Nightjar vocalizations

These are some unusual Nightjar (Caprimulgus europaeus) vocalizations, I recorded recently. They were recorded with a Dodotronics Hi Sound stereo, parabolic microphone, with a Tascam Portacapture X6 audio recorder. I processed the audio, to make it more audible, by applying a strong high pass filter, to low frequencies under 1100 Hz, to filter out traffic and aircraft sound, and normalized it. Otherwise, no other filtering or noise reduction was used.
I should add, that this was coming from quite close, and it is not just normal churring at distance. I am fairly certain this was coming from Nightjars, as there was other frequent Nightjar vocalizations, churring and cuicking coming from this area. Through the headphones, it was fairly quiet, and it's only the high pass filtering, and the normalization, that makes it more audible.