欧博官网State of the World's Migratory Species
Migratory birds travel vast distances across countries and continents, relying on diverse habitats to feed, breed, and rest. These birds play vital roles in maintaining healthy ecosystems but face increasing threats from human activities. The State of the World’s Migratory Species report, released by the Convention on Migratory Species (CMS) in 2024, provides a comprehensive overview of the conservation status, threats and conservation measures for migratory species. It highlights the deteriorating status of many of these species, and emphasizes the urgent need to expand protected areas, restore habitats, maintain migratory routes and scale up successful conservation efforts already underway. Despite current challenges, the report underscores that effective solutions exist, and stronger global action is necessary to secure the future of migratory populations.
Migratory birds, remarkable for their long-distance journeys and ecological importance, serve as both indicators and ambassadors for the health of global ecosystems. Their reliance on an array of habitats and stopover sites across broad geographic areas makes them particularly vulnerable to the cumulative effects of environmental pressures. Threats occurring at bottlenecks in the flyways can have impacts at population scales, and many pressures are transboundary in nature, necessitating coordinated international conservation responses.
Since 1979, the Convention on the Conservation of Migratory Species of Wild Animals (CMS) has served as a global treaty dedicated to the conservation of migratory species. The listing of species on CMS Appendices reflects their conservation status and the need for international collaboration. Appendix I includes species facing a high risk of extinction in the near future, requiring strict protection, while Appendix II lists species that would benefit from international agreements to improve their conservation outlook. Birds are by far the most represented group listed under CMS, comprising approximately 962 species (including 134 globally threatened species) which make up over 80% of all CMS-listed species. These include raptors, shorebirds, songbirds, and waterbirds that traverse continents and oceans during their annual cycles.
The first State of the World’s Migratory Species report, prepared for CMS by UNEP-WCMC, provides the most comprehensive assessment to date of the global status of migratory species (UNEP-WCMC 2024).
The conservation status of migratory birdsThe report’s “State” chapter synthesizes available data from the IUCN Red List and the Living Planet Index to assess both extinction risk and population trends. The report reveals that the status of many migratory species remains precarious. Overall, one in five CMS-listed species is threatened with extinction, and nearly half (44%) are experiencing population declines. Of the bird species listed, 48% have declining trends, while just 13% have increasing trends (BirdLife International 2025). While many bird species covered by Appendix II are currently categorised as Least Concern on the IUCN Red List, around a third are undergoing population declines, highlighting the need for proactive conservation before extinction risk increases (BirdLife International 2025).
Changes in extinction risk over time can be measured using the Red List Index (RLI). Disaggregation of the RLI reveals that CMS-listed birds have a higher overall extinction risk than all migratory birds combined, but a lower risk than all bird species combined (see figure 1). Notably, the RLI for CMS-listed bird species is steeper than for migratory birds and for all birds, suggesting that the rate of increase in extinction risk is highest for this group. This may be partly due to CMS selecting species of conservation concern for listing, but could also reflect that species in need of international cooperation are those that are the most vulnerable to environmental change.
Figure 1: The Red List Index for all birds, all migratory birds, and all migratory birds listed on the CMS appendices
The Red List Index (RLI) measures trends in extinction risk over time (illustrating its inverse: survival probability). The index is based on the number of species in each category of the IUCN Red List and the movement of species between categories owing to genuine changes in status. An RLI value of 1 equates to all species being categorised as Least Concern, and hence that none are expected to go extinct in the near future. An RLI value of 0 indicates that all species have gone extinct. A downward trend in the RLI indicates an increase in extinction risk. Data from BirdLife International (2025)
The Living Planet Index (LPI), which measures changes in population abundance since 1970, paints a similarly concerning picture. Abundance information from 15,923 populations of 1,710 migratory species of mammals, birds, reptiles and fish shows an overall average decline of 15% for all migratory species. These declines tended to be worse in the tropics, with declines ranging from 66% in Asia to 27% in Africa. The LPI indicates that populations of CMS-listed birds have increased by 11% on average. However, grouping all birds together may mask population declines in specific species groups and geographic regions, such as the loss of 2.5 billion migratory birds in North America since 1970 (Rosenberg et al. 2019).
While the global picture is concerning, there are regions and species showing improvements. The Red List Index suggests that CMS-listed migratory species in Europe and South and Central America have seen relative stability or even modest improvements in recent years. These changes are often linked to conservation policies, habitat protection, and flyway-level coordination. Species such as the Humpback Whale have shown dramatic recoveries due to coordinated international protection under CMS and other treaties.
The importance and status of Key Biodiversity AreasKey Biodiversity Areas (KBAs) play a critical role in the survival of migratory birds. These are sites of global importance identified for their contributions to the persistence of biodiversity. According to the report, 9,469 KBAs have been identified for CMS-listed species, with nearly 9,000 being identified for CMS-listed birds. Of the 962 bird species listed on CMS, 655 meet KBA criteria at one or more sites.
Despite their ecological importance, many of these KBAs are not currently protected or conserved under formal frameworks. Protected area coverage averages 49% globally but varies regionally, with an average of 27% in Asia and 66% in Europe (see figure 2). Even among those sites that are protected, many face significant and growing human pressures. Hunting, recreation, agriculture, and water management are the most prevalent threats to these vital habitats. Alarmingly, 58% of monitored KBAs important for CMS-listed species are under unsustainable levels of anthropogenic pressure.
Figure 2: The average protected area coverage of Key Biodiversity Areas identified for all CMS-listed species in six regions
Protected areas are defined as those from the World Database on Protected Areas (UNEP-WCMC & IUCN, 2020), as well as Other Effective Area-based Conservation Measures (OECMs) from the World Database on OECMs.
Conservation of KBAs is one of the most strategic and scalable interventions available. Safeguarding these areas—especially those that serve as stopover or breeding grounds—can help prevent extinction of migratory species. Increasing the coverage of KBAs within global protected area networks and ensuring their ecological integrity is central to reversing the decline of migratory bird populations.
Data gaps and new prioritiesA key contribution of the report is a novel analysis that identifies 399 globally threatened or Near Threatened migratory species not currently listed in CMS Appendices that may meet the criteria for future CMS protection. Most of these are birds (107 species) and fish (32 species). Within the birds, Procellariiformes (albatrosses, petrels and shearwaters; 49 species) and Passeriformes (passerine birds; 34 species) were most prevalent. Many of these bird species are already recognized as vulnerable in other conservation frameworks but have yet to benefit from CMS coordinated international action.
A total of 460 species listed under CMS (of which 67% are birds) have not yet been confirmed to meet KBA criteria at any sites. Notably, this group includes 70 species that are globally threatened, highlighting significant gaps in the current KBA network for migratory species.
Conservation responses and successesThe report also highlights a range of conservation initiatives and policy responses that have shown promise. Notable efforts include:
These efforts show that when countries collaborate and implement evidence-based action plans, populations can recover. However, these efforts must be scaled up and more widely applied to halt widespread declines.
The State of the World’s Migratory Species report is a sobering but vital benchmark. It shows that migratory birds are under increasing pressure, with population trends heading in the wrong direction for many species. Yet the report also shows that conservation works—when it is strategic, science-based, and internationally coordinated. Migratory birds are a shared global heritage. Their journeys link landscapes and cultures, and their presence in skies, wetlands, forests, and coasts is both a symbol and a measure of ecological health. By investing in the protection of key sites such as KBAs, closing data gaps, and continuing to monitor trends through indices like the RLI, the international community has the tools to reverse these declines.