Birds warned of food shortages by neighboring birds change physiology and behavior to prepare

CORVALLIS, Ore. — Songbirds that learn from nearby birds that food supplies might be running out respond by changing their physiology as well as their behavior, according to a study from the Oregon State University College of Science.

After receiving social information from neighbors with dietary restrictions for three days, the crossbills in the study increased their eating rate, increased their intestinal mass and maintained the size of the muscle responsible for flight. when their own eating opportunities were then restricted to two short feeding periods per day.

The results of OSU’s Jamie Cornelius study, published in the journal Proceedings of the Royal Society B, suggest that birds can use social information about food shortages to gain an adaptive advantage for survival.

“This is an entirely new form of physiological plasticity in birds and builds on previous work showing that social cues during stress can actually alter how the brain processes stressors,” said said Cornelius, assistant professor of integrative biology.

Cornelius, an ecophysiologist, examines the mechanisms wild animals, especially songbirds, use to cope with unpredictable and extreme events in their environment, including fluctuations in food availability. His research combines natural history, endocrinology and biotelemetry to probe to better understand what limits an animal’s fitness under harsh conditions.

“Animals have all sorts of strategies to cope with harsh environments, ranging from seasonal avoidance strategies like hibernation or migration to behaviors like caching or altered foraging activity,” a- she declared. “Physiological adjustments in metabolic rate, digestive capacity, and energy stores can sometimes accompany behavioral changes, but these things can take time to execute. This means that the unpredictable environmental conditions are particularly difficult for many animals. »

Cornelius has shown in previous research that a Red Crossbill with a food-restricted neighbor will secrete higher than usual levels of the stress hormone corticosterone during its own times of food stress and will also experience changes. of brain activity that prepare the bird to respond more strongly to the challenge. .

The Red Crossbill, known scientifically as Loxia curvirostra, is a nomadic species that migrates based on food availability and incorporates the calls or behavior of other birds into its decision making on how to respond to food deprivation.

Found throughout Europe and North America, the crossbill is part of the finch family. It is known, as its name suggests, for its intersecting upper and lower beak tips, a feature that helps it extract seeds from conifer cones and other fruits.

“Crossbills are an interesting system of study because of their reliance on conifer seeds,” Cornelius said. “Coniferous seed crops are somewhat unpredictable, both in terms of where seed crops grow each year and how long a seed crop can sustain birds. We’re using crossbills as a study system to try to understand what strategies birds might have when food suddenly dwindles because crossbills may have to deal with this more often than other species.

In this research, which involved captive crossbills, some of the birds received three days of social information from food-deprived birds before their own dietary limitations; other birds received three days of food-deprived bird social information along with their own food deprivation.

Cornelius refers to the first collection of birds as the social predictive focal group and the second as the parallel social focal group.

“Birds were more successful in maintaining body mass during food restriction if social information was predictive of declining food resources,” she said. “Social information is important for animals in many different contexts, and this study demonstrates a new benefit: advance warning of declining food can lead to better outcomes in times of scarcity.”

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