Early Bird Catches the Worm: Great Tits Scout in the Morning for a Later Meal

The early bird may catch the worm, but it doesn't eat the meal until much later. Scientists have discovered that birds such as great and blue tits scout for food in the morning but only return to eat it in the late afternoon in order to maximize their chances of evading predators while at the same time avoiding the possibility of starving to death overnight.

The researchers first spotted this strategy when they studied the winter foraging behavior of birds in Wytham Woods near Oxford. They fitted over 2,000 birds with tiny PIT radio tags and 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, the scientists revealed that the birds gathered information about new food sources during the morning so that they could eat it later.

"Birds have to store body fat to avoid starving during the cold winter nights, but this can make them slower and less maneuverable so they are more likely to be caught by predators," said Damien Farine, one of the researchers, in a news release. "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."

It seems that the birds combat this issue by actually eating food sources later in the day. In fact, the researchers found that food sources put out in the morning were quickly discovered, supporting the "early bird" strategy of scouting for food. By employing this method, the birds could secure a food source that they could later feed on.

"Because small birds can't reproduce without surviving the winter, they have evolved a complex set of behaviors that enables them to maximize their chance of both surviving predators and avoiding starvation," said Farine in a news release. "It's a good example of how animals alter their behavior 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."

The findings are published in the journal Biology Letters.