Do­minic Couzens

Bird Watching (UK) - - Contents -

Telling Knot and Dun­lin apart is tricky, but look out for some tell-tale signs

Telling both birds apart in a crowded es­tu­ary may be a chal­leng­ing task, but it’s worth the time and ef­fort

HOPE­FULLY EV­ERY BIRDER has ex­pe­ri­enced ar­riv­ing on an es­tu­ary at low tide and be­ing faced with a seething mass of mov­ing bod­ies – waders all feed­ing busily on the ooze. It’s an im­pres­sive sight, and there is usu­ally a de­light­ful au­ral ac­com­pa­ni­ment of the un­fet­tered wind and the ur­gent calls of the birds, from the shout­ing Oys­ter­catcher to the eu­pho­nious Curlew ‘bub­ble’.

And then, of course, comes that sink­ing feel­ing: you’ve got to iden­tify this lot. You aren’t re­ally com­pelled to, but you feel you should try, so you at­tempt to get com­fort­able and pan your binoc­u­lars or tele­scope hope­fully across the es­tu­ar­ine shop­ping mall. You feel bet­ter when you see the tri-coloured Oys­ter­catcher, the odd­ly­pat­terned Turn­stone and the Curlews tow­er­ing over ev­ery­body. But af­ter this, on most Bri­tish es­tu­ar­ies at least, a seething mass of pre­dom­i­nantly grey mites dom­i­nates the mud­scape. You can tell they are waders, but which ones? Your book is full of Red­shanks, Spot­ted Red­shanks, Grey and Golden Plovers, Knots, Dun­lin, Lit­tle Stints and a whole wealth of rare Amer­i­cans. For a while, you study hard and then, some­what de­feated, you de­cide that you will sim­ply let the scene sink in and en­joy it. Of course, it is pos­si­ble to de­ci­pher the many dif­fer­ent wader plumages and shapes, but it takes time and ex­pe­ri­ence. I was highly amused to read re­cently in a thor­oughly learned book that the Knot, even in non-breed­ing plumage, was “un­mis­tak­able when in com­pany with its smaller

con­geners”. That’s a load of rub­bish. The Knot is em­i­nently mis­tak­able for a Dun­lin, and it is en­tirely ap­pro­pri­ate that it should be so. It would not be go­ing too far to say that it is bi­o­log­i­cally ap­pro­pri­ate that Knots and Dun­lin (and Red­shanks and Grey Plovers) should look alike. Waders are grey and plain in win­ter for the same rea­son that war­blers are brown or olive-green; the plumage af­fords them a de­gree of cam­ou­flage within their en­vi­ron­ment. Waders are nec­es­sar­ily mud-coloured. If you do take the time, it is fun to dis­tin­guish them. The plump-bod­ied Grey Plovers have star-like spots on their up­per­parts, plus a short, thick bill and large eye. Red­shanks show off their epony­mous bare parts and are mid­dling in ev­ery way: middle-length bill, middle-length legs, middle-sized. Knots and Dun­lin are much harder to tell apart. Af­ter a while you can ap­pre­ci­ate that the Knot is slightly larger and a lit­tle plainer. It looks slower in move­ments than the scam­per­ing Dun­lin and it seems to lean over more when it is feed­ing, but the mar­gins of iden­ti­fi­ca­tion are thin. But the fact is that, on the es­tu­ary, Knot and Dun­lin are very sim­i­lar, and not just in ap­pear­ance. Their day­time rou­tines are al­most iden­ti­cal, be­cause th­ese are de­ter­mined by the tide; at high tide they roost, at low tide they feed, and on a ris­ing or fall­ing tide they revel in newly ex­posed or cov­ered in­ver­te­brates. The ‘ground’ over which they feed can be ex­actly the same, and they will of­ten gather food in much the same way. Take a look at a de­scrip­tion of the feed­ing meth­ods and it isn’t easy to dis­cern much dif­fer­ence; Dun­lin and Knot both “peck” and they both “probe”. As far as prob­ing is con­cerned, Dun­lin “stitch” and Knot “plough”. A Dun­lin will some­times feed by a se­ries of rapid in­ser­tions of the bill, as if it were sewing. And as for plough­ing, the Knot will insert its bill into the mud and move for­ward for a few cen­time­tres, mak­ing a fur­row in a bid to touch an ed­i­ble ob­ject. The fact is, there­fore, that they live al­most in­ter­change­able lives on the mud­flats of Bri­tain, for a good six or seven months of the year. Com­bined with their sim­i­lar ap­pear­ance, you could guess that al­most ev­ery­thing else they do is sim­i­lar. But you would be mis­taken.

Of course, it is pos­si­ble to de­ci­pher the many dif­fer­ent wader plumages and shapes, but it takes time and ex­pe­ri­ence Win­ter Dun­lin

On the es­tu­ary, Knot and Dun­lin are very sim­i­lar, and not just in ap­pear­ance. Their day­time rou­tines are al­most iden­ti­cal Dun­lin on the move

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