Several years ago, the prolific science blogger Carl Zimmer (of National Geographic, Discover Magazine, and really any place worth going to for good science writing), published a book called “Science Ink” – a compendium of the artwork various researchers have had immortalized on their skin to show off their devotion to their field of choice:

“Body art meets popular science in this elegant, mind-blowing collection, written by renowned science writer Carl Zimmer. This fascinating book showcases hundreds of eye-catching tattoos that pay tribute to various scientific disciplines, from evolutionary biology and neuroscience to mathematics and astrophysics, and reveals the stories of the individuals who chose to inscribe their obsessions in their skin. Best of all, each tattoo provides a leaping-off point for bestselling essayist and lecturer Zimmer to reflect on the science in question, whether it’s the importance of an image of Darwin’s finches or the significance of the uranium atom inked into the chest of a young radiologist.”

Science inspires me more than anything else (it would have to, or grad school would definitely be off the table!), and besides the sweat, blood, and tears normally dedicated to this pursuit, I believe that body art is a beautiful medium for celebrating this passion.

I got my first tattoo too late to be included in Zimmer’s book (alas! alack!), but did make it onto his National Geographic blog with this beautiful line-drawing of a Dicranurus trilobite.

As I say on the website (click image for the link), I was inspired to fossil-hunt as a young child by my geologist parents and had, in all seriousness, the best trilobite collection of any six year old in northern United States. Trilobites, for the unfamiliar, are not aliens – despite all appearances to the contrary. They were one of the most prolific arthropods in all of evolutionary history, ranging from the mundane and button-looking to the highly ornamented creature crawling between my shoulder-blades. Their evolutionary history and biology is fascinating (their eyes, for example, are made of calcite – a kind of mineral!), and I highly recommend Richard Fortey’s book, “Trilobite!”, for anyone wanting to learn more.

Continuing to mine the fossil vein, my second tattoo features an allosaurus in the classic preserved “death pose” – not to be confused, of course, with “death throes”. The thrown back head and gaping mouth arise after death as the body of the organism dries and is shuffled around by its environment.

Adoring my other ankle is a tattoo I see fairly commonly among biologists, in particular, evolutionary scientists. Anyone recognize this image?

This is the first sketch Darwin ever made of a ‘tree of life’ – the first depiction of his great idea that we could have all evolved from a single common ancestor. Really, the beginning of biology as we know it today. Most poetic and moving, for me at least, is the line he scrawled above his figure: “I think…”

I bring all this up because yesterday I completed a second sitting for my newest science tattoo. It’s all red and healing and kind of sore right now, but hopefully I should have pictures to show soon! A homage to the birthplace of evolutionary ideas — to be revealed at another time.

## Today’s blog is a guest post from Craig Packer, the director of the Serengeti Lion project. ##

In the summer of 2006, I sent my 19-yr old son, Jonathan, and 18-yr old step-daughter, Carrie down to the land of man-eating lions with my graduate students, Hadas Kushnir and Dennis Ikanda. They crossed the Rufiji River every day in dugout canoes to collect data on lion attacks from previous years, dodging hippos and crocodiles in the slow moving waters.

Cell phone coverage in Rufiji was sparse, so Jonathan only sent the occasional message:

   A woman and a child were attacked last night in a village we had visited two days ago. they’re both recovering in hospital.  26-June-2006 18:31:15

Rufiji is just outside the Selous Game Reserve, Tanzania’s largest protected area, and the Selous is reputed to be the home of the largest lion population in Africa. There was a signboard near the site where a man-eater named Osama had been shot after killing 40 people, and things had been relatively quiet for the past few years.  But more lions were starting to appear, and Hadas and Dennis wanted to figure out how people could protect themselves in the event of future outbreaks.

Dennis had recruited a couple of staff from the Wildlife Division in Dar es Salaam for the first big man-eating survey in September 2004.  Dennis drove south towards Rufiji while Bernard headed west towards Dodoma.  As soon as they reached the outskirts of Dar they were already in man-eating country.

