One in 5 species of migratory birds, fish, reptiles, mammals and insects tracked by the United Nations is threatened with extinction due to increasing environmental pressure and overexploitation by humans, according to a landmark report published on Monday.
The UN report, “State of the world’s migratory species,” represents the first ever comprehensive assessment of the conservation status and population trends of species whose members “cyclically and predictably cross one or more national jurisdictional boundaries.” Some notable examples include green turtles, snowy owls, and Monarch butterflies.
The UN Convention on the Conservation of Migratory Species of Wild Animals, or CMS, tracks more than 1,180 species that are already threatened or that would “significantly benefit” from being protected under an international agreement. The report finds that 44 percent of these species are experiencing population decline and 22 percent are threatened with extinction. Its release coincides with the start of a high-profile UN wildlife conservation conference in Samarkand, Uzbekistan, where experts are calling for greater international cooperation to combat climate change, habitat loss, pollution and overexploitation of animals, such as hunting and fishing .
“Conservation of migratory species is extremely difficult because they cross nations, continents, even hemispheres,” Amanda Rodwald, director of the Center for Bird Population Studies at the Cornell Lab of Ornithology, told Grist. “It requires a lot of coordination between different countries … and thinking across geopolitical boundaries.”
The report reinforces previous research on the declining health of wild animal species worldwide, almost entirely due to human activities such as agriculture, hunting and fishing, as well as the pressures of climate change. In 2019, a separate UN panel reported that a “unprecedented” 1 million species worldwide was threatened with extinction. A follow-up study from late last year doubled that number to 2 million by considering a greater number of insects, which make up the majority of species worldwide.
Migratory species are particularly vulnerable to anthropogenic pressures. Their migratory journeys require large, intact tracts of land, water, or airspace—and these pathways are becoming more difficult to access, whether due to dams, boat traffic, roads, skyscrapers, or other development. According to the CMS report, 75 percent of listed migratory species are affected by lost, degraded or fragmented habitats, which can prevent them from finding mates or food.
A previous report from the CMS, published during the UN’s annual climate conference in Dubai last December, highlighted how climate change is affecting the timing of some species’ migrations and making it harder for them to reproduce and survive. As climate change progresses, other studies suggests that fragmented landscapes will prevent species from moving to cooler areas where they are more likely to survive.
However, the most pervasive threat to migratory species is overexploitation, which affects three-quarters of the species it tracks, according to the new report. It says people intentionally – and often illegally – hunt too many wild birds and terrestrial mammals for their populations to recover. They also inadvertently kill too many marine species as bycatch – fish, dolphins and other non-target animals caught in the industrial fishing process. Since the 1970s, populations of migratory fish species have declined by 90 percent, and nearly every fish species the CMS tracks now faces a “high risk of extinction.”
The decline of migratory species also has serious implications for humans. As noted in the new report, migratory species provide critical “ecosystem services” that benefit humans by dispersing seeds and pollinating food crops that people eat, as well as supporting livelihoods for fishers and farmers and maintaining healthy ecosystems. “If environments are not healthy for other species, they are unlikely to be healthy for humans,” Rodewald said.
Migratory species can also directly to mitigate climate change. Large migratory animals – such as humpback whales, for example – sequester carbon in their bodies and then transfer it to long-term storage in the soil or seabed after they die. Other migratory animals conserve carbon storage in grasslands by walking on the snow or soil and compacting, or producing nutrient-rich excrement that keeps plants healthy and prevents erosion.
To reverse migratory species’ decline, the CMS lists more than two dozen priority actions for policymakers. This includes cracking down on illegal and unsustainable hunting, fishing and bycatch; creating and protecting more natural habitats; and phasing out toxic pollution from sources such as plastics, pesticides and lead weights used in fishing. The report also recommends global coordination to curb light and noise pollution, which kills millions of birds and marine animals every year.
It is extremely important that many of the interventions recommended by the CMS have co-benefits for the climate. Restoring mangrove ecosystems, for example, can support migrating green turtles and dugongs while also pulling carbon from the atmosphere and storing it in biomass. And stop destructive overfishing practices can protect fish while helping to preserve the ocean’s crucial role as a carbon sink.
The UN conservation conference in Uzbekistan began on Monday and is expected to end on Saturday. Delegates are expected to review more specific action plans for a number of particularly vulnerable migratory species, and to consider new species for inclusion under the CMS – the report says there are nearly 400 “threatened and near-threatened” species that could benefit from the list. Non-binding global guidelines for light pollution, which have been under development since last year, are also expected to be submitted for adoption.