ScienceDaily (May 14, 2012) — A male robin will be more diligent in caring for its young if the eggs its mate lays are a brighter shade of blue.
The blue colour in robin eggs is due to biliverdin, a pigment deposited on the eggshell when the female lays the eggs. There is some evidence that higher biliverdin levels indicate a healthier female and brighter blue eggs. Eggs laid by a healthier female seemed to encourage males to take more interest in their young.
ScienceDaily (Apr. 2, 2012) — Sparrows in San Francisco’s Presidio district changed their tune to soar above the increasing cacophony of car horns and engine rumbles, details new Mason research in the April edition of Animal Behaviour.
"It shows a strong link between the change in song and the change in noise," says David Luther, term assistant professor in Mason’s undergraduate biology program. "It’s also the first study that I know of to track the songs over time and the responses of birds to historical and current songs."
The navigational challenges faced by migratory songbirds
are both immense and complex. Whether migrating short
or long distances, within or between continents, or to
reach wintering or breeding sites, migratory songbirds
must navigate across diverse landscapes, often facing
large ecological barriers and adverse weather conditions,
to reach habitats appropriate for their needs; indeed,
many individuals are capable of migrating to the same
breeding site and/or wintering site year after year. Such
navigational feats impress amateur birders, naturalists,
and scientists alike, and beg for questions about how
small birds, often weighing only a few grams or tens of
grams, manage to find their way.
Deutschlander, M.E. and R. Muheim from “Magnetic orientation in migratory songbirds.”