Saturday, November 22, 2025

Mystery of how turtles read their magnetic map solved: they feel the magnetism

Hatchling loggerhead turtles feel the Earth’s magnetic field when using a magnetic map

The Company of Biologists

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A young loggerhead turtle 'dancing' in response to a magnetic field it has learned to associate with food.
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Credit: Photo credit: Alayna Mackiewicz

Loggerhead turtles are able to sense the Earth’s magnetic field in two ways, but it wasn’t clear which sense the animals use to detect the magnetic field when navigating using the magnetic map they are born with. Now researchers from University of North Carolina at Chapel Hill reveal in Journal of Experimental Biology that hatchling loggerhead turtles feel the Earth’s magnetic map to tell them where they are on their epic migration routes.

Setting off from the beach of their birth, hatchling loggerhead turtles embark on some of the world’s most impressive migrations, covering thousands of kilometres over decades. But the intrepid youngsters are not without direction. Equipped with the ability to sense the Earth’s magnetic field, loggerhead hatchlings are born with a compass, which tells them in which direction they are travelling, and a map of the planet’s magnetic field that tells them their location, to navigate successfully.

There are two possible ways for animals to sense the Earth’s magnetic field: one where light-sensitive molecules are affected by the magnetic field, which could allow animals to see the field, and a second where tiny magnetite crystals embedded in the animal’s body move in the field to allow them to feel the magnetism. But it wasn’t clear which of these two mechanisms might tell turtles where they are located during their extraordinary odyssey, and scientists at the University of North Carolina at Chapel Hill wanted to know.

Fortunately, Kayla Goforth, Catherine Lohmann, Ken Lohmann and colleagues from the university had recently discovered that hatchling turtles can learn to associate the magnetic field found at a location with the arrival of food. But instead of learning to salivate like Pavlov’s dogs, loggerhead turtle hatchlings ‘dance’ to show their recognition, tilting their bodies out of the water, opening their mouths and waggling their front flippers.

By locating the youngsters in a specific magnetic field while feeding them, the researchers were able to train the hatchlings to perform their dance when transferred later to the same magnetic field.

‘They are very food motivated and eager to dance when they think there is a possibility of being fed’, laughs Alayna Mackiewicz from the University of North Carolina at Chapel Hill.

The team then realised that they could use this clever trick to tell them whether the turtles were potentially seeing, or feeling, the Earth’s magnetic field if they zapped the hatchlings with a strong magnetic pulse that temporarily disabled their ability to feel the field. If the zapped hatchlings stopped dancing, then they were feeling the magnetic field, but if they continued to dance, then they were using some other sense to detect the magnetic map.

But training the hatchlings was no mean feat. ‘It’s really fun but takes up quite a bit of time’, says Mackiewicz, who, with Dana Lim (University of North Carolina at Chapel Hill), spent 2 months feeding 8 newly hatched loggerhead youngsters in the magnetic field that is found around the Turks and Caicos islands, so they would learn to dance when they experienced the magnetic field later. In addition, the duo trained other hatchlings to recognise the magnetic field near Haiti.

Then, Mackiewicz and Lim transferred each youngster to a large metal coil that produced a strong magnetic pulse that would temporarily disable the hatchling’s ability to feel a magnetic field. After that, they placed each youngster in the magnetic field that they had been trained to recognise to find out whether they had stopped dancing.

Sure enough, after being zapped, the turtles danced less, suggesting that they were feeling the magnetic field, which tells them where they are on their map, and not seeing it.

The team admits that the hatchlings may also use other senses to tell them where they are located on their global magnetic map, but feeling the field is an essential component of their ability.

And, as the youngsters are known to use their additional magnetic sense – which may enable them to see magnetic fields – as a compass that tells them in which direction they are travelling, it is clear that the two senses complement each other, allowing the youngsters to identify their location and set a bearing wherever they might be.

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A hatchling turtle 'dancing' [VIDEO]

A young loggerhead turtle 'dancing' (tilting its body, opening its mouth and waggling its front flippers) in response to a magnetic field it has learned to associate with food.

Credit

Video credit: Alayna Mackiewicz

IF REPORTING THIS STORY, PLEASE MENTION JOURNAL OF EXPERIMENTAL BIOLOGY AS THE SOURCE AND, IF REPORTING ONLINE, PLEASE CARRY A LINK TO:

https://journals.biologists.com/jeb/article-lookup/doi/10.1242/jeb.251243

REFERENCE: Mackiewicz, A. G., Glazener, A. M., Goforth, K. M., Lim, D. S., Lohmann, C. M. F. and Lohmann, K. J. (2025). Disruption of the sea turtle magnetic map sense by a magnetic pulse. J. Exp. Biol. 228, jeb251243. doi:10.1242/jeb.251243

DOI: 10.1242/jeb.251243

This article is posted on this site to give advance access to other authorised media who may wish to report on this story. Full attribution is required and if reporting online a link to https://journals.biologists.com/jeb is also required. The story posted here is COPYRIGHTED. Advance permission is required before any and every reproduction of each article in full from permissions@biologists.com.

