Male robin catches fecal sac eliminated by a nestling

When the Poo Piles Up

Globs of disgusting doo dotted our gate.

The poo’s origin was no mystery. Robins had nested overhead, on our pergola. But still, I wondered why I was seeing so much of the sticky stuff. Robins, like many bird parents, remove their nestlings’ excrement after each feeding. It comes out wrapped in a fecal sac—a convenient package that parents swallow during the first week and then carry away from the nest as fecal quantities grow. In addition to helping keep the young ones healthy, nest sanitation minimizes any scent trail that might lead predators to the nest. And yet, just a few feet directly below the nestlings lay a stinking pile of poop.

Was I looking at the dereliction of parental doo-ty?

I began filming to find out.

What goes in…

I was certain I’d see some sanitation shortcuts. Maybe the parents figured ‘mostly clean’ was clean enough and didn’t always scoop the poop. Or when loads grew heavy, perhaps they dropped the doo overboard instead of winging it away.

Food goes in and inevitably comes out. Note the remnants of white fecal sacs.

I filmed steadily for days, before, during, and after feedings. Here’s what I saw, over and again:

The kids pooped consistently within seconds of eating. With each feeding, one or both parents took care to swallow or carry off some fecal sacs. I couldn’t tell if there was a complete count of sacs each time, so as I filmed, I couldn’t rule out that some sacs were left behind.

And then, there was this interesting feed-and-clean sequence:

Dad spotted what Mom had missed and diligently retrieved the errant sac. I think this scene shows the parents were not sanitation slackers at all. Mom’s eyes just didn’t see when one poop sac plopped.

I’m still a bit puzzled, however. If sac removal is a predator-avoidance strategy, why didn’t the parents remove the poop piling up just four feet below the nest?

When we took down the nest after the nestlings fledged, it was surprisingly clean. So, even when a sac was missed, or if a nestling pooped outside the normal feed-and-clean schedule, the parents at some point must have discovered the poo and did their doo-ty. Why, then, leave it on our gate? Maybe they assumed the resident humans would take care of that. Which we did, but not until after the fledge, fearing we’d spook the robins needlessly by scraping and scrubbing so close to the nest. Seriously, though, leaving that scent trail makes no sense to me.

Even so, I’m giving this robin mom and dad credit for faithfully executing their parental duties. I have to believe the parents noticed the errant poo. But as a parent myself, I can relate. Keeping up with the kids can be overwhelming.

I have one final thought: The American Robin’s scientific name is Turdus migratorius. Is there some cheeky scientist humor at work here? No, but the thought is giggle-worthy for sure. I checked the etymology of that name and learned that Turdus comes from the Latin word for thrush. Robins are in the Turdidae, or thrush, family. Merriam-Webster online notes that turd has been used since before the 12th century and has its root in the Old English word tord, meaning dung. Still… considering the quantity of said dung that migrated to my gate, doesn’t the robin’s scientific name seem particularly apt?

I doo hope you will share this post with the nine-to-twelve-year olds in your life. As you’ll see below, I’m also recommending a fantastic poop-science book written for that group.


In this Audubon article, fecal sacs are likened to diapers. The author explains that not only is fecal sac cleanup important for sanitation and to avoid leaving a scent trail, but scientists suspect the sacs may also offer nutritional benefits to the parents. Yum…

Here’s the Audubon Field Guide to the American Robin.

A Terrific Related Kids’ Book

With this blog post, I’m suggesting kids read Who Gives a Poop? Surprising Science from One End to the Other, by Heather L. Montgomery.

This nonfiction book is geared for kids aged 10-14 years, grades 4-6. Readers will find out that poop science is indeed quite surprising! Montgomery explains how scientists use feces to ferret out answers to serious puzzles and important research questions. The science is front-and-center, and so is the fun. Montgomery’s writing is kid-friendly: lively, loaded with puns, and often irreverent. She even includes a poop lexicon. ‘Grow your vocabulary with this list,’ Montgomery says, ‘but don’t forget to mind your manners.’ Readers may be inspired to scout for scat, one of the discovery activities Montgomery suggests for inquisitive readers. I highly recommend this book. You can find it at your local bookstore or at, where your purchase also benefits independent booksellers.

Image Credits: Carol Doeringer.

3 thoughts on “When the Poo Piles Up”

  1. WOW. I never knew they carried away the fecal sacs. I have written a PB bio about a woman who allowed bluebirds into her house and I’ve always wondered why there wasn’t more mention of how dirty her house became. There was a mention once about her capturing their poo in a spoon. Now I get it.

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