Snakes, Numbers, Poisonous, Harmless

Factual Questions
1

I hope this questions hasn’t been asked before, and no, I’m not asking for personal advice regarding travel. Actually, I’m fond of snakes and would like to know if anyone can answer these basic questions:
1.) On what continent are there estimated to be the largest number of snakes? (In the case of India, it’s probably best to treat the sub-continent as a continent or else the answer will be Asia rather than India.) This gets tricky-sticky when it comes to islands and island groups, and this is worth pursuing if people are interested. I am. Others may not be. Let’s play it by ear. For instance Indonesia could be crawling with snakes, everywhere, underfoot, in your linen closet, in the back seat of your car,–or not. Melanesia may be relatively snake-free, have a low snake population. The Philippines, I suspect, have a high snake population. Madagascar? I haven’t a clue.

2.) Next question: where are the snakes most poisonous? In other words, where is it most dangerous if you see and/or are bitten by a snake? My guess is the Indian sub-continent, but I don’t really know (or I wouldn’t be asking the question). For instance: let’s say your favorite activity is hiking and camping in rain forests and jungles. In the jungles-forests of which continents or island groups is one most likely to be bitten by a poisonous snake and NOT make it safely to the nearest hospital, health care facility or witch doctor?

These are the two burning questions. Lesser issues,–and I’m hoping there’s someone trained in science who can answer these questions:

a.) Are snakes really more numerous in warmer, tropical regions than cooler ones? It appears that way. There are surely few if any snakes in the North and South Poles, but what about the difference between, say, Pennsylvania and Georgia? Or coolish Wisconsin compared to the much warmer Texas? I’m guessing that Florida has a lot more snakes than Maine, but maybe it’s more a matter of size than number.

b.) Is the danger of snakes, i.e. the likelihood that if one meets up with a snake it can bite you, cause you serious harm, even kill you, greater in warmer regions than cooler ones? Once again, just using my intuition, I must say that it seems that way.

c.) More broadly: does anyone know the proportion of dangerous (i.e. constricting or lethal due to their venom) snakes to harmless ones? In the entire planet,–and this is obviously an estimate, as no one can know the precise number–in ballpark terms, what’s the ratio of “safe snakes” to dangerous ones? Two to one? 75% safe, 25% dangerous to lethal?

Serious answers shall be greatly appreciated. These questions are not jokes but they’re obviously not so serious as to require a lengthy scientific explanation. I’m looking for general answers to general questions.

2

  1. Probably Asia just due to size, but that’s just a guess.

  2. Australia. By a long shot. Depending on how ‘poisonous’ is defined and measured, Australia contains between five to ten of the 10 most poisonous snakes in the world. Southeastern Asia would probably be second place.

a) Snakes are cold blooded creatures so thrive in warmer climates. I suppose that can be generalized to say that northern areas tend to have less snakes than southern areas, but keep in mind that America has deserts that are warmer and further north than Florida, so that would be a VERY general statement.

b) Probably not. Many snakes, poisonous or not, don’t attack unless you mess with them. Humans are too big for many snakes to consider us a meal, which means they attack for defense instead. Just walking where snakes are is usually not much of a problem unless you happen to alarm one, like say if you stepped on it.

c) Some vaguely official numbers put total snake species at 2500 to 3000, of which about 500 are poisonous. Constrictor snakes that are a danger to humans are relatively rare. So a ration of 1:5 to 1:6 would be about right. However, it’s entirely possible that dangerous snakes tend to have smaller populations than non-dangerous (or vice versa) so the ratio of snake safety by total number of snakes could be different.

3

Well of course if you separate out India, then the answer will only refer to India. Nonetheless India is part of Asia, so I’m struggling to see why you would want it separated. Why not also separate out Central America from North and South America, or separate Indonesia form Asia?

There’s no hard data on these sorts of things that I’m aware of. In terms of continents, rather than regions, I suspect that Australia would win out for several reasons. The continent is deficient in mammalian predators, and the reptiles are have filled most of the the cat/dog sized predator niches. This is further helped by the climate. There are no regions of Australia that are so cold that they don’t have high densities of snakes. In contrast large chunks of Asia and the Americas are too cold to support snakes in any abundance, which will bring the average density well down. Africa is the other continent with an entirely tropical/subtropical climate, but I suspect the high population densities and numerous small-medium sized mammalian predators would result in lower snake densities than Australia.

