Colourful male European Serins Serinus serinus are more careful with their plumage

Ornamental traits typically advertise individual condition and can be costly to maintain. Plumage maintenance behaviour can increase plumage quality and positively influence female mate preference. We investigated this prediction by performing female mate‐choice trials and measuring male plumage maintenance behaviour in the European Serin Serinus serinus. More colourful males spent more time in plumage maintenance than less colourful males, but this was not correlated with body condition or ectoparasite load. Females preferred more colourful males, although this was not influenced by male plumage maintenance. Our findings highlight the fact that investment in plumage maintenance depends on individual coloration and this may reinforce the honesty of ornamental plumage and convey positive information for mate choice.