Animals display remarkable differences in anatomy, behavior, reproduction, movement, and survival. Meet living and extinct species while examining how their biological traits and adaptations allow them to occupy environments across the planet.
A salmon returning from the open ocean does not follow one continuous trail back to its birthplace. It solves the journey in stages. Broad-scale cues guide the fish across marine waters toward its home region, after which the chemical character of rivers and tributaries becomes increasingly...
Bar-headed geese cross the Himalayan region during migrations between breeding areas in Central Asia and wintering grounds in South Asia. Their route carries them through air with roughly half the oxygen pressure available at sea level, while flight itself demands far more energy than rest. The feat...
Monarch butterflies do not simply fly south until the weather feels warm. Migratory populations gather at restricted sites whose temperature, moisture, trees, and shelter allow them to survive for months while using little energy. For eastern North American monarchs, those conditions occur mainly in...
An Arctic tern can link the polar regions within a single annual journey. After breeding in the Arctic and subarctic, the bird travels toward productive waters around Antarctica, remains in the Southern Hemisphere during its summer, and then returns north to breed. Tracking studies of terns from...