Publication details

Ultraviolet and green parts of the colour spectrum affect egg rejection in the song thrush (Turdus philomelos)



Year of publication 2007
Type Article in Periodical
Magazine / Source Biological Journal of the Linnean Society
MU Faculty or unit

Faculty of Science

Field Zoology
Keywords brood parasitism; cuckoo; egg appearance; evolution of mimicry; reflectance
Description We investigated effect of different colors of the experimental eggs measured by UV–visible reflectance spectrophotometry on rejection behavior in the song thrush. We carried out a set of experiments with four blue model eggs representing mimetic eggs, whereas six other colours represented nonmimetic eggs. Our results revealed that two colors originally designed as a mimetic were rejected at a high rate, whereas one group of the nonmimetic was accepted. A multiple regression model of absolute differences between song thrush and experimental eggs on rejection rate showed that the level of mimicry in the UV and green parts of the color spectrum significantly influenced egg rejection. To our knowledge, this is the first detailed study showing that different color perception by the birds can affect their responses towards the parasitic egg. These findings suggest that the combination of UV and visible ranges of the spectra plays a major role in the evolution of discrimination processes.