A network of global partners has called for urgent and sustained action to protect both migratory birds and the insects they depend on for survival.

In a report issued to commemorate the yearly World Migratory Bird Day 2024 themed, “Protect Insects, Protect Birds,” the conservationists emphasised the critical role insects play in the lifecycle of many migratory birds and drew attention to the alarming global decline in insect populations.

The day is an international educational and awareness-raising campaign that promotes conservation efforts for migratory birds and their journeys across borders.

This year’s Convention on the Conservation of Migratory Species of Wild Animals (CMS) –a biodiversity treaty of the United Nations and one of the main partners behind the World Migratory Bird Day campaign– prepared the first study of its kind on insect decline and its relevance for migratory species, which it presented at its 14th Session of the Conference of the Parties (COP14) in Samarkand, Uzbekistan.

The report ‘Insect Decline and its Threat to Migratory Insectivorous Animal Populations’ found that insect decline is contributing to population losses of many migratory insectivorous (insect-eating) species, particularly those which rely on them as their main source of food.

Insects are essential to the survival of not just migratory birds worldwide, but also bats and fish. Their decline could also have indirect effects by altering ecosystem functions and the habitats therein –such as changing vegetation, which in turn may provide less cover for ground-breeding species, or supply less insect-pollinated fruits for frugivorous (fruit-eating) birds.

Findings of the report revealed that the decline in insect biomass, abundance, and diversity poses a major threat to migratory insectivorous species, reducing food availability during migration and other stages of their life cycles, and endangering many species monitored by CMS.
Land-use change, climate change, and pollution are the main drivers of insect decline worldwide and these drivers are often intertwined and may act simultaneously.

Insects and the migratory species that feed on them are important for ecosystem functioning and provide critical ecosystem services, such as pollination.

Also, there are still gaps in understanding the impacts of insect declines on migratory insectivorous species, with more information needed on the population status and trends for several species for both birds and also bats in particular.

“Despite variations in magnitude across ecosystems and regions, scientific evidence revealed that without doubt, we face an insect decline on a global scale. This can be measured for example as the losses in total insect biomass or species richness over time,” said Dr David Ott from the German Leibniz Institute for the Analysis of Biodiversity Change (LIB) and one of the authors of the report.

“To deal with the effects of insect decline, we need to understand that species are part of complex, interconnected communities, and that biodiversity is essential for ecosystems to work properly and provide services to humans. The causes of insect decline are also not separate, but a mix of several connected factors,” he said.

According to the Executive Secretary of the Convention on Migratory Species (CMS), Amy Fraenkel, “The alarming decline of insect populations is not just an isolated environmental issue—it is a cascading crisis that affects migratory birds, bats, and entire ecosystems.

“Without further research, as well as swift, coordinated global action to protect insects and their habitats, we risk losing vital species that are critical to maintaining ecological balance. The stakes are high, and this year’s World Migratory Bird Day serves as a crucial reminder of our shared responsibility to address this growing threat.”