Migratory birds are losing ground. Study cites key areas needing protections.

The planet's migratory birds may be in trouble.

Habitat destruction has compromised many species' migration routes, leaving birds with fewer stopover and wintering locations to recover from their arduous journey, according to a study published in Thursday in the scientific journal Science.

The study tracked the migratory routes, including stopover and wintering locations, of over 1,451 bird species and found that 91 percent travel through areas that are not currently safeguarded from development. The findings suggest that expanded restrictions on development in areas known to be frequented by migratory birds may be needed to ensure their survival.

“Migratory species cover vast distances and rely on an intact series of habitats in which they can rest and feed on their long journeys," conservation scientist Richard Fuller of the Australian Research Council's Centre of Excellence for Environmental Decisions (CEED) and the University of Queensland told the Associated Press. "If even a single link in this chain of sites is lost for a species, it could lead to major declines or even its extinction."

International treaties to protect migratory bird species have seen some success in several parts of the world.  Next year will mark the 100th year of the Migratory Bird Treaty between the US and Great Britain, who signed in 1916 on behalf of Canada. The treaty “unites the efforts in the United States and Canada to protect birds that cross our international boundaries,” according to a government statement.

Similar treaties have been made with Mexico (1936), Japan (1972), and Russia (1976).

However, the problem of habitation destruction is most rampant in North Africa, Central Asia, and the coastlines of East Asia, where conservation efforts are not as prevalent. Countries in the regions do not offer as many protected areas and the areas that are safeguarded do not overlap enough to offer a route for birds.

Safe stopover points and wintering spots are crucial for migratory routes. Birds use them to feed and build up energy reserve for the rest of the journey. They are essential for survival, conservation scientist Claire Runge told the AP.

Ms. Runge pointed to the bar-tailed godwit as a species facing acute risk in the near future. The godwit migrates from the Arctic to Australia and New Zealand, stopping at sites in China, North Korea, and South Korea along their route.

“Many of these critical sites have been lost to land reclamation owing to urban, industrial and agricultural expansion, and the species is undergoing a rapid decline," Runge told the AP.

Conservationists have called for creating new protected areas for migrating birds and expanding international conservation efforts.

This report includes material from The Associated Press.