A study published in the most recent issues of the journal Biology Letters has found that female guppies will risk their lives to avoid the unwanted attentions of amorous males.
Safi Darden and Darren Croft examined male harassment of females as a factor promoting sexual segregation in habitat use in wild Trinidadian guppies (Poecilia reticulata), and found that females would spend more time in deeper areas (where there are more predators) in the presence of males.
The authors placed either five large females and five males (mixed-sex experimental treatment) or five large females and five small females (same-sex experimental treatment) within enclosures on the Turure River in Trinidad.
They then recorded the behaviour and location of four focal individuals (two large females and two males in the mixed-sex treatment and two large females and two small females in the same-sex treatment) for a period of 10 minutes.
The authors also assessed predation risk to female guppies as a function of water depth by lowering single female guppies confined in a clear, colourless plastic container tethered to a monofilament line in shallow (23 cm) and deep (60 cm) areas of the river to observe predator behaviour towards this prey stimulus over a period of 10 minutes.
The scientists found that males and females occupied different areas of the enclosures in the mixed-sex trials, with males using the shallow zone more than females and females using the deep zone more than males; the females consistently occupied the shallow zones of the enclosures in the same-sex trials.
According to the authors, indicates that in the presence of males, females use deep water, a habitat with a higher risk of predation, as a refuge from male harassment (the exposure of the females to a higher risk of predation by piscivorous fishes with increased use of deep water was confirmed by the authors' assessment of predation risk).
For more information, see the paper: Darden SK and DP Croft (2008) Male harassment drives females to alter habitat use and leads to segregation of the sexes. Biology Letters 4, pp. 449"451.