The rapid decline in insect populations is endangering migratory species that rely on insects as their main food source. Birds, bats, and fish are all feeling the impact. Insects are not only vital to their survival, but also crucial for maintaining healthy ecosystems. The loss of insects could lead to long-lasting damage to ecosystems across the globe, says a new report — Insect Decline and its Threat to Migratory Insectivorous Animal Populations.
Insects play a critical role in the food chain. Migratory birds, such as swifts and flycatchers, rely heavily on insects to fuel their long journeys. Insect-eating bats and fish are also deeply affected by this decline. Without enough insects, these species face starvation, reduced breeding success, and potentially severe population drops.
The decline in insect numbers doesn’t only affect insectivores. It also disrupts ecosystems by altering vegetation and reducing available resources for other species, such as fruit-eating birds that depend on insect-pollinated fruits.
GLOBAL INSECT DECLINE: SCIENTIFIC EVIDENCE
The problem is global. According to Dr. David Ott from the Leibniz Institute for the Analysis of Biodiversity Change, insect decline is measurable worldwide. “We face an insect decline on a global scale, whether measured by total insect biomass or species richness,” Dr. Ott explains.
This issue cuts across ecosystems, from tropical rainforests to temperate regions. The causes are complex and interconnected, making it a challenge to fully understand the scale and impact of this decline.
CAUSES OF INSECT DECLINE
Several factors are driving the sharp reduction in insect populations, many of which are tied to human activities.
Land Use and Agriculture
One major cause is habitat destruction due to agriculture. Large-scale farming and the use of pesticides have devastated insect populations. Forest management practices that involve clear-cutting also reduce insect habitats.
Pollution
Pollution, especially from agricultural runoff, is another culprit. Chemicals from fertilizers and pesticides kill insects or disrupt their development. Water pollution affects aquatic insects, hindering their larval growth and reducing adult populations.
Climate Change
Climate change further accelerates the problem. Shifting weather patterns disrupt insect breeding cycles, and rising temperatures can make some habitats uninhabitable for certain insect species. Migratory birds and bats that rely on predictable insect availability may find themselves without food during crucial times of the year.
IMPACT ON BIRDS
Migratory insectivorous birds are particularly vulnerable. Their migratory routes depend on insects being available at stopover points. Reduced insect populations mean birds arrive in worse physical condition, unable to refuel for the next leg of their journey. This has led to population declines in many migratory bird species.
Birds that breed on the ground face additional threats. The changes in vegetation linked to insect loss may reduce their nesting cover.
IMPACT ON BATS
Bats also face significant threats due to insect decline. Clear-cutting of forests and artificial light pollution at night disrupt insect habitats, leading to food shortages. These pressures are particularly intense in Europe during winter when insect numbers naturally decrease. As a result, insectivorous bats are forced to forage for longer periods, using more energy, which could lead to higher mortality rates.
IMPACT ON FISH
Fish that depend on aquatic insects are feeling the strain as well. Modifications to waterways, like the construction of dams, alter water conditions in ways that harm insect populations. Pollution adds to the stress on aquatic ecosystems. Polluted water can kill insect larvae, cutting off a vital food source for fish.
ECOSYSTEM SERVICES PROVIDED BY INSECTS
Insects are not just food for animals. They play a central role in pollinating plants, including many crops that humans depend on. As insect populations decline, we may also see a decline in plant pollination, which could affect food production globally.
Moreover, insects help with decomposition, nutrient cycling, and soil formation. Their loss threatens these vital ecosystem functions, which in turn affects biodiversity and human well-being.
LACK OF DATA ON INSECTIVOROUS MIGRATORY SPECIES
Despite clear evidence of insect decline, there is still a lack of data on how this is affecting specific insectivorous species. Many migratory birds and bats have not been adequately studied. This makes it difficult to predict the long-term effects of insect loss on their populations.
A better understanding of population trends and the specific threats faced by these species is needed to inform conservation efforts.
CMS RECOMMENDATIONS TO COMBAT INSECT DECLINE
The Convention on Migratory Species (CMS) has issued recommendations aimed at slowing insect decline and protecting insectivorous species. These include:
Conservation Measures for Food Availability
One of the key steps is ensuring that there is enough food available for migratory species. This means protecting and restoring insect habitats, such as forests and wetlands. Reducing the use of pesticides and other harmful chemicals in agriculture is also essential.
Intensify Insect Monitoring
CMS calls for more extensive monitoring of insect populations. This will help scientists track trends over time and identify areas where conservation efforts should be focused. Improved data collection and sharing across countries will be crucial in tackling this global issue.
Improving Habitat Diversity
Another recommendation is to enhance habitat diversity and connectivity. This involves restoring natural landscapes and creating corridors that allow species to move between different areas. Increasing the variety of habitats can help support a more diverse insect population.
Urgent Action Plans
The CMS report also emphasizes the need for urgent action to address the cascading effects of insect decline. Governments and organizations must work together to create guidelines for prioritized actions, such as reducing pesticide use, limiting pollution, and addressing the impacts of climate change.
THE NEED FOR GLOBAL COOPERATION
Insect decline is not a problem that any one country can solve on its own. It requires global cooperation. The factors driving insect loss—land use changes, pollution, and climate change—are interconnected and cross borders. Governments, NGOs, and private organizations must collaborate to create effective solutions.