The Dunnock (or Hedge-sparrow as it used to be called) is rather an interesting bird; though I would forgive you for not agreeing with me based on its modest appearance. I cannot say it is one of my favourite birds, yet I appreciate its short-but-sweet song and I have empathy for it due to how often it is overlooked or plain ignored. As is often the case in nature a plain visage hides interesting behaviour in the Dunnock, although often mistaken for a sparrow it is actually a peculiar looking thing – more like a mouse with its shuffling, jerky movements close to the ground. The Dutch even call it a ‘heggemus‘ which translates as ‘Hedge-mouse’, but the truth is that Prunella modularis is the only British representative of the Accentor family – the only other species in Europe being the Alpine Accentor. The Dunnock is a bit of a black sheep in the family, as nearly all of the thirteen other species are strict residents of mountainous regions throughout Eurasia – but this odd little bird was not too keen on the thin air and harsh weather, so like the ‘southern nancy’ it is, the hedge-sparrow retired to the comfort of lowland hedges.
So the Dunnock is the odd one out, being neither a sparrow or a proper Accentor, not that that is a bad thing; in fact it rather singles it out among British birds. Now to reveal its dirty secrets, for as it transpires the unassuming Dunnock takes a rather blasé attitude to Victorian morals – to the extent that it makes the Bourgeois look like nuns. When spring comes around and the Dunnock begins breeding the male and female go through a strange dance in the lead up to copulation. The female will shiver her wings and run in circles, with the male giving chase; after a while the female crouches, with tail raised and wings a-quivering. The male then begins to peck her cloaca (genital opening) to get the female to eject any sperm that previous males have left. He then leaps over the female as though playing leap-frog, to a human eye nothing has happened yet in actual fact the male has ‘deposited’ his sperm package in the female in one-tenth of a second of contact with her cloaca.
But bum-pecking is not the worst of it, it seems that while some Dunnocks are happy to be monogamous, many play fast-and-loose with the oath of marriage. It gets rather complicated but it appears that some males will mate with multiple females, and some females will mate with multiple males, also Dunnocks have been recorded mating up to one-hundred times a day. This is all for the genetic benefit to the population, as any one clutch will have a mix of genes from different fathers and the strongest males will mate the most times and therefore have many, many offspring in many nests.
Dunnocks don’t have all the fun though, they are a particular favourite of the Cuckoo as hosts for its eggs; many nests will be overtaken by a parasitic changeling that will dwarf its foster parents and give them no rest. Despite its extravagant mating behaviour this blue-grey and nut-brown bird is rarely given a second glance by birders or anyone else. I want to defend it as a bird worth looking for, its song is one of the first of the spring to grace the dawn and is a honey-sweet tinkling up the musical scale. It may retire into the leaf mold for much of the year yet when it sings it always does so from a lofty perch, in full view of any passing sparrowhawk – and for that you have to give it credit for having balls. (coincidentally, while many birds do not possess penises, they do have protuberances which are often small in Robins or Wrens, yet the Dunnock has a rather large one).
So this mountain-shunning, mating mad, fluidly singing, territorial, Cuckoo-cursed, mousy, lone-ranger of a hedge-rustler is perhaps more interesting than people give it the credit for; so I hope I have encouraged you to give it more than a glance next time you see one.