Dec 22nd 2010, 13:48 by The Economist online
FEEDING birds sounds the sort of thing that no one in his right mind could oppose. In Britain, the world capital of amateur ornithology, roughly half of households put food out for their feathered friends, and it is estimated that around 30m of the country’s birds are given nourishment this way every year. Other places are somewhat less generous, but the general principle holds. Encouraging birds is good, and what better way to encourage them than to feed them?
Science is nothing, however, if it is not iconoclastic, so one scientist, Valentin Amrhein of the University of Basel, in Switzerland, asked himself if feeding birds this way really is good for them. The answer, it turns out, is “no”—at least, not always.
Dr Amrhein’s team conducted their study in the suburbs of Oslo, in the spring of 2007. The objects of their attention were 28 male great tits, each of which was observed at dawn three times, with 16-17 days between the observations.
The first observation took place in the absence of supplementary food. Immediately afterwards, a feeder was provided within the observed male’s territory. Half of these feeders were kept filled with food, but half remained empty. Full or empty, each feeder was left in place for 16-17 days, at which time a second observation was made and the feeder was removed. The third and final observation was made 17 days after this.
The object of the exercise was to look at the effect of feeding on a male’s performance in the dawn chorus. This chorus might sound lovely to human ears, but it is a gruelling challenge for birds. Males have to get up early and, having fasted all night, expose themselves to extreme cold while singing their little hearts out to show females that they are worth breeding with. In general, those males that start singing long before the sun comes up get the best mates and best defend their territories from rivals.
Dr Amrhein expected that males who were being given extra food would perform better during the dawn chorus than those that were not. To his surprise, he discovered exactly the opposite. Those who received food supplements got lazy. He and his colleagues report in Animal Behaviour that 36% of the males whose feeders were filled started singing only after the sun had already come up. Among the birds without this extra food, that happened only 10% of the time. Moreover, the effect was sustained after feeders were removed, for it was still apparent at the time of the third observation.
Why extra food has this effect is unclear. What is clear is that delaying dawn singing is a dangerous game for males to play. The worm is not the only thing caught by the early bird. Fat and lazy tits risk losing out on a mate, as well.
In this blog, our correspondents report on the intersections between science, technology, culture and policy.
Follow Babbage on Twitter »
Advertisement
Over the past five days
Over the past seven days
Advertisement
Subscribe to The Economist's free e-mail newsletters and alerts.
Subscribe to The Economist's latest article postings on Twitter
See a selection of The Economist's articles, events, topical videos and debates on Facebook.
Advertisement
Readers' comments
The Economist welcomes your views. Please stay on topic and be respectful of other readers. Review our comments policy.
Sort:
An interesting topic worthy of investigation, but surely no conclusions worth mentioning can be drawn out of a study of 14 individuals (half the population was the control group).
Also, when commenting on research like this, it's invaluable to have a link to the actual research paper, so that readers can make up their own minds. (Presumably it's this: http://www.camargue.unibas.ch/anim_behav2010.pdf)
Another result of the study was that while 79% of the fed males managed to make their females lay eggs, compared to only 64% in the control group.
More research needed.
@popup
Excellent point, and one which a science writer should always be aware of. Saying that one study of 28 of a single species of birds in a single city can tell you much of anything about bird behavior in general is grossly overreaching.
We don't feed birds, but we do feed possums. In our neighbourhood in inner Brisbane, many large, treed blocks with lush sub-tropical gardens have been transformed into generally tree-less multi-dwelling sites. There has been a notable disappearance in the last few years of some species, such as blue-tongued lizards and water dragons, and an increase in possum visitors seeking porridge oats. Still plenty of birds of many varieties.
"The objects of their attention were 28 male great tits..."
That would attract anyone's attention. ;)
@Genghis Cunn, not sure what to make of your comment. That's very discouraging, the notable disappearance of some species in your neighborhood.
Food vouchers for the poor(human types) have the same effect.
Ole Geiser wrote: Feb 15th 2011 9:58 GMT
Food vouchers for the poor(human types) have the same effect.
For singing at 3am or egg laying?