Freshwater and terrestrial ecosystems are tightly linked, yet conservation efforts often overlook the flows of energy and nutrients that connect them. At the same time, both river biodiversity and bird populations are declining, with growing evidence that reductions in insect prey may be a key driver.
Although local studies show that emerging aquatic insects can support riparian birds, it remains unclear whether these relationships persist across larger landscapes and under human disturbance. Understanding these cross-ecosystem linkages is critical for designing conservation strategies that effectively sustain biodiversity across both land and water.
Schürings, C., and Olden, J.D. 2026. Cross-ecosystem linkages between freshwater insects and riparian birds across the USA. Nature Ecology & Evolution. DOI: 10.1038/s41559-026-03041-1
To better understand the connectivity between freshwater and terrestrail ecosystems, a new study reveals how processes linking rivers and land can shape biodiversity at continental scales. Focusing on the United States, the authors examine how emergent aquatic insects—particularly mayflies, stoneflies, and caddisflies—support riparian bird communities by providing nutrient-rich prey at critical times for bird breeding and survival.
Using data from more than 14,000 river sites and over two million bird observations, the study shows a strong and consistent relationship between freshwater insect richness and bird prevalence. Sites with higher insect richness supported significantly more bird species, especially aerial insectivores that feed on insects in flight. In fact, these birds were more than three times as prevalent in areas with high insect richness compared to low-richness sites. This relationship held across diverse river types, including intermittent systems that are often overlooked in conservation planning.
Importantly, the findings demonstrate that local ecological interactions scale up to influence biodiversity patterns across entire landscapes. However, the strength of these linkages depends on landscape context. Urbanization weakens the connection between aquatic insects and birds, likely due to altered hydrology, light pollution, and barriers that disrupt insect movement. Agricultural landscapes show a more nuanced pattern: while intensive farming can reduce insect quality and availability, aquatic insects may become especially important where terrestrial prey is scarce. Riparian vegetation also plays a dual role, supporting bird habitat while sometimes reducing reliance on aquatic prey.
These results have clear implications for conservation. Protecting freshwater ecosystems not only preserves aquatic biodiversity, but also sustains terrestrial food webs and bird populations. Declines in water quality and river integrity can ripple outward, reducing the availability of high-quality insect prey and contributing to broader biodiversity loss.
For managers and policymakers, the study underscores the value of integrated conservation strategies that bridge freshwater and terrestrial systems. Actions such as improving water quality, restoring river-floodplain connectivity, and protecting riparian corridors can generate multiple benefits across ecosystems. In the context of global biodiversity goals, maintaining these cross-ecosystem linkages will be essential for building resilient, connected landscapes.
Related Posts
World’s largest dam removal leads to rapid fish recolonization
The removal of four dams along the Klamath River in Oregon enabled Chinook salmon to rapidly recolonize nearly 90% of their historical range.
High-quality matrices support bird diversity in forest fragments
Global data from forest islands and forest fragments show that improving tree cover and landscape connectivity around small forest fragments can dramatically increase bird diversity and reduce local extinctions.
Aquatic-terrestrial connectivity sustains communities
Extensive surveys across the United States show that aquatic insect richness strongly shapes bird communities, underscoring the deep ecological connections between freshwater and terrestrial ecosystems.
