A hardy bird that has adapted well to the un­for­giv­ing en­vi­ron­ment of bit­terly cold and windswept es­tu­ar­ies

Bird Watching (UK) - - Contents -

Do­minic Couzens ex­plains how this hardy bird has adapted well to tough liv­ing con­di­tions

ONE OF THE great sights of bird­ing is the mass of waders on an es­tu­ary, fly­ing back and forth around high tide. There is some­thing sat­is­fy­ing about ap­pre­ci­at­ing how waders roost in large num­bers when the tide is high, but go back on to the mud once the tide falls, and how dif­fer­ent waders then spread out over dif­fer­ent kinds of ooze. Over the years, I have been so over­whelmed by the sump­tu­ous shore­bird dis­plays, that I tend to over­look other birds that are af­fected by the depth of wa­ter.

Sev­eral cat­e­gories are: es­tu­ar­ine wild­fowl, es­pe­cially Shel­ducks and Brent Geese; cor­morants and, to a lesser ex­tent, gulls and terns. All th­ese are wed­ded to tidal cy­cles. And then, how about a left-field ad­di­tion to this list, a bird that you wouldn’t in­stantly as­sume was in such com­pany – the Twite? It doesn’t have long legs, or a long bill. But, in parts of its range, it is just as much an es­tu­ar­ine bird as the most com­mit­ted Red­shank or Dun­lin. Rather than seek­ing out worms, crus­taceans or mol­luscs in the mud it­self, how­ever, the Twite sub­sists on the seeds of es­tu­ar­ine plants that grow in patches reg­u­larly in­un­dated by the tide, es­pe­cially the Glass­worts (Sal­icor­nia spp) and Se­ablite (Suaeda mar­itima).

The Twite feeds by hop­ping over the mud and perch­ing on the plants them­selves. How­ever, it can only do this when the tide al­lows. As the wa­ter comes in, flocks of Twite feed­ing far out on the mud, usu­ally with­out com­pe­ti­tion from other shore­line seed-eaters such as Snow Buntings and Shore Larks, are forced to­wards the in­ner salt­marsh. At high wa­ter, they will feed in ad­ja­cent fields, of­ten flock­ing with th­ese other birds, and even Lin­nets. How­ever, once the tide re­treats, the birds re­turn to their ex­treme feed­ing grounds. Glass­wort, the Twite’s sta­ple, is of­ten abun­dant where it oc­curs, and forms ex­ten­sive ‘forests’ of branched, suc­cu­lent forms that look a lit­tle like mini Christ­mas trees (or at least, those sorts of

spindly Christ­mas trees you buy from the back of lor­ries.) On big es­tu­ar­ies, patches of Glass­wort can be very ex­ten­sive and can oc­cur a con­sid­er­able way from shore. There are also sev­eral dif­fer­ent species that oc­cur on dif­fer­ent parts of a salt­marsh. Th­ese plants don’t all set seed at the same time, ei­ther, mean­ing that at least some are avail­able for most of the Twites’ win­ter stay from Oc­to­ber to Fe­bru­ary. There are also other salt­marsh plants avail­able if their sta­ples run out, such as Sea Aster, and on cul­ti­vated fields th­ese birds aren’t so sniffy that they avoid such com­mon stuff as Dan­de­lion seeds, or Shep­herd’s Purse or even Chick­weed. How­ever, the seeds of salt­marsh plants are un­usu­ally high in nu­tri­ents, and thus highly favoured. Twites do have some ex­otic tastes, though; they are among a very few song­birds known to con­sume sea­weeds, pre­sum­ably in times of food short­age. The Twite’s most favoured es­tu­ar­ies – the Wash, the Hum­ber and More­cambe Bay – at­tract large flocks, of­ten hun­dreds strong. Apart from al­low­ing the birds to feed far away from hu­mankind, th­ese es­tu­ar­ies of­fer a habi­tat that is fre­quently bit­terly cold, un­for­giv­ingly windswept and also very damp. The birds can hide among the plants and keep their heads down, but they can­not avoid in­clement con­di­tions en­tirely. This, though, lies at the heart of the Twite’s unique­ness as a species. Twites are de­fined by their har­di­ness; they thrive in con­di­tions that other, sim­i­lar species can­not cope with. One of their pre­vi­ous coun­try names, now ob­so­lete, was Moun­tain Lin­net. But they have no spe­cific at­tach­ment to moun­tains, nei­ther in the win­ter nor in the breeding sea­son, so a bet­ter nick­name would be some­thing like Tough Lin­net or Se­ri­ously Hard Lin­net (or maybe No Lin­nets.) In­stead they are drawn to tree­less places, open to the full force of the el­e­ments, lack­ing in both sun and warmth. The Twites that win­ter in salt­marshes are mainly from the pop­u­la­tion that breeds in the Pen­nines, which is one of the species’ strongholds. Once you reach prop­erly up north, though, in the He­brides, Shet­lands and Orkneys, where Lin­nets fear to tread, Twites are abun­dant and typ­i­cally stay close to the breeding ar­eas all-year-round. Here, they typ­i­cally build the nest on or close to the ground, among low, thick veg­e­ta­tion. Heather or Bracken suf­fice, and Gorse bushes are used in Scot­land. Twites, though, are ex­perts at us­ing all kinds of dif­fer­ent places for the nest site, in­clud­ing un­der rocks and boul­ders and even on cliff ledges. On the lat­ter, they might rub shoul­ders with birds such as Puffins and Guille­mots, which must make a pleas­ant change from hordes of win­ter­ing waders. The nest is bulky and ex­tremely well

