In all vertebrates, mothers transfer variable amounts of hormones into eggs and embryos, which influence development and traits of offspring in later lives. In a recent study the researchers looked at the transferred hormones in different bird species eggs, and found a hundredfold difference in the thyroid hormones, which control development and growth in birds. Migratory and precocial bird species provide the highest levels of thyroid hormones to their offspring.
Click here for original story, Migratory bird species get a different early start than non-migratory species
Source: Phys.org