How do migratory birds like the Arctic Tern and the Swallow navigate their long journeys, and what are some of the environmental challenges they face during migration?

Migratory birds like the Arctic Tern (Sterna paradisaea) and the Swallow (Hirundo rustica) use a combination of navigational tools, including the Earth’s magnetic field, celestial cues (sun and stars), and environmental landmarks to guide their migrations. They also rely on genetic predisposition and learned behaviors. During migration, they face challenges such as habitat loss, climate change, and barriers like urban areas and large bodies of water, which can impact their ability to find food and suitable resting places.