Chard eating birds?

I have a bit of a puzzle. My Swiss Chard and only the Swiss Chard was throughly munched on this year by something. I was not able to find any sign of insects and the damage did not look like slug damage. The leaves were eated from the outside in (from the edge of the leaves to the stems). Only these plants. I had a great growing year relatively free of pests. A friend said that sparrows will eat Chard. I had not hard that before, but we have a huge amount of feathered visitors this year (and increasing). Is this possible? I have never heard of Swiss Chards loving birds.

Getting ready to buy netting

Hello,
I have never heard of sparrows eating swiss chard, but I would believe it. Sparrows are normally seed and insect eating birds, but I see no reason why they wouldn't eat swiss chard. We have had rabbits and the occasional deer mow off swiss chard, so now we just grow it in a cold frame. This way we can have fresh chard greens all year long.
Have a great day,
David Burton