what's eating holes in my spinach at this time of year?

[anthea]

I got my allotment last year and soon realised the soil was very depleted. I've been focussing over the winter on getting horse manure onto it. The only plants I left in for the winter were perpetual spinach, silver beet and autumn spinach. I realised the rabbits were eating that, so have built up my fences. By comparing my spinach with my neighbour's, who has no fence, I can see the rabbits must be leaving mine alone now - it's not nibbled to the ground like his - so what IS eating it now? Some allotments have lovely shaped leaves on their spinach plants, while the leaves on mine have holes and/or big chunks missing. I didn't think slugs were active at this time of year, am I wrong about that, or, does it mean I have some sorts of pests in my soil?
Any clues very welcome, I'm dead keen to get the soil in tip top condition by the spring.
Thanks, Anthea

[anthea]

[kt.]

Could be birds feeding ::). Without a picture it would be difficult to be specific.

[natasha]

On my site slugs are active all year round :'(, they don't hibernate. it is wet and not that cold, not much food for them at this time of a year too, so they just distroy what they can find.