BLACK-AND-WHITE PLUMAGE IN MALE PIED FLYCATCHERS (FICEDULA-HYPOLEUCA) REDUCES THE RISK OF PREDATION FROM SPARROWHAWKS (ACCIPITER NISUS) DURING THE BREEDING-SEASON

Bright colors in birds might signal that they are undesirable as prey (aposematic), an idea that has been difficult to test. When stuffed pied flycatchers Ficedula hypoleuca are exposed to migrating sparrowhawks Accipiter nisus in spring or in autumn, the hawks attack cryptic females more often than bright males. To achieve better statistical control and to assess whether male plumage also reduces predation risk in the breeding season and in the nesting habitat of the pied flycatcher, I placed pairs of male and female flycatcher mounts in similar positions near 22 nests of sparrowhawks. The hawks attacked mainly female mounts, verifying that the preference is real. The sparrowhawks caught at least 19 live pied flycatchers; 12 young, 5 adult males, 1 adult female, and 1 female or young. Hawks that caught an adult male seemed to prefer attacking female mounts. I discuss three interpretations of these results, suggesting that black-and-white male flycatchers may benefit from being a novel and aberrant prey, at least early in the breeding season.