The study of homosexuality in nonhuman animals is woefully understudied. It is perhaps one of the few truly controversial research subjects.
But sperm is not!
Search pubmed for "sperm" and you will garner 77,926 results. Ovaries are more popular, though, with 116,000 results. Search for "homosexuality"or "homosexual behavior" and you'll get less than 20,000 results and almost ALL have to do with humans.
I should not find this surprising. By all accounts, a small percentage of between 500-1,500 species exhibit homosexual behavior. About 50% of males produce sperm! I cannot explain why ovaries are way more popular than sperm, except that ovaries rule and sperm drool. I kid. Sperm cannot drool.
Anyways, so NPR turned a neat phrase: Sperm of a feather flock together. I love this and have been telling everyone about it. You do not often get to say that with a straight face (or while sober, you probably don't say it inebriated, either). Turns out when a female copulates with multiple males, the sperm of each male herd up and hang out with one another. See the dyed sperm here. They're actually quite pretty. In another recent publication, researchers genetically modified fruit fly sperm so their heads glowed different colors. That's crazy. They did this study because the female reproductive tract is super mysterious. So mysterious that we have to modify the genes of sperm to reveal its hidden something or other.
Consider yourself enlightened. Sperm of a feather flock together, and glow in the dark sperm - you may want to hold your breath - are constantly on the move. Breaking news.