Spring migration has taken flight, but with rising temperatures and shifting seasons, birds are adjusting when and how they migrate to keep up with a rapidly warming climate.
Morgan Tingley, a professor of ecology and evolutionary biology at the University of California, Los Angeles, studies the effects of climate change on birds.
The Conversation has collaborated with SciLine to bring you highlights from the discussion, edited for brevity and clarity.
How is climate change affecting birds?
Morgan Tingley: In the spring, birds migrate north across the United States in order to get to where they will be spending their spring and summer. They try to time their migration so that they can arrive at their breeding grounds, build their nests and lay their eggs at the time of year when there’s going to be maximum food available.
But climate change is causing spring to happen earlier, which can cause real problems for birds. These earlier springs can result in birds falling behind local springtime because they arrive too late on their breeding grounds.
Are there particular birds climate change is affecting more than others?
Tingley: About 70% of the bird species found in the United States are migratory. Some migrate just 50 to 100 miles, and others migrate all the way from the farthest tip of South America in order to breed in Canada. Our work has found that the birds that migrate the farthest are the ones that are having the hardest time keeping up with climate change.
Why is that? If you can imagine going from Tennessee to New York and it’s an early spring in New York, it might be also an early spring in Tennessee. In that case, these birds can keep pace with an earlier spring.
But if you’re a bird living in Argentina and then migrating all the way to New York in the springtime, the temperatures and seasons in Argentina versus New York are going to be very disconnected from each other. So a bird in Argentina might not actually have the information it needs to arrive on time and keep up with the local pace of a changing climate in New York.
What happens when they can’t keep up?
Tingley: When the timing is off, it could mean that there’s not enough food available for their young, or it could be that they’re more susceptible to really extreme summer temperatures. Whether it is high temperatures or missing peak insect food, birds that are out of sync with the seasons may respond by laying fewer eggs or suffering reduced hatch success. Another issue is that once the eggs hatch, the birds might not be able to raise as many young.
As a result, we’ve seen that when birds become mismatched with climate and changing seasons, it can lead to population declines. In North America, we’ve seen many bird populations decline over the past 40 years. As bird populations decline even further, this can cause a variety of problems for humans.
For example, birds are a key link in many food supplies, as they can be key pollinators, important seed dispersers and critical consumers of insect pests.
In addition, birds generally make people happy! Recent work has even shown that bird-watching can help prevent mental decline in older adults.
Is there something people can do to help?
Tingley: Climate change is a stressor that is being added on top of everything else going on in the environment. A lot of the greatest effects of climate change are not in the past. They’re going to happen in the future. These effects are coming next year, or five years from now, or 10 years from now. So wildlife managers are trying to sustain bird populations as much as possible and help them grow.
Helping save birds means keeping populations high by conserving land, reducing other types of threats, such as by keeping pets indoors or installing bird-friendly glass, and allowing birds to adapt to this changing world as best as they possibly can.
