American Kestrels Rejecting Intestinal Tract of Prey
Several times I have photographed American Kestrels discarding the intestinal tract of their prey. The prey has always been a vole or mouse when I’ve seen it happen, though it may occur with small birds also. I was surprised by this behavior. Every time I’ve seen it happen has been during our harsh winters when I would assume every last morsel of food would be significant for their survival. Below is a series of photos where a female American Kestrel demonstrates the behavior with a vole kill. Female kestrel begins to pull small intestine out of a vole And deliberately drops it The cecum? is discarded: the intestine is still attached to the body and hanging down the side of the post She pulls more intestine out of the vole Breaks it loose from the body And deliberately drops it to the ground Finally, she pulls out the last of the small intestine, which she also dropped I know of others who have seen similar behaviors in other raptors – a variety of hawks and Osprey. Several theories to explain it have been mentioned by bird photographers and others who have seen my photographs. Among them: “These organs are filled with potentially harmful bacteria”. Then how are many raptors, owls for example, able to consume their prey whole without harmful effect? “These organs are filled with food of low value to the kestrel (vegetative matter). Why fill up on carbs when it’s protein you need? Begs the question – Would they also discard intestines of insectivorous birds? I don’t know……