World Migratory Bird Day 2024Protect Insects, Protect Birds

 

Key Messages

 

 

Background

 

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.

 

Summary of Key Messages

 
  • 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

 
  • The causes of insect decline include land-use change, climate change, agriculture, introduced species, nitrification, pollution, insecticides, herbicides, urbanization and light pollution. (PNAS. 2021)
  • The terrestrial bird population reliant on insects as a food source has dropped by 2.9 billion in the last 50 years (Tallamy & Shriver. 2021)
  • Supporting native plant species that productively sustain insect herbivores could help reverse these declines and benefit birds and other wildlife. (Tallamy & Shriver. 2021)
  • 96% of North American terrestrial birds feed their young exclusively or in part on insects. (Tallamy & Shriver. 2021)
  • Caterpillars are preferred over other insect options due to size, softness and higher nutritional value. Low caterpillar availability has been linked to reduced nestling fitness; for example, smaller clutch sizes, greater mortality from starvation, fewer fledglings, slower growth rates and lower body mass have been reported. (Tallamy & Shriver. 2021)
  • Recent bird population declines in North America, totaling over 3 billion individuals, are concentrated among terrestrial insectivores due to declining insect numbers. (Tallamy & Shriver. 2021)
  • Studies show that insect abundance is declining by 1-2% yearly, leading to potential shifts or losses of ecosystem function. (PNAS. 2021)
  • Not all insects are declining: some species are expanding in range and population size, and those associated with humans may be thriving due to human assistance. (PNAS. 2021)
  • Factors contributing to the decline of honeybees include mites, viral infections, microsporidian parasites, poisoning by pesticides and overuse of artificial foods. (PNAS. 2021)

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.

Actions We Can Take as Individuals

  1. Insect friendly gardens: plant native flowers, shrubs, and trees that provide habitat for insects.  Insects prefer plants that are native to your area and need cover to survive. These plants are accustomed to the local weather and provide a good habitat for bugs.
  2. Support organic farming: choose organic products whenever possible to avoid agricultural practices that use harmful pesticides and prioritize biodiversity.
  3. Minimize habitat destruction: when developing or landscaping your property, minimize habitat destruction, try to compensate for the loss and preserve natural areas.
  4. Don’t rake! Create a thriving ecosystem for insects and birds by leaving leaves in your garden or yard. The leaf litter acts as a natural shelter, food source, and breeding ground for various insect species. The decaying leaves also attract insects that are essential for insectivorous birds’ diets, promoting biodiversity and ecological balance. By refraining from raking leaves, you contribute to a healthier and more sustainable environment for both insects and birds.
  5. Keep water clean by using eco-friendly soaps and cleaners. Some cleaning products and salts can be harmful to insects if they get into the water. 
  6. Teach your friends and family about the significance of insects. Support programs that educate people about insects and speak up for conservation in your community. Make sure rules about lawns and pesticides protect insects and get involved locally to support decisions that protect natural habitats, insects, and other wildlife.
  7. Appreciate insects for the good things they do, like pollinating plants and being part of the food chain. Share positive pictures and stories about insects with your family and neighbors and on social media  to help others learn their importance.
  8. Supports pollinator-friendly initiatives: advocate for and support local policies and initiatives that protect insects and their habitats. 

Species

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.

Cliff Swallow

Petrochelidon pyrronota  

Cliff swallows are small migratory passerines that form nesting colonies across North America. In the fall, they depart for their wintering grounds, ranging from southern Brazil to Argentina and Chile. Cliff swallows migrate during the day, catching flying insects along the way. Many Cliff Swallow’s colonies are hosts for ectoparasite insects. These insects use the birds to disperse in the environment, or inhabit their body and flight feathers like Swallow Bugs, Fleas, and Louse Flies. Birds nesting in colonies often live closely with humans, and their large groups provide ecological benefits like natural pest control in urban and rural areas.

Bobolink

Dolichonyx oryzivorus 

 

 Migratory grassland birds, like the North American Bobolink, flutter and sing atop expansive grasslands. In autumn, they travel south to Bolivia, Paraguay, Brazil and Argentina. Although their diet is granivorous most of the year, during the nesting season, insects become the preferred resource to feed their chicks; prey includes grasshoppers, beetles and butterflies. Bobolink flocks can eat large quantities of grain, and the species’ scientific name, _oryzivoru_s, means “rice-eating.” They are often hunted and exposed to chemical pollution as agricultural pests, particularly in wintering grounds.