They spent three weeks on the road, passing through dozens of agricultural villages that had suffered lion attacks, covering the coastal Tanzanian districts as far as the Mozambique border then up the west side of the Selous, visiting sites where attacks had taken place as long as 15 yrs ago, as recently as last week.

No one ever forgot a lion attack.  Survivors relived their experiences as if they’d only been attacked the night before.  Relatives of victims still felt the loss as keenly as if their loved ones might miraculously walk in through the front door.

I had helped Dennis design a questionnaire, and each survey team asked the circumstances of each attack, the location, time of day, time of year.  They also asked which prey species the lions might be eating in the vicinity.  Were there still any zebra or buffalo? Anything at all?

I sat down with Dennis in December 2004 and studied the data.  Most lion attacks took place in the wet season, at harvest time, and most of the attacks were in agricultural districts where there was nothing else for the lions to eat – no wildebeest or buffalo, no zebra or impala.

Most attacks occurred when lions pulled someone out from a temporary hut or dungu – usually just a simple A-framed roof above a raised platform a meter or two off the ground. These people were subsistent farmers with a single crop per year; their lives depended on a good harvest, and crop pests could quickly destroy an unguarded field – especially at night.

The worst man-eating areas lacked the lion’s usual prey species, but there was an abundance of one particular crop pest.  The bush pig turned out to be the magnet that drew lions to the farm fields, right into the areas where people slept in their flimsy huts. The worst hit areas were mostly Muslim, so people were unwilling to touch a pig – and there was no market for bush pork.

People might also be attacked while walking home alone in the dark or heading off to Mosque at dawn.  People might be pulled out of bed, and kids might be attacked while playing around the house in the evening.

But we suspect these were later victims of lions that first saw the connection between people and food once they had been drawn to the fields by the bush pigs.

Pig control is impossible.  No one will ever eradicate the bush pigs from rural Tanzania – no one will ever be able to fence off all their fields – but we thought it might be possible to find an alternative way to reduce pig damage so that people wouldn’t have to sleep in a dungu.

So Jonathan and Carrie went to Rufiji in 2006 to help Dennis and Hadas.  Hadas was born in Israel, and the kids were frustrated to be left in the care of such a determined mother hen.  And Dennis was driving the same clapped-out Land Rover he had used when he was my field assistant in Ngorongoro Crater. So their most memorable adventures seemed to involve wild rides, steering rods and duct tape.  I was worried about money, so I was half hoping our impending college expenses might be avoided with the help of a hungry lion…

Now, I’m fairly certain that you guys enjoy looking at a nice critter picture or two. Or three. Or a hundred. (Looking over the Zooniverse stats for membership and ID counts is always a humbling and awe-inspiring experience!) To mix it up a bit, and to give you all a better feel for the scientific background I am coming from, here is a taste of what I experienced during my last job before starting graduate school. I worked for the USGS on the Pacific island of Guam, conducting research on the invasive and highly destructive Brown tree snake (Boiga irregularis).

Guam!

Photo Credit: Meredith S. Palmer

For those of you who aren’t familiar with this case study, the island of Guam was invaded in the 1960s by what was most likely a single pregnant female Boiga. Over the course of the next few decades, this generalist predator caused the extirpation of almost all native forest bird species, destroyed all nesting seabird populations, led to the extinction of 2/3s of the native mammalian life, and contributed to drastic declines and loss of native reptile and amphibian populations. This situation is highly unique in that it was the first (and remains one of the only) situations in which an invasive reptile caused such a degree of ecological damage. There is currently a higher density of Boiga on Guam – 13,000 per square mile – than there is of all combined snake species in the Amazon basin. Snake populations continue to be sustained on invasive skinks and pose not only severe ecological threats to Guam and surrounding islands, but also cost the island economy millions of dollars per year through losses relating to power outages caused by snakes, snake bite hospitalizations, decline in tourism money, the costs involved with ensuring that snakes do not leave the island, and agricultural losses.

Brown tree snake munching on an invasive gecko species

Photo Credit: Bjorn Lardner

A few of the species still on island, including a mangrove monitor, the moth skink, the highly endangered Mariana fruit bat (attempting to nest, apparently, in my hair), and another native skink species, the blue-tailed skink.

