Nearly Half of UN-Protected Migratory Species Are Now in Decline, Up From 44% Just Two Years Ago
Two years ago, the first comprehensive global assessment of migratory species delivered sobering numbers: 44% of populations listed under the Convention on the Conservation of Migratory Species (CMS) were declining. The hope was that attention and action would bend the curve.
The curve has bent the wrong way. An interim update released ahead of CMS COP15 in Campo Grande, Brazil, shows the proportion of declining populations has risen to 49%. The share of species facing extinction has climbed from 22% to 24%.
What is getting worse, and how fast
The update, developed for CMS by the UN Environment Programme World Conservation Monitoring Centre (UNEP-WCMC), tracks changes since the 2024 baseline report. Twenty-six CMS-listed species, including 18 migratory shorebirds, have moved to higher extinction risk categories on the IUCN Red List. The two biggest threats remain overexploitation -- hunting, fishing, and capture -- and habitat loss and fragmentation.
The scale of the challenge is vast. Billions of individual animals -- birds, fish, mammals, reptiles -- migrate across national borders and oceans. They pollinate plants, transport nutrients, regulate ecosystems, control pests, and store carbon. Their survival depends on coordinated action across every country along their migratory routes, which can span continents.
The numbers from the 2024 baseline were already grim. Migratory fish populations had declined by 90% on average since the 1970s. Ninety-seven percent of CMS-listed migratory fish faced extinction. More than half of Key Biodiversity Areas important for listed species lacked protected status.
Some species are recovering
The picture is not entirely bleak. Seven CMS-listed species have improved in status, including the saiga antelope, scimitar-horned oryx, and Mediterranean monk seal. These recoveries demonstrate that coordinated international conservation action can work when sustained.
Progress has also been made in identifying where protection is most needed. The update identifies 9,372 Key Biodiversity Areas important for CMS-listed species. But 47% of the area covered by these sites remains outside protected or conserved areas -- a major gap between identification and actual protection.
New mapping initiatives are gathering momentum. The Global Initiative on Ungulate Migration, the Migratory Connectivity in the Ocean system, and BirdLife International's work to map six major marine flyways are all expanding the scientific understanding of where animals travel and where they are most vulnerable.
What COP15 will try to address
The week-long meeting, running March 23-29, faces roughly 100 agenda items spanning deep-sea mining impacts, illegal and unsustainable taking of wildlife, bycatch, habitat fragmentation, marine pollution from light and noise, vessel strikes, infrastructure and renewable energy impacts, insect decline, and climate change.
A Global Initiative on Taking of Migratory Species is expected to launch at the meeting. The initiative focuses on a finding from recent research: the threat from domestic use of migratory species is far greater than from international trade. The aim is to help governments and communities ensure that any taking of migratory species is legal, sustainable, and safe.
CMS currently lists species in two appendices. Appendix I covers 188 species in danger of extinction, including 103 birds, 28 terrestrial mammals, 23 aquatic mammals, 8 reptiles, and 26 fish. Countries that host these species are required to provide strict protections, including prohibiting hunting and capture, protecting and restoring habitats, and removing migration obstacles.
Emerging threats: deep-sea mining and freshwater fish
Two additional reports being presented at COP15 highlight emerging concerns. A review of deep-sea mining impacts finds that sediment plumes, wastewater, and metal-contaminated particles from mining at depths of 1,000 to 6,000 meters could affect almost half of marine mammals covered by the Convention, along with sharks, rays, sea turtles, seabirds, and bony fish.
A separate global assessment of migratory freshwater fish identifies 325 new candidate species that could benefit from CMS listing. Some of the longest and most important animal migrations on Earth occur beneath the surface of rivers, and they face threats from overuse, dam-related fragmentation, and pollution.
The gap between knowledge and action
CMS Executive Secretary Amy Fraenkel framed the situation directly: the baseline exists, the tools are better, and public awareness is growing. The question facing governments at COP15 is whether that knowledge will be matched with the political will and investment needed to reverse the trends.
The interim update is not the full picture -- a comprehensive follow-up report is planned for COP16 in 2029. But the direction of the key indicators is clear, and it is not encouraging.