1.   The small bats known as horseshoe bats have long been known to emit long, fixed-pitch hoots rather than staccato clicks or descending wolf-whistles.

2.   Imagine, first, a horseshoe bat giving out a continuous hum of ultrasound as it flies fast towards a still object, like a tree.

3.   Another curious trick of horseshoe bats concerns movements of their outer ear flaps.

4.   Unlike other bats, horseshoe bats move their outer ear flaps in fast alternating forward and backward sweeps.

5.   A colony of endangered horseshoe bats roosts in the rafters.