Buy wooden dolly pegs and see if they like them.
I forgot to get back about this thread I have been a bit busy so have not been doing so much washing, but the wooden ones seem to be holding up so far.
Wood pigeons are pretty dim. They don't have the opportunistic decision making ability of the average crow. Crows tend to be aggressive being predators and scavengers. Wood pigeons are usually timorous and easily scared away, as lots of creatures eat them. Surprisingly, the other day I saw a wood pigeon chase off a magpie in a dispute over a hunk of bread in the garden. Maybe it was a bit of a territorial thing, too where the wood pigeon perhaps felt it had the rights in this case. Assuming it has the brain power to actually process that concept.
I can see how crows and magpies might find clothes pegs interesting, as they seem to like to manipulate objects with their powerful beaks, especially if they can crunch them, but if a wood pigeon can't eat something, it usually loses interest.
Actually, talking of confidence, we have lots of baby blue tits and other small birds. At first, the pigeons, crows and magpies scared them away, but they are getting bolder now and will now share a feeder with a bigger bird!
I wonder if there's something nearby that attracts the crows like a rubbish dump. Perhaps the pegs in the OP's garden are just a bit of light entertainment once they've eaten and are on the way back to their roost?
We live near to a large park and golf course, not to mention in an urban setting. The dump is quite a distance off.
My neighbour has been feeding the birds for years (as have I, on and off), so I think they have just learned. Also I had a lot of seed which the birds never touched in the feeders, but when scattered on the grass, they loved it. Whenever anything lands on the ground now, they are right in there like a shot.
They have also learned to stand below the feeders and collect what one on the feeder drops.
They are, of course, all feeding their chicks - Even crows don't just 'appear'.
Anyway, I have now learned, after seeing my neighbour's feeders empty for a while (and mine full) that he has stopped feeding the birds to deter the big birds, so I am in something of a quandary, because I need to help him deter the crows and a so on, but, the young birds need a bit of help and I don't want to make them go away completely, especially the more unusual species like the Woodpeckers!
Reminds me at our last factory, they placed a plastic, life sized owl with a moving head for reality on the roof where they were getting lots of bird nesting problems.
I walked up the yard one day to see a pigeon sat a foot away from the supposed deterrent.
Well, that worked well....
Oh, they aren't daft (relatively speaking).