built, typ­i­cal of finches, and ideal for chicks that are be­ing brought up in a chilly cli­mate.

A Twite feed­ing quirk

One of the quirks of the Twite, also shared by its sun-lov­ing rel­a­tive the Lin­net and, to a greater or lesser ex­tent by most other finches, is that it feeds its young not on in­sects but on the re­gur­gi­tated paste of seeds that it has in­gested. If you for­give the as­so­ci­a­tion, it is hard not to think of tough nestling Twites be­ing fed on good Scot­tish por­ridge, and the anal­ogy isn’t so far off. Other species of finch, such as Goldfinch and even Hawfinch, al­ways add some in­sects to the mix, but it seems that Twites don’t nor­mally do so. It doesn’t seem to do them any harm. The Twite, in com­mon with other finches, has a long breeding sea­son and will some­times squeeze three broods into a busy sum­mer, not fin­ish­ing un­til well into Au­gust. And why shouldn’t it carry on? Be­ing such a con­firmed seed-eater, it makes sense to con­tinue breeding when there are still abun­dant seeds around. When the young hatch they soon join into large flocks with the adults, and hun­dreds may be seen to­gether. There is some, highly in­trigu­ing ev­i­dence that sib­lings some­times as­so­ciate for much longer than is nor­mal for a typ­i­cal song­bird. It is thought that most brood-mates of small passer­ines sim­ply drift apart as soon as they fledge, but sib­ling Twites have been found in the same part of a win­ter­ing flock when more than two years old. Whether this is typ­i­cal, or just a quirk, is not known. One very im­por­tant trick you need when you live in a chilly, wind-blasted cli­mate is to find a secure place to roost ev­ery night. And here, Twites show an adapt­abil­ity that bor­ders on the in­ge­nious. They have been recorded sleep­ing in all man­ner of places, likely and un­likely. They are of­ten in thick ground veg­e­ta­tion, such as Bracken or heather, in stub­ble or cut crops and will also use hol­lows on the ground. They roost in reedbeds quite fre­quently. The Twite has been recorded in slopes of boul­der scree, on houses and in walls, and in­side the thatch of a build­ing. They have been known to con­struct their own tun­nels in the snow. My top favourite, though, is an ob­ser­va­tion of Twites nestling down within the downy in­flo­res­cences of cot­ton-grass in the mid­dle of a pond. Soft and cosy, this must rank as a top-notch com­fort­able airy B&B. It isn’t quite in keep­ing with the bird’s tough guy im­age, though. On most nights, Twites roost com­mu­nally – not close, but within con­tact calls of their kind. And in that re­spect, they are once again united in be­hav­iour with the noisy waders that shift and set­tle on the tidal es­tu­ar­ies around our shores.


Sub­tly plumaged is a po­lite way of de­scrib­ing this LBJ With good views, the ‘drab’ plumage of the Twite is com­ple­mented with glimpses of the pink rump



Twites usu­ally spend the win­ter months in flocks

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