THIS ARTICLE IS EMBARGOED UNTIL THURSDAY 20 NOVEMBER 2025 18:00 HRS EDT (23:00 HRS BST)

Journal

Journal of Experimental Biology

DOI

10.1242/jeb.251243

Method of Research

Experimental study

Subject of Research

Animals

Article Title

Disruption of the sea turtle magnetic map sense by a magnetic pulse

Article Publication Date

20-Nov-2025

An electric discovery: Pigeons detect magnetic fields through their inner ear

Ludwig-Maximilians-Universität München

LMU neurobiologists have identified a neural pathway for processing magnetic information that originates in the inner ear.

In 1882, the French Naturalist Camille Viguier was amongst the first to propose the existence of a magnetic sense. His speculation proved correct, many animals – from bats, to migratory birds and sea turtles use the Earth’s magnetic field to navigate. Yet despite decades of research, scientists still know surprisingly little about the magnetic sense. How do animals detect magnetic fields? Which brain circuits process the information? And where in the body is this sensory system located?

Viguier audaciously proposed that magnetic sensing might occur in the inner ear relying on the generation of small electric currents. This idea was ignored and then forgotten; a historical musing lost with the passage of time. Now more than a century later it has been resurrected by neuroscientists at LMU in a paper published in Science. A team led by Professor David Keays took an unbiased approach studying pigeon brains exposed to magnetic fields.

“State-of-the-art microscopy allowed us to identify specialized circuits that process magnetic information. Moreover, it provided a critical clue to the location of the primary magnetic sensors”. PhD students Grégory Nordmann and Spencer Balay observed robust activation in a brain region called the vestibular nucleus, which is connected to the inner ear. Genetic analysis of inner ear tissue revealed cells with highly sensitive electric sensors, the same ones used by sharks to detect their prey.

“The cells we describe are ideally equipped to detect magnetic fields using electromagnetic induction – enabling pigeons to find their way home using the same physical principle which permits the wireless charging of phones.” In both cases, a magnetic pulse is converted into an electrical signal. For the pigeon, this powers their natural GPS.

The researchers emphasize that it is likely not the only magnetic sensing strategy in nature. “Our data suggests that there’s a ‘dark compass’ in the inner ear, while other studies point to a light-dependent compass in the visual system,” explains Keays. “In all likelihood, magnetoreception has evolved convergently in different organisms. Much remains to be discovered!”

Journal

Science

DOI

10.1126/science.aea6425

Article Title

A global screen for magnetically induced neuronal activity in the pigeon brain

Article Publication Date

20-Nov-2025

Want to make new friends? Take a lesson from these birds

Parakeets 'test the waters' of new relationships

University of Cincinnati

Making new friends has its challenges, even for birds.

Researchers at the University of Cincinnati found that monk parakeets introduced to new birds will “test the waters” with potential friends to avoid increasingly dangerous close encounters that could lead to injury. They gradually approach a stranger, taking time to get familiar before ramping up increasingly risky interactions.

The study was published in the journal Biology Letters.

“There can be a lot of benefits to being social, but these friendships have to start somewhere,“ said Claire O’Connell, the study’s lead author and a doctoral student in UC’s College of Arts and Sciences.

O’Connell collaborated on the study with UC Associate Professor Elizabeth Hobson, former UC postdoctoral researcher Annemarie van der Marel, and Princeton University Associate Professor Gerald Carter.

“Many parrots, for example, form strong bonds with one or two other birds. Partners often spend most of their time together, preen each other or sometimes form reproductive relationships,” O’Connell said. “Generally, maintaining these strong social bonds is associated with decreased stress and higher reproductive success.”

But making that first contact carries risk, especially when animals are unfamiliar to one another.

O’Connell said birds that don’t welcome a newcomer’s attention can react aggressively, which can lead to injuries.

Researchers combined groups of wild-caught parakeets in a large flight pen. Some parakeets were strangers to each other. They collected data on when and how new relationships formed by studying how close the birds approached over time and which birds groomed each other or engaged in other friendly behaviors.

Then they analyzed more than 179 relationships using computational methods and statistical models to determine whether relationship formation followed the pattern predicted by previous studies exploring the theory of testing the waters.

“Capturing the first moments between strangers can be challenging, so we were really excited that our experiments gave us the chance to observe that process up close,” O’Connell said.

They found that strangers were more likely to approach each other with caution compared to birds they knew. Stranger birds took time to share space before eventually perching shoulder to shoulder, touching beaks or preening others. Some strangers escalated further to sharing food or mating.

The UC study had results comparable to a 2020 study of vampire bats that found that newcomers likewise test the waters, gradually escalating from social grooming relationships to food-sharing relationships with trustworthy partners.

“What’s really fascinating about testing the waters is how intuitive it feels,” O’Connell said.

“I can definitely relate! I started observing the parakeets shortly before I moved to Cincinnati to start graduate school,” she said. “I was excited but also a little nervous about making new friends. At the same time, I was literally watching the parakeets make new friends themselves, although some did better than others. I started realizing there may be something I could learn from the parakeets.”

A monk parakeet preens a friend. Researchers used dye markers to identify individuals for their social experiment.

University of Cincinnati researcher Claire O'Connell found that monk parakeets "test the waters" with potential friends as they ramp up social behaviors.