When a species is quite difficult to catch, you have to make the most of bizarre opportunities. Over the last couple of years our local paintballing site has developed a few holes in the 'roof'. Rooks from the local rookery have taken advantage of this and regularly 'break in' to feed on the unexploded paintballs. The balls are relatively harmless; a polyethylene glycol shell with a gelatin and water-soluble paint filling.
So the birds can get in easily enough, but find getting out more difficult! Over the years we've caught a good number, using a net slung at roof level on a simple pulley system. The results have been interesting, and we even have some regular offenders (one bird was now been liberated four times). Its interesting that these aren't stupid juveniles, as one bird had been ringed as a nestling in the local rookery 11 years ago!
So yesterday we caught a few more, and have now started colour ringing these to track them back into the rookery. They really are amazing birds, and do actually do interesting things.... Of the 63 foreign-ringed Rooks found in Britain and Ireland, 45 were pre-1960, with none in the last nine years. Most come from The Netherlands (23) and Germany (20), but from as far as Finland (2), Lithuania (5) and Russia (5).
Thanks to Mark Hulme for the photos, and to Kate and Amy for helping to catch the birds!