Quantum Birds
Contact
Prof. Dr. Henrik Mouritsen
AG Neurosensorics/Animal Navigation
University of Oldenburg
Faculty V - Institute of Biology and Environmental Sciences
Carl-von-Ossietzky Str. 9-11
26129 Oldenburg
Germany
Phone: +49 441 798 3081
Room: W10 0-010
henrik.mouritsen@uni-oldenburg.de
SFB 1372 “Magnetoreception and Navigation in Vertebrates”
Quantum Birds
The Secret Compass of Migratory Birds
Every year, millions of birds embark on epic journeys - some flying thousands of kilometers across continents and oceans, guided in part by an invisible force: the Earth’s magnetic field. But how do they sense the magnetic field? Could the answer lie not just in biology, but in quantum physics?
More than 15 groups within the SFB 1372 collaborative research center “Magnetoreception and Navigation in Vertebrates” at the University of Oldenburg work alongside international partner groups in highly interdisciplinary collaborations to explore one of nature’s most intriguing mysteries: how migratory birds may harness quantum processes in their eyes to navigate. This bold scientific adventure brings together molecular biology, biophysics, and quantum chemistry to explore something no GPS could ever explain.
A Molecular Compass Hidden in the Eye?
The key suspect is a light-sensitive protein called cryptochrome 4, found in the retinas of night-migratory songbirds. We have collected evidence that this protein could be a quantum sensor - a biological molecule that acts like a compass by producing radical pairs whose electron spins can be influenced by the Earth’s magnetic field. This sensitivity relies on the spin-coherent quantum superposition with which the radicals are formed. Proving this requires diving deep—into cells, molecules, and quantum interactions.
From Protein to Proof
In the groundbreaking Quantum Birds project funded by the European Research Council (ERC), biologists from the University of Oldenburg and physical chemists from Oxford University (UK) are working together to test whether these proteins really respond to magnetic fields as predicted by quantum theory. In Oldenburg, researchers grow and purify the cryptochrome proteins in the lab. In Oxford, physical chemists have developed exquisitely sensitive spectroscopic methods allowing them to test magnetic field effects in the Oldenburg protein samples.
By combining expertise in biology and physical chemistry, we have begun to unravel the workings of the birds’ likely quantum sensor. We were the first to successfully measure the magnetic sensitivity of cryptochrome 4 from the European robin (Xu et al. 2021 - doi.org/10.1038/s41586-021-03618-9). Our measurements showed that electrons move within the molecule and are magnetically sensitive exactly as it had been predicted by quantum mechanical theory decades ago. The measurements are the clearest evidence yet of quantum physics playing a direct role in protein dynamics and effects of radiofrequency magnetic fields on birds’ magnetic compass shows that it is ultimately used in animal behaviour (Engels et al. 2014 - doi.org/10.1038/nature13290; Leberecht et al. 2023 - doi.org/10.1073/pnas.2301153120).
But how does a quantum event at the molecular level turn into something a bird can use to navigate?
We have shown that cryptochrome 4 interacts with a specific type of signaling molecule found in the eye: a cone-specific G-protein alpha subunit. This protein is well-known for its role in the phototransduction cascade - the process by which light is converted into electrical signals in the visual system. By demonstrating this interaction using advanced imaging techniques like FRET (Förster Resonance Energy Transfer) in quail neuroretinal cells, we revealed a possible pathway by which magnetic information could reach a bird’s brain (Görtemaker et al. 2022 - doi.org/10.3390/cells11132043).
Nature’s Navigation Network
The research doesn’t stop at the molecule. Using advanced imaging and behavioral experiments, the Oldenburg team has also traced magnetic sensing into the brain. One region, called Cluster N, processes magnetic compass information. If this region is lesioned, the birds lose their magnetic sense - but keep their sun and star compasses intact (Zapka et al. 2009 - doi.org/10.1038/nature08528).
Other experiments have shown that birds might in fact possess two distinct magnetic senses: a quantum-based compass in the eye and another, most likely map-related sense linked to the trigeminal nerve.
Why It Matters
If cryptochrome 4 is confirmed as a quantum sensor, it would not only solve a decades-old puzzle in biology, but also show that evolution has harnessed quantum mechanics in ways we are only beginning to understand. It could inspire new ideas in quantum sensing technologies, deepen our understanding of environmental risks like electromagnetic pollution, and offer a glimpse into the hidden connections between life and physics.
In the Cluster of Excellence research proposal “NaviSense: International Cluster of Excellence Proposal for the Sensory Basis, Mechanisms, and Impacts of Animal Navigation” we aim to understand in more detail not only the mechanisms used by animals to navigate, but also how these mechanisms can inspire technology and impact society, ecology, and biodiversity. Among other research questions, we would like to investigate with an interdisciplinary team of biologists, physicists, chemists and computer scientists how quantum mechanical effects can affect processes at ambient temperature. The mechanisms we expect to discover in animals rely on very similar laws of physics as some types of recently developed quantum technologies. However, most of these only work at very low temperatures. If we can understand how these quantum mechanisms work in the wet, warm, noisy environment of a cell in a bird’s eye, this should have huge technological impact.
Studying bird navigation is not just about navigation – it’s about uncovering the hidden rules that govern how living beings interact with the planet. And that’s something worth exploring.
Learn more about Quantum Birds
Video: How quantum mechanics help birds find their way
Review articles: Mouritsen 2018 - doi.org/10.1038/s41586-018-0176-1; Hore & Mouritsen 2016 - 10.1146/annurev-biophys-032116-094545
Book chapter: Mouritsen 2022 - doi.org/10.1016/B978-0-12-819770-7.00040-2