Aotearoa New Zealand is famous for birdsong. The haunting music of the kōkako, the diverse harsh calls and whistles of the kākā, the piercing screams of the kiwi, and the complex and varied song of the tūī are the iconic sounds of a native forest.
Birds generally sing the most in spring – the time they start nesting. This is because the two most important functions of birdsong are directly related to reproduction – it serves as a signal of territorial ownership to rivals, and lets potential mates know that they are welcome to come by for a bit of romance.
However, some species also sing during winter and currently there is one familiar (non-native) species that is stepping up the romance and putting on quite a show: the song thrush. Originally from Europe, song thrushes can be easily spotted in the mornings and evenings, perched on the tops of trees or powerlines, and singing with gusto.
In 1845 the romantic poet Robert Browning wrote these lines describing the song thrush’s melodies in his famous poem about England, Home Thoughts from Abroad:
That’s the wise thrush; he sings each song twice over, Lest you should think he never could recapture The first fine careless rapture!
What I love about these lines is that they so beautifully capture the characteristic aspect of the song thrush’s song that makes it so graceful and distinctive.
First, it is incredibly musically diverse – composed of seemingly countless unique phrases. Second, each phrase gets repeated typically just once, before moving on to the next one.
So the song is a musical phrase, instantly repeated and then a pause. And then a new musical phrase, instantly repeated and then a pause. And so on, seemingly never to come back to the original phrase that started the whole thing. Once you tune into recognising this song, you will start hearing song thrushes all over the place.
Robert Browning was in Italy when he wrote the poem and at the time he was longing to be back home in England. Around the same time he wrote these lines, various NZ Acclimatization Societies, established by European colonists, started to release familiar species from the old country. They did this for various reasons – for quarry, to control pests, and in some cases (as happened with the song thrush) to simply help colonists deal with their own Browning-like longing and nostalgia for the flora and fauna of home.
Obviously, it would be unthinkable today to widely release diverse exotic organisms into NZ. And indeed, many of the species released by these societies have had a catastrophic impact on the native environment. But unfortunately, it happened, and as a result we now have heaps of song thrushes cheerfully chirping away throughout the winter. As far as introduced species go, these guys are pretty charming.