Groundbreaking Insight into a Remarkable Hunting Strategy
For years, researchers have known that some bats can prey on sizable, nimble birds. Now a comprehensive study using high-resolution biologging has confirmed that Europe’s largest bat, the greater noctule (Nyctalus lasiopterus), routinely captures and consumes nocturnally migrating passerine birds in flight high above the ground. This discovery sheds light on a highly specialized hunting strategy that allows these bats to exploit a vast, seasonal food resource—one that remains largely inaccessible to most other predators.
How the Study Traced the Predator–Prey Dance
In a collaborative effort, scientists equipped 14 greater noctules with advanced biologging tags that logged altitude, echolocation bursts, and three-dimensional movement. This approach provided continuous, real-time data on bat altitude, speed, and hunting behavior. The team contrasted these high-altitude pursuits with the more typical, short-range insect-hunting bouts that characterize most bat foraging.
The results revealed two striking attack sequences. On separate occasions, the bats climbed above 400 meters before locating prey and then launched prolonged, rapid chases. Each pursuit produced more than 40 rapid echolocation buzzes, signaling intense, sustained pursuit of a single target across a substantial vertical distance.
From Chase to Capture: A Robin’s Fate
In one observed event, the chase ended with the capture of a European robin. Audio analyses captured the bird’s distress calls, confirming the kill. After the capture, the bat carried the bird and, according to the recorded chewing sounds, fed on it during flight for about 23 minutes while maintaining altitude. This is notable because most carnivorous bats that feed on large prey do so on the ground or perched, not mid-flight.
Evidence Beyond Audio
The researchers also analyzed wings found beneath the bats’ hunting grounds. Predator DNA barcoding and x-ray analyses revealed bite marks consistent with greater noctule activity. The combination of audible prey distress signals and physical bite marks provided converging lines of evidence for high-altitude predation on birds.
How Bats Handle Large, Agile Prey Aflame with Flight
A striking aspect of the study is the method by which these bats manage large, evasive prey in mid-air. After capturing a bird, the greater noctule appears to remove the wings in flight to immobilize the prey, reduce aerodynamic drag, and simplify handling. This aerial processing mirrors some aerial-hawking strategies used against large insects and stands in sharp contrast to most birds of prey and other carnivorous bats, which typically consume large prey on land or while perched.
Implications for Ecology and Conservation
The findings emphasize the nocturnal and migratory patterns that shape predator–prey dynamics across Europe. Migratory birds—from billions migrating at night—represent a colossal, seasonally available resource. The greater noctule’s ability to exploit this resource showcases a remarkable ecological niche and highlights how behavioral adaptations enable predators to capitalize on otherwise inaccessible prey. Conservation strategies for these bats must consider both their insect foraging and their occasional, high-altitude bird predation, as both rely on intact roosting habitats and migration corridors.
Future Research Aims
Moving forward, scientists aim to quantify how often greater noctules engage in this behavior, whether it targets specific bird species, and how weather, wind patterns, and migratory timing influence hunting success. The integration of biologging, acoustic monitoring, and genetic analysis will continue to illuminate the complex foraging strategies of bats and their role in ecosystem dynamics.
