Dr. Navtej Kohli Blog

Feeding birds with peanuts and other treats helps them to survive the coldest months but could affect migratory species, which are in decline, according to a study published recently.

For the first time, scientists have produced hard evidence to show that the extra food we provide garden birds in winter makes for a more successful breeding season in the spring.UK and US households provide some 500,000 tons of food for garden birds each year.

With enough bird food sold in the UK to sustain more than 30 million great tits just eating the supplementary feed, householders putting out nuts and seeds may have a substantial impact on numbers of birds such as finches and tits, because chicks from earlier broods are more likely to breed and gain territory the next year.

But it may also have a knock-on effect on other species - for example migratory birds which could face increased competition from species fed in the winter when they return in the summer, according to the study the University of Exeter and Queen’s University Belfast, published  in the journal Biology Letters.Dr Stuart Bearhop, of the University of Exeter, says: “While this research shows how the extra food we provide in winter helps the birds that take it, it is still unclear whether this has a knock-on effect on other species,” he said, referring to migratory species, such as willow warblers and pied flycatchers which have seen declines in recent years.However, the effects of climate change and the rise of modern farming in Africa are also significant. “This is something we are keen to investigate, but in the meantime I will certainly be putting out food for garden birds for the rest of the winter.”Dan Chamberlain of the British Trust for Ornithology, which collaborated on the project, also urges bird lovers to keep feeding them. “These results demonstrate that feeding birds in gardens over winter can be vital to their breeding success.”It is highly likely that the benefits of extra food continue year-round, so don’t just stock your bird feeders in winter if you want to do the best for the birds in your garden.”

The study compared 10 deciduous woodlands in County Down, Northern Ireland, which were either assigned a series of wire mesh feeders hung from trees and kept supplied with peanuts or left with no feed from the beginning of November to early March. Nesting boxes were also provided and monitored, most of which were used by blue tits.By providing some birds with extra food and leaving others to fend for themselves, the team was able to compare productivity between the two groups. Those that were given extra food laid eggs earlier and, although they produced the same number of chicks, an average of one more per clutch successfully fledged.