Bird Diapers?

Not really, but kinda…

A Bewick’s Wren emerges from its nest with a fecal sac. Photo by Carol R. Comeau

When I was working at the outdoor school Camp KEEP a while back, I was notified by an adult chaperone that a kid had defecated in the shower. For those of us who work at outdoor schools we know that’s not uncommon. Kids away from home for the first time sometimes have issues using a group bathroom to conduct that task and try to hold it in, unsuccessfully, for days. Eventually, as the week progresses, reality sets in; and with the warm water cascading upon them, and the pressure building, they can no longer hold it, and, well …it happens.

We have a whole protocol for cleaning it up and sanitizing the space, but when I went in that day, I realized I needn’t worry too much about a mess because the material was quite compact, and as a dog owner, I was prepared. The mutt mitt I always have in my back pocket was the perfect solution. I’ve found those bags to be quite handy, and not just for dog poop! They can also be used in a pinch as a water bowl for the dog, or to wrap around a slimy ball to transport it home in my pocket, or… for use in a camp shower after an accident!

If someone had told me twenty years ago that I’d be following my dog around with a little bag in my pocket for when he pooped, I would have laughed at them and told them they were out of their minds. Yet that’s exactly what I do now. I get it, I think it’s a great invention, a sack for disposing of feces. But the thing is, we didn’t invent it; birds have been doing it for centuries.

Oak Titmouse with a fecal sac. Photo by Carol R. Comeau

Baby birds eat a lot, and what goes in must go out. The problem is if they were to just hang their butt over the side of the nest and let it go it would create a smelly mess that could attract predators. Not really a problem for birds that nest high in trees, on cliffs, or that have young that are precocial and can walk around soon after hatching (ducks, quail, shorebirds and the like). But for birds that nest lower, or on the ground, that’s an issue. For cavity nesting birds it’s pretty much a physical impossibility for young to poot it out the hole. So, to keep the nest nice and tidy, baby birds excrete their waste wrapped up in a mucous membrane, a fecal sac.

The parents, after feeding their youngsters, will pick up any fecal sacs left in the nest or excreted by the young after feeding. At times merely the act of eating stimulates production of a sac, or the parents will sometimes poke or prod the babies to get them to poot* one out (*Technical note: poot actually means an emission of intestinal gas from the anus, but… you know what I mean). Once the adults pick it up, they’ll fly off and dispose of it away from the nest or, and here’s a fascinating fact, they’ll eat it. Yup, you don’t have to go back and re-read that, they eat it. The eating of poop is called coprophagy and is practiced by all sorts of animals (maybe that will be a future Rumination).

The adults will eat the fecal sacs for the first week or so of the babies’ lives. It makes sense, as the baby birds’ digestive systems are not fully developed, and their diminishing yolk sack is still providing some nutrients. Therefore, the feces still have nutritional value. Plus, the young have not developed enough bacteria in their digestive system to be a problem for the adults. Although some species will consume them for the entire time that the young are in the nest.

Once the sacs are produced (and the adults are not consuming them), they will carry them off a fair distance away from the nest and drop them. Grackles are famous for dropping them in water like a river, lake, or, as some homeowners have found out, swimming pools.

So, there you have it, it’s not just in the human world where adults are always cleaning up after their kids.