The highest density of snakes in the world is to be found on Guam, thanks to an introduced pest species.

Impossible to answer because danger is dependent on a great many factors, including the activity of the venom, the aggressiveness of the snake, the length and shape of the fangs, the chances of encounter, the availability of treatment and many other factors. The snakes with the most potent venom aren’t very aggressive and live in regions with low human population densities and world class medical facilities. As a result they have staggeringly low death rates. In contrast snakes with much less toxic venom in India kill far more people because they are more aggressive, live alongside billions of people and medical treatment is often non-existent.

Probably South America, simply because there is so much area that is so remote, combined with limited availability of air ambulances. In contrast most of Asia has very low snake densities and high population densities with reasonable levels of development. Nobody is really likely to die of snake bite in Turkey or Japan, for example.

Yes.

With some odd exceptions, the warmer the climate the more snakes. Even a few degree annual average temperature differencemakes a huge difference to reptiles.

Yes. The snakes with the most potent venom, the most aggressive snakes and the snakes with the highest human mortality rates are all tropical/sub-tropical species.

For all practical purposes, constrictors are all harmless to humans. You have a better chance of being killed by a duck than by a constrictor.

In terms of species, there are about about 3, 000 snake species in the world, of those somewhere between 120 and 500 species are capable of killing humans, depending how you define it. So in species terms about 10% of snakes are potentially deadly.

In terms of numbers of individuals, I doubt anybody knows. Because you tend to get more deadly species in warmer areas in conjunction with higher snake densities, it would be higher than the species ratio suggests, but how much higher I haven’t a clue.

4

By the way, something that just occurred to me, you seem to have some mistaken assumptions about where snakes are. Many islands are totally snake free, Ireland for example. Other islands only have one or two snake species on them, England only has three species of snakes for example (two of which are rare) while in France just across the channel there are about a dozen species. So it doesn’t really get more complicated including island or island groups since they generally have few, if any, snakes.

Secondly, snakes are not just in jungles/forests. They can be found in almost any sort of climate short of the artic. Consider the rattlesnake…

And lastly, I just noticed, the real answer for your second question actually depends on the level of health care available rather than the number of dangerous snakes. Australia has many hospitals so many be safer to be bitten in than Africa with it’s few hospitals, even though Australian species are at top of the list for most poisonous snake.

5

Asia is big, but the actual snake populations of Siberia/Asian Russia aren’t likely to be very high, which you;d expect to bring the average density down significantly.

Australia wouldn’t even make into the top 50 list. The average death rate by snakebite in Australia is less than half that of the United States, for example. An Australian has a much, much greater chance of being killed by lightning than snake bite. While Australia has its fair share of snakes, you can’t possibly support your claim that it is the place where an encounter with a snake is most likely to be fatal.

6

Got a cite for this? Not that I doubt you, mind: I just want to read stories about people getting killed by ducks.

7

11/21/2001:

8

So are there documented cases of a constrictor killing - and successfully eating if possible - a full grown human. I’ve seen anecdotal stories, but never anything reliable.

9

For those planning vacations, my understanding is that Sri Lanka has the highest per capita death rate from snake bite. Minor, quick cites here and here.

10

Snakes Alive! Here is a listing by country. India wins easy.

11

What is the most venomous snake in the world?

12

Thanks for all the great answers, everyone.

Blake: the reason I separated the Indian sub-continent from the rest of Asia was due to its large snake population and the enormity of the Asian continent as a whole, a good portion of which is cold, thus if one were to factor India’s snake statistics into Asia’s as a whole one would get skewered statistics that would not accurately reflect on the snake populations of, say, Korea, Manchuria and Siberia.

13

The Black Mamba snake is the largest venomous snake in Africa and the second largest venomous snake in the world, the only other snake larger is the King Cobra. The Black Mamba snake is found in Eastern Africa, from southern Ethiopia to southwest Africa.

