David Emery has posted an intriguing piece of netlore concerning the gender of Santa's reindeer. Here's the text of the email that's going around:

According to the Alaska Department of Fish and Game, while both male and female reindeer grow antlers in the summer each year (the only members of the deer family, Cervidae, to have females do so), male reindeer drop their antlers at the beginning of winter, usually late November to mid December. Female reindeer retain their antlers till after they give birth in the spring.
Therefore, according to every historical rendition depicting Santa's reindeer, every single one of them, from Rudolf to Blitzen ... had to be a female.
We should've known this when they were able to find their way.


David confirms that most male reindeer lose their antlers by early December... but it is possible for younger bulls to keep their antlers until well into the spring. So it's technically possible for Santa's reindeer to be male. However, it does look like it's more probable that Donner, Blitzen, and the rest of them are female, based on the antler evidence.