Triumph of the bumbarrel (aka the long-tailed tit)

Run of mild winters propels tiny bird into top 10 of British garden birds

One of Britain's most charming small birds, once known as the bumbarrel, has entered the garden birdwatch top 10 for the first time. The tiny long-tailed tit is so small – the tail is longer than the body – that it is very vulnerable to cold weather. In harsh periods as many as 90 per cent may die.

However, the recent run of mild winters (with the exception of 2009) has produced a population boom, and in this year's Big Garden Birdwatch, run by the Royal Society for the Protection of Birds, the long-tailed tit was the 10th commonest bird seen in gardens across the country – almost double the previous number.

During the weekend of 24 and 25 January, more than half a million people took part in what is thought to be the biggest natural history mass-participation exercise in the world, observing their gardens for an hour and recording all the birds that visited. This was a week before Siberian weather conditions hit Britain – and may also have hit long-tailed tits, to an extent which is not yet known.

During the observation weekend, the birds were very much in evidence, numbers having nearly doubled from 2008. An average of 1.34 long-tailed tits were seen per garden, compared with 0.71 per garden last year. They are typically seen in small foraging parties.

In Birds Britannica, Mark Cocker writes that "outside the breeding season they rove through their communal territory enveloped in a perpetual cocoon of soft, bubbling contact notes". When a party flew off, he said, "they resemble a succession of whirring sticks with globular, pink ping-pong ball foreparts".

More than 552,000 people took part in the survey this year – a record number – counting over 8.5 million birds, with a total of 73 species recorded in 279,000 gardens across the UK. The house sparrow retained its top spot for the sixth year running, with an average of 3.70 seen per garden. The starling, a former number one, came second with an average of 3.21 per garden. The blackbird completed the podium spots with 2.84 per garden.

Although remaining at the top of the list, both house sparrow and starling have suffered huge declines since the survey began 30 years ago, the former going down by 63 per cent, and the starling by 79 per cent. Ten sparrows were seen per garden in 1979, compared with 3.70 this year, while 15 starlings were seen in gardens 30 years ago, compared with only 3.21 in 2009.

All the other birds in the top 10 – blue tit, chaffinch, woodpigeon, collared dove, great tit, robin and long-tailed tit – were slightly up in numbers. "Many species have seen a very slight increase in the last year," said the Big Garden Birdwatch co-ordinator Sarah Kelly.

"The significant increase in long-tailed tit sightings highlights the impact that feeding can have on some species. They have only started coming to feeders fairly recently, and more people are seeing them as this behaviour develops. As more and more people realise the importance of feeding and gardening for wildlife we are seeing an increasing variety of birds on our tables and feeders."

The goldfinch dropped out of the top 10 rankings after its entry for the first time last year. Both the goldfinch (in 11th place) and the greenfinch slipped a place in 2009, although both species have steadily increased in recent years. Another finch, the striking siskin, which made it into the top 20 for the first time in the survey's history last year, dropped back to number 26