Kinda reminds me of an island fox off... California somehwere. (Read about it in the dentist's office.) The population was doing great, naturalists thought all was fine. 8 years later someone went there to check on them and they were almost all gone. Poof.
They had no idea what happened.
A year or so of researching (interviewing people, observing the islands and the lands around it) and they found that DDT (gotta love how that is the route of so many problems) had soften bald eagle eggs and dropped their population. Golden eagles moved in. They started feeding on an introduced pig that escaped and spread like bunnies. This food supply brought in many goldens. They also started picking off this easy furry little creature - the island fox. Almost wiped it out.
They've been able to reintroduce bald eagles, which are so teratorial they drive off the goldens' but eat fish so the foxes are safe. And they are trying to trap the pigs (easier said than done.) And the foxes are slowly recovering.
I agree, they should study the bunnies. I bet there is a good deal to learn from them. That type of issolation almost always leads to interesting things.
ps. Ok, that was a digression. But an interesting one, I hope.