BEND, Ore. (AP) – Three calves have been added to a one of the largest herds of the rare white buffalo.

The Oregonian reports that the three calves were born over Mother's Day weekend at a 288-acre sanctuary near Bend, Ore. The additions bring the total number of white bison at the sanctuary to 14.

Sanctuary operator Cynthia Hart-Button says two of the calves are females and one is male.

With their color coming from a recessive gene, white buffalos are rare among bison. They are not albinos.

Bison ranchers estimate there are about 50 white buffalos in the United States.