According to research by Queen’s University biology professor Bob Montgomerie, a male robin will care more diligently for its young if the eggs its mate lays are a brighter shade of blue.
Prof. Montgomerie has studied robins on and off for 25 years and has been especially fascinated with the bright blue colour of their eggs.
To test his theory on the significance of the bright color of these eggs, Dr. Montgomerie and MSc student Philina English replaced the eggs in robins’ nests with artificial eggs of different shades of blue at the Queen’s University Biological Station (QUBS) and other sites around Kingston. And just before the real eggs would have hatched, researchers replaced all of the artificial eggs with baby robins.
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“We were testing the idea males can use egg colour as a signal of the quality and health of their mate, and that healthy mates create better babies,” said Dr. Montgomerie, whose research focuses on sexual selection and parental care in birds. “Sure enough, males whose nests contained the brightest blue eggs fed their newly-hatched babies twice as much.”
The blue colour in robin eggs is caused by a pigment called biliverdin, which is deposited on the eggshell as the female lays the eggs, with some evidence showing that higher biliverdin levels indicates a healthier female who therefore produce brighter blue eggs. The study reveals that eggs laid by a healthier female seems to result in the males taking more interest in their young.
The University’s research has been published in Behavioral Ecology and Sociobiology.
Photo: Wikimedia Commons