Why does this matter for conservation?

Raptors face heavy persecution in West Africa. People there often see them as potential livestock predators, and the birds are also targeted for the lucrative regional wildlife trade for belief-based use.

The study cites one striking case: an osprey banded in Scotland was fatally shot in Ghana — a fate the researchers say illustrates what enormous numbers of raptors in West Africa experience each year.

Ospreys illustrate what is at stake over a lifetime. Birds nesting in northern regions may fly more than 200,000 kilometers (124,000 miles) to and from their southern wintering grounds over the course of their lives. Scotland's ospreys were wiped out in the early 1900s by human persecution and reintroduced only in the 1990s. The researchers warn that significant reintroduction and protection efforts on nesting grounds may be undone if the birds are not also protected along their migratory routes and on their wintering grounds.

The broader picture is bleak. Populations of many Afro-Palearctic migratory birds are declining, with long-distance migrants suffering more pronounced declines than short-distance migrants or European resident birds. Most resident raptor species in Africa have also declined in recent decades, and those declines have been steepest in West Africa. Protected areas play a vital role in raptor conservation, but many in West Africa suffer from poaching and other illegal activities because of insufficient law enforcement.

What should happen next?

The researchers recommend that ongoing and future studies of migratory connectivity between Europe and Africa include increased conservation awareness, stronger law enforcement and continuous monitoring to understand and mitigate negative human impacts on Palearctic raptors wintering in West Africa.

They call for collaboration on research and conservation at a flyway scale — an approach modeled in the Americas by Partners in Flight, a network formed in the 1990s that now includes more than 150 organizations linking birds' breeding and wintering grounds across continents. West African migration hot spots in Senegal and the Gambia, among others, could serve as ideal locations for such collaboration, the authors suggest.

How firm are the findings?

The results come from banding recoveries, which have known limits: a banded bird must be found and reported, so recoveries can be geographically biased. Still, the authors note their findings on migratory connectivity appear consistent with data in the Eurasian African Bird Migration Atlas, which combines both banding and tracking data.

Many questions remain about the links between raptors' European breeding grounds and African wintering grounds. The researchers encourage future studies that combine banding data with new tracking technologies to better determine the origins and migratory routes of raptors and other birds wintering in Africa.

The story of European-African bird migration began with hard evidence in 1822, when a white stork arrived in Germany with an African hunter's arrow — made of tropical African wood — still embedded in its body, having survived a 5,000-kilometer flight to the Baltic coast. Two centuries later, scientists are still tracing those same routes, now with the aim of keeping the travelers alive.