From Monarch Butterflies that journey from Eastern North America to the Sierra Madre Mountains of Mexico to Atlantic Salmon that travel between the freshwater and the salty ocean, moving long distances in search of a new habitat is truly a remarkable behavior.
Though curiosity certainly motivates us to pay close attention to migration patterns that span the globe, scientists understand that this journey is critical to the survival of countless species. By relying on external cues including the availability of resources (such as foods and mates), local climate, and the season of the year, animals are prompted to leave an unsuitable area for a more manageable one. Each species has its own way of navigating the unexplored terrain: Indigo Buntings rely on an internal mapping of the stars in the sky; Sea Turtles and Bats use a magnetic field; and Sperm Whales depend on the presence of continental landmarks.
Perhaps one of the most spectacular but grueling migrations belongs to the Emperor Penguin, following along a path in Antarctica far from its home near the sea to raise young. Once the female lays an egg inland, she is exhausted, and must return to the ocean to rest and feed. The male will spend the four winter months keeping the egg warm within its highly specialized feathers. Once it hatches, the mother will exchange places with the father to take care of the baby penguin. Soon after, the mother will retreat back to the ocean, leaving behind a baby penguin that must now rely on its instincts and ability to learn to take care of itself. Though survival may be difficult, the parents of the baby penguin have worked tirelessly to give it the best possible start. Then, someday, it will follow in the migration-footsteps of its parents, the same movements Emperor Penguins have been making for thousands of generations.
Sadly, many species are threatened by the presence and spread of human civilization, interfering with the migratory routes they heavily depend on. Despite initiatives to track animal migration, serious gaps in our understanding remain. For example, there is debate among scientists as to why migratory birds such as Gray Catbirds have experienced a northward expansion over the past several decades. Some ecologists attribute the range expansion to climate change while others argue habitat fragmentation is the primary cause.
As we move forward in the 21st century, understanding our impact on the environment in hopes of changing our behavior will be a critical challenge. It is one we must strive to overcome, though, if we hope to conserve the migratory animals and their essential role in the functioning of the planet’s ecosystems.