Trogons have movie-star eyelashes, and I’d always admired and wondered why they had them. My bird artist friend, Mike DiGiorgio, says, “I thought it was so they could wink at their mates.” After watching a pair excavating a nest hole in a termite ball yesterday, I have another theory.

I whiled away a pleasant hour yesterday on Barro Colorado Island, sketching and photographing a pair of slaty tailed trogons digging into a termite ball outside a lab building. There’s construction underway on BCI right now, with much shoveling, dredging, backhoe driving, circular sawing, and jackhammering. They are carving out new work space from the red clay, the barro colorado. In spite of the disruption and workers in safety vests walking around their tree, the trogons are excavating, too. The male is doing the work (wearing his red safety vest). The female sits nearby, supervising.

He digs fiercely for a couple of minutes at a time, chomping and scraping the termite nest wall with his orange bill until tired, he flies to the nearest vine loop and pants for a few minutes. I watch closely through the scope, and clearly see the eyelashes catch and shed crumbs of dirt as he digs.  That’s how I came up with a hypothesis: trogons evolved long lashes to protect their eyes during nest excavation.

Now I wonder if other burrow-digging birds have long lashes, too. I’m thinking of motmots and kingfishers and other burrow digging birds who might get dirt in their eyes.

And of course, this raises the question: why do humans have long eyelashes? Think about it. Did we start out digging caves with our teeth?

Happy Friday.