Eider sis­ter­hood

Fe­male Eiders pull to­gether and are quite re­mark­able when it comes to bring­ing up the young – but this colony sis­ter­hood is not free from abuse

Bird Watching (UK) - - Contents -

Fe­male Eiders re­ally pull to­gether in a colony, ex­plains Do­minic Couzens

IN 2014, A Mid­lands’ art gallery caused a rum­pus by un­veil­ing a life-sized bronze statue called A Real Birm­ing­ham Fam­ily out­side the city li­brary. Cost­ing a small for­tune of pub­lic money, it caused con­tro­versy by de­pict­ing noth­ing more than two sin­gle moth­ers with their young chil­dren, and not a man in sight. Bear­ing in mind that it was meant to de­pict ‘the most real’ fam­ily in the city, that seems some­thing of an over­sight, since there are plenty of fa­thers in Birm­ing­ham. I know, I’ve been there. There is, how­ever, an en­tirely ap­pro­pri­ate place to put this statue – in­deed, mul­ti­ple places.

These are fortresses where fam­i­lies are truly bas­tions of fem­i­nine ex­clu­siv­ity, power and to­geth­er­ness, where males re­ally are rel­e­gated al­most to a place of sperm-providers, sep­a­rated from the up­bring­ing of their chil­dren. Let me in­tro­duce you to colonies of Bri­tain’s most so­cia­ble duck, the Eider. This heavy-bod­ied sea-duck is found around the rock­ier coasts of Bri­tain, where it feeds on mus­sels and other shell­fish, priz­ing them off rocks un­der­wa­ter. In the breed­ing sea­son, it re­treats to nearby low-ly­ing is­lands cut off from the land, and hence ground-preda­tors; but far­ther north, in the Arctic, for in­stance, it may set­tle on main­land penin­su­las and coast­lines. It nests on the ground. Eiders most typ­i­cally breed in colonies, and these are some­times huge. There may be a few tens scat­tered about, but in parts of the range, such as Ice­land, there may be 10,000 to 15,000 nests at high den­sity. If you bear in mind that the male Eiders in­vari­ably exit stage left soon af­ter the last eggs are laid, that sets the scene for what must be some of the largest gath­er­ings of adult fe­male birds in the world (this is un­usual, be­cause in most bird colonies, in­clud­ing gulls, auks and cor­morants, the males bring food to the fe­males and to the de­vel­op­ing young). For the next three months – about 26 days to hatch­ing, then 55 more days to in­de­pen­dence – the young­sters are im­mersed in an all-fe­male en­vi­ron­ment. It isn’t only moth­ers. Many young fe­males, less than four years old, will spend sub­stan­tial time in the colony and some will help with chores later in the breed­ing cy­cle. Eiders are fa­mous for their nests. In struc­tural terms, these are noth­ing spe­cial, just

There is a ‘Cuckoo’ in the nest. And what she does is sim­i­lar to that of the fa­mous brood par­a­site

a de­pres­sion on the ground, of­ten among veg­e­ta­tion of­fer­ing a de­gree of shel­ter. It is the com­po­nents that are ex­tra­or­di­nary, the ‘eider down’ that lines the nest and may cover the eggs. This is in­deed down plucked from the mother’s breast, ready-made nest ma­te­rial of ex­cep­tional soft­ness and co­he­sive­ness. In the Arctic con­di­tions into which many an Eider egg is laid, the down helps to in­su­late against the cold. The down has been har­vested by peo­ple since the Mid­dle Ages, and prob­a­bly well be­fore. A very small, al­beit lu­cra­tive in­dus­try, still ex­ists in Ice­land, ex­port­ing Eider down for the lux­ury mar­ket in du­vets, sleep­ing bags and clothing. The down is ap­par­ently un­usu­ally light and, un­like syn­thetic ma­te­ri­als and goose down, it doesn’t so eas­ily fall apart. Ap­par­ently, a sleep­ing bag with true eider down fill­ing keeps you warm when it is -35°C out­side, while syn­thetic fills pro­tect you down to -7°C. The birds in the har­vested colonies are looked af­ter well by the op­er­a­tors, who pro­tect the nests from gulls and other po­ten­tial preda­tors. In turn, the in­cu­bat­ing birds are typ­i­cally tame, even al­low­ing peo­ple to stroke them as they in­cu­bate. The Eider’s ded­i­ca­tion to its in­cu­ba­tion is also rightly cel­e­brated. These birds sit tight on their clutch of be­tween three and five eggs, to the ex­tent that they barely even leave them alone, even only for a mo­ment. In colonies that reg­u­larly suf­fer dis­tur­bance, they some­times don’t move at all af­ter the first week of in­cu­ba­tion. They don’t feed, liv­ing in­stead off ac­cu­mu­lated fat. They can­not eas­ily drink, although they do some­times sip from a small pud­dle of rain wa­ter that might ac­cu­mu­late in a de­pres­sion in the feath­ers of their dor­sal area – adding a new di­men­sion to the phrase ‘wa­ter off a duck’s back’. In­cu­bat­ing fe­males have been known to lose

