Gibbon in my garden?

The other day, my wildlife camera in the back garden picked up what sounded like, not kidding, a gibbon. Obviously, it is a bird, but there wasn't picked up by the video, just the audio. Tried to add the recording, but was not successful. Neighbour said she thought it might be a baby blackbird in distress, but there was no sign of one. My wildlife area has gone a bit wilder this spring, so there are bits I couldn't check. Any suggestions as to what this may be?

Regards,

Glenna from Southport