If you’re a prey animal, you spend an awful lot of your time trying to not wind up like this:
As we’ve talked about an awful lot on this blog (here, here, and here, for example), the same holds true for a lot of predators. Just because you kill and eat other animals, doesn’t mean you don’t have to worry about being killed yourself (as this hyena so unceremoniously discovered).
But, what we haven’t talked so much about, is that the same holds true for plants. If you’re a plant, you get eaten by these terrifying animals:
But, just like prey animals and mesopredators can change their behaviour to minimise the risk of being killed, plants have a few tricks up their sleeves. They can spend a lot of energy growing big thorns, for example, that makes them less delectable.
Or! They can grow in places that their predators avoid — the places where their predators’ predators hang out. Got that? It’s a trickle-down landscape of fear, which had, until now, only been really well documented in small experimental systems with critters like spiders and grasshoppers. But researcher Dr. Adam Ford and colleagues just published an elegant paper in Science showing that leopards and African wild dogs can make the Kenyan savanna less thorny through this cascade. Basically, leopards and wild dogs eat impala. Impala eat Acacia trees. Impala much prefer to eat acacias with fewer thorns (because really, who doesn’t?) – and, if given the opportunity, impala will can eat these small-thorned acacias so much that they can suppress the acacia population.
But! Leopards and wild dogs seem to be offering these tasty small-thorned acacias a refuge. Leopards and wild dogs spend most of their time in denser thickets, where they have more cover to hunt. Impala avoid these thickets and rarely venture in — when they do, however, they have a much higher probability of being killed. And this creates this spiral – those tasty small-thorned trees survive and grow in these thickets because predators scare impala away.
So it’s a trickle down landscape of fear – a compelling and really exciting story. But, what sets Adam’s paper apart from many other attempts to document this effect in large predators, is the series of elegant experiments in which he and colleagues explicitly tested each step in this cascade. Controlling for habitat use to confirm that impala aren’t getting killed in the woods simply because they spend more time there (and in fact, they get killed more even though the spend less time there). Adding and removing thorns to acacias to see if it was really the thorns that mattered. Creating herbivore exclosures to measure whether impala could really suppress acacia density. I spent my entire time reading the article alternating between saying “This is so cool!” and “I am so jealous!” It’s an amazing story. Read more about it here (or here, or or here)!
Hey everyone – I just wanted to introduce you to one of the Zooniverse’s newest members, Darren McRoy, who is our new Community Builder.
As Community Builder, Darren serves as the Zooniverse’s liaison with its citizen science community, including Snapshot Serengeti. He also assists with Zooniverse’s general communications efforts and is working closely with designers and developers on the next generation of the Talk discussion system.
Darren is a 2010 graduate of the Medill School of Journalism at Northwestern University and has a background in journalism and digital communications. He is a resident of the northern Chicago suburbs, and enjoys golf, volleyball, fiction writing, gaming, and participating in a variety of online communities.
Darren can be reached at email@example.com, and posts on Talk under the handle “DZM.” Please feel free to get in touch with him if you have any thoughts, comments, questions, etc about how the Zooniverse communicates with its community — you!
You might remember that National Geographic did a big story on “our” lions last year. David Quammen spent a while being bounced around in our land rovers and Nick Nichols and his crew spent months on end camping in the southeastern corner of our study area, following the Vumbi pride’s every move.
Well, one of Nick’s pictures from that trip has just won him the prized Wildlife Photographer of the Year award! The competition, co-run by London’s Natural History Museum and the BBC, has just turned 50 years old, and is a pretty big deal (you can read about it here). Nick’s winning piece is a black and white photo of the Vumbi pride sprawled in rather epic fashion over the kopjes. We can’t post the picture here for copyright purposes, unfortunately, but go check it out! And go check out some of the other fantastic runners-up here while you’re at it.
Cheetahs, it seems, just can’t stop shattering everything we believed to be true about them.
Scientists have long believed that lions (and hyenas to some extent) threaten cheetah conservation efforts — in large part because they kill so many cheetah cubs. But last year, researchers from South Africa revealed that lions probably don’t kill as many cheetah cubs as folks previously believed. And shortly after that, our research showed that regardless of the amount of lion-inflicted cheetah cub mortality, cheetahs do just fine around large lion populations.