Photo Credit Meredith S. Palmer

While the island itself is beautiful, due to the snake, it was completely depauperate of animal life. It is a Twilight Zone experience to walk through a forest devoid of any natural sounds, without crickets chirping or birds calling. The real beauty and biodiversity of Guam lies underwater, in the coral reefs and shallow oceans that surrounding the island – a place I would retreat to often.

The ocean’s vertebrate life (the massive pink object on the left is a dead sperm whale which snagged up on the reef half a mile off-shore)

Photo Credit: Meredith S. Palmer

The tropical fish diversity in Guam was absolutely mind-boggling. In addition, nothing would liven up a good snorkel like running into a ferocious eel or a encountering one of these enchanting sharks.

Photo Credit: Meredith S. Palmer

But everybody knows that invertebrates are really where it’s at. Cephalopods!

Photo Credit: Meredith S. Palmer

If anyone has questions about the snakes or invasive species situation on Guam, please feel free to ask. I can also highly recommend the USGS Brown tree snake lab website (http://www.fort.usgs.gov/resources/education/bts/) and the excellent book, “And No Birds Sing”, by Mark Jaffe, which documents the process by which scientists discovered the culprit behind these rapid extinctions.

It’s a surreal experience, sipping your breakfast coffee at a table where some of the most brilliant minds in ecology are chowing down on sausage and eggs while gleefully recounting scandals in Canadian politics (there are, apparently, a number of these). No matter how many conferences I attend, I am always a bit shocked to discover that generators of fundamental theorems, the authors of Science papers and the case studies in my textbooks are actual flesh-and-blood human beings. People with personalities and foibles, but also scientific minds that, unlike their journal articles, offer the opportunity for interaction and discussion. At the Predator-Prey Interactions conference this last week, there were plenty of brains for me to pick and researchers for me to pester – they put up with it rather well, and the experience offered my great insight into where the field is going and how to tackle the next big ideas in fear and the indirect impacts of predation.

Above is a copy of the poster I presented: I may have described it to someone as containing “idea vomit.” So, I’m going to have to work on that phrasing, but essentially what it contains is a splurge of all of the questions I want to answer, variables I think I worth investigating, and the methodologies at my disposal that could be used to dig down into the core of these issues. Over the course of the week, with its deluge of presentations, posters, workshops, meetings, and the occasional poolside chat, this splurge became refined into a more coherent and plausible set of research objectives.

Okay, so, that may be a bit of a wistful exaggeration. What actually happened is that I received a million suggestions, compiled a list of literature to read that will keep me busy for the next few months, and met a number of interested and informed people who will certainly be useful resources as my research progresses.

Great ideas for the course of my research certainly did come out of this conference. Our system has the major advantage, of course, of the massive camera trap grid and the extensive duration over which the project has been running – no one else has this quantity of information. As you can see on my poster, I can use this data to map out the distributions of herbivores on different time scales and then overlay features (here, a “greenness” index of vegetation) to get an idea of what is attracting or repelling herbivores to different places at different times. This method is extremely useful and often employed by people constructing landscapes of predation risk. However – something that would be informative to do, I learned, would be to ask the animals themselves exactly where they feel safest or most as risk. I don’t mean passing out surveys, but I certainly became excited about incorporating a larger manipulative element to my study.

I had already planned on blasting predator calls around camera traps to see who responds (flees!) and how long it takes for their fear response to go extinct. We can look at this over the long-term using the camera traps. Now, in addition to playing predator calls, I am also interested in obtaining alarm calls from a variety of herbivores to broadcast, which may also shed light on coexistence mechanisms for different herbivore species. If anyone knows where I might be able to snag some audio recordings, let me know!

Another methodology to utilize would be examining “giving up densities” (GUDs). To determine a GUD, feeding trays are set up in different areas around the study site containing food (delicious) mixed into an inedible substrate (like corn cobs, or chunks of PVC piping). The idea is that initially, it’s fairly easy to extract food from the matrix when there’s a lot of it, but over time, you get less and less food return for grubbing around in the PVC. If you don’t feel safe in a particular location AND you’re not extracting enough food to make it worth your while, you should give up and move along sooner than if you were more comfortable in a safer area. The amount of food left in the tray can be measured – this is the GUD. A lower GUD means that less food was left and the animal perceived the area in which it was eating as less risky. This idea was championed by Joel Brown and Burt Kotler, who have used it extensively in rodent systems and impalas.

