TitleObservations of a female North Atlantic right whale (Eubalaena glacialis) in simultaneous copulation with two males: supporting evidence for sperm competition
Publication TypeJournal Article
Year of Publication2005
AuthorsMate, B, Duley, P, Lagerquist, BA, Wenzel, F, Stimpert, A, Clapham, P
JournalAquatic Mammals
Keywordssperm competition

Given the huge size of their testes (approximately 1,000 kg), it has been hypothesized that North Atlantic right whales (Eubalaena glacialis) have a mating system that is based upon sperm competition. Herein, we report an observation which provides support for this hypothesis. On 11 August 2000 in the Bay of Fundy in Canada, a mature female right whale was observed copulating simultaneously with two mature males. The female made no attempt to resist copulation. For anatomical reasons, double copulation would be difficult or impossible in most mammals; however, it is quite feasible in right whales, and the fact that it actually occurs provides strong support for the belief that females of this species promote sperm competition as a mating strategy.