The ex­tra­or­di­nary ad­van­tages that fe­male Eiders con­fer upon their eggs – be­ing cosily wrapped in the world’s best in­su­la­tor, un­der one of the world’s best in­cu­ba­tors

45% of their ini­tial body mass while dis­charg­ing their du­ties. The ex­tra­or­di­nary ad­van­tages that fe­male Eiders con­fer upon their eggs – be­ing cosily wrapped in the world’s best in­su­la­tor, un­der one of the world’s best in­cu­ba­tors – don’t ex­tend far be­yond the point of hatch­ing. Young Eiders en­ter the out­side world well de­vel­oped, and al­most im­me­di­ately can walk about, swim and dive un­der their own steam. But while they leave the warm phys­i­cal em­brace of their mother’s body, they en­ter into a dif­fer­ent kind of em­brace – that of the colony sis­ter­hood. These Eider colonies are highly un­usual for their benev­o­lence. In a gull colony, a peri­patetic in­di­vid­ual wan­der­ing away from its par­ents’ ter­ri­tory might well be at­tacked and even killed. There is no prospect of that here. A youngster is born into the care of Eider So­cial Ser­vices. Even dur­ing the hatch­ing process, a mother Eider might find her­self sur­rounded by an ad­mir­ing coali­tion of in­ter­ested fe­males. These are typ­i­cally adults that have failed to breed at all or have, per­haps be­cause of poor body con­di­tion, had to aban­don their clutches. These birds join the mother in ac­com­pa­ny­ing the chicks to wa­ter, and will take part in their sub­se­quent pro­tec­tion by mak­ing threat dis­plays to­wards po­ten­tial preda­tors. They are of­ten known as ‘aunts’, and there is ev­i­dence that some at least might be re­lated to the mother. Even where there are no aunts present, Eider fam­i­lies co­a­lesce eas­ily, and sev­eral may join to­gether on the walk to wa­ter, to such an ex­tent that the broods be­come fun­da­men­tally mixed up. Within a few days crèches form, usu­ally with 20-30 chicks in each one. Oddly, an at­tack by a preda­tor is of­ten the trig­ger for crèche-for­ma­tion. The young bunch to­gether for pro­tec­tion and, even more oddly, may then stay to­gether un­til they are in­de­pen­dent. The cri­sis leads to sev­eral weeks of min­gling. Brood-mix­ing of a kind does seem to

SEA DUCKS

Eiders are birds of the coast and sea, div­ing to the seabed to col­lect shelled mol­luscs be a theme with Eiders. It is not at all un­usual for chicks to be adopted into dif­fer­ent fam­i­lies, even where crèches don’t form. And even eggs are a cur­rency for co-op­er­a­tion.

Fe­male Eiders some­times ‘dump’ ad­di­tional eggs in a nest and, re­mark­ably, an­other fe­male will some­times in­cu­bate these suc­cess­fully, adopt­ing them as its own. The birds con­cerned might be in­ex­pe­ri­enced in­di­vid­u­als wish­ing to ‘prac­tise’. How­ever, be­fore you whoop too quickly at the tri­umph of sea­d­uck fem­i­nism, you should be aware that Eider co-op­er­a­tion is not en­tirely free from abuse. There is a Cuckoo in the nest, the rogue fe­male. And what she does is, in­deed, sim­i­lar to that of the fa­mous brood par­a­site. Some in­di­vid­u­als at­tempt to in­crease their pro­duc­tiv­ity by lay­ing eggs in the nest of an­other bird, in ad­di­tion to eggs that they lay in their own nest. In other words, they sub­con­tract some of their in­cu­ba­tion du­ties on to the bur­den of a dif­fer­ent in­di­vid­ual. When you bear in mind the ex­cep­tional ef­forts Eiders make to look af­ter their eggs, it cer­tainly looks like a dirty trick to pull. Brood par­a­sitism by Eiders tar­nishes the ap­par­ent fem­i­nine idyll within the colonies, but one thing it does prove. There is noth­ing av­er­age, and noth­ing or­di­nary, about the breed­ing of these re­mark­able birds.

EIDER DOWN Eider nests are lined with down of ex­cep­tional qual­ity PER­FECT CAMOUFLAGE Fe­males may look dull com­pared with males, but their plumage is all about be­ing cryp­ti­cally cam­ou­flaged to pro­tect the nest

BIG DUCK! Eiders are heavy ducks, but re­mark­ably fast fliers

BLACK BELLIES Male Eiders are easy to pick out in flight, with their strik­ing black bellies ‘GAK-AK-AK-AK’ The fe­male’s call is said to re­sem­ble the “dis­tant throb­bing of an en­gine”

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