Just last month, another story broke that shakes up how we think about cheetahs. It turns out that not only are cheetahs not as vulnerable to killing by lions, but they cheetahs aren’t nearly as vulnerable to non-lethal bullying either. It was thought that because cheetahs couldn’t fight back against lions – or hyenas – they lost a lot of their hard-earned kills to these ruthless scavengers. (Yes, both lions and hyenas do steal food from each other and from cheetahs.) We knew that wild dogs expend so much energy hunting that they can’t afford to lose even moderate levels of food, and assumed that cheetahs were similarly vulnerable. But, as a recent study from Bostwana and South Africa found out, they aren’t. It turns out that despite being super fast, cheetahs don’t expend all that much energy chasing down their prey. Researchers estimate that cheetahs could lose a full 50% of their kills to lions and hyenas, and still get all the calories they need!
All in all, it’s beginning to look a lot like the biggest threats to cheetahs aren’t lions and hyenas. Instead, availability of denning sites (as suggested by our research) and human destruction of habitat that forces cheetahs to travel far and wide in search of prey (suggested by this most recent study) are probably much, much greater threats to their survival.
One of our long-time Snapshot Serengeti members (thanks Reid!) sent me this NY Times article on African wild dogs. As you know, we don’t have wild dogs in the study area (though keep your eyes peeled! TANAPA did reintroduce them into the western corridor the other year, and I keep hoping we’ll catch one traveling through our grid).
But I am very interested in how dogs interact with the larger carnivore community. And these animals are just *so* cool – incredibly energetic and full of nerve. Watching a small group of dogs defend their kill against a hunting party of hyenas was one of the highlights of my trip to South Africa in June.
The article points out that wild dogs may fare better when lions fare worse (which I’ve reported on here) — and that raises some questions about questions about how to target conservation efforts. Do we have to choose between which species to protect? I’d say “not necessarily.” My dissertation research suggests that although dogs fare worse in small reserves with lions, there are places where wild dogs seem to do just fine. Selous Game Reserve (TZ) and Kruger National Park (SA), for example – big areas that have complex habitat structures. So the answer to protecting the entire carnivore guild may lie in larger, diverse reserves.
There are currently efforts in place to do create a protected area the size of Sweden that spans five southern & east African countries. If successful, according to the NY Times, the Kavango-Zambezi Transfrontier Conservation Area will be the largest terrestrial protected area in the world. Now that’s something to celebrate.
Hi guys! Sorry for the long hiatus on my front. Africa was just as exciting and frustrating and marvelous and difficult as I had imagined it would be, and I’m missing it terribly. I made it back to the US just a week or so ago, my suitcases full of lion manes, camera traps, dead telemetry equipment for repair, and several very important hard drives full of new data to analyze! It’s going to be a busy semester synthesizing everything I learned this summer and planning ahead for the next go around.
Coming home from the field for me typically means a week of celebratory eating (ice cream for breakfast! fruits all day every day!), celebratory showering (hot water! running water!), celebratory lavatory use (it flushes!), among other things. This time, though, I’ll have to admit that even these luxuries didn’t soften the blow of leaving.
(Impending statistics classes awaiting me in Minnesota probably didn’t help either).
There is one primary advantage to coming home, the one thing that makes me appreciate every day that I’m back, and it the fact that for a few blissful months, I will no longer have to deal with these little devils:
Good riddance, tsetses! Hello, Minnesota!
The Snapshot Serengeti science team has been a bit remiss at blog posts over the summer. Meredith has been battling tsetses in Serengeti for her first ever Serengeti field season, and I’ve been kept busy traveling on three continents – between finishing my dissertation, crewing for my partner in the world hot air balloon championships, and…moving to Oxford to join the Zooniverse!
We’re still working out exactly what my job title and job description are (details!), but now that the dissertation is officially finished and I’m settling in here, expect more posts to come!
We have just been awarded a second Expedition Council grant from the National Geographic Society to extend Snapshot Serengeti until the end of the year. This covers the end of Season 9.
You, our Snapshot Serengeti volunteers, are the people who make this work possible. Your careful classifications provide the necessary rigor to make Snapshot a truly scientific endeavor, and we also rely on your enthusiasm and insights in highlighting the many interesting, intriguing and unusual photos, which will someday be compiled in articles and books.
The following paragraphs are taken from our successful application, and give an overview of Snapshot Serengeti’s success broadly:
Our large-scale camera trap grid provides a continuous record of the abundance and distribution of herbivores, insectivores and carnivores in the northern 1000-km2 of the long-term Serengeti lion study area. The camera traps provide accurate abundance estimates of 20 different herbivore species across the Serengeti and near-perfect measures of lion numbers in the woodlands portion of our long-term study area. The camera traps also reveal that cheetahs are able to coexist with lions by waiting a minimum of 12 hrs after the lions have departed from a particular site and that lions and hyenas largely come into contact with each other as a result of their mutual attraction to wildebeest and gazelle. Our grid also provides a remarkably detailed portrait of the wildebeest migration, showing how movements vary from year to year in response to annual variations in rainfall. Besides providing novel scientific data, many of the camera-trap images are artistic, captivating, breathtaking and hilarious. Because daytime pictures are taken in sequences of three, they can be combined into a brief animation that make the portraits come alive.
