This morning I witnessed an extraordinary bit of behaviour between a crow and a lamb in the field below my house which I've never seen before. A carrion crow was persistently harassing a lamb by chasing it stealthily but with caution this action clearly annoyed the lamb as it reacted by chasing the crow with its head down in the 'butting' mode! The crow took evasive action and was not at all put off by the lambs defensive action it just took part in some 'displacement activity' by picking up some grass and dropping it presumably to give the lamb a 'false sense of security'. What happened next solved the mystery of this crows incessant interest in this particular animal. When the lamb had his back turned the crow sauntered up to it and gave its tail a couple of sharp tugs with its beak! I then saw that an elastic band had been fitted higher up on the lambs tail by the tenant farmer effectively stopping the blood flow to the tail which would eventually result in it dropping off. This of course is common practice among sheep farmers and in fact the 'severed' tails are a good source of food for kites in the spring! Anyway the crow's 'tug of war' trying to 'dislodge' the lambs tail failed as the startled lamb bolted off to a safe distance away from the crows unwanted attentions.
Postscript- Of course 'intelligence' in corvids is a well known fact but what intrigues me about this incident is what was the 'trigger' which caused the crow to behave in such a manner? I wondered whether it might have been the coloured rubber ring on the lambs tail which stops the blood flow or did the crow somehow 'know' that the tail was probably close to disengaging with the lamb's body! If anyone has any theories on this I'd like to hear them.