question: If some of the birds are eating something that is on the ground.
#1 return birds 
#2 return ground 
#3 return something on #2 
#4 return #1 that are eating #3 
#5 return number of  #1 
#6 return number of  #4 
#7 return difference of #5 and #6 
#8 return if  #6 is at least one 
#9 return if  #7 is at least one 
#10 return if  both  #8 and #9 are true