Birds generally avoid unusual things and prefer green and blue objects  But when researchers injected baby mallard ducks at 4, 9 and 14 weeks with sheep red blood cells to simulate a parasitic infection, but when researchers injected baby mallard ducks at 4, 9 and 14 weeks with sheep red blood cells to simulate a parasitic infection  The birds began to explore new things in their environment and approached the small orange toys-They usually keep away from the color because it seems to be associated with poisonous food  The researchers speculate that these so-called personality changes will help adult individuals explore larger areas, and find more food
Proteins released by sheep red blood cells bind to the retina cells of the mallard duck, affecting its colour recognition.
 These things in turn, make up for the energy they lose in fighting infectious diseases