Great Tits' Appearance Linked To The Health Of Chicks

A new study of great tits (Parus major) correlates females' appearance to the health of her offspring.

The mother birds' black breast stripe and white cheek patches are correlated with chicks' weight and immune strength, respectively.

Researchers from Palacky University in the Czech Republic examined the birds, taking two mothers with different patterns and swapping their chicks in an attempt to investigate the health of the hatchlings and the "ornamentation" of the mothers.

They compared the offspring's weight, size and immune strength and found correlation between the chick's weight and the size of the black breast stripe on the genetic mother.

"The immaculateness of both genetic and foster mother's white cheek patch was related to the strength of chick's immune response suggesting that this was due to both nurture and genetics. In contrast the body size of a chick was related only to the body size of its genetic mother and not to ornamentation at all," a news statement stated.

Breast and cheek ornamentation of male birds did not correlate with the health of the chicks, according to the statement.

"Bigger healthier babies are important to the reproductive success of individuals, because they are more likely to survive to adulthood - so it is useful for birds to be able to work out which potential mates will produce the best babies. Maintaining bright coloration uses up resources which could otherwise be invested in reproduction or self-maintenance - consequently the evolution and maintenance of ornamentation in female great tits is probably due to direct selection by males," said the study's authors in the statement.

The full study is published in Frontiers In Zoology and is available online.