Our mystery today comes to us from regular reader, Connie. Thanks, Connie!
Yes, it’s those little blobs, about the size of a small acorn.
I’ll check back later for your guesses, but if you’d like a hint, scroll down:
Hint: Connie found these on her pontoon boat.
One brave reader guessed that these particles were the stuffing from the boat. No, but that was our first guess, too! No mice or insects were burrowing inside. This was deposited on the boat and appears nearly every morning, Connie tells us.
And every morning someone visits the boat.
If the light is a bit too dim for you, here’s another photo.
That’s a Great Blue Heron. A very old one, we believe, because his beard–the feathers trailing from his neck–is full. Now we squirrels had heard of owls regurgitating pellets of fur and bones after they eat, but not herons, so we did a bit of research. Turns out herons do as well, and it’s called “casting.”
If you look closely, this deposit, or regurgitation, contains small fish bones and scales!
Herons also have a throat pouch. When they have young in the nest, they swallow a fish or two and carry them back to the nest and regurgitate them for the young birds. Young birds might do the same if a predator attacks their nest to frighten it away.
Want to learn more about Great Blue Herons? The Cornell Lab of Ornithology has a camera on a heron nest and answers many questions about these birds on their Bird Cam FAQ website.