New Study Challenges Energy-Saving Belief Behind Bird Migration: Key Insights from Eurasian Blackbirds

Scientists have long believed that birds migrate during winter to save energy. The reasoning has been very obvious: away from the cold, birds would have to spend less energy to stay warm.

According to the Mongabayone new research changed this idea. Examination published in the journal Nature & Evolutionary Ecology concluded that a group of Eurasian blackbirds (Black-eyed Thrush), a semi-migratory species that spent time in warmer regions did not conserve energy compared to a population of the same species that remained in a cold environment.

“We suspected that there was a lack of energy for resident birds, but there was no significant difference between the net energy they expended compared to migratory birds,” he said. Nils Lineklead author and researcher at the Max Planck Institute for Animal Behavior. “If there is no overall energy benefit, there must be cues or other reasons for migration.”

As part of the study, researchers set biologists which has been surgically implanted in birds. The sensors in the charts measure heart rate and body temperature every 30 minutes.

Heart rate is an indicator of energy expenditure, the more energy used, the higher the heart rate. “It was like looking through a keyhole into their internal systems, as if they were using their a smart watch“, Linek says.

Over three years, starting in 2016, the team implanted sensors in 118 birds in southern Germany. Radio transmitters with an external link allowed scientists to track whether the birds were dead or alive, as well as track their movements. Eventually, the team outgrew him 890 000 measurementsof the recordings he took from 83 birds.

“We finally had an innovative image of these things heifers doing to support their migration,” he said. Scott Yancoco-lead author and researcher at the University of Michigan’s School of Environment and Sustainability. “They’re changing their heart rate and their entire metabolic organization in very complex ways.

Analysis of data related to heart rate and body temperature helped scientists calculate the birds’ daily energy expenditure. They discovered that migratory birds began to reduce their heart rate and body temperature near a a month before they leave to save energy for the trip. In theory, their energy expenditure should decrease when they reach their destination. But this was not found to have happened.

“It doesn’t show up in the heart rate data,” Yanco said. “Energy goes through their system that is not counted. “

The decisions left some of the team interesting questionsin other words: Where did this energy go? And if there is no energetic benefit in migration, why do so many birds do it?

Linek and Yanco raise the hypothesis that the migration must have hidden costs which may include defensive actions, the energy needed to stay alert in a new environment, or competition from other birds in the area they have migrated to. “It’s clear that the thermoregulatory advantage is offset by something else that’s more difficult down there. “

While seeking answers to these questions, Linek said he wants to take advantage of “conversion of biologists“ to collect more data and better understand how the environment “travels through the physiology and energetic organization of birds.”

Understanding physiological responses to migration will also help scientists predict how climate change yes pollution of domain influence future migration patterns.

“Predicting where and when animals will be, what will cause their numbers to increase or decrease, and how we can intervene to change those things,” Yanco said. “These are the questions we have to answer.”