Selective bird predation on the peppered moth: the last experiment of Michael Majerus

Released peppered moths in a single wood over seven years, allowing them to settle in natural resting positions at natural densities rather than being placed on trunks, and recorded disappearance attributable to bird predation for pale and melanic forms.

Studied in

Biston betularia, Aves

Sample size

4864 moths released over seven years and monitored for predation

Melanic moths suffered significantly higher predation than pale moths in this now-unpolluted wood, at a rate sufficient to account for the observed decline in melanic frequency.

• One wood, in a period when melanic frequency was already falling.
• Published after Majerus’s death from his data by colleagues, so the analysis was not completed by the person who designed it.

• Running the famous experiment properly

  The classic peppered moth experiments put moths on tree trunks, where the species does not normally rest. Does the result survive if the moths choose their own positions?

• Peppered moth

  The classic experiments had real methodological problems — including that the moths were put on tree trunks, where they do not normally rest. A seven-year experiment that fixed them reached the same conclusion.