Here’s Where U.S. Bird Populations are Dwindling (and Why)

Bird populations within the United States are declining fastest in the very habitats where they should be thriving, according to a new study published in Science. Researchers at the Cornell Lab of Ornithology analyzed 36 million bird observations submitted to the eBird platform by birdwatchers. They combined those records with high-resolution satellite data to track population trends for 495 bird species across North America from 2007 to 2021.

To make sense of the vast amount of data, the researchers used a scientific method known as double machine learning. In other words, computers search for patterns in large data sets. Because birdwatchers vary in how often they go out and how likely they are to spot certain species, the models were corrected for differences in observer effort and visibility. The findings were that 76 percent of the bird species studied have declined in over half of the areas where birdwatchers previously observed them in abundance.

The Midwestern Decline

The Midwest’s tallgrass prairies have been reshaped into wide stretches of cropland. Since 1970, Bobolinks have plummeted by over 60 percent. With native grasslands mostly gone, these migratory songbirds are increasingly forced to raise their young in hayfields. Regrettably, early mowing and heavy pesticide use often destroy broods and wipe out the insects they depend on for food. The Bobolink Project and several state programs partner with farmers to delay mowing, limit chemical use, and replant native prairie grasses. These changes aim to give Bobolinks a better chance at nesting success in today’s working landscapes.

Greater Prairie-Chickens have been stripped of over 90 percent of their historic range, much of it converted to farmland. In Kansas and Nebraska, the grasslands for breeding now exist in small, scattered patches. Wildlife agencies and restoration groups are collaborating with landowners to stitch fragmented grasslands back together. They use strategies such as conservation easements, prescribed burns, and native grass replanting to revive the open terrain these birds depend on.

Fenced In Western Birds

The Greater Sage-Grouse and Sagebrush Sparrow are in retreat as roads, expanding infrastructure, and fencing reduce the size and quality of sagebrush habitat. The grouse avoids breeding sites near human activity, and the sparrow needs thick sagebrush for cover and open ground nearby to feed. Federal land managers and local conservation groups are working to restore the landscape. They are removing nonnative plants, adjusting grazing schedules, and partnering with ranchers to support long-term, sustainable land care.

Tides Rise, Wetlands Sink

The secretive Black Rail is vanishing with the tides along the Atlantic and Gulf coasts. These tiny marsh birds lay their eggs in the driest, highest parts of coastal wetlands, now routinely swamped by rising sea levels. As saltwater encroaches, Black Rails are scrambling for dry ground to rear their young. In response, conservationists are working to preserve high marsh habitat, manage tidal flooding, and support the inland migration of wetlands to give the species a fighting chance.

Hawaiian Birds Lose Refuge

Malaria-carrying mosquitoes have pushed the Hawaiian ʻAkikiki to functional extinction. As rising temperatures allow mosquitoes to reach higher elevations, the birds have lost their last disease-free habitats. This small insect-eating songbird has dwindled from several hundred to just a handful of wild individuals. Scientists are breeding the ʻAkikiki in captivity and testing mosquito control methods, including releasing Wolbachia-infected males to reduce mosquito populations.

Thrush Song Grows Silent

In the northeastern United States, the population of Bicknell’s Thrush is declining due to rising temperatures, which hinder the growth of spruce-fir forests at high elevations. To date, fewer than 100,000 Bicknell’s Thrushes are estimated to be left in the wild. Ongoing urban development, including logging, ski resorts, and housing construction, further reduces their breeding habitats. Recovery efforts focus on reforesting high-elevation nesting areas, establishing protected zones.

The Cornell analysis reveals that U.S. birds are being displaced from a wilderness, which they have help to shape for generations. Nature’s balance is shifting, and our window of opportunity to align it is closing fast.

The post Here’s Where U.S. Bird Populations are Dwindling (and Why) appeared first on A-Z Animals.