They'll die together.
Server scripts are single-threaded, so process can't do two separate things at the same time.
First animal notices there's no wild friend here and dies. Second animal does the same.
It's not done to disallow reseeding, but disallow unlimited seeding. There's no in-game mechanism to limit number of wild species in location. Peaceful animals are just free source of meat and other stuff. There'd be nothing to stop people from eventually seeding an island with ~200 animal species (or at least not aggressive ones).
It'd be extreme exploitation of the system. I think that, for example, even importing one type of sheep to an island which lacks them would have negative impact on economy. Why spend time for feeding sheep when you can have similar wool source for free? If it's not enough then import black sheep, fat-tailed sheep, snow sheep.
Of course, it would require much effort, but generally it's example of a very bad principle: one time cost => no upkeep + infinitive benefits.
One of my chars lives on an island which lacks big animals and it makes things interesting. Some islands have many animals, some don't.
SekoETC wrote:It sounds like a bug if a fattened animal can give 0 of everything.
It's not a bug. It's intentional generalization of animals resources system. Animal resources don't grow at all when animal is not in a pack. Milk, wool, meat, they all work the same.
It would be possible to, for example, add values got from hunting to resources got from butchering. It sounds like a fair and good solution.
ChromaKey wrote:'Fattened' isn't an indication of an animal's meat level at all.
Yep, it's hunger level. It wouldn't make sense to have description referring to different properties depending on their level. Word "fattened" is used because I didn't have better idea when developing the system and nobody proposed any better.

ChromaKey wrote:I am just wondering if there is any way to check if an animal has "grown enough" for butchering.
There's no other way. But it's enough to do it once for a few days.
Uma wrote:If there are bulk, harvest machines that pick potatoes for you, I'd think there would be a place for hay-makers, grass harvesters, things like that. It's very hard to maintain a 'large herd' ranch.
It's possible to have more animals, you just need help of other people

It's also aimed that nobody will be able to maintain all interesting animal species in own location.
I think that system is pretty well balanced. Scythes already offer quite good crop gathering rate. Adding grass harvesters with double production would require doubling feed requirement or reduction of milk/wool output.