Robins and wrens: harsh winter hit resident UK birds

Fewer robins were recorded after last year's harsh weather

Resident British birds struggled in the 2009-2010 harsh winter, while migrating birds benefited from the break, says the British Trust for Ornithology.

The latest results from bird-ringing studies co-ordinated by the BTO showed that many resident bird populations fell significantly after the harsh weather of last winter, while the numbers of many returning migrant species were higher than average.

The conclusions are based on 70 sites across the country where volunteers caught and counted the birds.

The volunteer bird ringers caught 27% fewer robins and 20% fewer wrens compared to average catches over the previous five years.

Wrens suffer due to their small size

Dunnock and Greenfinch numbers also fell.

David Leech from the BTO said that some of the over-winter residents were may not have survived the particulaly harsh 2009-2010 winter.

"A wren is very small and it loses heat very quickly," he told BBC News.

"And something that feeds on insects and on the ground will experience problems when there's a snow covering."

Migrant species fared much better.

Blackcap, whitethroat and reed warbler numbers were higher than average and many migrant species produced significantly more nestlings than in recent years.

Migratory willow warblers fared better

This included the willow warbler, which is on the BTO's "Amber List" because of the moderate decline in its population.

"The cold, wet summers of recent years do make you wonder why some of our migrant birds even bother coming back" said Greg Conway, organiser of the trust's Constant Effort Scheme for bird-ringing.

"The 2010 breeding season was a complete contrast, however, with good numbers of birds returning and producing bumper broods."