I actually saw the medical records and legal case history from the Crotalus atrox bite case you mentioned. The man was aware that the snakes were still alive, and they had been placed in the refrigerator, not the freezer. A snake at extremely cold but not freezing temperatures does not immediately die, but does become immobile. If it remains in this state for an extended period of time it will die. If an animal's tissues actually freeze, there is no recovery from that, as their cellular structure is severely damaged by the resulting crystallization. Unless an organism possesses special evolutionary adaptations to prevent massive cellular damage from ice crystals, which tropical species don't, if temperatures reach freezing, it's dead. Medical doctors face some of the same issues reviving hypothermic humans. Veterinarians used to use "cryo-anesthesia" routinely for reptile procedures in zoos until about twenty years ago, when it was demonstrated that reptiles in cold torpor were physically immobilized but fully sensate. Non tropical species can recover from cold torpor because it's already built into their physiology and the environment they evolved in. The tropical species, not so much. They simply haven't evolved to deal with the situation, because they never needed to. We spend quite a bit of time and money delicately maintaining tropical conditions inside our cages. It's absolutely crucial to our animals' health. If the power were to go out for any length of time, I guarantee my patient roster would be instantly full of seriously sick snakes. Documented in the veterinary literature (ARAV, ICE and NAVC proceedings) are a number of catastrophic veterinary emergencies in reptile collections triggered by a power outage in areas even more temperate than ours, such as North and Central Florida. Some resulted in the loss of the entire collection, or close to it, even with vet care and devoted nursing. I would not like to bet that I could save the life of a mamba whose cage conditions were set at Wilmington outdoor temperatures overnight. I might be able to if I were able to bring that animal back up to 85F+ immediately and put it on a course of prophylactic antibiotics, but it would definitely be touch and go. Go longer than 24 hours at extreme temperatures and we're talking about a critical patient with damage that may be irreversible. Without veterinary support care, it's a dead animal. Even with that care, I wouldn't give much for its chances. Unfortunately I really do have a tragic amount of experience working with venomous snakes that have suffered extreme temperatures during transport, since I used to offer free and sponsored vet care for them at the South Florida import facilities. It's really touch and go in those situations. I can save some of them with intensive support care, but serious damage is always done if a tropical snake is chilled to the core for any length of time. That doesn't take long at all, especially with the smaller species. The eyelash vipers surviving refrigerated transport? Technically alive at the end of the trip, but most likely dead snakes walking. I'd do my best to save them, but wouldn't be surprised if I failed. It does take a snake a lot longer to die of conditions that would be rapidly fatal to a mammal, and they can remain remarkably mobile and responsive to stimuli long after their vital body systems have been irreparably damaged and have ceased to function. Even a decapitated snake head is capable of envenomation, but don't expect it to have a long and productive life thereafter. So no, I find it hard to credit the notion that green mambas could invade Wilmington, even if we were inclined to let them. Which we certainly are not.