I dunno about red eyes and darts, but native to the same area does not necessarily mean cohabitation is possible. An example I've read about in multiple books is the Pickerel frog, Rana palustris. In closed quarters like a vivarium they will kill off other species (via toxic skin secretions) that you can see them sharing the same large pond with outdoors. Think of it like being stuck in an elevator with me after I've had a large helping of garlic toast and baked beans. You'd rather be in a great big windy field with me than in the elevator, you might not pass out then. Same effect, the toxins will build up much more rapidly in confined quarters and you just can't get that far away from the source.