A couple of weeks a go, we saw two bitterns leave the reserve, on their journey back to their breeding grounds in mainland Europe. They were "gull calling"; the migratory ritual of the bittern.
Just before dark, on a still, clear evening in early spring, they will get up in the air and circle above the reedbed, making a funny, gull-like call (http://www.xeno-canto.org/33716). They do laps of the reedbed, calling out to let everyone else know "I’m heading home, who else is coming?" If there are any other birds ready to leave, these will join up and they will circle together. They will get higher and higher, calling as they go, then eventually head off east.
Bittern in flight (David Tipling rspb-images.com)
This winter has been relatively mild, and our reduced recordings of bittern activity was thought to be associated with this; less birds needed to migrate to Britain as their own breeding grounds were warm enough. Therefore, when two birds migrated a couple of weeks ago (and one was left booming), we thought that was all we had. Well, last night put pay to that theory...
I'd been out on the reserve checking bearded tit nest sites (so far we've got 5 nests incubating eggs), and was waiting for it to get dark so I could go out on a fox survey. It wasn't quite dark so wandered along the causeway to see what was around. All along the track pipestrelle bats were hawking the plethora of insects on the wing, and over 200 sand martins were flocking, making shapes like starlings do in the autumn. Then I heard a gull calling bittern! Not only that, but I heard another respond! Obsessed, I ran along to an area clear of trees to see what else I could see. There were three of them, all calling and circling above Public pool. Then I heard more behind me; another three, circling over the southern end of the reserve. All six joined up and did several laps of the whole reedbed, calling constantly, getting higher and higher! I just stood there in absolute awe as they became pinpricks in the sky and disappeared east. Where were all those birds hiding all winter?!
Just as I was walking back, I heard another odd sound that I couldn’t quite place – it sounded a bit like a barn owl, but why would it be screeching in the middle of the reedbed? Sure enough, I glimpsed the dark shadow of a barn owl quartering the marsh, accompanied by it’s call! I’d never heard that in flight before – I researched it when I got home and apparently it is a territorial call often made in spring time. That makes sense, as a couple of seconds later, I heard a responding call from the other side of the reedbed; two owls were circling me, marking their own territory. Absolutely fantastic! Understandably, I was jumping up and down with excitement, texting anyone I could!
Barn Owl by John Bridges (rspb-images.com)
Yesterday was one of those days where everything happens at once and you realise just how brilliant nature (and this reserve) is – not sure if I can get away with calling this my “job”!