Transcript:
Thanks for listening to Interlochen Public Radio. I’m Cheryl Bartz with a quick look at What’s Up Outside.
I enjoy finding animal sign, whether it’s tracks or scat or holes in the ground. It’s the next best thing to seeing the animal itself.
Each sign presents a little mystery. Can I figure out what animal made it?
The first time I saw a crayfish hole, I was stumped. It was a fairly large hole – more than an inch in diameter, close to a river. I had to consult the internet for the answer.
Michigan has ten species of crayfish and they have varied habits. Some live in holes they dig and some hide under rocks or vegetation on lake bottoms.
And at least one species builds little volcanoes. At least, they’re shaped like volcanoes. Cones can be around 3 inches tall, with a base about as big as my outspread hand.
The walls are built of uniformly sized mud balls about the size of cherries.
I saw one of these recently for the first time and figured it was a crayfish hole. But what kind? The paintedhand mudbug builds this kind of chimney. They have big claws, well-suited to digging.
They spend most of their lives in their burrows and prey on insects and small animals that pass by.
The biggest threat to Michigan’s crayfish are two non-native species that have been introduced to Michigan’s waters: the rusty crayfish and the red swamp crayfish. They’re big, aggressive and grow quickly so they can out-compete the natives.
They likely got into our lakes and streams as escapees from bait buckets.
There was a lot of human activity around the little volcano I saw the other day, so I didn’t wait around for the resident to poke its claws out of the hole. That’s a pleasure I will save for another day.
You can see my photo of the crayfish volcano at Interlochen Public Radio dot org.