There's a good wiki article here:

http://en.wikipedia.org/wiki/Homosexuality_in_animals

Apparently male giraffes are almost all gay. And male bison definitely take it in the ass.

There are giraffes in Uganda, and their habits are well known, so Buturo is either extremely ignorant of the fauna of his country, or he's telling porkies for his own purposes.

The evil men do lives after them. Dammit.