I am not a birder - but right after Tres Cantos (you walk down to a river that you follow for a good while) the bird song was amazing. I took out my phone and the Merlin (bird song identification) app and used it every day on that Camino (usually looking up the same songs over and over!). I did not keep a list or all the recordings on the app -- but I did keep a few of them, and here are some of the birds that Merlin identified (mid-April): nightingale, blackbird, short-toed treecreeper, european goldfinch, chaffinch, crested tit, coal tit, western bonelli's warbler, dunnock, skylark, corn bunting, calandra lark, cirl bunting, european robin....There definitely would have been others; I know I deleted some recordings. Others know better than I do how accurate the app is! The birds were one of my favourite things on the Madrid!