In the bird reserve the evening before last I heard a very striking song, which the BirdNET app reported as "almost certainly" Cetti's warbler. Comparing the song with online recordings confirmed the identification.
Cetti's warblers don't seem to have bred in the UK until the 1970s, when they first appeared in Kent. Since then, possibly as the result of global warming, they have pushed as far as Wales, the north of England, and recently Scotland. There are now perhaps 5,000 or more breeding pairs across the UK.
I didn't see the bird.They are hard to spot; small and inconspicuous and in the words of the RSPB like to skulk in patches of scrub (although "skulk" seems a bit pejorative to my mind).
Traditionally people talked about bird watching but when it comes to birds like warblers bird listening is more appropriate, because warblers recognise potential mates not by conspicuous plumage, but by conspicuous song. I'm not very good at recognising birdsong, but the phone app is, and it's opened up a whole new world for me, where I can observe birs even though I can't see them.
And who was Cetti? Francesco Cetti was a Jesuit, mathematician, scientist and naturalist who published three volumes on the natural history of Sardinia in the 1770s. This is the volume on birds,
The bird was collected on Sardinia and described by Alberto della Marmora, who named it Cettia cetti in Cetti's honour.
Fun Fact: The eggs of Cetti's warbler are bright red.