Study reveals uncertainty over the benefits of feeding birds in winter

Jun 24, 2013
Two blue tits are shown at a fat feeder in winter. Credit: John Harding/BTO

Wild bird populations are generally thought to benefit from being given additional food in winter but our understanding of the effects of such food provision is incomplete. The results of a new study, carried out by researchers at the University of Exeter and the British Trust for Ornithology (BTO), has found that feeding wild blue tits in winter resulted in less successful breeding during the following spring.

The research, just published in Scientific Reports, revealed that woodland blue tits that were provided with fat balls as a supplementary food during the months went on to produce chicks that were smaller, of lower body weight and which had lower survival than the chicks of birds that did not receive any additional food.

Dr Jon Blount from the University of Exeter who led the research said: "Our research questions the benefits of feeding wild birds over winter. Although the precise reasons why fed populations subsequently have reduced reproductive success are unclear, it would be valuable to assess whether birds would benefit from being fed all year round rather than only in winter. More research is needed to determine exactly what level of additional food provisioning, and at what times of year, would truly benefit wild ."

Dr Kate Plummer, lead author of the paper, said: "There could be a number of different explanations for our results. One possibility is that winter feeding may help birds in relatively poor condition to survive and breed. Because these individuals are only capable of raising a small number of chicks, they will reduce our of breeding success within the population. But more research is needed to understand whether winter feeding is contributing to an overall change in the size of bird populations."

A young blue tit chick is getting ready to fledge the nest in spring. Credit: Christine M Matthews/BTO

It is estimated that around half of UK householders feed birds in their gardens. This equates to around 50-60 thousand tonnes of bird food provisioned each year and contributes to a thriving bird food industry.

Jane Lawler, Marketing Director at Gardman, commented: "As the wider scientific evidence shows, feeding wild birds with appropriate foods delivers a range of positive benefits. A number of unanswered questions remain, however, and this is why we have been supporting this and other research, using the information gained to inform our products and the advice that we provide to our customers."

An adult blue tit is on the hunt for caterpillars to feed its hungry chicks. Credit: John Harding/BTO

The three year study was conducted across nine woodland sites in Cornwall. During winter, populations of were left unfed, given plain fat balls or given fat balls enriched with vitamin E – a vitamin commonly present in bird food such as nuts and seeds. Nest boxes and bird feeders were distributed around the woodland study sites and was investigated by checking the nest boxes in the spring to determine the number of eggs laid and the growth and survival of .

Studies elsewhere have shown that feeding wild birds in winter can have almost immediate benefits for survival and can enhance future breeding success, so the latest results provide important new information and inform the debate around the role that feeding may play in their population processes. Whether providing food is detrimental or beneficial to wild bird populations, it is clear that more research is needed to better understand its effects.

Explore further: Sexual selection isn't the last word on bird plumage, study shows

add to favorites email to friend print save as pdf

Related Stories

Feed the birds: Winter feeding makes for better breeding

Feb 06, 2008

Keep feeding the birds over winter: that’s the message from research by the University of Exeter and Queen’s University Belfast, published today (6 February 2008) in the Royal Society journal Biology Letters. The study ...

Blue tits provide insight into climate change

Apr 15, 2013

( —Researchers believe that the size of birds' nests created in response to changing weather patterns may be partly to blame for reproductive failures over the last two years.

Bird poo study to help Great Bustards thrive

Dec 17, 2012

Move over Gillan McKeith – scientists at the University of Bath are studying the droppings of Great Bustards to help understand their diet and nutrition with the aim of boosting their survival in a conservation ...

Food for thought

Apr 03, 2008

Millions of people tend bird feeders in their backyards each year, often out of a desire to help the animals. But a new survey of research on the topic finds that feeding may not always bring a positive outcome for the birds.

Recommended for you

A peek at the secret life of pandas

Mar 27, 2015

Reclusive giant pandas fascinate the world, yet precious little is known about how they spend their time in the Chinese bamboo forests. Until now.

Flocks of starlings ride the wave to escape

Mar 26, 2015

Why does it seem as if a dark band ripples through a flock of European starlings that are steering clear of a falcon or a hawk? It all lies in the birds' ability to quickly and repeatedly dip to one side to avoid being attacked. ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

1 / 5 (6) Jun 24, 2013
This makes some sense: we tend to feed them without understanding their nutritional needs. Giving birds only bread and various seeds does not offer the proteins they can get from insects. We tend to forget that birds are not vegetarians, and need meat in their diets... fat balls are not usually from the sorts of critters birds prefer to eat. Also, feeding birds tends to make them lazy and may affect their overal health... But still, I do enjoy the bird songs... and feeding them gets me a chorus of hungry birds in the mornings...

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.