The frequency and severity of heavy storm events is expected to worsen amid our changing climate. Heavy rainfall can cause flooding and infrastructure damage, devastating human communities around the nation. In the spring of 2019 alone, floodwaters overwhelmed levees across the Midwest, causing billions of dollars of crop damage. Record downpours in Tennessee caused severe mudslides, and heavy precipitation in California damaged thousands of buildings.
Heavy rainfalls also impact birds and other wildlife in damaging ways. Increased precipitation and rising coastal waters can inundate shorebird nests and flood seabird burrows, washing out eggs or killing chicks. For Piping Plovers and other species with precocial young that can feed themselves soon after hatching, heavy rainfall can impact chicks’ thermoregulatory and foraging abilities. This can lead to decreased chick survival. Parental nest visitation rates also decline with increasing amounts of daily rainfall, with this effect becoming stronger after consecutive rainy days. Thus, heavy rain during the nestling stage not only relates to fledging success, but also has longer-term effects on recruitment and subsequent parental survival.
Outside of the breeding season, increased precipitation in the form of snowfall could reduce food resources for birds overwintering in northern latitudes. For example, due to deeper and longer snow cover during harsh winters, small mammals are unavailable for hunting Barn Owls, leading to decreased survival of both adult and juvenile owls. Climate change is quickly degrading important characteristics of seasonal snow cover in the U.S., which can lead to distributional changes for many overwintering birds, further accelerating range shifts and the creation of new avian communities.
Rainfall-induced changes in seasonal bird behavior can also negatively impact species populations, especially those that are migratory. Annual variation in tropical rainfall and food resources are associated with substantial changes in the timing of spring departure for American Redstarts, while trans-Saharan migrants adjust their autumn migration timing according to temperature and precipitation effects. Rainstorms also tend to ground birds, preventing the start or continuation of long-distance migratory journeys.
Without immediate action, climate change is projected to increase the frequency and variability of heavy precipitation events that both birds and people will need to weather. But we can help. Lowering carbon emissions will slow the rate global temperature rise and reduce the risks that vulnerable birds will face. More immediately, you can make sure that birds have access to dry seed, keep extra-large capacity feeders for use in inclement weather, and provide bird houses year-round. You never know when a bird will need shelter from the storm.
