Migratory birds are well-known for their remarkable journey, covering thousands of kilometers to reach their seasonal habitats. A study conducted by Bangor University on Eurasian reed warblers (Acrocephalus scirpaceus) found that these birds rely solely on the Earth’s magnetic inclination and declination to navigate and locate themselves. This finding challenges the previously accepted notion that all elements of the Earth’s magnetic field, particularly the total magnetic intensity, are crucial for precise navigation.
For many years, scientists have thought that these birds utilize a ‘map-and-compass’ strategy: they identify their position using a ‘map’ and then figure out their direction with a ‘compass’. However, the exact details of what constitutes this ‘map’ have been debated.
In an innovative experiment, researchers exposed the warblers to manipulated magnetic inclination and declination values, simulating a change in their geographic location while keeping the overall magnetic intensity constant.
Even with this simulated change, the birds altered their migratory paths as if they were in the new location, showcasing adaptive behavior. This indicates that they can gather both positional and directional cues from magnetic indicators, even when other aspects of the Earth’s magnetic field, such as total intensity, are unaltered.
The study strongly supports the idea that migratory birds depend on magnetic inclination and declination to establish their location, even when these signals contradict other magnetic field factors.
“What’s fascinating is that these results show that the birds may not need all parts of the Earth’s magnetic field to determine where they are,” stated Professor Richard Holland, a specialist in animal behavior and the study’s lead researcher. “They can depend exclusively on inclination and declination, which are also used for compass orientation, to find their location.”
This research disputes earlier beliefs that all elements of the Earth’s magnetic field, particularly total intensity, are essential for successful navigation. “It remains uncertain if birds rely on total magnetic intensity for navigation in other scenarios, but our findings suggest that these two elements—magnetic inclination and declination—suffice to provide them with positional guidance,” Richard elaborated.
This new insight enhances our understanding of how birds navigate and supports the idea that they have a sophisticated and adaptable internal navigation system. This capability enables them to modify their behavior in response to environmental changes, even in unprecedented conditions.
The outcomes of this research pave the way for further exploration into animal navigation and may have broader implications for biological studies, including how creatures perceive and interact with their surroundings.
