The Weasel That Could

The science behind the Snickers-sized weasel’s unlikely attack on a resourceful Green Woodpecker.

The flash of green feathers that photographer Martin Le-May caught on camera has delighted and intrigued the Internet at large this week. Hopes of cross-species friendship and animal getaways abound, but at heart, these lucky snaps result from a more common animal interaction—predation.

The weasel was attempting to take this Eurasian Green Woodpecker as lunch when the bird, squawking, pulled off a lucky escape. Le-May, who was enjoying a walk in Hornchurch Country Park in East London, was in the right place at the right time: The photogenic flight is a Green Woodpecker’s typical form of defense. If they don't fly, “they'll usually head straight for tree cover, calling loudly,” says Gerard Gorman, author of Woodpeckers of the World

The woodpecker's terrified flight was two-edged. Unfortunately, the assailant, a least weasel, hung on for the ride. Luckily, it was on the small side. Gorman says he’s only seen big hunters, like house cats, pursuing these birds before. To have the predator be a weasel, he says, is awfully rare.

In fact, this fearless hunter was even more petite than average. It was likely “quite a young individual,” says Tim Webb of the Royal Society of the Protection of Birds in London—weighing no more than a Snickers bar, about 1.7 ounces. This may have allowed the Green Woodpecker, which can weigh up to 8 ounces, to muster its usual defensive trick: lift off.

“It's not surprising that the woodpecker would be able to fly a short distance with the little predator on its back,” says Audubon’s field editor Kenn Kaufman.

When the mammal-bird duo landed, the weasel seemed distracted, possibly by Le-May’s camera-wielding presence (or perhaps by its recent flight). The bird used this crucial hot second to escape, and flew off unscathed. The weasel also seemed unharmed, albeit with an empty stomach.