Nacunda Nighthawk

Chordeiles nacunda

 

 The Nacunda Nighthawk is a migratory bird found in the southern Neotropics. It is most active during twilight, night hours, and dawn. It is an aerial hunter and takes advantage of artificial lighting in urban and rural areas to capture insects. Their diet includes mayflies (Ephemeroptera) and beetles (Coleoptera). When there is a large emergence of moths (Lepidoptera: Noctuidae) or water bugs (Hemiptera: Belostomatidae), significant numbers of Nacunda Nighthawks are observed flying and hunting in groups.

Semipalmated Sandpiper

Calidris pusilla

 

Semipalmated Sandpipers forage in shallow water on mudflats, targeting aquatic insects like flies and larvae, particularly during the breeding season. Despite its Latin species name ‘pusilla’ which means ‘very small’, this characteristic does not limit these long-distance migratory shorebirds. They can cover vast distances, flying from North America to central and South America, including the Caribbean, to reach their preferred habitats, which include shorelines, mudflats, and sandy beaches.

Broad-tailed Hummingbird 

Selasphorus platycercus

 

The Broad-tailed Hummingbird, a medium-sized hummingbird, breeds in western North America and migrates south to Mexico and Central America. While their primary diet is nectar, which is low in protein, they supplement it by hunting insects in flight or perched on foliage between trees. A nesting female can capture up to 2,000 insects in a single day, a useful source of protein-rich food for raising chicks. They also hunt mosquitoes in the air or consume mites while feeding on nectar. Chemical pesticides and heavy yard cleaning can impact both hummingbirds and the insects they depend on for survival.

American Kestrel

Falco sparverius

 

Contrary to what many people think, we often underestimate how much birds of prey rely on insects for their diet. The American Kestrel is a species found all over the world and loves soaring over fields to snatch insects from the air. It captures the big ones like grasshoppers, cicadas, beetles, dragonflies, butterflies and moths. About 82% of the kestrel’s diet is made up of insects, especially during breeding seasons or when they stop at certain points on their migratory routes. Sadly, the use of chemicals in agricultural fields can dramatically decrease the population of these natural insect controllers.

Wood Duck

Aix sponsa 

 

Wood Ducks primarily forage in shallow waters, and research on their feeding habits indicate that during the breeding season, Coleoptera and Diptera are the two main insect groups they eat. While adult Wood Ducks mainly follow a herbivorous diet, including seeds, algae, small fish, and both terrestrial and aquatic plants, young ducks rely on insects, making up about 70% of their diet. These migratory ducks travel from North America to coastal and wetland areas in Mexico and a portion of the Caribbean. Wetlands with plenty of water resources with insects are essential for Wood Ducks.

Insects

Vivid Dancer 

Argia vivida

 

The Vivid Dancer is a bright blue to violet colored damselfly with black markings. Argia vivida has three life stages (egg, nymph and adult) and a life cycle that is partly aquatic and partly terrestrial. Adult Vivid Dancers are aerial predators and both sexes hunt. Damselflies’ wings fold when resting, unlike dragonfly wings, which protrude.

The species is threatened by habitat loss and degradation in most hot spring habitats due to intensive recreational use (e.g., bathing, diversion of water to create pools), trampling by livestock in fresh springs, and possible predation by introduced aquatic species. Vivid Dancers play several important ecological roles as predators, prey, and indicators of ecosystem health.

Willow Sawfly

Nematus corylus

 

As with all insects, Nematus corylus has several stages of development. They are: Egg, Larva and Chrysalis. The larvae resemble caterpillars and feed on young, tender leaves. Nematus corylus are related to wasps and bees; adults are 6 to 9 millimeters (mm) long. The larvae of Nematus corylus have six or more pairs of legs.

 

The larvae are slug-shaped and bright olive-yellow in color. Larvae feed on leaf margins and consume the entire leaf leaving only the midrib. Each larva can eat 1 to 2 willow leaves in its short life, and a sufficient number of larvae can defoliate large willows. These trees often grow new leaves, which are then eaten by the next generation of Nematus corylus.

