Therefore the bird has difficulty seeing the worms , but the worms can see the bird 's shadow from underneath .
To make it more difficult for the bird , the participants around the outside edge are waving the parachute up and down .
The bird has difficulty seeing the worms , but the worms can see the bird 's shadow from underneath .
To make it more difficult for the bird , the participants around the outside edge are waving the parachute up and down .