ʻŌpeʻapeʻa are sneaky and secretive, so to learn more about their behavior we use some special tools.


Listen in…

Bat detectors let us record the high frequency echolocation calls of bats as they fly over.

One challenge is that it is impossible to determine if 100 calls belong to 100 bats flying over or a single bat that remained near the microphone.

For humans to hear the bat’s echolocation calls they must be slowed down and lowered in frequency 10x, as you can hear below.


Fishing in the sky

Researchers use very fine mist-nets to capture bats in flight. Nets are monitored very frequently and bats and are safely removed within a few minutes. Sometimes bats chew through the net and escape before researchers arrive, leaving a tell-tale hole in the mesh.

ʻAmakihi pictured. The ultra thin nets for capturing bats are challenging to photograph at night



Researchers record bat’s forearm length, mass and sex
(trust us, that last one is easy)



Allows researchers to follow bats as they forage and back to their roosts


radio tags

Very small radio tags (0.7g) are used to study bats. The tags need to weigh less than 5% of the bat’s body weight so as to not limit their maneuverability

Radio tags are attached to the back with veterinary glue and fall off after 1-2 weeks.