Space weather disrupts nocturnal bird migration

Area of Science:

• Ecology
• Animal Behavior
• Space Physics

Background:

• Animals, including birds, rely on Earth's magnetic field for navigation during seasonal migrations.
• The impact of space weather-induced geomagnetic disturbances on migratory animals is poorly understood.

Purpose of the Study:

• To investigate the relationship between space weather geomagnetic disturbances and disruptions in bird migration.
• To assess the macroecological effects of space weather on nocturnal bird migration patterns.

Main Methods:

• Utilized 22 years of long-term radar data to analyze nightly migration dynamics of North American birds.
• Developed a local magnetic disturbance index (ΔBmax) using concurrent magnetometer data.
• Controlled for atmospheric weather and spatiotemporal variables in the analysis.

Main Results:

• A 9-17% decrease in migration intensity was observed during severe space weather events in both spring and fall.
• During fall migration, reduced effort was noted in flying against the wind, suggesting impaired navigation.
• The combined effects of overcast conditions and high geomagnetic disturbance most significantly reduced fall migration effort against the wind.

Conclusions:

• Space weather-induced geomagnetic disturbances demonstrably disrupt nocturnal bird migration on a community-wide scale.
• Geomagnetic disturbances may depress active navigation, leading to increased drift with the wind.
• Navigation may be particularly compromised when both celestial cues and magnetic fields are disturbed.