Introduction
When large broods of cicadas emerge every 13 or 17 years, it creates a feast for birds. This sudden abundance of food has a cascading effect on other animals and plants in the ecosystem.
Researching Cicada Impacts
John Lill and his team at The George Washington University have been studying the ecological impacts of cicadas since 2004. They planned to study the emergence of Brood X, a huge brood that appears once every 17 years, in 2021.
Birds and their Changing Diet
When cicadas emerge, birds opportunistically change their diet, focusing on this new food source rather than their usual prey, such as caterpillars. The researchers placed dummy caterpillars made of clay and observed bird beak marks. They found that during cicada season, fewer than 10% of the dummies showed signs of bird strikes, compared to about 25% in non-cicada years.
Unexpected Bird Diversity
The team also observed that over 80 different bird species, including those that don’t typically eat insects, were feeding on cicadas. Even small songbirds, whose beaks were initially thought to be too small to eat cicadas, eventually figured it out.
Impact on Caterpillar Populations and Forests
The decline in predation during cicada season resulted in a higher population of caterpillars causing twice as much damage to trees and leaves compared to a normal year. Although these effects are temporary, other studies have reported enduring effects, such as increased bird populations in the year following a cicada emergence and the influence on oak tree “masting” events.
The Importance of Birds in Ecosystems
The research emphasizes the significance of birds in regulating insects in forestry and agriculture. With declining bird populations due to climate change and human interference, there could be increased damage to forests and food crops.
Unforeseen Ripple Effects
David Beresford of Trent University highlights the importance of exploring unexpected outcomes resulting from changes in an ecosystem. Ripple effects can occur throughout the entire system, demonstrating the interconnectedness of species.
