Savannah backcrosses, called the BC1 generation, can be as high as 75% serval. Such 75% cats are the offspring of a 50% F1 female bred back to a serval. Cases of 87.5% BC2 Savannah cats are known, but fertility is questionable at those serval percentages. More common than a 75% BC1 is a 62.5% BC1, which is the product of an F2A (25% serval) female bred back to a serval. The F2 generation, which has a serval grandparent and is the offspring of the F1 generation female, ranges from 25% to 37.5% serval. The F3 generation has a serval great grandparent, and is at least 12.5% serval.