When you're trapped in an airport, relax and have some fun.
That's one possible takeaway from this small bird filmed earlier this year, riding the handrails of an airport's moving walkway.
The bird swoops in the air, lands on the handrail and repeats the whole sequence. Doesn't that look playful? Play isn't an outlandish explanation, in fact, because animal-behavior scientists agree that different species of birds do play in a variety of ways.
A widely shared video clip from a few years ago shows a crow at play on a snow roof.
Ravens, too, are well-known for playful exuberance as this short excerpt from a Nature documentary shows.
Ethologist Gordon Burghardt noted last year in the journal Current Biology that play is defined as some nonfunctional behavior that's repeated in some atypical form or at some atypical time by an individual — anyone from a monkey to a fish to a bird to a human — who is in a relaxed setting and experiencing some enjoyment.
So when I first watched the clip, I felt pretty satisfied that "Airport Bird's" rail-riding fit a scientific definition of play.
Yet something nagged at me. I know little about birds. I do know about grieving and other expressions of emotion in primates and other mammals — and I'm forever cautioning people not to jump to conclusions based on an image or two, without enough background information.
Shouldn't I be consistent and check my own conclusions in the case of this bird?
To do that, I contacted biologist Dan Cristol, my longtime colleague at the College of William and Mary, who has carried out behavioral and ecological studies on birds for more than two decades. And wouldn't you know it, in preparing to respond to my emailed questions, Cristol saw things in the airport video clip that I did not.
First of all, he could identify the rail rider as a songbird, probably in the weaver finch group and possibly a house sparrow. The presence of a black throat patch would indicate an adult male, but it's not possible to discern clearly whether a patch is indeed present; the bird may be an adult male or female, or even an immature.
Next, Cristol pointed out what I had missed entirely: On one flight, the bird hits the ceiling, then drops and flies erratically, with irregular wing beats. Then when riding the rails, the bird scans the environment. Is this a relaxed animal, or one that is confused, or caught in a situation that he or she experiences as unsafe? That's an open question, Cristol says.
Cristol thought the bird might even be in the midst of foraging, that is, searching for crumbs left accidentally on the handrail by hurried humans who eat on the run.
But by no means did Cristol dismiss play as a possibility.
"Birds definitely play; it's a very important part of learning and it is no longer controversial among biologists," he told me. "But [for the reasons he explained and that I have cited here] I'd need to actually study it with lots of examples, and approach it by ruling out each hypothesis."
That kind of careful observation to tease apart play from competing explanations is just what Cristol and his colleague Jennifer Gamble did some years ago in observing herring gulls at a Virginia site for 80 hours during 38 days spread across a three-year period. Herring gulls strategically drop clams on hard surfaces to crack open and eat them, but sometimes they don't let the clams drop and, instead, try to catch them in midair — before they hit the ground. Is this pure fun for the birds?
Or could it be that the birds practice this "drop-catch" maneuver for some functional reason? Might, for example, the birds be trying to reposition the clams in their beaks (by letting them go then re-catching them) for a more precise drop? As Gamble and Cristol reported in a paper for Animal Behaviour, they weighed three explanations through a quite rigorous method and concluded that the evidence is consistent with play behavior.
That study underscores my own bottom line: It's just not possible to do good science by assessing a few seconds of video.
Now we're back to Airport Bird and this key question: If you find yourself delayed in an airport and in need of something to do, should you draw on this bird's example?
Maybe — if the bird really is at play. But maybe not. Our species of primate really shouldn't seek bits of food left behind on the walkway handrails.
Barbara J. King is an anthropology professor emerita at the College of William and Mary. She often writes about the cognition, emotion and welfare of animals, and about biological anthropology, human evolution and gender issues. Barbara's most recent book on animals is titled How Animals Grieve, and her forthcoming book is Personalities on the Plate: The Lives and Minds of Animals We Eat. You can keep up with what she is thinking on Twitter: @bjkingape