World Migratory Bird Day

Bird migration is a natural phenomenon that has captured the imagination of people across cultures for centuries. These annual journeys involve the mass movement of birds across vast distances, often spanning continents, and are driven by a combination of instinct, environmental cues, and survival strategies. Migration is a complex behavior that serves various ecological, evolutionary, and survival purposes. Yet, the very phenomenon of bird migration is under threat, particularly due to declining insect populations, upon which many migratory birds rely for sustenance.

Insects provide essential energy for migratory birds, offering a rich source of nutrients critical for their survival. They rely on insects for energy during migration and other stages of their life cycles, especially when feeding their offspring. However, the massive decline in insect populations in many parts of the world is having serious implications for migratory birds. This year’s World Migratory Bird Day will therefore shine a spotlight on the interdependence between insects and birds, urging action to protect insects as a means to safeguard avian populations.

The campaign will explore the intricate relationship between birds and insects, and highlight the challenges faced by both as well as actions people can take to address the threats and halt the decline in insects. Below you will find a set of key messages and recommended actions and conservation measures which will be promoted through this year’s campaign.
 

• Insects provide the necessary energy for migratory bird species, because they contain remarkable nutrients, providing birds with protein-dense, high-energy sources of food. Migratory bird species depend on insects during migration and at other stages of their life cycles when feeding their offspring.

• The presence of insects greatly influences the timing, duration, and overall success of bird migrations. During stopovers at various locations along their migration routes, birds actively forage for insects in fields, forests, wetlands, and other habitats. They catch flying insects in mid-air, or they search for insects among leaves, bark, and vegetation. Many birds’ journeys coincide with peak insect abundance in their stopover areas.

• This reliance on insects is especially pronounced for species such as warblers, flycatchers, swallows, and swifts. However, many other bird species such as ducks or shorebirds, and some raptors depend on insects during migration and at other stages in their lifecycle, in particular for raising their young before they are able to fly.

• Insect populations are declining globally, and this phenomenon is mirrored by a decrease in populations of birds that depend on insects for their survival.

• Migratory birds bring multiple benefits to humans as insect eaters, providing pest control for mosquitoes, and other insects that may damage crops and spread disease.

• 85 percent of flowering plants require animal pollination; in most cases this job is done by insects. If we lose those pollinators, many plants will struggle to survive, and by extension many migratory birds that depend on them. 

• Actions taken to reduce insect declines will benefit birds across their flyways.

• Migratory bird monitoring has shown that insectivorous migrants associated with farmland ecosystems, especially grassland species, have declined considerably (13% on average in Europe during the period 1990-2015).

• Restoring grassland ecosystems, providing support to farmers to secure flower strips and fallow land is vital to restore insect and migratory bird populations globally.

• Close monitoring of migratory birds, using citizen-science tools and raising awareness through environmental educational campaigns, can deliver vital data to restore and manage critical habitats, and ensure their connectivity, for migratory birds.

• Maintaining and/or restoring water bodies is essential to protect insectivorous aquatic communities, including many waterbird species.

• The insect-eating bird diet encompasses a diverse range of insects including: Aerial insects such as flies and mosquitoes, moths and caterpillars, butterflies and beetles, and aquatic invertebrates.

 
CHALLENGES AND THREATS TO INSECT POPULATIONS AND THEIR EFFECT ON BIRDS The decline and disturbance in insect populations across the flyways compounds the threat to birds’ existence and overall welfare.
 

1. Habitat Loss and Change: Where natural spaces, such as forests or grasslands, are transformed or destroyed by activities such as intensive agriculture or urban development, insect populations decline. This decline has very negative implications for both plants, migratory birds, and the entire food chain in a negative cascading effect that results in severe bird population declines across an entire flyway.
2. Toxic Trouble: Pesticides and herbicides, which are intended to protect crops, often have unintended negative consequences. They often affect non-target insect species, either directly (by killing them) or indirectly (for example by polluting water bodies and affecting water invertebrates’ development). This collateral effect affects migratory birds, ending up in lower body condition at stop-over sites or lower breeding success.
3. Decreased Bird Populations: Without an adequate supply of energy-rich insects, birds may struggle to complete their migrations. Insufficient nutrition can lead to weakened immune systems, reduced reproductive success, and increased mortality rates among both adult birds and their offspring.
4. Ecosystem Imbalance: Birds and insects are a classic example of ecological coevolution. Altering this relationship brings negative impacts to both communities. Maintaining and/or restoring healthy ecosystems means ensuring vital ecosystem services provided by birds and insects, such as pollination, seed dispersal, pest control and human well-being.  
5. Climate Change; A negative consequence of the current climate is the desynchronization of bird migration: birds arriving at their breeding ground before or after the insect peak, reducing the breeding success, and increasing the damage insect populations can cause to some agricultural or forestry products.

