Santa's reindeer all have to be female because male reindeer drop their antlers at the beginning of winter, whereas female reindeer retain their antlers until the spring. Big Gary, who's wintering in Alaska, has sent along this photo of "a bull reindeer in Fairbanks, Alaska, this Wednesday, December 21, 2005," which pretty much settles the question of whether male reindeers can have their antlers in late December, around Christmas time. They obviously can. So Santa's reindeer could be male or female. Thanks.