What's happened ?

I live on the North Norfolk coast, up until mid June my garden feeders were visited by small flocks of Goldfinch including several juveniles. Also there were a few Greenfinch, Blue, Great and Coal Tits etc and up to 7 Blackbirds at a time. Since then virtually nothing. Blackbirds and their young usuall attack my blackberry and rapberry bushes but not this year. I have hardly seen a Blackbird for months and not a single juvenile.; they usuall feed on my Pyracantha and strip my Rowan tree of berries this time of year - this year they are untouched. The Goldfinches have all but disappeared and sightings of any Tits are now rare.

Is this the effects of avian flu already?