Which factors, from most to least, determine a bird's (duck, turkey, chicken, etc) feather color intensity?  Is it mostly genetics, then time of year, then diet?
 
For example, male mallard ducks (drakes) have various color intensities of their green heads; iridescent beetle green to a mottled green. Which factors cause this variation? (greatest to least important)
	
		
			
		
		
	
				
			For example, male mallard ducks (drakes) have various color intensities of their green heads; iridescent beetle green to a mottled green. Which factors cause this variation? (greatest to least important)
	
	
