Early bird catches the worm...for dinner

Oct 10, 2013
Early bird catches the worm... for dinner
A great tit in Wytham Woods.

(Phys.org) —Birds, such as great and blue tits, scout for food in the morning but only return to eat it in late afternoon to maximise their chances of evading predators in the day without starving to death overnight, Oxford University research has found.

This 'early bird' strategy was revealed by a team studying the winter foraging behaviour of birds in Wytham Woods, near Oxford. The researchers fitted over 2,000 birds with tiny PIT radio tags. They then used 101 feeders which detected these tags and captured the exact time individual birds found each feeder. By moving 36 of these feeders around the forest throughout the day, and recording the results, the team showed that birds gathered information about new sources during the morning so that they could then eat it later in the day.

The birds studied were a mixture of (Parus major), blue tits (Cyanistes caeruleus), marsh tits (Poecile palustris), coal tits (Periparus ater), and nuthatches (Sitta europaea). A report of the research is published in the Royal Society journal Biology Letters this week.

'Birds have to store body fat to avoid starving during the cold winter nights, but this can make them slower and less manoeuvrable so that they are more likely to be caught by predators,' said Damien Farine of Oxford University's Department of Zoology, who led the research. 'So there is a trade-off, where birds need to remain lean enough in order to "outrun" their predators, or at least the next slowest bird, during the day but also store enough fat to survive each night.'

The team knew from previous studies at Wytham Woods that, when the predation risk appears high, birds delay putting on fat until late in the day. The researchers wanted to test the idea that, instead of simply 'idly waiting' until the afternoon, birds were actively seeking out new sources of food to work out where their next meal was coming from.

'We used new tracking technologies to investigate how great tits, , and other common garden birds balance the competing risks of predation and starvation,' said Damien Farine. 'Our results show that these birds display very different patterns of food discovery in the morning and afternoon – very few new food sources were found during the afternoon, whereas nearly every new food source that we put out during the morning was quickly discovered. It supports the idea of an "early bird" strategy of scouting for food early on so that they can return to feast a couple of hours before dusk in preparation for a long winter's night.'

Winter is a tough time for small garden birds as not only is there less natural food available but their predators, such as the sparrowhawk, are keen to stock up their own fat reserves and so are hunting every day. The short days and long cold nights mean that small birds can lose around 10% of their body weight over a single night so that individuals failing to pile on the grams on even one day can starve and won't be around to pass on their genes the next summer.

'Because small can't reproduce without surviving the winter, they have evolved a complex set of behaviours that enables them to maximise their chance of both surviving and avoiding starvation,' said Damien Farine 'It's a good example of how animals alter their behaviour to respond to constantly changing environmental conditions. It also shows how new technologies, like tiny PIT tags, are enabling us to explore questions about animal survival strategies at an unprecedented scale.'

Explore further: 'Shy' male birds flock together—and have fewer friends

More information: rsbl.royalsocietypublishing.or… content/9/6/20130578

Related Stories

'Shy' male birds flock together—and have fewer friends

Sep 17, 2013

Male birds that exhibit 'shy' social behaviour are much more likely to join flocks of birds with a similar personality than their 'bold' male counterparts, a new study has found. But shy birds also have fewer ...

Bright birds make good mothers

Aug 13, 2013

Female blue tits with brightly coloured crowns are better mothers than duller birds, according to a new study led by the University of York.

UK garden bird avian pox virus spreading

Aug 04, 2011

A team at the Zoological Society of London, led by Dr. Becki Lawson, is tracking an increased spread of an avian pox virus that is rapidly moving through the UK and affecting the great tits. Researchers are asking the public ...

Big personality birds find the best homes

Apr 18, 2011

(PhysOrg.com) -- Birds willing to move around and take risks are better at finding the best places to live, researchers have found. Those with ‘fast-exploring’ personalities – birds tending ...

Recommended for you

New research reveals clock ticking for fruit flies

5 hours ago

The army of pesky Queensland fruit flies that annually inflict many millions of dollars-worth of damage on the nation's horticultural industry may be about to see their numbers take a significant dive thanks ...

The ABC's of animal speech: Not so random after all

7 hours ago

The calls of many animals, from whales to wolves, might contain more language-like structure than previously thought, according to study that raises new questions about the evolutionary origins of human language.

User comments : 0