To survive the cold birds must balance eating enough while staying light enough to escape predators.

“Every gram of fat matters,” Leniowski said, highlighting the delicate balance birds maintain between energy intake and survival. Unlike humans, he explained, “Wild birds never overeat, even though they have food at the feeder ad libitum, meaning as much as they want. They eat just enough to maintain the optimal amount of fat. Just enough to survive the next few hours, no more. They know they cannot eat too much because they will be too slow to escape if threatened.”

Predators such as sparrowhawks and domestic cats regularly patrol feeding sites. “They regularly visit the area, anticipating that there might be more potential prey there,” Leniowski said.

Great tits are usually the first to arrive at winter feeders, followed by blue tits, greenfinches, sparrows, nuthatches, and corvids. Magpies and rooks are especially intelligent and observant, he said, able to recognize people who regularly provide food.

“If the same person, usually dressed similarly, is pouring out treats, a magpie can recognize its carer from a distance. It can even build a map and visit known food spots in a specific order. Seeing a person leaving their home, it does not even wait for seeds to be poured out, but proactively appears in the area, anticipating an upcoming meal opportunity,” Leniowski explained.

Birds follow a precise daily feeding schedule, tailored to light levels. “They appear at the feeder as soon as it starts getting bright to quickly replenish their energy after the night. At noon, they only peck a little, and the peak of their feeding occurs just before sunset,” he said. Frost disrupts this rhythm, forcing birds to take greater risks to consume more food.

Urban birds, exposed to artificial light, adjust their schedule accordingly. “They appear at feeders earlier than those near forests, and forage longer. They do not go to sleep as soon as it gets dark, but at least an hour later. In the case of short winter days, this is a significant change,” Leniowski said.

Small birds such as tits also employ a cooperative strategy to reduce predation risk. “Each tit +understands+ that if it plays fair and signals the presence of food, everyone will feed. It counts on another tit also calling when it finds food. This allows them to survive from one day to the next,” Leniowski explained. Other species, including house sparrows, tree sparrows, and nuthatches, take advantage of these signals.

Birds also constantly assess the condition of their companions to determine the safest time to flee from predators. “Each tit tries to assess whether its neighbours are already full and therefore slowed down, or whether they are still swallowing their first morsels. This means that birds most likely accurately estimate how sluggish they are at the table,” he said.

Consistent and hygienic feeding is critical for survival. “If we start pouring seeds, we must do it consistently until the turn of March,” Leniowski said. Irregular feeding can create an ecological trap, leaving birds uncertain whether the food is worth the risk of predation.

The quality of the food is equally important. “The bird won’t die immediately, but it will become a carrier of pathogens and an easy target for predators. Good food means fresh seeds in a clean feeder,” Leniowski added. (PAP)

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