5 strange bird behaviours, explained

Waterbirds in the grebe family (including the red-necked grebe, pictured) eat their own feathers. They’ll even pull out their feathers and feed them to their offspring. Ornithologists aren’t entirely certain why, but one theory is that the feathers help protect the birds’ digestive tracts from other, sharper things that they eat—the bones of prey, for example.

Cardinals—both males and females—are incredibly territorial. And they’re smart enough to recognize that they’re seeing a bird in the reflection of a car window, a mirror, or any other shiny part of the vehicle. But they’re not smart enough to understand that they’re looking at themselves. Consequently, cardinals will spend hours fighting their own image, especially in the spring.

Actually, more than 200 species seem to do this. It’s called “anting” and it’s not always with ants; some birds prefer millipedes. (Shudder.) Experts believe that squishing the insects into their feathers releases natural chemical defenses inside the bugs—fungicides, for example—which helps keep the bird clean. They’re bathing in ants. Which…must be weird for the ants.

Okay, well, this behaviour does make a lot of sense once you understand that every year, this bird travels from one pole to the other (more than 40,000 km) when it migrates from wintering grounds to breeding grounds. For obvious reasons, this is a difficult behaviour to study, but one theory is that the birds can sleep by shutting down one half of the brain while the other half stays alert. It’s called unihemispheric sleep, and scientists have studied it in marine mammals. It certainly seems possible: Arctic terns spend a good portion of their flying time gliding on rising air, no wing flapping necessary. It can’t take that much brainpower to float, can it?

In fact, they’ll pull paint right off the side of your cottage in the spring. One theory why? They could be eating the paint as a source of calcium, which is necessary for successful egg-laying. Ornithologists don’t believe the jays are consuming the paint right away. More likely, they’re gathering it, storing it in their crops, then stashing it at the nest for later, when they expect they’ll need to replenish their calcium resources. Maybe they’re lactose intolerant?