Universities of Cornell (New York) and Bath (UK) can corroborate what twitchers worldwide have always tuned into. The songs of the European nightingale are more complex even than the tune-smiths among blackbirds and tropical tweets as witnessed by this paper in - Nightingale tops the song charts. (Our title!) The authors included Professor Tamás Szekely and Jordan M. Moore.
We have written on Luscinia megarhynchos several times, as German and other researchers have attempted to demystify their song culture. See the article in A Nightingale Sings. But when males from 49 species in 17 families were compared, the poets' favourite came out top. The nightingale is classed nowadays as a flycatcher, whereas it was previously thought to be one of the thrush-like songbirds.
The measurements taken were brain size and shape, alongside the length and complexity of song. Higher brain areas (comparable to human frontal lobes) were larger than lower brain areas in those species that learned dozens of notes. The learning or cognition involved in a song was obviously connected to the number of syllables that birds could remember to put in their songs. Such behavioural specialisation commonly links to the expansion of appropriate regions of the brain.
Blackbirds, my personal favourite have 108 syllables according to this study while the effervescent skylark has 341. The common nightingale excels with a repertoire of 1160! At the bottom of the class with low numbers of syllables in their songs were tree pipits, yellowhammers and sand martins. The possibility is that this research can lead into even deeper studies in other species, including humans. This is the first evidence that learning capacity is related to the structure of the brain, not just its size. The evolution of speech in humans could be very closely related to those changes in brain structure we can see in fossils. With frontal lobes maturing late, in our 20s, even basic learning itself could be influenced by their development over years. However, the birds almost certainly select their males through female preference. Wouldn't that be a relief for the basic human geek!