Scientists observe rare bird-hunting behaviour in Greater Noctule bats

Noctule Bat with blood and feathers around its mouth. (Image: Jorge Sereno)

Scientists, after twenty-five years of investigation, additionally discovered how the larger noctule bat, hunts and eats tiny birds in the air. This bat is the largest bat in Europe. An international team of researchers has shed light on how this bat hunts.

Innovating Biologger Technology

At Aarhus University, biologists implanted the greater noctule (Nyctalus lasiopterus) with lightweight biologgers, which monitored the movement, height, echolocation signals and acceleration. The gadgets were able to display the aerial hunting behaviour of the bats.

The new study shows that these bats can fly high into the night sky to locate and attack unsuspecting birds. Unlike certain insects, birds cannot hear the bats’ echolocation calls and may only realise the danger at the very last moment, giving them little chance to escape.

Hunting High Above

In the study more noctules were observed to sense the presence of passerine birds with loud, low-frequency echolocation calls. They prey above one kilometre high, making steep dives that are fast, and still airborne and preying.

Biologgers revealed noctules dive steeply at breakneck speed, reminiscent of fighter aircraft. They can dive up from 30 to 176 seconds. They can spend twenty‑three minutes of chewing followed low flight. X‑rays and DNA confirmed biting, wing removal. This bat pull wings, slow drag and fed on birds.

Ecological and Conservation Significance

In order to conserve the greater noctule, it is important to know the hunting methods of this species. The predatory behaviour of the species is rare and endangered because of the loss of habitats, and the knowledge of predatory behaviour has informed the habitat management and protection strategies.

Future Steps

This study published in Science offers the first direct observation of a bat preying on birds. It shows the ecological purpose of greater noctules in the European ecosystem. The study also describes about biologger technology and how this tech may reveal concealed wildlife behaviours.