A dissonant cuckoo in Rothbury

We were up in the Rothbury Hills yesterday, and serenaded by at least four cuckoos at various points around the circuit - these being the first of the year for me. 

The sound of this bird is, of course, absolutely characteristic - being a repeating and loud minor third (i.e. three semitones) descending interval; and was immortalized by Handel in the delightful second movement of his organ concerto in F No. 13 - coming-in after about fifty seconds:

(Delius made a good stab at the subject too.) 

But the third of these cuckoos was distinctly 'off-key' - repeatedly and boldly emanating the disturbingly dissonant-seeming interval of just one tone (i.e. two semitones, instead of three). 

This is something I've not heard before; although slightly-'wrong' tuning (slightly less than a minor third) is reasonably common. 

It struck me as a deliberate act of musical subversion, by a cuckoo with a grudge.