77885
The females and immature males are grey birds with chestnut foreheads and crowns , and can be confused at a distance with the ruddy duck ; they are often known as " redhead " smew .
 ruddy duck
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 ruddy duck