has stayed pretty much the same. Sure, there are some ups and downs, but on average, the population has been holding steady over the last 40 years.
Wait a minute, if lions are really bad for cheetahs, then why haven’t cheetah populations declined in the Serengeti? How can they possibly be holding steady when lion numbers have tripled? What is going on???
It’s a good question. Tune in next week for an answer!
If you are a nerd like me, the sheer magnitude of questions that can be addressed with Snapshot Serengeti data is pretty much the coolest thing in the world. Though, admittedly, the jucy lucy is a close second.
The problem with these really cool questions, however, is that they take some rather complicated analyses to answer. And there are a lot of steps along the way. For example, ultimately we hope to understand things like how predator species coexist, how the migration affects resident herbivores, and how complex patterns of predator territoriality coupled with migratory and resident prey drive the stability of the ecosystem… But we first have to be able to turn these snapshots into real information about where different animals are and when they’re there.
That might sound easy. You guys have already done the work of telling us which species are in each picture – and, as Margaret’s data validation analysis shows, you guys are really good at that. So, since we have date, time, and GPS information for each picture, it should be pretty easy to use that, right?
Sort of. On one hand, it’s really easy to create preliminary maps from the raw data. For example, this map shows all the sightings of lions, hyenas, leopards, and cheetahs in the wet and dry seasons. Larger circles mean that more animals were seen there; blank spaces mean that none were.
And it’s pretty easy to map when we’re seeing animals. This graph shows the number of sightings for each hour of the day. On the X-axis, 0 is midnight, 12 is noon, 23 is 11pm.
So we’ve got a good start. But then the question becomes “How well do the cameras reflect actual activity patterns?” And, more importantly, “How do we interpret the camera trap data to understand actual activity patterns?”
For example, take the activity chart above. Let’s look at lions. We know from years and years of watching lions, day and night, that they are a lot more active at night. They hunt, they fight, they play much more at night than during the day. But when we look at this graph, we see a huge number of lion photos taken between hours 10:00 to 12:00. If we didn’t know anything about lions, we might think that lions were really active during that time, when in reality, they’ve simply moved 15 meters over to the nearest tree for shade, and then stayed there. Because we have outside understanding of how these animals move, we’re able to identify sources of bias in the camera trapping data, and account for them so we can get to the answers we’re really looking for.
So far, shade seems to be our biggest obstacle in reconciling how the cameras see the world vs. what is actually going on. I’ve just shown you a bit about how shade affects camera data on when animals are active – next week I’ll talk more about how it affects camera data on where animals are.