I was researching the Vile Deathroach on wowhead and one commenter said this:
Shares a spawn with Deathroach and Scurrying Mawrat within the Beastwarrens. Follow the roads for the spawns.
This is a Rare spawn, and you can no longer kill physically the others to spawn it, you need to defeat each deathroach or scurrying mawrat in battle to despawn them for a chance of a Vile Deathroach spawn.
First, I wondered how they discovered that only killing shared spawns via pet battle (as opposed to combat) worked. Then I wondered if this was a general change. I’ve been doing the safaris and I’ve had trouble finding snoeshoe hares. However, if there was a change at some point where you can only kill shared spawns via pet battles that would explain my difficulty.