Progress in protecting the world’s migratory birds

Migratory species need safe places all along their migratory routes. Image by bird1444

Migratory birds live astonishingly international lives.

A single bird might breed in the Arctic, refuel in East Asia, and spend the non-breeding season in Australia. Along the way it crosses oceans, continents, and dozens of political borders. For these species, conservation is only as strong as the weakest link in their migratory chain.

In a new paper published in Frontiers in Ecology and the Environment, Marina Corella Tor set out to ask a deceptively simple question: how well does the global network of international agreements actually protect migratory birds?

To answer it, Marina built the first comprehensive global database of International Migratory Bird Agreements (IMBAs). They identified 49 agreements spanning 187 countries and covering 1,677 (86%) of the world’s 1,958 migratory bird species .

At first glance, that sounds reassuring. But as is often the case in conservation, the details matter.

Only 28% of migratory bird species have all of their range countries participating in at least one agreement. For 14% of species, none of their range countries are covered at all. In many cases, a species may be protected in one country but not in another along its flyway. For birds that depend on multiple sites across their annual cycle, partial protection can mean incomplete security.

The geography of agreements is also uneven. Europe emerges as a hotspot of international cooperation. By contrast, relatively few agreements are found in Central America, northern South America, much of Africa, and parts of Western, Central and Southeast Asia. Countries with stronger governance, larger land areas, and more shared borders tended to participate in more agreements. Interestingly, middle-income countries had the fewest agreements — a pattern consistent with broader theories about how environmental engagement changes during economic development.

The study also reveals something about history and priorities. Waterbirds — long the focus of international flyway initiatives — are usually explicitly named in agreements. Many non-waterbirds, however, are covered only indirectly through references to higher taxonomic groups such as Families or Orders. That might sound technical, but it matters: implicit coverage can create ambiguity, especially when taxonomic revisions shift species between groups.

There is good news. Endangered species tend to be listed in more agreements than species of Least Concern. Yet five Critically Endangered and six Endangered migratory species currently have no coverage under any agreement at all .

What this study ultimately provides is clarity. The new International Migratory Bird Agreements Database (IMBAD) offers a transparent way to see where the global safety net is strong — and where it has holes. About 86% of migratory bird species are at least partially covered, but full-route protection remains the exception rather than the norm.

Migratory birds have evolved to connect the world’s ecosystems. Ensuring that our governance systems are equally connected remains one of conservation’s great challenges. This work gives us a map of where to start strengthening the links.

Read the paper: Spatial and taxonomic coverage of international migratory bird agreements.