In most bird species, males are more ornamented and compete for females,
who contribute more to offspring care. In a minority of species this
pattern is reversed, with more colourful females competing for mates and
males taking care of parental duties. In such sex-role reversed species,
the links between colourful ornamentation, individual quality and mating
success are not well established. The red phalarope (Phalaropus
fulicarius) is a colourful sex-role reversed migratory shorebird with
regular social polyandry, in which both sexes show considerable colour
variation. Here, we describe sex differences in colour and quantify
associations between colour variation and indicators of quality and mating
success in both sexes. Using a large sample of photos collected across
three consecutive years on the Arctic breeding grounds, we scored colour
variation for four body parts (bill, crown, cheek and breast), and
analysed scores separately and combined into an overall colour score.
Females were more colourful and larger than males, and individuals could
be unambiguously sexed by crown colour. Nevertheless, there was
substantial variation within sexes and some overlap between males and
females in bill, cheek, breast, and overall colour scores. Assortative
mating by colour was only found for the bill. Colour variation did not
correlate with plasma testosterone levels, except for male cheek colour.
Females in better body condition had yellower bills and higher overall
colour scores, while early-arriving birds had higher breast and overall
scores. Phalaropes that bred locally were heavier than those that did not,
but they did not have higher colour scores. Female colour variation did
not predict the probability of local social polyandry nor variation in
clutch size, and male coloration did not predict the probability of nest
predation. In conclusion, phalarope colour variation showed modest
correlations with individual quality and was unrelated to variation in
local reproductive success.