Ecological Solutions

Yesterday evening I was watching discovery channel, they were talking about black rhinos, how they are threatened and in some areas there are very small populations, and they're worried about inbreeding. Meanwhile it was showing them in a helicopter chasing down and tranquilizing a rhino. So, I was thinking maybe they were gonna do some artificial insemination or something. The narrator comes back on and says that the national parks and reserves often capture and exchange their balls.

Totally shocked for a moment. Did they actually just say that?! And did they actually mean it?! I briefly imagined them chopping them off two bulls and reattaching them to the other, so when they mate they'd be delivering another bull's sperm... But no, that doesn't make sense, it couldn't possibly work out, could it? And discovery channel wouldn't such informal terminology like "exchange their balls," would they?

A little later I realized they had said "Exchange their bulls." Which definitely eases my mind.