I thought I had some kind of insect eating my chard. However today I noticed that the culprits were my goldfinches! I know the goldfinches don't eat insects and I definitely saw them tearing out the tender portions of the chard between the veins. Not that I mind too much I have enough but I'd never seen this before.
I only had my cell phone camera so I didn't get the birds but this is what the chard looks like.
Grik - I have also noticed this. We have a thistle feeder in front of our living room window, which is surrounded by a shrub/perennial garden, and I planted a few extra chard starts there just for kicks, and one fine summer day I was surprised to watch the goldfinches tear off little chunks of chard and eat them.
Just saw this thread. I luv Swiss Chard and grow it as well but had never noticed the goldfinches eating it here. And we are loaded with goldfinches. I have a thistle feeder too and they also love the sunflower seed feeder. This year has been so warm though that I think they have been able to get at least nibbles of green things all winter. I wonder if weather has anything to do with it ... or if they just have good taste and love chard. :)