How climate change is rewriting the journeys of migratory birds

Each year, millions of birds take to the skies, following ancient paths that stretch across continents and oceans. These migrations—some lasting tens of thousands of kilometers—are among nature’s most extraordinary events. But now, the skies are shifting. Climate change is altering the timing, routes, and success of these journeys in ways that pose serious risks not only to birds but also to ecosystems worldwide.

The changing clock of migration

Bird migration is finely tuned to the seasons. Birds time their travel to ensure they arrive at breeding grounds when food is abundant. But rising global temperatures are throwing off this delicate timing.

Studies show that many species are now arriving at their breeding sites earlier in spring. For every one-degree Celsius increase in temperature, birds have advanced their arrival by about one day. Data from weather radar, stretching over two decades in the U.S., confirms this trend, particularly in regions warming the fastest.

However, while spring migration is clearly shifting, autumn movements are less predictable. The need to reach breeding grounds quickly doesn’t apply as strongly in fall, leading to more varied changes in timing.

Timing Trouble: When early isn’t early enough

While early arrival might sound like a good thing, it can create serious problems for birds. Migration timing evolved to match peak food availability—like insect hatches or blooming plants. If birds arrive before or after these food peaks, it creates a phenological mismatch.

One example is the Afro-Siberian Red Knot, a shorebird that breeds in the Arctic. As the Arctic warms, snow melts earlier and insects emerge sooner. But the Red Knot hasn’t adjusted its arrival time fast enough. Chicks born after the food peak face malnutrition and lower survival rates. This has already led to smaller body sizes and population declines.

This issue affects many species, especially long-distance migrants with fixed schedules and narrow diets. As climate change disrupts seasonal cues, birds may stop at places where expected food is missing or not yet available. This weakens their ability to complete migration or raise their young.

Please also read: World Migratory Bird Day highlights the need for global cooperation

New routes, new risks

As temperatures rise, birds are also changing where they go. In North America, over 300 species have shifted their winter ranges northward by an average of 40 miles in recent decades. Some birds are moving inland, seeking milder conditions away from coasts.

In Europe, short-distance migrants are especially quick to adapt. Milder winters allow them to stay closer to their breeding areas or even skip migration altogether.

Some species are establishing entirely new migration paths. Richard’s Pipits, for example, traditionally wintered in South Asia but are now increasingly found in Southern Europe. This shift might be due to changing climate suitability in Europe and environmental pressures in their original wintering grounds.

But not all species can adapt. And new routes can lead to competition with resident birds for food and space.

Bigger picture: Why bird migration matters

Migratory birds play a vital role in ecosystems. As they travel, they help pollinate plants, spread seeds, and control insect populations. They also serve as bioindicators, reflecting the health of the environments they pass through. When birds avoid certain areas, it can signal poor air or water quality.

Birds like the Arctic Tern and Bar-tailed Godwit have pushed migration to its limits. The Arctic Tern travels between the Arctic and Antarctic—around 90,000 kilometers a year. The Godwit has flown more than 13,500 kilometers nonstop. But these incredible feats are becoming harder to achieve as extreme weather events and changing landscapes make journeys more dangerous.

Rising sea levels are flooding coastal stopover sites. Ocean acidification weakens crustaceans and other food sources. Stronger storms can exhaust or kill birds mid-flight. These challenges compound existing threats like habitat destruction and pollution.

What we can do to help

Protecting migratory birds requires global cooperation. Birds cross multiple borders, relying on habitats in different countries throughout their life cycles. Conservation must focus on breeding sites, stopover points, and wintering grounds alike.

Efforts include:

• Expanding protected areas through international agreements.
• Restoring and preserving habitats likely to remain suitable in future climates.
• Creating bird-friendly urban spaces, reducing window collisions and light pollution.
• Supporting citizen science projects like eBird to monitor bird movements.
• Reducing carbon emissions to slow the pace of climate change.

Wind farms, for example, can be made safer for birds with proper planning and technology. And rather than feeding migratory birds, experts suggest focusing on habitat restoration, which supports the right types of food and shelter.

Conclusion

The transformation of bird migration is more than a scientific curiosity—it’s a clear warning. When birds change their behavior or disappear altogether, they reveal deeper shifts in our environment. The loss of species like the slender-billed curlew, declared extinct in 2024, shows what happens when adaptation is no longer possible.

Yet, these changes also bring hope. Our growing understanding of climate’s impact on birds offers a chance to act. With the right tools, knowledge, and cooperation, we can help migratory birds continue their journeys—reminding us of the resilience of nature and the power of global action.