In The New York Times travel section Sunday, Stephanie Rosenbloom described a hot day this summer when she sat in the Roman amphitheater in Arles, France.
As she imagined scenes Van Gogh may have observed there during the 19th century, she says, a soft whirring sound broke into her reverie. Rosenbloom writes:
"Something was drawing near. I looked around and saw nothing — until it and I were eye to eye. Or rather, eye to lens. A drone resembling one of those round Roomba robotic vacuums had levitated from the pit of the nearly 2,000-year-old arena and was hovering in the air between me and the cloudless horizon."
I'd wager that chimpanzees Tushi and Raimee, residents of the Royal Burgers' Zoo in Arnhem, Netherlands, could relate. Video of Tushi knocking a Dutch TV crew's $2,000 unmanned drone out of the sky with a stick went viral back in April.
A new paper in the journal Primates, authored by ethologists Jan A.R.A.M. van Hooff and Bas Lukkenaar, offers the back story to what happened that day and offers new evidence of chimpanzee planning skills.
The TV crew, at the zoo to shoot a documentary, sent up the drone over the enclosure of the chimpanzees without, at first, filming anything — a sort of dry run. The apes, all on the ground at that point, reacted with excitement: "Some were seen to grab a willow branch, and four of them were seen to climb the scaffolding on the side where the drone was hovering, holding a branch," van Hooff and Lukkenaar write.
When the drone took off again, this time filming, it closed in specifically on Tushi and Raimee. The paper continues:
"The operator of the drone had clearly underestimated the significance of the fact that both individuals had carried with them a long twig when they climbed the scaffolding. This is not a frequently observed behavior of these chimpanzees."
Tushi swiped at the drone twice and, on her second pass, she crashed it. During this action, she grimaced — it wasn't a fear face she made but rather an indicator, the ethologists write, of "an assertive and determined exertion of force, homologous to what humans do in comparable situations."
The key point is that Tushi and Raimee had climbed the scaffolding already carrying the sticks. As van Hooff and Lukkenaar say, "The sequence of events is highly suggestive of an interpretation of the use of the stick as a planned, deliberate action."
This isn't unexpected news; chimpanzees have been known to have the cognitive skills for planning, including for tool-use and hunting actions, for some time. But it's an important observation, nevertheless. These chimpanzees thought ahead quickly then acted decisively about a perceived threat.
It's not only we primates — humans and chimpanzees — who react to hovering drones. Last month, NPR reported on a new study in the journal Current Biology that indicates the heart rates of wild bears zoom when drones overfly them — by as much as 400 percent past baseline. Outwardly, the bears acted laidback about the proximity of the drones; only by measuring their cardiac rates did we learn the whole story. (The four bears in question were already monitored via implanted heart sensors for other research, which I recognize is something of an irony in making a point about stress and wild animals.)
And last year, Audubon Magazine told of a father osprey who crashed a drone hovering over the nest he, his mate and two offspring inhabited in Montana.
Drones aren't all bad for animals, by any means. They may enable scientists to conduct projects in environmental and conservation science with greater efficiency and reduced risk, and this, in turn, may lead to positive results for endangered animal populations. Over at National Geographic last month, Jennifer Holland took a look at this precarious balance of benefits and risks.
As drones begin to clog our air space as well as our personal space, it's clear that we do need to pay attention to both sides of the equation.
Chimpanzee Tushi responded intelligently when a drone invaded her habitat. Are we, her close cousins, smart enough to use drones in ways that minimize the stresses and risks to ourselves and other animals?
Barbara J. King, an anthropology professor at the College of William and Mary, often writes about human evolution, primate behavior and the cognition and emotion of animals. Barbara's most recent book on animals is titled How Animals Grieve. You can keep up with what she is thinking on Twitter: @bjkingape