Many migratory birds have been declining for decades. The UK's European Turtle Dove population has plummeted by 98%, while such iconic birds as Common Cuckoo, Common Swift and Common Nightingale are returning to the UK from Africa each spring in ever-diminishing numbers.
We may be aware of some of the challenges faced by these long-distance travellers, but each species face their own set of obstacles as they cover vast distances from north to south and back again.
One of the many issues facing declining species is the poor condition or loss of habitat at some, or all, of the stages of their life cycle. This can be particularly problematic for migrant species as they rely on different areas at different life-cycle stages.
Populations of migrant birds such as Common Cuckoo may recover with consistent protection along their migration route (Chris Lake).
Migration routes examined
Researchers from the British Trust for Ornithology (BTO), in collaboration with the University of Durham and others, have examined the migration routes of 30 bird species to see how much of their life cycles are spent in areas that provide adequate protection and quality habitat.
For some species, breeding areas may be protected and in good condition while their wintering grounds are not. The essential feeding and resting areas on some species' migration routes are seriously denuded, resulting in key stop-over destinations being in far from optimal condition.
Habitat destruction, pollution, hunting and climate change are all contributing to declining populations across multiple bird species. Protected areas may provide productive, safe habitats at certain points in the birds' year, but there are critical periods where the landscapes they inhabit are of poor quality, or pose potential threats.
In December 2022, Parties to the Convention on Biodiversity agreed a global target to conserve 30% of Earth's land and seas by 2030. This initiative is known as '30 x 30' and seeks to ensure that countries are proactive in securing protected areas that not only meet the requirements on paper, but also deliver effectively for nature.
International effort
Providing effective protection for migratory bird species can be difficult when they pass through several nations, and ensuring protected areas along the entirety of a bird's flyway is rarely an achievable task. However, by better understanding the peaks of movement in certain areas, temporary conservation measures such as seasonal hunting bans, or changes to livestock grazing regimes in specific places could help significantly.
It is hoped that by using the study's analytical method to identify specific weeks of the year when key migratory species are most vulnerable, due to a lack of protected area cover, conservationists can then focus on protecting primary sites at those particular points in the calendar. For example, seasonal hunting bans have been shown to significantly benefit European Turtle Dove across areas of Europe.
European Turtle Dove has shown a recovery in numbers in Western Europe during the last few years (Jim Mountain).
This approach could guide planning for new protected sites being designated under the 30 x 30 target. In this way, migratory species can be adequately covered by protected areas in the future and this may help to halt or reverse their declines.
Jennifer Border, Senior Research Ecologist at BTO, said: "Many migratory birds are lacking effective protection or access to protected areas, when it matters most. By better understanding each migratory species' requirements at all stages of their lifecycle, we can hope to implement practical protection for key sites, at peak periods of their journey."
She added: "This study provides important new evidence that protected areas make an important contribution to the conservation of migratory bird species, as the species whose distributions overlap the least with protected areas have declined the most. Increasing protected area coverage, in line with internationally agreed targets, should therefore make an important contribution to the future conservation of these declining migratory birds that have so much cultural significance across Europe."
Reference
Border, J A, et al. 2025. Expanding protected area coverage for migratory birds could improve long-term population trends. Nature Communications. DOI: https://doi.org/10.1038/s41467-025-57019-x
