Climate change affects every living organism on Earth. From polar bears to rabbits, each creature struggles to adapt to rising temperatures, longer and shorter seasons and limited resources. Among them are birds. Hundreds of species rely on subtle changes in temperature to find food, breed, nest and relocate.
So how does climate change affect bird migration?
Collecting data on birds can be incredibly difficult, especially when scientists attempt to study and document migratory patterns. It’d be simpler if they could hop in a plane and follow the creatures, but that’s impossible. Moreover, while there is a large amount of historical data concerning birds, there isn’t much regarding their migratory patterns. A few 18th-century writings by Johann Bechstein and Daines Barrington provide some information. However, more recent migration research didn’t ramp up until the introduction of bird banding in the 1980s.
Researchers and migratory forecasters must rely on limited history, algorithms, radar, citizen science data and a range of other tools to gather information. Mobile phone reception is incredibly helpful, as well when scientists work in teams. While one camps out at a species’ summer location, another can stay at the birds’ migratory winter destination, and they can still communicate effectively.
Likewise, social media platforms allow conservationists to connect with the public and gather more comprehensive data sets. They also educate people on ways to protect the environment, such as by planting new trees and throwing trash in waste receptacles instead of waterways.
Through the data scientists have managed to collect, they’ve noticed birds are migrating farther north than they have in the past to adapt to warming temperatures. In North America, 177 bird species shifted their wintering grounds more than 40 miles northward since 1966. Plus, a few species migrate hundreds of miles further than that. For instance, the Carolina wren, the state bird of South Carolina, now relocates to New York or as far as Maine.
Other species move their wintering grounds further from coastal areas as inland temperatures become less severe. As sea levels rise, dry land and wetland turn into open water, and stronger storms also contribute to flooding. Moreover, increased carbon emissions continue to make the oceans more acidic, killing off crustaceans and other marine life. This situation forces birds to travel inland in search of more suitable nesting areas and food sources.
Missing Out on Food
Warming temperatures also cause birds to miss out on food. Historically, these creatures arrive at the first sign of spring, when the first leaves begin to appear. However, temperature changes cause them to either arrive too early or late during the season. If they come too soon, they risk freezing to death due to a lingering winter and no food. If they return too late, they may miss the prime breeding season, and other species may have already picked over the food.
For birds migrating east, spring arrives progressively earlier and, in the west, later by the year. Two years ago, the first leaf arrived a staggering three weeks early in some places, throwing many species’ migration patterns off-kilter. In the Arctic, some grasses bloom an entire month too early. By the time birds arrive, other species picked the vegetation over, and they have less time to eat before they must migrate once again.
Breeds Most at Risk
In 2017, the Mass Audubon evaluated 143 breeding bird species and their migratory patterns. The study found that 61 species are highly vulnerable to climate change and its effects. Among those most at risk are long-distance migrants, as they can’t adjust their migration time to match the bloom of their far-away food sources. This factor negatively affects population counts as birds can’t feed their starving chicks. Thus, some species may face extinction if conditions worsen.
Salt-marsh and coastal nesting species, as well as forest-breeding birds, are also among those most vulnerable to climate change. As previously mentioned, changing weather patterns, rising sea levels and ocean acidity all affect migration patterns and populations of coastal species. However, forest birds face a different problem. As temperatures rise, forest compositions will change. Although many birds rely on northern hardwoods for food and shelter, oak, hickory and pine will eventually overtake them as the climate warms.
How Does Climate Change Affect Bird Migration in 2020 and Beyond?
While many people think global warming and bird migrations to be entirely out of their control, there are, in fact, ways the general public can mitigate risks to certain species. For instance, North American cats kill more than three billion birds each year. Thus, pet owners can protect these animals by keeping their pets indoors. People can also reduce window strikes by covering glass with screens.
Of course, these actions only go so far to protect birds. As the overarching problem is global warming, people should focus on minimizing their carbon footprints. They can switch to renewable energy, compost and recycle. However, the only way these efforts will make a difference is if everyone participates, turning individual actions into a global revolution.