Sods' Law for the birds

We recently had our garden returfed, as the grass had degenerated into 90% weeds. Just as last time we did this, within the next few days we found on several occasions that the local birds had succeeded in turning over some of the the squares of turf, presumably to get at the bugs or other tasty morsels beneath them.

I don't know which bird is doing this, but as each piece is about one foot square, it must take quite a bit of strength. Does anyone know if this is common behaviour for birds? And which species might be responsible?