Last month we started to talk about building the kind of supernatural monster ecology that would make sense, one that had numbers behind it and had some sort of internal consistency to it. If it took place in the real world, for example, then you couldn’t have more people mysteriously vanishing off the face of the Earth than actually do disappear.
We went into the subject in more depth but there are a few points that we should bring back so that you don’t have to go to another issue in order to refer to them:
- · 500 ml of blood is the most that you can lose without symptoms becoming severe and noticeable. 250 ml causes barely any change at all.
- · We divided our example monsters into four categories: standard living types, who need 2,400 calories per day; standard dead types, who need 200 calories per day; active dead types, who need 500 calories per day; and wolf types, who need 4,080 calories per day.
- · James Cole’s research tells us that a 143lb male contains 81,500 calories. Yum.
For the purpose of example we’re using vampires, but the ideas can be applied to trolls, goblins, or whatever you’ve come up with yourself (there are some interesting numbers to work with for Lovecraft-style ghouls, but that’s another topic for another time).
How Often Would Vampires Feed?
A vampire who drains 250 ml of blood from each person will consume 230 calories. A standard living type would need to feed on nine or ten people a night. A standard dead type would get away with feeding just once every night, and could potentially skip a meal every now and then. An active dead type would need to feed on two or three people a night. A wolf type would have to feed up to seventeen times every night.
For vampires who drain 500 ml from each person, simply halve these numbers. This will result in noticeable symptoms, however, so vampires who resort to this strategy will hopefully be draining volunteers who won’t wonder at their symptoms or else have some sort of way to mask those symptoms (they might produce a saline solution as a kind of waste product and inject this as part of the feeding process, for example).
It is also plausible that, with such tight demands, female standard living types may have a slight but noteworthy advantage over males if they have different caloric needs— at 2,000-2,200 calories a night, a female vampire would need eight or nine 250 ml servings to a male’s ten or eleven servings. The difference is even greater in wolf types, with females needing 3,740 calories a night (fifteen servings) and males needing 4,760 calories (nineteen servings a night).
What about a vampire who completely drains a person of blood, consuming (on average) 4,700 calories per person? A standard living type would have to feed every other night, killing 182 people a year. A standard dead type could survive for 23.5 nights on a single person, killing fifteen or sixteen people a night. An active dead type would only need to feed every 9.4 nights, killing about thirty-eight people per year. A wolf type would finally get away with eating no more than once a night, and could skip about every eleventh meal, killing 317 people per year.
Finally, let’s consider a spider vampire who was able to get 81,500 calories from a person (we are ignoring that some of this comes from the skin, but also ignoring that most adult males in the United States weigh more than 143 pounds). A standard living type would have to feed once about every 34 days, killing 11 people each year on average. A standard dead type could “live” on a single person for 407.5 days, killing less than one person per year. An active dead type would need to feed every 163 days, killing two or three times a year. A wolf type would need to feed about once every twenty days, killing around eighteen people every year.
So How Many Vampires Could the United States Support?
It all depends on which choices we’ve made in the past two sections, and a few other factors. If vampires can rewrite memories, then you could have thousands of standard dead type vampires taking 250 ml doses from people one night at a time without anybody suspecting, although they would have to be smart about it. In fact, three thousand would only need 168,000 people, meaning that they’re feeding on only 0.05% of the population.
Basically, with this kind of strategy your upper bound is limited only by how many vampires you think can move around without being detected, a matter which would probably be a couple of articles in itself.
What about vampires which practice total exsanguination? If we assume, say, two thousand vampire-related deaths per year in the United States, then this could support a population of perhaps 125 standard dead type vampires. Now we’re getting somewhere with all this number crunching, aren’t we? The same mortality rate could sustain ten or eleven standard living types, fifty-two active dead types, or six wolf types. According to the Law of Conservation of Ninjutsu, those wolf types are going be very dangerous.
