Birding: Secreats from the kingfisher's nest

"That's too much information," the man told me. "I've gotta run."

I was halfway into answering a question about kingfishers. (If you ask me a bird question, I will try to give you a complete answer.)

Why this kingfisher interest? In 50 years of looking, give or take, I've found two kingfisher nesting burrows. One was in a private sand pit. The other, found in early May, is in a municipal maintenance yard.

Following the bird's rattling call, I watched a kingfisher disappear into a fist-sized hole on the steep side of a large dirt pile. Dumb luck. I was given permission to observe.

Belted kingfishers are common throughout North America. They are shy birds, easily disturbed. You often see them flying away, the distinct call trailing.

You can find them on power lines over rivers, on bridges, boat ramps, lakeside light posts, anything with height and diving opportunity. Their fishing technique is to plunge.

The birds are blue and white, larger than blue jays, sleek in flight, with large heads and heavy bills. Males carry one broad blue stripe across the breast. Females have two stripes or belts, one blue, one red.

That's an oddity. In most bird species the male is decorative, the female cryptically dressed for anonymity on the nest. Of course, kingfishers nest deep inside a burrow. Being seen on the nest is highly unlikely.

It is thought the red band might be defensive, a visible way to inform a male that the bird approaching is a female, a possible mate, not a competitor looking for a fight. Male kingfishers are very defensive of territory, in a rush to challenge.

Kingfishers dig long burrows in soil or sand. At the end is a chamber where eggs are laid and chicks raised. Kingfishers have two webbed toes on each foot, used to scrape the tunnel. Work can take a week.

Kingfishers mostly eat minnow-sized fish — scales, bones, everything. They feed baby birds a partially digested fish slurry.

Adult birds make pellets of scales and bones, much as owls and gulls do with undigestible parts. A vigorous cough accommodates disposal.

Chicks cannot do this. It takes three weeks to fledge. The usual family of six or seven kingfisher chicks coughing up pellets for three weeks in that burrow would be unmanageable. But chicks are born with a very acidic digestive system. Everything is dissolved. (The digestive system switches to alkaline when the chicks fledge.)

Most baby songbirds (kingfishers are songbirds) deliver waste in fecal sacs, neat packages that adult birds pick up and carry away.

But kingfisher chicks are like owl, hawk and eagle chicks. No fecal sacs. They simply raise their butts, point and squirt. Where in that crowded nest chamber do baby kingfishers aim? At the walls. Then they turn to peck dirt down and cover the mess. The burrow remains inhabitable.

How did that come to be? It's been an effective solution for as long as kingfishers have existed. But how did it become part of the bird's genetic map?

Kingfishers are interesting birds. I would've stayed to hear the full story.

Read Jim Williams' birding blog at startribune.com/wingnut.