Garden birds need you. The annual Big Garden Birdwatch this weekend (on January 29-30) is of even greater significance this year as conservationists try to assess the effect of the coldest December for 100 years on smaller birds.

The RSPB will particularly be looking out for sightings of small-bodied birds such as the wren or long-tailed tit, which can struggle in freezing conditions. Other birds come off badly from competition at the bird table, and the survey can be a useful checklist for the balance of Nature.

During the last 30 years, the Big Garden Bird Watch has provided a useful snapshot into the rise and fall of common bird numbers. Most recently, starlings and house sparrows have showed a decline.

Last year, the most commonly seen bird was the blackbird, in 96.3% of gardens, followed by the robin and blue tit. The rarest sightings were of bramblings, stock doves, tree creepers and willow tits. About 20 species tend to be spotted per county, with a few regional variations for water birds and pheasant.

Birds recorded should be actually in the garden, in their highest numbers during a one-hour period, and not flying overhead. Visit the RSPB website for further information.