Nature Science Update - Careless Whispers Cost Chicks


Careless whispers cost chicks

Females stray when mates lose song battles.
3 May 2002

A male chickadee risks his reputation.
© D. Mennill

Female birds that overhear their partner lose a singing contest are more likely to mate sneakily with another male, researchers have found1

Just two defeats send a female looking for alternative mates. "Females are deciding who's going to father their children on the basis of a six-minute interaction," says zoologist Tom Peake of the University of Copenhagen, Denmark. "That's got to worry pretty much every male on the planet."

Female eavesdropping shows that there's more to fighting than letting the combatants know who's boss - everyone within earshot is also picking up information.

Daniel Mennill of Queen's University in Kingston, Ontario, went into the woods to do battle with male black-capped chickadees (Poecile atricapilla). He provoked the birds using a laptop loaded with song recordings.

Against half the males, Mennill was the aggressor, playing songs at the same time and pitch as the singing male. This stops them getting their message across, he says.

He showed subservience to the other males, waiting until they finished singing and then broadcasting at a higher pitch. This signifies low status in a real male.
Daniel Mennill plays at being a chickadee.
© Stephanie Doucet

Mates of the high-ranking males Mennill defeated were significantly more likely to breed with other males, DNA tests showed. "It's probably quite a shocking thing for females to hear - they're accustomed to their males winning every fight," he says.

Chickadees form pairs to raise a family, but they are not always monogamous. In the wild, about one in three broods contain chicks sired by a male other than the female's mate. Chickadees live in flocks with a strict pecking order; females paired with low-ranking males are more likely to seek out other mates.

Spectator sport

"There's growing evidence that males and females eavesdrop," says Peake. He has found that male Siamese fighting fish are more aggressive towards males they have seen win a fight.

Watching a fight gives fish a testosterone rush. The same happens to football spectators: "Their hormone levels go all over the place depending on which way the match is going," says Peake.

Being watched probably also changes behaviour. The benefits of a hard-man reputation might make witnessed fights more violent.

On the other hand, if neither contestant is sure of winning, they might want to conduct their battles in private. This could explain why, in song thrushes and robins, the longest song duels are the quietest, says Peake.


  1. Mennill, D. J., Ratcliffe, L. M. & Boag, P. T. Female eavesdropping on male song contests in songbirds. Science296, 873, (2002). 

  2. © Nature News Service / Macmillan Magazines Ltd 2002