Olympus digital camera / wikipedia
Scientists have long assumed that birds migrate during winters to save energy. The reasoning has been quite obvious: away from the biting cold, birds would need to expend less energy to stay warm.
According to the Mongabayone new research changed this assumption. A study published in the magazine Nature Ecology & Evolution concluded that a group of Eurasian blackbirds (Blackbird thrush), a partially migratory species, which spent time in warmer regions did not save energy when compared to a population of the same species that remained in a cold environment.
“We suspected an energy deficit 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 other clues or reasons to migrate.”
As part of the study, researchers placed biologgers that were surgically implanted into birds. The sensors in the recorders measured heart rate and body temperature every 30 minutes.
Heart rate serves as an indicator of energy expenditure, the more energy is used, the higher the heart rate. “It was like peering through a keyhole into their internal systems, as if they were using a smartwatch“, says Linek.
Over three years, starting in 2016, the team installed sensors in 118 birds in southern Germany. Externally linked radio transmitters allowed scientists to monitor whether the birds were dead or alive, as well as follow their movements. In the end, the team obtained more than 890 000 measurementsfrom the recorders he took from 83 birds.
“We ended up with a groundbreaking image of what these birds are doing to support their migration,” he said. Scott Yancoco-lead author and researcher at the University of Michigan School of Environment and Sustainability. “They are adjusting their heartbeat and their entire metabolic organization in really complicated ways.
Analysis of data relating to heart rate and body temperature helped scientists calculate the birds’ daily energy expenditure. They found that migratory birds were beginning to decrease their heart rate and body temperature by almost a month before departure to save energy for the trip. Theoretically, their energy expenditure should decrease when they reach their destination. But this was not found to happen.
“It doesn’t show up in the heart rate data,” Yanco said. “There is energy that is passing through their system that is not accounted for.”
The findings left the team with some intriguing questionsin other words: Where did this energy go? And if there is no energetic benefit to migrating, why do so many birds do it?
Linek and Yanco raise the hypothesis that the migration must have hidden costs which may include immune functions, the energy needed to remain vigilant in a new environment, or competition from other birds in the area to which they have migrated. “The thermoregulatory benefit is clearly offset by something else that is more difficult down there.”
While seeking answers to these questions, Linek said he wants to take advantage of “revolution of biologgers“ to collect more data and better understand how the environment “is traveling through the physiology and energetic organization of birds.”
Understanding physiological responses to migration will also help scientists predict how climate change ea degradation of habitat could affect migration patterns in the future.
“Predicting where and when animals will be, what causes their populations to increase or decrease, and how we can intervene to change these things,” Yanco said. “These are the questions we have to answer.”
Teresa Oliveira Campos, ZAP //
Diving Into The Avian Conundrum: Why Do Birds Migrate?
So, scientists have been operating under the rather charming assumption that birds migrate to escape the biting cold and save some precious energy. You know, like humans fleeing to a tropical island for winter to sip piña coladas – only with feathers and a slightly more complex navigation system.
But hold onto your birdwatching binoculars because a recent study published in Nature Ecology & Evolution has flipped the script like a pancake on a greasy diner griddle. Yes, it turns out that our feathery friends aren’t saving as much energy as we once believed. Nils Linek, the lead researcher from the Max Planck Institute for Animal Behavior, has revealed that Eurasian blackbirds, while enjoying a warmer climate, didn’t show any significant energy savings compared to their chilly cousins still braving the frost.
Just picture it: these blackbirds packed their bags and took a little holiday, only to discover that lounging on a sunny perch didn’t come with the energy dividends they had anticipated. Instead of getting a well-deserved break, they were running around like the rest of us trying to justify a summer body while snacking on holiday treats!
So, how did scientists conduct this feather-brained investigation? They implanted biologgers into the birds, turning the entire thing into a real-life episode of a science fiction show. It’s like putting a Fitbit on a bird and saying, “Let’s see how much you actually work out!” These biologgers monitored heart rate and body temperature with the frequency of a squirrel on caffeine. And guess what? Over three years, they collected more than 890,000 measurements. That’s right, significantly more than I’ve ever recorded while trying to count sheep at night!
So what did they find? Turns out, migratory birds tinkered with their heart rates and metabolic systems about a month before their grand departure. Imagine prepping for a vacation – packing your bags and then having a panic attack about that piece of gym equipment you bought that you’ve never used. That’s basically what these birds were doing. But shockingly, once they arrived at their sunny getaway, the expected drop in energy expenditure didn’t materialize. It’s almost like they arrived at the beach, only to realize they left their sunscreen at the hotel!
