Final answer:
The proximate cause for bird migration in the Northern Hemisphere is the change in the environment like shorter days, while the ultimate cause is to find better living conditions such as warmer climates and more food. Birds migrate annually thousands of miles following consistent patterns, and these behaviors contribute to their survival.
Step-by-step explanation:
The proximate cause for birds flying south during autumn in the Northern Hemisphere is due to environmental changes such as shorter days. The ultimate cause is the need for birds to relocate to areas with warmer climates and more food availability during winter months.
Migration is an innate behavior that is most common in birds, fish, and insects, and occurs in response to changing environmental cues. For birds, the decreasing daylight and dropping temperatures signal the time to move to warmer regions where food can be found more abundantly. This behavior ensures their survival during harsher conditions. Such migratory patterns are consistent and species-specific, with some birds covering thousands of miles every year. For instance, the spectacular great migration of wildebeest and zebra in East Africa, and the extensive journeys of humpback whales and various species of birds all exemplify the magnitude of these movements.
Birds, including robins and geese, have been observed to adjust their migration patterns in response to climate changes, such as increasing average winter temperatures. This adaptation may be linked to larger environmental shifts and offers insight into the dynamic nature of species' migratory habits.