A function of the pairbond in the Common Eider

Abstract

The male Common Eider Somateria mollissima plays no part in the care or protection of nest, eggs or ducklings. Despite this, the male forms a pair with a female to whom he remains closely attached for a period prior to laying. One function of this pairbond is for the male to protect the female from disturbance by other birds while she is feeding. She must form a clutch of large eggs, and lay down sufficient fat reserves to maintain her through the incubation period. Interactions with other birds in feeding flocks lower the female's feeding rate significantly, but this effect is reduced if her mate chases off intruding birds. Mere presence of the male close to the female gives some protection from disturbance and increases her feeding time.