You knew it would happen eventually. Harvard is going to study the MIT mascot and learn more about the dams they build. Not about the ecology they create mind you, just about the nuts and bolts. Apparently it’s not been studied a lot because – are you sitting down? – beavers work at night when all the grad students are usually busy partying, downloading porn or writing bad poetry.
Dammed if They Do
Today the beaver thrives in many biomes throughout North America because of the animal’s ability to modify its environment to suit its needs. In the foothills of the Rocky Mountains, where the Blackfeet nation is located, annual floods wash out beaver dams every spring allowing a unique opportunity to watch the colonies rebuild them from scratch. When Kennedy returned to this region as a graduate student she had a simple question: How do beavers build dams? To her surprise, there was relatively little research on the topic—particularly from the perspective of an engineer rather than a naturalist.
“Beavers can transform an ecosystem thousands of meters in length over a single summer,” she says. “Dams are only a small part of it. They need extensive trail networks so that they can travel back and forth to support material transport for lodges, dams, and food cache construction. They also excavate extensive canals and fell trees right alongside so that they can float them back to the dam. It’s a pretty sophisticated and large-scale engineering project, particularly when you consider that we’re talking about rodents only as big as a mid-sized dog.”
The kind of indirect coordination between animals based on environmental cues that Kennedy describes is called stigmergy. A termite, for instance, digs up some soil and leaves pheromones on it, which attracts another nestmate who does the same. Multiply by a million or two termites and you get a mound nearly three meters high. In her research, Kennedy explores whether stigmergy applies to beaver behavior.
Hmm that’s actually interesting. Here in old Martinez we got to watch beavers build dams directly, because our internet was down I guess and we went outside. And we saw beavers learn to build better. Beavers who were very bad builders. And beavers who improved over time. Whether they got better because of STIGMERGY I cannot say, but I do think that if you put a stick in a certain place and it was the wrong place the water will come and show you why. Especially when the creek is tidal and the water comes twice a day. Hey did you know Jordan attended the California Beaver Summit? Yes it’s true.
Around here we call it STICKMERGY!
Beavers are not termites. Besides being much larger and smarter than insects, the mammals’ works take much longer to construct than a termite mound. Moreover, beaver building behavior is not a response to pheromone cues. But Kennedy believes that beavers respond to the flow of water similar to the way that her mentor Mahadevan found termites respond to temperature and the flow of air. While it’s long been suspected by researchers that the sound of running water is a trigger for dam building, though, Kennedy says the reality is likely more complicated.
“If it was just that they hear running water, then beavers would be trying to build across Niagara Falls,” she says. “Other environmental factors work together to create a kind of ‘Goldilocks zone’ where things are just right and beavers are going to build.”
“I took measurements and you can see that, when the flow of water is sufficiently low enough, beavers will start building dams,” she says. “So, although my field sites were all more or less in the same location—all on Blackfeet land—beavers started building at different times depending on the flow rate I measured at their particular location. I think the data set shows that flow is a very strong trigger.”
Okay I guess you can say the water is operating like the pheremones here and stimulating more building or different building, but just remember that beavers in rehabilitation who have been raised from orphans are constantly “Building dams” our of their caretakers rainboots or newspapers or coffee cups. Building dams appears to be somewhat hard wired. The water teaches ways it could be better.
And the beaver LEARNS.
Kennedy’s findings address a much larger question: How big can a stigmergic system get? Her other faculty mentor, Fred Kavli Professor of Computer Science Rhadika Nagpal, has leveraged research on social insects to develop kilobots, “a low-cost, easy-to-use robotic system for advancing development of ‘swarms’ of robots that can be programmed to perform useful functions by coordinating interactions among many individuals.” A reflection of the insects that they imitate, however, kilobots are quite small—only about 33 millimeters in diameter. Beavers are orders of magnitude larger—as are their works.
“Yes, beavers cut down the trees, but then they bring in all this other plant life,” she says. “A number of papers demonstrate that plants start to flourish and invertebrates start to populate the areas beavers inhabit. Even if you don’t think that beavers are sacred, it’s coming more and more to the forefront how important they are to the health of our waterways and everything that lives there.”
Sure. That’s why I’d go to Yale to study beavers. Not to understand how they improve the environment; Or to learn how their decimation lead to historical and environmental ruin. Or even the destructive of biodiversity in early America or see if they help fight fires or end drought. I’d study beavers to learn if they can inform robotics. Because that that smells like funding to me.
Sheesh.
