"The blackbird broke into song, was joined by wrens, blackcaps, a chiffchaff..." (March 22, 1814)

This is none of the above, it's one of a tribe of coal tits living in the ancient cedar in the garden of Hawksfield Manor.

 

If you'd like to hear these birds, the best thing is to do as Justin does in Chapter 15 of An Independent Heart, and take an early-morning walk in the countryside in spring. Alternatively, try the website of the Royal Society for the Protection of Birds, where you'll find the nuthatch (Chapter 9, p. 112). I was sure I'd put a willow warbler in the book, because I love their song, but I can't find it anymore! 

Here's the blackbird breaking into song:

(by courtesy of Harriet)

A blackcap chattering away in the bushes:

(my own recording)

A sky full of skylarks (Chapter 17, p. 206):

(my own recording)