correct word for filling in the blank

It works, but it sounds more natural to me without the word 'up'.

'trapping' [no 'up'] would also work, T.

Hi JTT

What about 'detacting' (without 'up')?

Many thanks.

don't know about "detacting", but "detecting" would work. Is this true, by the way? I thought they just used their ears, and differential strength of the echo in each ear. They use their wings too? Or is this just an example sentence?

There is no such English word as "detacting".

If the 'up' is required, as the quoted question certainly seems to suggest, then to complete the phrase I am sure that the missing word is 'picking'. Definitely not 'catching'.

In English, radio receivers, radar equipment, microphones etc are often informally said to 'pick up' signals or echoes of signals or sounds, when the more formal 'detect' is implied.

You need a sensitive microphone to pick up the sound of a pin dropping on the floor.

My TV set cannot pick up many channels because we live in a valley.

The radar at the airport can pick up echoes from planes when they are many miles away.

Bats make sounds and pick up the echoes with their ears.

Hi Contrex

I agree that the word is 'picking'.

Yes, I meant 'detecting'. It's a typo.

Thanks, JTT and Monterey, for your response to my query.