 FACTS ABOUT INSECT & BIRD POPULATION DECLINES 

ACTIONS TO ADDRESS INSECT DECLINES To preserve the delicate balance between birds and insects, it is crucial to take proactive and effective conservation measures. A range of strategies can safeguard these vital components of our ecosystems.
 

1. Habitat restoration and management: Identifying suitable habitats and adequately managing and/or restoring them, through the creation of protected areas when needed that are adequately connected will have immediate and positive impacts for both birds and insects to flourish.
2. Sustainable Agriculture: Reducing pesticide and chemical fertilizer use, crop rotation, and maintaining natural vegetation corridors within agricultural landscapes benefit both insects and birds.
3. Pesticide Alternatives: Opt for organic alternatives, targeted application, and integrated pest management systems minimize negative impacts on insect populations and the birds and other species that depend on them.
4. Public Awareness: Raising public awareness about the importance of birds and insects fosters an understanding and empathy that is the basis for any conservation action. Communities can support conservation efforts, from local clean-up initiatives to creating bird-friendly urban spaces.
5. International Cooperation: Join forces beyond political boundaries to protect critical stopover points, coordinate conservation measures, and ensure the availability of a chain of habitats required by migratory birds.
6. Corporate Accountability: Encourage the private sector, companies and industries to adopt sustainable practices that reduce pollution and minimize habitat destruction through both regulations and incentives.

7. Recognizing the Value of Insects: Insects have a critical role in our survival. They contribute to food production, serving as pollinators for numerous fruits and vegetables. Insects enrich the quality of soil for plant growth and contribute to the overall health and balance of our planet. Ensuring the protection of insects enables the sustainability of our ecosystems and the food production industry.

We’ve handpicked seven bird species to be ambassadors, showing the important role of insects in the lives of migratory birds. These species not only demonstrate the diversity of migratory birds but also highlight their dependence on insects and healthy insect habitats. Cliff Swallows capture flying insects and provide natural pest control benefits around their colonies. Despite being primarily granivorous, the North American Bobolink relies on insects as a crucial food resource during the nesting season. The Nacunda Nighthawk, active during twilight and night, skillfully uses artificial lighting to hunt for insects. Semipalmated Sandpipers scour mudflats for aquatic insects, while the Broad-tailed Hummingbird supplements its nectar diet with insects, essential for nurturing its chicks. Even the American Kestrel relies significantly on insects as a food source. Finally, the migration of Wood Ducks to coastal areas shows just how important wetlands with plenty of insects are. Learn more about each species below.

Douglas W Tallamy , W Gregory Shriver, Are declines in insects and insectivorous birds related?, Ornithological Applications, Volume 123, Issue 1, 1 February 2021, duaa059, https://doi.org/10.1093/ornithapp/duaa059

PNAS. “A new approach for predicting the evolution of COVID-19.” Proceedings of the National Academy of Sciences of the United States of America, vol. 118, no. 1, 2021, e2023989118. https://www.pnas.org/doi/full/10.1073/pnas.2023989118.

Both, C., R. G. Bijlsma & M. Visser (2005) : Climatic effects on timing of spring migration and breeding in 351 a long-distance migrant, the pied flycatcher Ficedula hypoleuca. J. Avian Biol. 36 : 368-373. 352

Both, C., S. Bouwhuis, C.M. Lessells, M. Visser (2006) : Climate change and population declines in a 353 long-distance migratory bird. Nature 441, 81-83 354