Bittern : male booming (dawn) : RSPB Otmoor

A male Eurasian bittern (Botaurus stellaris) 'booms' from a relatively open position amongst the reedbeds.
This clip was filmed on an #iPhoneXs around fifteen minutes before sunrise at RSPB Otmoor nature reserve, Oxfordshire, UK, using the phonescoping technique. I was filming a pair of bitterns in the distance when I caught sight of this male sitting around 95m from my position. Luckily he stayed in sight for a little while, during which he boomed shortly after a brief threat display - the threat display presumably to something overhead or nearby which I didn't spot.
The actual conditions were quite a bit darker than it appears here; the necessary high-ISO filming resulting in quite a lot of video 'noise' and lack of fine detail in the original file. There's also some 'heat haze' contributing to a slightly wobbly image, even though the sun hadn't yet appeared over the horizon.
Shooting at such a distance meant that the boom call ended up being around a third of a second behind the image in the original clip, so the audio has been adjusted in the edit to bring it back into sync.

[@jenniferann6956]

What a magnificent bird!!! 😍 Magical beauty 😍🐦

[@Havoc5429]

Love the bittern, nearly outdone by the cetti's warbler, nice mix of reedbed sounds 😊

[@bohdaj]

incredible .... exactly like a cow such a small bird

[@ascensiondoorway]

I can hear a chorus of birds around it - but when it shudders then opens & closes its beak I hear nothing 😐

[@robcaddphotography]

In this clip, little sound is produced the first five times that the bill is opened (it varies, might be less or more) - this is sometimes termed the 'pumping' phase and is where the bird is taking in air in readiness for the next phase. The main, very low-frequency, 'boom' sound is then heard; in this clip, it's when (or slightly after) the bill is opened for the sixth time, and then again for the next three openings.
As to why you can't hear anything - that could be for a number of reasons, eg.:
1. the sound may've gone out of sync with the image, perhaps due to some local internet or wifi issue (I usually resolve this by restarting the app, or sometimes restarting the viewing device).
2. Most often though, the reason is that the small speakers on certain devices just cannot reproduce the low-frequency sounds that these birds produce (or the sound settings on the device are set so that low-frequency sounds are filtered out).
There may be other reasons too; all I can say is that the sound is still on the clip - I've definitely not deleted anything! :)
Thanks for watching the video! I hope you do manage to eventually hear the booming!

[@ascensiondoorway]

Thanks - I turned my phone up as high as it would go but obviously it was not high enough to hear the 'booming'

[@KayGreylai]

Sounds off at about 1:18 sounds kinda like an oboe for the peoole who arent sure what their looking for.

[@davidelgar4371]

Where's the boom then

[@robcaddphotography]

1:18 approx - although may not be audible on a small-speakered (eg. mobile) device.

[@ibiza_andy]

Sounds like a muffled oboe if that helps

[@meoldfruit]

Like waiting for paint to dry...

[@ibiza_andy]

Shut up.. go play with your iphone