The camera-trap imagery has also provided the foundation for a successful online “citizen-science” initiative, called Snapshot Serengeti, where hundreds of thousands of volunteers have counted and identified the animal species captured in over 4,000,000 photographs. We have developed a series of “consensus criteria” for accepting their species identifications, which have 97% accuracy compared to the assessments of a panel of expert field biologists, and our Snapshot volunteers have developed an active online community who share particularly exciting images.
With funding from the Howard Hughes Medical Institute, we have partnered with the College of Biological Sciences at the University of Minnesota to develop an undergraduate laboratory sequence in “Savanna Ecology” where students read relevant articles from the scientific literature, form hypotheses about the behavior and ecology of a species of particular interest, classify and count animals from a random subset of online camera-trap photos, access the overall database, test predictions with simple statistics and present lab reports in a group setting.
Our pre-proposal to extend the camera-trap project for an additional 3-5 yrs has recently been approved by the National Science Foundation, and we will submit the full proposal at the beginning of August. If funded, we will collaborate with National Geographic to submit a proposal to the educational program at NSF to expand the classroom activities of Snapshot Serengeti to middle- and high-school students around the US.
We have discussed the pictorial potential of SnapshotSerengeti with senior staff at National Geographic, who are interested in featuring a selection of Snapshot highlights in a 2015 article for the Magazine and are also considering publishing the Snapshot photos in either hardcopy or as an e-book. Many of the individual photos are stunningly beautiful, and many more have a unique freshness because the animals have no sense of a human presence. The daytime “triplet” animations live and breathe like pictures in a fantasy novel.
Our first Expedition Council grant covered the first 3 mos of a 15-month gap in NSF funding when our most recent NSF grant ended in September 2013. In addition to the first EC grant of $30,000, we raised $55,000 from an Indiegogo crowd-funding effort. A small NSF grant to support my upcoming sabbatical includes a supplementary $25,000 to cover fieldwork in July, August and September. The $30,000 awarded in the second Expedition Council grant assures continuity of the Serengeti studies until the end of December 2014.
For the upcoming NSF renewal, we have assembled a well-regarded scientific team to study the Serengeti food web by integrating the lion tracking and Snapshot cameras with new measurements of grasses and soils. The approval of our NSF pre-proposal means that we have survived the first 75% cut in grant applications, so we have a reasonably good chance of sustaining the project long term. But even if not successful, the extension of the camera traps for another few months will be extremely valuable, as this will be the first opportunity to measure the wildebeest migration during an active El Nino – rainfall in the Serengeti is highly sensitive to the Southern Oscillation Index (SOI), and the short rains of November-December have largely failed during the past 3-4 yrs of La Nina weather patterns.
Just a quick update on a room change for the seminar — it will be in Borlaug 365 at 1pm, July 11. The official announcement is below!
PhD Defense Seminar in the
Ecology, Evolution, & Behavior Graduate Program
Advised by: Dr. Craig Packer
1:00 pm, Friday, July 11
365 Borlaug Hall
“Living with lions: spatiotemporal mechanisms of intraguild predator coexistence”
Top predators often suppress their smaller guild members and this can have profound consequences that cascade throughout the larger community. Suppression is mediated primarily through interference competition: direct aggressive interactions and behavioral avoidance by mesopredators to minimize the risk of aggression. These avoidance responses can be costly, especially when they result in large-scale displacement that reduces access of the subordinate species to resources. My dissertation explores the role of behavioral avoidance in driving intraguild predator dynamics, specifically hypothesizing that large-scale displacement drives mesopredator suppression, but that fine-scale avoidance strategies may promote coexistence by minimizing risk without costly large-scale displacement. Specifically, I examine how African lions affect spotted hyenas, cheetahs, and African wild dogs in Serengeti National Park, Tanzania. I first evaluate evidence for mesopredator suppression and large-scale displacement using long-term historical data. I then evaluate patterns of avoidance at fine spatiotemporal scales using novel camera-trapping methods and citizen science. Together, these studies identify large-scale displacement as a key driver of mesopredator suppression and fine-scale avoidance as a key mechanism for mesopredator persistence.