[Marika (OP)]

Nikolaus wants to know:

In my garden, I see blackbirds picking into the soil and (sometimes) pulling out an earthworm. On rainy days, I see hundreds of earth worms on the pavement, yet no birds taking advantage of this free all-you-can-eat buffet. How come? Can birds not recognise earthworms by shape on the roads?

What do you think?