That’s right. Even though many of us probably ID photos on Snapshot Serengeti because we really don’t feel like writing up that expense report or answering emails or formatting our bibliographies, Snapshot is also a fantastic tool for *deliberate* learning.

Check out how post-doctoral researcher Annika Moe has incorporated Snapshot Serengeti into college classrooms.  It’s a pretty compelling argument for engaging students with authentic research — I’m just glad that Snapshot Serengeti got to be part of such a cool new approach to learning.

I don’t think this will work…

A cute article came out a few weeks ago in a one of the big methodological journals in my field. (Methods in Ecology and Evolution, published through the British Ecological Society.)

The article pointed out that researchers often have to leave equipment out in the field to collect data (sound familiar?), and that this equipment sometimes gets damaged or stolen. So they did a little experiment where they labeled the equipment with a note. The note was in one of three “tones”: personal, neutral, or threatening.

The equipment and labels used by Clarin et al. 2013.

 The personal note read: ‘Part of my thesis – Please do not touch – Please call me if you have any questions and would like to know more:’ and a photograph of a juvenile squirrel. 

The neutral note read: ‘Part of an  experiment – Please do not touch’ and a warning sign. 

And the threatening note: ‘Part of an experiment – Every theft will be reported to the police! GPS monitored!’

Lo and behold, cameras with the personal note and a picture of a cute baby squirrel had the fewest instances of vandalism and theft! (Also note in the chart below that the equipment with the “threatening” note had the most encounters!)

Figure 3 from Clarin et al, showing the # of incidents experienced by cameras with different note types.

I thought this experiment was fun and the results heartening. Unfortunately, though, I’m not so sure nice notes will work so well on the Serengeti wildlife…

The last picture *this* camera ever took…

Reference: Clarin, B.-M., Bitzilekis, E., Siemers, B.M. & Goerlitz, H.R. (2013) Personal messages reduce vandalism and theft of unattended scientific equipment. Methods in Ecology and Evolution, doi: 10.1111/2041-210X.12132.

A few weeks ago, I wrote about how losing top predators from ecosystems can produce effects that radiate throughout the ecosystem, and talked a bit about how sea otters provide one of the better known of these examples. Today I want to talk a bit more about these reverberating consequences and how they come about.

These patterns are known as “tropic cascades.” Derived from the Greek word for “food”, trophic refers to the position that a species occupies in a food web. Plants consume sunlight. Herbivores consume plants. Carnivores consume herbivores (and sometimes other carnivores). Some carnivores, like bears, are really omnivores — eating both other animals as well as plants. So, things in one trophic level typically consume things from a lower trophic level. And critters within a trophic level compete with other critters in that trophic level for resources — sunlight, water, food, whatever. Trophic cascades are when changes in one trophic level (say, the top carnivores) have effects that cascade down to affect herbivores and plants.

The ways in which these cascades can happen are many and complex. The classic example describes how sea otters protect kelp forests by keeping sea urchin populations low. Without otters, the sea urchin populations explode and eat all of the kelp. But this is just one story of just one pathway.

For example, research on the Aleutian Islands reveals that foxes can change island grasslands into tundra. The islands provide a fantastic natural experiment, because 19th century fur traders brought foxes to some islands but not others, creating a whole pile of very similar islands, some with, and some without, foxes. On islands without foxes, seabirds eat fish from the sea and and…deposit…the nutrients from those fish on land (yes, in the form of droppings). All of the nitrogen and phosphorous in seabird droppings provide the nutrients to support long, lush grasses. But foxes reduce seabird populations, which in turn reduces the influx of nutrients to the islands, an results in a very different tundra-like plant community.

One of my favorite recent papers is a 2011 Science review by Dr. Jim Estes and colleagues that documents the many and complex changes that apex predators trigger in natural systems.  This figure from the Estes et al. publication gives us a tiny hint of just how complex these pathways are.

A figure from Estes et al. 2011 documenting the various pathways in which the loss of a top consumer affects many other things. For example, in this last row, coyotes suppress mesopredators (smaller predators). Mesopredators suppress small vertebrates. So losing coyotes means more mesopredators and thus fewer small vertebrates. The blue bar shows high levels of biodiversity in systems with coyotes. The brown bar, which is so low it’s invisible, indicates that in systems without coyotes, biodiversity is really, really low.

You can see from this figure that it’s not only predators that have reverberating consequences for the larger ecosystem.  In the late 1800s, a disease called rinderpest decimated wildebeest populations. This led to increased woody vegetation and increased incidence of savanna wildfires, When wildebeest populations recovered, their grazing patterns transformed the Serengeti back into a grassland and reduced the fuel available for wildfires. Fires since then are far fewer and far less intense.

So there are many, many ways in which one species can have cascading effects on the larger system. You can hear Jim talk more about the paper here.

Ultimately, we’re left with two profound and lingering realizations. The first is that everything inside an ecosystem is connected to everything else in a complex web of interactions. Sometimes shaking this web doesn’t do much, but sometimes losing a species from this web can have dramatic and unexpected effects. Everything is connected to everything else. The second realization is that people are inexorably changing the shape of these webs as they exist in the natural world. Because of their large body size, need for large spaces and lots of food, and tendency to come into conflict with people, large predators are one of the first things to go in human dominated landscapes. With everything connected to everything else, we don’t yet know what the extent of these losses will be.

## 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…