Cuckoos have declined drastically in the UK in recent years and it has now been suggested that the harbinger of Spring should be the chiffchaff, which is on the increase and arrives in April. Pretty unmissable as well, as it's song is the same as it's name, eponymous I think the word might be. The other bird on the increase in the UK is the buzzard. Used to be a bird of Wales and the West Country, but I saw one in Kent last week and have heard of them starting to nest in the South East. Have also seen a big cat in Kent a few years ago when driving back from the folk club - and yes, I was still sober. Looked like a panther as it hit the road in front of my car and bounced off into the bushes at the roadside - I can still see it's big green eyes caught in the headlights - fair took me breath away!