This left researchers with a head full of questions. If the birds aren’t saving energy, then what’s the catch? Are they joining secret fitness classes and burning calories while we’re none the wiser?
Well, Linek and his co-researcher Scott Yanco threw a few hypotheses into the mix. Perhaps these migratory jaunts carry hidden costs such as superhuman vigilantism in foreign lands or fierce competition with local bird residents. Who knew that the world of avian tourism could be so brutal? It’s a bit like arriving for your beach holiday only to find the resort is overrun with partygoers who do nothing but compete for the sunbeds!
As they continue their quest for answers, Linek is all set to exploit the “revolution of biologgers” – which sounds like a high-tech superhero movie waiting to happen – to further decipher the birds’ physiological languages and how they cope with environmental challenges. Given the current climate crisis, understanding these patterns could help scientists predict how our feathered friends will navigate a changing world.
In the end, if there’s a life lesson to be learned from this study, it’s that migration isn’t just about dodging the cold. Sometimes, chasing the sun comes with a few more hiccups than you’d expect – be it for blackbirds or humans. So let’s raise a glass (or a bird feeder) to the incredible journey of our avian pals!
And who knows, maybe next time you see a flock of birds flying overhead, they’ll be on their way to a wellness retreat – energy deficit and all!
Teresa Oliveira Campos, ZAP // Join us for more avian insights on our next adventure!
Olympus digital camera / wikipedia
Scientists have long assumed that birds migrate during winters to save energy. The reasoning has been quite obvious: away from the biting cold, birds would need to expend less energy to stay warm.
One recent study has upended this long-held belief. Research published in the journal Nature Ecology & Evolution revealed surprising insights about the energy expenditure of a specific group of Eurasian blackbirds (Blackbird thrush). This partially migratory species, observed in both warmer and colder regions, exhibited no significant energy savings when compared to those that remained in colder environments.
“We suspected an energy deficit for resident birds, but there was no significant difference between the net energy they expended compared to migratory birds,” stated Nils Linek, the lead author and a researcher at the Max Planck Institute for Animal Behavior. “If there is no overall energy benefit, there must be other motivations or factors at play that drive migration.”
To obtain their findings, researchers employed advanced technology by surgically implanting biologgers into the birds. These innovative devices monitored heart rate and body temperature at 30-minute intervals, providing critical data on energy expenditure.
Heart rate serves as an indicator of energy use, with higher rates reflecting increased expenditure. “It was like peering through a keyhole into their internal systems, as if they were using a smartwatch,” explained Linek, emphasizing the revolutionary nature of these biologgers.
Over a three-year period beginning in 2016, researchers fitted 118 birds in southern Germany with these sensors. Externally linked radio transmitters provided ongoing monitoring of the birds’ well-being and movements. The comprehensive study yielded over 890,000 measurements from data gathered from 83 of these birds.
“We ended up with a groundbreaking image of what these birds are doing to support their migration,” said Scott Yanco, co-lead author and researcher at the University of Michigan School of Environment and Sustainability. “They are finely adjusting their heart rates and overall metabolic processes in remarkably intricate ways.”
The detailed analysis of heart rate and body temperature data revealed that migratory birds began to lower their heart rates and body temperatures nearly a month before embarkation, optimizing energy reserves for the journey. However, contrary to expectations, there was no observed drop in energy expenditure after they reached their destination.
“It doesn’t show up in the heart rate data,” Yanco remarked. “There is energy that is passing through their system that is not accounted for, raising new questions about migration dynamics.”
These findings prompted the researchers to ponder some intriguing questions: Where did this missing energy go? And if migrating offers no energetic advantage, what compels so many birds to undertake such risky journeys?
Linek and Yanco propose that the migration may carry hidden costs, which could include the energy expended on immune responses, the vigilance required in unfamiliar environments, or the competition faced from other migratory birds. “The apparent thermoregulatory benefits of migration are clearly offset by other, more complex challenges,” they noted.
As they seek answers to these compelling questions, Linek expressed a desire to harness the ongoing revolution of biologgers to gather more comprehensive data regarding avian physiology during migration. Understanding these physiological responses is crucial for predicting how climate change and habitat degradation may impact migratory patterns in the years to come.
“Predicting where and when animals will be, what causes their populations to increase or decrease, and how we can intervene to alter these patterns,” Yanco emphasized, “are essential questions we need to answer as we study these fascinating migratory behaviors.”
Teresa Oliveira Campos, ZAP //
