Are Santa's reindeer female?

So for all nine reindeer to have their antlers on December 25, they must be female.

Males drop their antlers and are without them until they grow back the following spring. 

Female reindeer keep their antlers until any calves are born around May time. 

Fun facts about Santa Claus

Santa’s sleigh is possibly the fastest vehicle ever made

In order to visit so many houses on Christmas Eve, Father Christmas has to travel at extraordinary speeds. 

This means he has to make 842 million stops on Christmas Eve and has just 31 hours to do it – due to time zone differences.

Scientists have calculated to get to every house in just 31 hours, his sleigh needs to travel at 1,800 miles per second.