The mild autumn weather has meant late sightings of summer migrants, late broods of young for birds like blue tits and empty feeders as birds were still finding food further afield.
Derek Brockway is warning of unsettled and changeable weather ahead with some short, sharp cold snaps which could have a significant impact on the needs and behaviour of garden birds.
Dana Thomas from RSPB Cymru, says: "The sudden change in weather almost certainly means that garden birds will start to turn up in gardens en masse one again, hoping to find supplementary food and water."
Blue tits on a feeder by Eddie Evans.
"Typically, this would have happened a few weeks ago, but it is just a bit later than usual. Once icy conditions set in, natural food like berries and insects are almost impossible to find so the extra treats we put out are really important."
"We may not be in the bleak midwinter just yet, but if the temperatures dip significantly, as is predicted, it will instantly become a tough battle for survival for lots of birds. Make sure you put out a little bit of extra food, and water to make their lives a little easier."
Bird food like seed mixes, peanuts and fat balls, leftovers like grated cheese, porridge oats, soft fruit and cooked rice and pasta are all ideal.
Water is also vital for both drinking and bathing and bird baths can be kept from freezing over using small floating items like twigs or ping pong balls.