Last week we carried out our second booming bittern survey, to work out how many male birds we have on site. I’ll immediately pass on the amazing news that we recorded seven males across the reserve, which equals the reserve record from 2011. We all switched positions from the week before, as it is very useful to have different ears taking on the different locations. I positioned myself at the point where Norfolk Fen reedbed meets Joist Fen North reedbed and it turned out to be a fantastic spot – I very quickly worked out that I was listening to four different booming male bitterns! There were two to the west in Norfolk Fen and two to the east in Joist Fen North.
When we survey bitterns in this way we record the timings of the booms, how many booms and grunts there were each time and try to pinpoint the location on a map. If you listen carefully though, you can actually distinguish between the different boomers as they each have their own unique style. The two in Norfolk Fen were particularly interesting to listen to. One male would fire out his booms in rapid succession – “Boom..Boom..Boom..Boom.” The other took a lot more time over his booms and interspersed them with lazy grunts, inhalations and wheezes – “Huh...Boom......Boom......Huh......Huh......Boom” and so on! Volunteer Phil was standing particularly close to this individual and was amazed to be able to hear the intakes of breath between booms. I found myself near it yesterday too and it almost sounds like he’s revving up before booming!
The two bitterns to my east were not quite so easy to distinguish in terms of style but luckily at 08.07am they both boomed at the same time so I was happy to record there were two. Standing in between the four bitterns, it was really interesting to hear how they competed against each other, especially the two in Norfolk Fen. It was quite a still morning so sound was carrying well and the bitterns were taking full advantage. In fact in the two hours I was surveying, I recorded 60 different booming occurrences across the four birds! Mr Lazy would start booming and almost as soon as he’d finished, Mr Rapid would fire out his booms as if to say “Hey ladies, I’m here too and I’m a much stronger boomer, this is where you need to be!” At one point I had three going at the same time – it doesn’t make it easy to count the booms I can tell you.
We all came back from the survey feeling very happy with our total. We’ll see how we go this week – who knows, maybe another will have joined the throng! After a cup of tea our hardworking volunteers were straight back out, replacing the barrier up at the washland viewpoint. It was starting to get a bit rickety and we didn’t really want anyone leaning on it, only for it to give way and see our visitors tumbling down the slope onto the washland! It looks very sturdy now and below is a photo of Dave finishing the post tops off with his chainsaw.
Photo credit: Ali Blaney – Dave putting the finishing touches to the replacement barrier
We are continuing to sneak new species into the bog and pond plant beds. Today saw the addition of purple loosestrife, cuckoo flower, hemp agrimony and common meadow rue. We’ll have to think about topping the water levels up in these two beds soon - with no rain and a lot of sun the water is evaporating almost before our eyes! Easter Sunday looks set to be rather a wet day, which will be very welcome for us here. Perhaps not quite what people want for their Easter holidays though! Suzanne and I were also very excited to spot one of our very small Brecks plants, wall bedstraw, sprouting anew in the Brecks bed. I had been slightly concerned that it had withered away but happily this morning it's doing well.
We're back listening to bitterns again tomorrow plus many other tasks on my long list of jobs. Thank heavens for our fantastic volunteers - what would we do without them!