14

I’m aware that some islands are snake free, godix, was using generalities because I was asking general questions.

It would be interesting to know the snake populations of tropical islands and island groups. I’m thinking of the south Pacific region in particular. There may well be warm islands that have no snakes, others loaded with them.

Deserts, of course, have lots of snakes.

The business of discussing snakes or any matter regarding a particular continent can get problematical. North America is probably one of the less snake rich land masses, excluding the arctic regions, and yet Mexico is North America, and so are Texas, Louisiana, Florida, Arizona and New Mexico, which all have large snake populations, so the issue gets tricky.

15

As fun as thta would be, I can;t seem to find any. People have been killed by ducks in various ways though. Collisions, as Squink noted, are the most common, particularly collisions with aircraft.

My favourite though is the woman who was strangling a duck for th pot, got scratched, developed tetanus, and died. She was literally kicked to death by a duck. What a humiliating way to go.

Depends how you define “most venomous”. The inland taipan has the most potent venom, measured in terms of amount needed to kill a mouse or dog. However other snakes produce less potent venom, but produce much more of it, so they can potentially kill more people with a single dose. Other snakes produce less and weaker venom, but have much better delivery mechanisms, so the actual amount delivered into the body is higher.

It all seems rather academic anyway. Whether you receive enough venom to kill exactly one man or a hundred men, the end result is the same.

16

Wouldn’t know, I’m Finnish; we’ve got exactly 2 snake species, and the one that actually IS poisonous isn’t lethal to a healthy adult. And both are amazingly fast… at running away from people.

17

The lethality of snakes is a great conversation. So here is a perspective from Australia. On one scale we boast number one and number two on the venomous scale - the most potent venom. As cited above - the Inland Taipan is the worlds most toxic venom. Number two is the common Ozzie brownsnake. I get brown snakes in my back yard. Can’t say I’m happy with that, and I’ve only seen one up close once - it was crawling along the windowsill one morning on the other side of the glass. I worry most about my cat trying to kill one. (The usual answer is that both animals die.) My next door neighbour ended up paying $800 to save his cat after it came off second best. Cats actually survive long enough to be treated, dogs don’t do so well.

The question about the lethality of “encountering” a snake in Oz is pretty easy. Without medical help an encounter with an Inland Taipan will kill you. They are also known as the fierce snake, and although timid, if they are threatened are capable of multiple bites in a a few seconds, and will inject enough venom to kill a busload of people. At 6 feet long they have a significant strike range. But no-one has ever actually died - because they live in the far outback, and are timid unless you provoke them. The biggest risk is to amateur herpitologists.

Brownsnakes kill a steady number of Australians. Without medical help you have a 50% chance (or so) of dying. The big issue is that their bite is swift, painless, and looks a bit like a slight scratch. Those that die usually didn’t know they had been bitten. A few years ago a local guy got bitten whilst mowing his lawn. He didn’t even realise there was a snake about. He simply didn’t wake up the next morning.

A number of Oz snakes can be aggressive, especially just after winter.

However in terms of numbers of people actually killed by snakes, Oz rates very low. Partly because we have a small population, and also because we can usually treat bite victims in enough time. With medical care the likelihood of dying is remote.

A national sport is telling tourists about our dangerous creatures. We have more than a fair share. One (British) friend of mine was quite put out to discover that the blue ringed octopus was both deadly and real - she was convinced it was a wind up.

18

Uh, if you have poisonous snakes like that, and you’re so worried about him getting bitten, why do you let your cat outside then?

My grandfather always said that the coral snake was the most venomous.

19

In terms of mouse LD50, that’s pretty close, probably only losing out to the most neurotoxic populations of the Mojave Rattlesnake. But as Blake noted that’s only part of the story. Even aside from extrapolating from mice to humans, coral snakes are relatively inoffensive, usually not at all “public” ( they’re fairly cryptic and not out prowling where folks will tend to run across them often ) and have small mouths. Consequently though pretty toxic, they’re not a huge threat.

20

What about sea snakes? I recall seeing some Discovery show years ago that claimed sea snakes were the most/among the most dangerous types of snakes.