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Mother ducks cooperate on parenting

Jan.11, 2007
Courtesy University of Chicago Press Journals
and World Science staff

Fe­male ei­der ducks are known to team up and share par­ent­ing du­ties. But new re­search shows they al­so ne­go­ti­ate how much ef­fort each puts in­to the ven­ture, sci­en­tists say. 

Wa­ter­fowl are "care­ful, so­phis­ti­cat­ed bar­gain­ers," ne­go­ti­at­ing not on­ly how much ef­fort each puts in­to com­mu­nal rear­ing of duck­lings, but al­so prof­it-shar­ing, says a new stu­dy. (Cour­te­sy Nils Sund­berg)

Each hen seeks to max­im­ize her ben­e­fits from the part­ner­ship with­out ma­k­ing it so un­at­trac­t­ive that oth­er hens with­draw their par­t­i­ci­pa­tion, the re­search­ers found. Their con­c­lu­sions were based on a study of ei­ders in a Fin­n­ish ar­chi­pel­a­go.

As hens ar­rive at a rear­ing ar­ea with their duck­lings, a pe­ri­od of in­tense so­cial­iz­ing en­sues, the sci­en­t­ists ob­served. The hens then sort them­selves in­to cliques—pairs, tri­os, or quar­tets—with each hen in a group as­sum­ing a dis­tinct role. 

“Wa­ter­fowl have a rep­u­ta­tion as be­ing none-too-bright, but we think they are care­ful, so­phis­ti­cat­ed bar­gain­ers,” said team lead­er Mar­kus Öst of the Uni­ver­si­ty of Hel­sin­ki. “The so­cial­iz­ing dur­ing the pe­ri­od pri­or to group for­m­a­tion is de­vot­ed to the search­ing for and ne­go­ti­at­ing with a suit­a­ble part­ner.”

As a group, each hen’s duck­lings are kept warm, led to food, and fierce­ly de­fended against pred­a­to­ry gulls—all tasks for which cen­tral po­si­tions in a group are the best and safest. Though the duck­lings look iden­ti­cal to hu­man ob­servers, hens can rec­og­nize them and care­fully man­age their duck­lings’ lo­ca­tions in the joint brood, ap­par­ent­ly ac­cord­ing to an agree­ment worked out with the oth­er hens. 

Be­hav­ior­al ecol­o­gists have long been in­ter­est­ed in so-called “co­op­er­a­tive breed­ers,” but nev­er put ducks in that cat­e­go­ry, Öst and col­leagues said. Their new stu­dy, ap­pear­ing in the Jan­u­ary is­sue of the re­search jour­nal Amer­i­can Nat­u­ral­ist, chal­lenges that view and sug­gests that the ducks’ be­hav­ior­al strate­gies are more com­plex than pre­vi­ously thought.

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Female eider ducks are known to team up and share parenting duties. But new research shows they also negotiate how much effort each puts into the venture, scientists say. Each hen seeks to maximize her benefits from the partnership without making it so unattractive that other hens withdraw their partici pation, the researchers found. Their conclusions were based on a study of eiders in a Finnish archipelago. As hens arrive at a rearing area with their ducklings, a period of intense socializing ensues, the scientists observed. The hens then sort themselves into cliques – pairs, trios, or quartets – with each hen in a group assuming a distinct role. “Waterfowl have a reputation as being none-too-bright, but we think they are careful, sophisticated bargainers,” said team leader Markus Öst of the University of Helsinki. “The socializing during the period prior to group formation is devoted to the searching for and negotiating with a suitable partner.” As a group, each hen’s ducklings are kept warm, led to food, and fiercely defended against predatory gulls – all tasks for which central positions in a group are the best and safest. Though the ducklings look identical to human observers, hens can recognize them and carefully manage their ducklings’ locations in the joint brood, apparently according to an agreement worked out with the other hens. Behavioral ecologists have long been interested in so-called “cooperative breeders,” but never put ducks in that category, Öst and colleagues said. Their new study, appearing in the January issue of the research journal American Naturalist, challenges that view and also suggests that the ducks’ behavioral strategies are more complex than previously thought.