Chullin 61: The Eagle and the Kashrut of Birds

Discussing what makes an animal kosher, we have learned that birds are only known for kashrut by the listed names that are not kosher.  The Sages decide whether or not all other birds are not kosher: 

• when a bird catches its prey in its fingers and lifts it up
• when the bird has an extra claw
• when the bird has a crop, where the food first stops in this place
• when the bird has a korkevan to store food 

The rabbis question whether or not the Torah mentions the nesher, the eagle, is actually not kosher.  It should be unkosher as it meets none of these four requirements for kashrut.  The rabbis also look at the turtledove, which meets all of the characteristics of kashrut animals.  

The rabbis determine that the nesher may not be an eagle.  The rabbis suggest that the eagle does have an extra finger and thus it cannot be a nesher.  Instead perhaps the nether refers to another similar animal.