It sounds like it can be more than a bit tricky to implement some of these manipulations, but that’s what pilot studies are for, right? Right. Until then, back to the literature…  

You’ll have to forgive me if I am less eloquent than I’d like to be. It’s late Sunday night, and my brain is still reeling from one of the most intellectually exciting and intense weeks I think my Ph.D. career has seen.

Right. So. Craig, Meredith, and I spent the last week at the first ever Gordon Research Conference on Predator-Prey Interactions. It was quite the meeting-of-the-minds for ecologists, and I spent much of the week rather star-struck.  See, while much of our scientific careers are spent collecting, cleaning, and analyzing data (not to mention trying to convince funding agencies that they should give us money), a significant portion of our time also goes towards pouring over the thoughts, insights, and experiences of other researchers as they are articulated in scientific journal articles. We are impressed and sometimes awed by their insight. Our own scientific aspirations are shaped by their creativity and vision.

At the GRC last week, I had a chance to meet the movers and shakers who fundamentally shape the way that we ecologists see the world around us…and it was awesome.

Dr. Jim Estes, a professor at UC Santa Cruz, was one of these movers and shakers. Dr. Estes is perhaps best known for his work on sea otters that provided one of the first and most spectacular examples of how a keystone predator could shape an entire ecosystem. A keystone predator is one that plays a crucial role in the larger community, and whose disappearance has disproportionate and dramatic consequences that cascade throughout the ecosystem in what we call a trophic cascade. (“Trophic” refers to different levels within the food web.)

A pacific northwest ecosystem with and without sea otters. From the recently published Ripple et al. (2014) Science article.

When sea otters disappear from pockets of oceans in the Pacific northwest,  the number of sea urchins (which otters love to eat) increases. And sea urchins increase a lot. Without the otters to keep sea urchins in check, the urchins eat up all of the kelp that many fish, crabs, and other underwater sea creatures call home. No otters means no kelp, and no kelp means that a vast array of other underwater sea creatures also disappear.

Otters were recognized as keystone predators back in the 1970’s. But they aren’t the only carnivore that can change the face of an ecosystem. In fact, Dr. Estes presented a “sneak peak” at results from a  review paper that he and colleagues were just about to publish in one of the world’s leading scientific journals.

Their article documents that at least seven of the world’s 31 large carnivores have been found to trigger trophic cascades. Some of these effects derive from the fact that big predators reduce herbivores by eating them. But some of these effects are mediated through “fear” — in which prey animals change their behavior to avoid predation. And some of these changes are because top predators suppress smaller predators, which in turn suppress their prey.

There are many, many ways in which top predators shape the face of ecosystems around the world. Furthermore, as Dr. Estes and his colleagues (all “biocelebrities” and many of whom were also at the GRC!) point out in this new paper, these top predator populations are declining. They are declining quickly and globally, and they are declining as a result of human disturbance. What’s worse is that even though we know that these top predators can have enormous influence over the structure and function of natural systems, we don’t really understand the general patterns that underlie their influence. So as they disappear, it’s anyone’s guess as to how our natural places will change.

It’s abundantly and urgently clear from the recent scientific literature and from the thoughts and interests of ecology’s biggest names at last weeks’ conference that we need to understand how top predators shape the natural world. I’m hopeful that our research here at Snapshot Serengeti will continue to provide tiny pieces of the puzzle towards this scientific understanding. Thank you guys for helping us understand how this amazing world works.

Sorry for the silence, everyone. Craig, Meredith, and I are currently neck deep in the first ever Gordon Research Conference on Predator Prey Interactions. 

We are busy trying to sound intelligent and trying not to be too “star struck.” Yes, believe it or not, there are “bio-celebrities.”

Today I’m hosting a break-out session on the role of “fear” in predator-predator coexistence — wish me luck and I’ll tell you all about it next week!