We could be hiking through an upland ravine, miles from civilisation, were it not for the graffiti and half-submerged washing machine. Hart’s-tongue ferns hang down from the steep banks above us. The tang of fox rises from fallen hemlock stems, their dried umbels pointing towards the River Hiz. The water, smutty and lacking in vegetation, slides past an almost‑bridge – two brick abutments joined by an arch of sky.
Further on, the river widens round a bend and we’re greeted by a lemon flicker of undertail feathers. Dip, flick, dip, flick. A grey wagtail bobs on a rocky corner. Judging by the mizzle of midges round my head, the area must be a rich feeding ground for these insectivorous birds. I’m so enjoying the wagtail’s light-footed antics that I hardly register the mallards under the willows. It’s not until they drift towards me that I see a mazy grey tracery on the breast of one of the males, and that distinctive black rear end – a gadwall! On the river! He keeps pace with a female and, as gadwalls form pairs in autumn and winter, I assume he’s accompanying his less-conspicuous mate.
Once home, I study my blurry phone photos, of the female in particular. Gadwall and mallard females look similar, but this one is longer and heftier than her partner, suggesting that she is, in fact, a mallard. A glimpse of her blue speculum confirms it. Imagining the lovesick drake has followed his beloved to my local river in pursuit of a Romeo and Juliet duck romance, I look up waterfowl hybridisation and learn that mallards can interbreed with at least 39 other species, including gadwalls and pintails, and that the offspring are often fertile.
A mallard-gadwall cross even has its own name – the Brewer’s duck – coined by John James Audubon in 1843, and was initially classed as a separate species. Females are hard to identify, whereas males often have a mallard-like iridescent green patch on the head and a gadwall’s intricate vermiculations on the flanks. And Brewer’s ducklings? Well, if this star-crossed pair lingers over winter, we might be able to answer that question next spring.
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