Define European Swallow Meaning

Migratory birds who can carry coconuts but need to do it in pairs while tied to the coconut in a line.

A type of bird that migrates, weighs 5 ounces, and CANNOT carry a one-pound coconut.
These birds are very different than African swallows, which are bigger, and most likely COULD carry a one-pound coconut. But African Swallows do not migrate, so they wouldn't carry one if they tried.