Australia's bogong moths undertake a spectacular migration each spring to the caves of the Australian Alps, traveling up to 1000 kilometers (about 620 miles) without any external assistance. Their ability to navigate accurately in darkness has long intrigued scientists, who have just uncovered surprising mechanisms behind this feat.
A recent study published in
Nature reveals that these insects use both the stars and the Earth's magnetic field to orient themselves. Researchers led by Professor Eric Warrant conducted laboratory experiments simulating the night sky and magnetism, demonstrating that the moths change direction when the celestial dome is altered and become disoriented when the stars are scrambled. In the absence of stellar visibility, they fall back on the magnetic field as a backup system.
Their brain, despite its small size, manages to integrate this information to maintain a correct trajectory. Scientists suspect the involvement of light-sensitive proteins called cryptochromes, which may play a role in magnetic detection. These proteins, present in the moths' eyes, would interact with light to create a kind of internal compass, although the exact mechanisms remain to be elucidated.
Future research will focus on how these moths recognize their destination once they arrive. The team is exploring sensory cues, such as odors or landscape features, that could signal arrival. Understanding these processes could shed light on broader aspects of animal navigation and even inspire human technologies.
This discovery highlights the incredible adaptability of migratory species in the face of environmental challenges. It also opens up perspectives for conservation, as magnetic or light disturbances, such as light pollution, could affect these journeys essential to their survival.
Star navigation in animals
Many species, such as birds or butterflies, use celestial bodies to orient themselves during their migrations. This ability, called astronavigation, relies on detecting the position of stars or the Moon.
In bogong moths, researchers have observed that they align themselves with the Milky Way, a luminous band in the night sky. Unlike humans, who need instruments, these insects have eyes adapted to perceive stellar patterns even in low light.
This form of navigation is particularly effective on clear nights but can be disrupted by cloud cover or artificial light. Animals often develop backup systems, such as the magnetic field, to compensate for these hazards.
Studying these mechanisms helps understand the evolution of migratory behaviors and the impacts of environmental changes on wildlife.
Earth's magnetic field as a guide
Earth's magnetic field acts as a natural compass for various organisms, from birds to insects and sea turtles. It is generated by the movement of liquid iron in the Earth's core and extends into space.
Animals perceive this field through specialized structures, such as magnetite crystals in their bodies or, as suspected in bogong moths, via light-sensitive cryptochrome proteins. These proteins could create chemical reactions influenced by magnetic orientation.
This sensitivity allows migrants to maintain a constant direction over long distances, even without visual landmarks. It is important for survival, especially during seasonal migrations.
Human disturbances, such as power lines or industrial activities, can interfere with this magnetic sense, posing risks for species conservation.