Putting it all together: To answer this question, let’s look at these factors in the context of baby versus adult rattlesnakes. Numerous studies have demonstrated that there are significant ontogenetic (age-related) differences in venom composition within a single species of rattlesnake. Young rattlesnakes have a venom that is rich in LMM toxins and low in HMM enzymes, while most adult rattlesnakes have a venom that is predominately composed of HMM tissue destructive enzymes. Baby rattlesnakes eat quick and agile animals like lizards and frogs, which seem particularly sensitive to fast-acting neurotoxins and consequently don’t manage to make it very far away before dying from the venom. Larger rattlesnakes usually eat mammalian prey (rodents and ground squirrels) with significantly more volume-to-surface area than a lizard or frog and likely benefit from the digestive properties of the venom since they will have the whole prey item sitting in their GI tracts for a while. It could be argued that the drop-for-drop potency of baby rattlesnake venom is greater, but here is where the issue of venom quantity comes into play. An adult rattlesnake produces, stores, and injects anywhere from 20–50x more venom (more sometimes, but let’s play this conservatively) than a baby. In this case, the huge increase in total quantity of venom injected has a much greater clinical effect on humans. Clinical evidence supports this, with strong correlations between the size of the rattlesnake and the severity of the bite (see below). It is therefore safe to say that the overwhelming majority of the time, adult rattlesnakes produce more serious envenomations than their younger counterparts.

Here are two of the many good articles to demonstrate that fact:

Hayes WK, Bush SP, Herbert SS, Rehling GC, Cardwell MD, Dugan EA. Defensive bites by rattlesnakes (genus Crotalus): venom expenditure, envenomation severity, and the importance of snake size. In: Program and Ab- stracts of the Biology of the Rattlesnakes Symposium. Loma Linda, CA: Loma Linda University; 2005:31.

Wingert WA, Chan L. Rattlesnake bites in southern California and rationale for recommended treatment. West J Med. 1988;148:37–44.

The takeaway is that while adult rattlesnakes are more likely to cause worse envenomations, a bite from a baby rattlesnake is no joke and can still kill you if you don’t get proper medical treatment. This is especially true in cases involving children due to their smaller masses. Treat all snakes with respect, give them a wide berth, and appreciate them for doing an excellent job of keeping rodent populations under control. Rattlesnakes have no interest in biting humans and we are fortunate to have a species of venomous snake that gives us fair warning before striking, so respect that fact and appreciate them from a distance.

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