Finally, how many spider vampires could the United States support? Assuming the same number of deaths as last time then even the hungry wolf types can get enough to eat with a population of 111 vampires. Alternatively, 181 standard living types, around 870 active dead types, or a whopping 2,234 standard dead types. In any of these cases, however, you probably don’t see vampires getting together and forming “covens” or “coteries” or whatever the cool kids call them these days.
These figures ignore don’t take into account that humans are not evenly distributed across the country, by the way. This is important.
What Kind of Adaptations Are Possible?
To segue directly from the last paragraph, we should talk about the differences between nomadic and settled types. Assuming that they kill in the process of feeding, vampires who move around will be able to hold a larger population than those that don’t. A single small town doesn’t experience enough unsolved murders or disappearances in order to consistently support even a standard dead type, unless there were some sort of conspiracy in place to prevent word from getting out. On the other hand, small towns as a whole do make up some of the total murders and disappearances which would be necessary to support these vampires, so they can’t simply set up shop in the big cities alone if they’re going to have the maximum allowable population.
Combining these strategies would not make use of available resources as pure nomadism, but it would still be pretty good. Under these conditions one might see big cities holding a small number of vampires (who probably have either staked out territories against each other or work cooperatively as a pack) while others, who are not strong enough to push out an established vampire, wander from small town to small town. They may establish broader territories in this context and take pains to keep other nomads out of the region.
Vampires who spread the burden of their support around the population, feeding a little here and a little there, would be depending on a sizable proportion of a small town’s population. For example, Male donors and female donors would have to wait six and eight weeks respectively to replenish their lost blood if drained of 250 ml, or twice that for 500 ml. This means that a standard dead type vampire who drains 250 ml a night could get by with a herd of 42-56 people, while a wolf type who did the same would need a herd of 714-952 people in order to avoid an overdraw on any of its accounts.
At any level this could be a difficult proposition. Even the standard dead type vampire who drank only a little every night would have to maintain relationships with several dozen people. If its nature as a vampire is known then any one of these is a potential security risk. Vampires may create literal cults in order to account for this, set up in places where their victims are unlikely to be believed (i.e. asylums), or rely on innate abilities such as a natural anesthetic to mask their feeding (and preferably something to mask the wound) or some kind of psychic power to modify the memories of their victims. In modern times it is also possible for a vampire to outright claim to be just that, counting on people to consider it an eccentric or member of this or that subculture, and collect a group of willing donors.
Hibernating bears experience a 75% drop in metabolism. If vampires go into something like hibernation when they’re asleep, and they are only awake for eight hours every night, then wolf types might need only 2,040 calories a night, allowing them to sustain a higher population than standard living types who didn’t hibernate. We could conceivably have a spider wolf type that hibernated eleven months out of the year and whose waking periods were marked by a feeding frenzy, killing… less than two people a year on average (its yearly caloric demand would be 153,000).
Dang. Hibernation is pretty neat!
Finally, vampires who need to feed often may mimic the behavior of vampire bats. These animals, who need to consume up to half of their body weight in blood every night and will die if they miss two nights in a row, will regurgitate some of their meal for fellow bats who have been unsuccessful in the night’s hunts. At lower levels of feeding (250 or 500 ml per person) this behavior would probably be most common among standard living types and wolf types, as the two dead types have low enough energy demands that it is unlikely that they would need help to begin with.
Regurgitation becomes more probable among vampires who practice total exsanguination. Standard living types need to feed every other night, exactly as vampire bats do, while wolf types would need to feed every night but, every two weeks or so, could afford skipping a meal entirely. Vampires who eat everything, however, would feed so infrequently (even among wolf types) that the sharing of meals would not hold such dire importance except for when a general famine was in effect.
No matter the level of feeding and demand for energy, this behavior presupposes that vampire are not solitary predators. Whole cities may support just a small handful of them, all working together, or nomadic packs may stake out larger territories than their solitary brethren would have need to do.
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