When your electrical system is working normally, the two upper chambers of the heart (atria) contract and pump blood into the two lower chambers (ventricles) in a well-coordinated way. This results in ...

Japanese tits have previously been observed combining different calls into phrases to convey meanings. The birds may also use their wings to signal to their partner that they should enter the nest ...

A Fork-tailed Flycatcher. Credit: Valentina Gómez-Bahamón, Field Museum Bird feathers have many different functions. Softer down keeps a bird warm and stiffer wing feathers are used for flight.

Atrial flutter is a type of irregular heartbeat, or an arrhythmia. It causes your heart to beat too fast. Atrial flutter doesn't always have symptoms, but it can sometimes have serious consequences if ...