Duck Physics

(SFX: spring time, birds chirping, ducks quacking)
     
     SPRINGTIME CONJURES UP IMAGES OF NEW FLOWERS SPROUTING, BABY
ANIMALS BEING BORN AND TINY EGGS HATCHING.  A CLASSIC SPRINGTIME
PICTURE--WHETHER YOU'VE SEEN IT IN REAL LIFE OR ON A DISNEY CARTOON--IS OF A
PROUD MOTHER DUCK WITH FOUR OR FIVE YOUNG DUCKLINGS SWIMMING ALONG
BEHIND HER.  IT MAKES SENSE THAT JUST-BORN DUCKLINGS SHOULD STICK CLOSE BY
THEIR MOM IN A SCARY NEW WORLD.  BUT PROTECTION ISN'T THE ONLY REASON BABY
DUCKS FOLLOW THEIR MOTHER SO CLOSELY, SAYS ZOOLOGIST FRANK FISH AT WEST
CHESTER UNIVERSITY.  HE HAS EXAMINED HOW MUCH ENERGY A DUCK USES WHEN
PADDLING THROUGH THE WATER, AND HE'S FOUND THAT THE DUCKLINGS SAVE
ENERGY WHEN THEY SWIM ALL IN A ROW.

     Fish: "A duckling that is swimming in formation. . .with about four ducklings, with the mother can
reduce energetic cost by over 50%. I've actually calculated up to 60%"
     AS THE MOTHER DUCK PADDLES ALONG, SHE CREATES A SWIRLING POCKET OF
WATER AS HER BODY MOVES ALONG THE WATER SURFACE.  THESE POCKETS, CALLED
VORTICES, TRAIL BEHIND HER IN TWO ALTERNATING ROWS. WHEN PUT ALL TOGETHER
IN ROWS LIKE THAT, THE SPINNING VORTICES CREATE A STREAM OF WATER DOWN THE
MIDDLE THAT FLOWS FORWARD. AND THAT'S RIGHT WHERE THE BABY DUCKLINGS SIT.

     FISH: "As the ducklings swim between these vortices the water moves in such a way that as it
contacts the ducklings it's moving forward and . . . as a result it helps to keep the duckling moving
forward." 
     THE BABY DUCKS AREN'T JUST PULLED ALONG, THEY STILL HAVE TO DO SOME
PADDLING TO KEEP UP, BUT THEY DON'T HAVE TO WORK NEARLY AS HARD. THE VERY
LAST DUCK GETS THE BIGGEST BREAK OF ALL, SINCE HE'S GOT 5 DUCKS IN FRONT OF
HIM CREATING A STRONG STREAM OF WATER PULLING HIM FORWARD. SO NOW YOU
KNOW WHY MAMA DUCK KEEPS ALL HER DUCKS IN A ROW.