posted
While I got a smattering of sciences in school, I never took any ecology. Now I find myself looking for the answer to a presumably basic question and failing to find it.
I want to know how many organisms predators need to survive. Like if I have a fox and he eats bunnies and birds, how many bunnies and birds do there need to be for the fox to keep going all year?
I got the Wiki basics on ecology and biomass, but I'm looking for some ratios. (A friend's designing a D&D world, and the lack of working ecologies has always bothered me.) Every time I google biomass looking for better answers, I get green fuel articles.
Would anyone know of some decent websites that might help me out?
Posts: 2283 | Registered: Dec 2003
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posted
Thanks, j_k. I'm still not finding exactly what I want (I'm guessing the question isn't as basic as I assumed) but predator prey ratio is getting me closer. I found the number of kinds of prey to predators, so that's cool. (3/4 if you were wondering.)
I'll start again in the morning with a clearer head.
Posts: 2283 | Registered: Dec 2003
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posted
I believe "Guns, Germs, and Steel" may speak a little about this, in the section detailing why humans have never domesticated a carnivore. I'll try to find it.
EDIT: Actually, I think I should have said "large" carnivore, meaning one that weighs more than 100 pounds when full grown.
Posts: 1080 | Registered: Apr 2006
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You could search for the classic examples of lynx-hare and timber wold-moose population fluctuations and see if they have absolute numbers tied to those.
Posts: 655 | Registered: May 2005
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posted
I'd say it can change by a great deal, depending on the animals involved. Some predators need to eat their body weight or more every day, others can eat once a week or longer.
Large or especially nutritious prey animals wouldn't have to be nearly as abundant as small, thin, or especially difficult to catch prey.
You could do some rough calculations yourself, increasing or decreasing your accuracy based on how much work you want to do:
Decide how much the predator eats, the predator's population growth, and the prey's population growth. Then you can figure out how many prey are needed simply to keep the predator alive, and beyond that number, how many more are needed so that the prey can keep a stable population (ignoring all other factors, for ease of calculation).
Posts: 3950 | Registered: Mar 2006
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