Great Reed Warbler at RSPB Ouse Fen

We had pencilled in Tuesday for Minsmere, but with cloud and then rain on the schedule and a trio of notable birds the other side of Cambridge we had a change of plan, so just before 9 we pulled into the car park at RSPB Ouse Fen for our first visit with Great Reed Warbler the target.

It wasn't long before we were at the mound listening to what sounded like an old diesel car slowly getting started. Finding it was another matter, but David got us onto it near the top of a reed and we had a good half hour or so of fantastic views. I'd seen one many years ago, but not like this. I even managed some photos down my scope. The views were so good this wasn't just a matter of getting it on a list, it also crossed it off a list. I'm not going to get views like that again unless someone puts a bird in my hand. It's unlikely I'd go for another one unless it was very near or there was something else on the day. What would be the point?

We carried on round the reserve. It's an excellent place and we resolved to come back, not imagining that our second trip would be the same day. Nevertheless we got great views of Cuckoo, Bearded Tit, Marsh Harrier, Great White and Little Egrets, heard several Bitterns booming, and lots of other fenland stuff too. We gave a large pit by the entrance a quick going over but saw only Redshanks and Oystercatchers.

Odonata started to come out and Mike identified many of the blue damselflies as Variable Damselflies. Mike explained the key is the segment just behind the head S2. On a Variable it has a U shape with a couple of blue spots each side but it is variable. You can see that on the photo below;  also shown is an Azure from a later visit on the day with a very different S2 with a narrow black line.

But back to that Great Reed Warbler. Two things strike me.

Firstly, hands up everyone who has seen a male GRW in the UK? That's both most of you I would think. Now hands up who has seen a female GRW in the UK? That's none of you I would guess. There's an obvious reason - most GRWs are picked up on song. But does that mean that at this moment there's a few females going unseen in reed beds? How do we know they aren't breeding somewhere? That a singing male doesn't manage to attract a female and breed? Or can females give a song too when they need to?

Secondly, why is there a GRW at all? Birds in reedbeds all seem to be the same size; the many varieties of acrocephalus warbler, bearded tits, reed buntings, all the same size. I assumed because reeds can only sustain birds or bird nests of a certain size. But then there's a bird the size of a song thrush that lives in reeds. So why aren't there lots of birds the size of song thrushes that live in reeds? Or is that why they don't breed in Britain - because we don't have the right reeds to support a nest?

GRW was only the first item on our list. Would we be as fortunate with the others? You'll have to wait for the next instalment.