Giant Cicada

Quesada gigas

 

The giant cicada is the only species of the Quesada genus found in North America, ranging from central Texas to central Argentina. It has a wingspan of 18 cm and a body length of 7 cm. The song of the giant cicada reaches 93 decibels at a distance of 50 cm, generated from a pair of organs in the abdomen called timbales. Its calls have been compared to various power tools such as motors, fan belts and steam engines.

Their larvae spend years underground feeding on the roots of trees. In times of mass emergence, cicadas are commonly consumed by birds, including birds of prey, as well as flycatchers, grosbeaks, wrens, and other aerial insectivorous birds. Interestingly, studies have shown that some bird populations may have larger clutches during the years when cicadas emerge. Cicadas benefit birds by providing significant amounts of food during their mass emergence events.

Buzzer Midge

Chironomus plumosus

 

The larvae of the species Chironomus plumosus, also known as the buzzing mosquito, is a non-biting mosquito species (Family Chironomidae) found in areas of the northern hemisphere. The larvae of this species play an important role in the aquatic food web and adult buzz gnats emerge rapidly from the water into the air. These mosquitoes are commonly known as “blind mosquitoes” because they have a mosquito-like appearance but do not bite humans. They fly in large swarms, often emitting a loud buzzing sound, and the adult male is distinguished from the female by its feathered antennae.

Buzzing midges can be found in fast-moving streams, deep slow-moving rivers, stagnant ditches, and in lakes and ponds rich in decaying organic matter. The larvae “clean” the aquatic environment by consuming and recycling organic debris. Larvae of the species Chironomus plumosus support migratory shorebirds during their arctic breeding season.

*Thenius, Ronald, et al. “Biohybrid entities for environmental monitoring.” ALIFE 2021: The 2021 Conference on Artificial Life. MIT Press, 2021.

Mayfly

Cinygmula ramaleyi

 

Ephemeroptera populations thrive in shallow, productive lakes with soft, organic-rich sediments. These adult stage insects have no mouthparts. Young mayfly nymphs prefer to burrow in soft underwater sediments. All the nutrients they need in their short adult life have been absorbed in the 2 years they spent underwater. In the short time they are, the birds feast on them. Emergent mayfly swarms in early summer are an annual event that helps migratory birds have full resources during their breeding season.

Emergent mayfly swarms are an annual event that helps birds have full resources during their breeding season. Mayfly populations do well in shallow, productive lakes with soft, organic-rich sediments. Mayflies are also useful indicators because they are highly visible, relatively easy to sample, and provide “real evidence” that restoration has been effective in wetlands, where high concentrations of contaminants are often transported in polluted areas.

Red-legged Grasshopper

Melanoplus femurrubrum

 

The red-legged Grasshopper, Melanoplus femurrubrum, is one of the most common leafhoppers and is distributed throughout most of North America. Members of the Orthoptera (crickets and grasshoppers) tend to contain a higher amount of protein than other insects; for example, adults of Melanoplus femurrubrum are 77% higher in protein.

Red-legged grasshoppers are found in both upland and lowland pastures, meadows, roadsides, lowlands, and cultivated fields. A grasshopper hatchling from the beginning resembles its parents, only it lacks wings and in its proportions is smaller. Grasshopper nymphs are an important source of food for birds, especially for chicks that cannot eat seeds.

Giant Water Scavenger Beetle

Hydrophilus triangularis

 

The water scavenger beetle is one of those types of beetles that can live both on land and in water while feeding on smaller insects and larvae. This beetle needs fresh water to reproduce and prefers to live in large, deep ponds. Larvae feed on small invertebrates such as insects and snails, but may also consume tadpoles and small fish. Adults have an adaptation that allows them to surface less frequently in search of air than their larvae. 

 

Adult Hydrophilus triangularis create an air bubble under their elytra (hardened wing covers) that they can use while underwater. Spiracles (tracheal openings) connect to this air bubble and oxygen can be accessed. Using their mandibles, they incapacitate prey, tear them apart and finally suck out their juices, playing an important role in controlling the population of other aquatic organisms.

Each of these creatures, insects, and birds alike, plays an essential role, from pollinating plants to being prey for larger organisms. They are threads in nature’s rich tapestry, a constant reminder of the interconnectedness of all living things.

Citations

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

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