Right - the analysis.
In short, I think it was a pretty decent first attempt. I recorded for about 7.5 hours, and in among the barking dogs, police sirens and neighbours listening to Whitney Houston, I had a few interesting birds fly over.
A small group of sandwich terns flew over at about midnight, a single dunlin went over at approx 01:00, and best of all, a couple of greenshanks went over at about 01:30. Apologies about the lack of precision re the times, I forgot to note when I pressed record...
All of these are new for the house list, to add a bit of context.
While the set up I used recorded well enough for the birds to be identified - (Roland R5, Rode mic, hung outside an open window in an old handbag (not one of mine) arranged so that the mic pointed upwards and away from the house) - the spectograms left a little to be desired. If you needed them to confirm an ID you'd be in trouble - but it's a reasoanble bit of kit for field recording so I suspect that the lack of quality is a result of birds not passing directly through the 'cone' of the directional mic, or perhaps passing very high. I did get a crystal clear recording of what I suspect was a duck spp going over, which only gave itself away due to the whistle of its wings. Anything that passes low enough and directly overhead should be recorded very clearly.
So, in short, it's not perfect for recording things overhead at night, but it's certainly a starting point.
The analysis took an hour or so but I suspect I'll get quicker than that as I learn what needs to be listened to and what doesnt. The file was just over 1 GB of data, which Audacity just about coped with, and I simply scrolled through the recording visually checking for anomalies. One drawback here is that from about 4 am onwards the local gulls and robins became very active, and showed up on the spectogram, making harder to visually pick up other stuff. There's every chance I missed things in amongst that racket as I don't have time to listen to 1.5 hours of herring gulls and robins. I stopped recording at about half 5 am, when I got up to go out and do some proper birding...
I'll do the same tonight - no real adaptations to the set up, but it's a bit windier tonight so it'll be interesting to see how the mic and recorder cope with that.