They're voles and good luck getting rid of them. I've tried for years.

Yes, you have voles. After the snowy winter of 2010 we had a population explosion, but finally this year they are under control and we finally got a full crop of potatoes. Trapping is impractical because they live underground. You can probably locate several runs coming into your carrot bed by poking around with a stick -- the tunnels are only a few inches down. You can try stuffing onion peels and aromatic herbs in the runs, and smashing down obvious tunnels. But since the voles know about your carrots they may keep eating them anyway. They love potatoes, parsnips and beets, too.

Hunting cats and digging dogs are the best controls.

hmm bummer :( sounds like I need to pull my carrots if I want to eat them myself... at least I grew way too many, that should make up for their size, lol.

Believe it or not, the best remedies for voles in my garden are owls and rattlesnakes. For that reason, I never use poison on the rodents, because that will kill the owls that prey on them. The snakes are harder to coexist with, but it's a lot better than losing everything to voles. So far, no snake bites.

Here is a link that might be useful: Alan Chadwick

In my previous garden I had numerous voles problems, and as soon as I would goon vacation snakes would move in. But they will not stay if you visit the garden even every second day and I did have to poison the voles eventually. I tried for a long time to establish owls, building a box nest out from a design on the Internet. No luck. The only sustained respite was when a female fox had a burrow at the end of my property, but at some point she moved on too.

We had the shoulders munched off most of our carrots a couple of years ago. Last year the carrots were untouched, but this year again, we have a couple of rows that are munched again. The teeth marks are obvious in places and they're larger than mice. Moles? Anyway... we have rows that we were more diligent about weeding than others. Those areas where you can see the ground between the rows are un-munched. Carrots are fine. The rows where the weeds got away from us, where there's a nice low canopy where whatever-rodent-it-is can maneuver unseen by predators, the carrots are munched. Obviously, we need to keep up with the weeding, but next year I'm also going to put an extra foot between my carrot rows as extra protection. I'm hoping that will do the trick. We don't have many snakes here, only very small garden snakes that we rarely see (maybe once every two or three years). We've got loads of owls and hawks and other birds of prey, though. I need to make sure the birds can see around the carrots so the moles (or whatever they are) don't feel safe in the rows.