Birds exhibit a range of behaviors when faced with changing weather, from seeking refuge to attempting to evade severe conditions entirely. Understanding these responses involves exploring the specialized sensory abilities that allow birds to perceive environmental shifts before humans do.
How Birds Sense Approaching Storms
Birds detect subtle atmospheric changes indicating an impending storm. They are sensitive to barometric pressure, which typically drops as a storm approaches. Birds have pressure-sensitive organs in their inner ears that enable them to detect these shifts, prompting them to alter their behavior. Research has shown, for instance, that white-crowned sparrows can sense and respond to declining barometric pressure.
Birds can also perceive distant storms through infrasound, very low-frequency sound waves. Storms generate these waves, which can travel vast distances with minimal energy loss, providing birds with an early warning system hours before a storm becomes visible or audible to humans. For example, golden-winged warblers have been observed fleeing breeding grounds over 900 kilometers away, likely due to detecting infrasound from an approaching severe storm. Birds also notice changes in temperature and humidity, contributing to their awareness of changing conditions.
Evasion Through Flight
Many bird species, especially migratory ones, attempt to fly away from or around storm systems. This strategy allows them to avoid the hazards of high winds, heavy rain, and potential injury. Birds can quickly cover significant distances to escape the worst weather.
Migratory birds often adjust their travel plans in response to approaching storms; for example, white-throated sparrows may accelerate their autumnal migration departure when barometric pressures fall. Some strong-flying birds, such as brown pelicans and magnificent frigatebirds, have been recorded moving far inland, sometimes over a thousand miles from the coast, after hurricanes, indicating an attempt to outrun or circumnavigate these events. In rare instances, some migratory birds have even been observed flying towards the calm eye of a hurricane, remaining there until the storm dissipates, though this can lead them hundreds of miles off course.
Seeking Shelter
When flying away is not possible or chosen, birds seek shelter. This involves finding safe havens to reduce exposure to wind, rain, and hail. Birds utilize dense vegetation, tree cavities, cliff crevices, and even human-made structures like sheds or the leeward side of houses.
Small birds, such as robins and wrens, often retreat into thick bushes or hedgerows. Cavity-nesting birds like woodpeckers and chickadees may hunker down inside their nest or roosting holes. Birds instinctively huddle down during poor weather, tucking their bills into their feathers and crouching low to minimize exposure, to stay warm and relatively dry. While most birds are somewhat waterproof due to their feathers and preen oil, heavy rain can still lead to chilling, making shelter essential.
Factors Influencing Bird Behavior
Several factors influence whether a bird chooses to fly away from a storm or seek shelter. The type and severity of the storm play a significant role; a mild thunderstorm might prompt seeking immediate cover, while a hurricane could trigger long-distance evasion. Bird species also exhibit varied responses based on their characteristics, with migratory status being a key determinant.
Body size also matters; larger birds like raptors and seabirds are better equipped to handle gusty winds in flight, while smaller birds may cease flying altogether during heavy storms. The energy demands of each strategy are also considered. Birds often feed intensely before a storm to build fat reserves, providing fuel for prolonged flight or sustained inactivity while sheltered.