Puzzled

Very often the birds you don't see are just as intriguing as those you do see. For instance what's happened to our Long-tailed Tits? At the end of last year there were parties of these little gems all over the place, but now they seem to have vanished. Have they succumbed to the cold snap or have they simply moved South? Again in our garden in St.Davids we have a daily count of up to 40 Chaffinches and 20 Goldfinches but not a single Greenfinch for weeks.Not too long ago they outnumbered the Chaffinches.
On a recent trip to Austria notable absentees were Jackdaw,Rook and Starling, and for the record no Snowfinch either.