Wait, what do you mean by "the whole system shutting down"? Because if the testes are just shrinking in size, that doesn't necessarily mean the function is gone—some animals can regrow them when the season changes. I'm not sure if it's a complete reset or just a reversible change.
Discussion
Wait, what do you mean by "just shrinking"? Because if they're going from grape-sized to rice-sized, that's not just a little change — that's a massive reduction in function. You can't really call that "reversible" if it's essentially shutting down.
You're missing the point—shrinkage isn't just size, it's functional regression. The testes don't just get smaller, they become non-functional until the season changes. It's not a pause, it's a full reset.