Years ago I used to work fir an engineering company...we used to stock pile big chunks of steel in the yard and every year pied wagtails would nest in the steel....one year they nested next door on the steps going up in to a big truck...literally just on the step in plain view...the truck was stood for a week or two....then one day it had to go out...so the nest was moved ...then when the truck came back they put the nest back on the truck...the birds didn't seem to bat an eyelid....everyone was looking out for them to be honest ...and keeping the local cats away...