大象传媒

Tweet of the Day is the voice of birds and our relationship with them, from around the world.

Chris Packham presents the North American blue jay. The loud warning screams of blue jays are just part of their extensive vocabulary. These birds are intelligent mimics. Blue jays are neat handsome birds; lavender-blue above and greyish below with a perky blue crest, black collar and white face. But the blue jay is not blue, but black. Its feather barbs contain a dark layer of melanin pigment; the blue we see is caused by light scattering through modified cells on the surface of the feather barbs and reflected back as blue. Common over much of eastern and central North America, blue jays will move in loose flocks to take advantage of autumnal tree mast. A single blue jay can collect and bury thousands of beechnuts, hickory nuts and acorns (in a behaviour known as caching) returning later in the year to retrieve these buried nuts. Any they fail to find, assist in the natural regeneration of native woodlands.

Producer Andrew Dawes