Creature territory size
Date: Thu, January 06, 2022
Topic: Monsters of Greyhawk

This article provides the Game Master guidelines on the amount of area a predator (i.e. animals and monsters) will need such that there is enough prey to hunt. Although for most of the Flanaess this might be irrelevant, it does help when planning out the amount of monsters on smaller islands.

Although the amount of territory a given creature needs to survive may not be relevant for most GMs, the following guidelines can be used for those that wish to do so. The guidelines are a blend of real-world predator territories sizes (wolves, tigers, jaguars) as well as the amount of grazing space needed for herbivores (horses, goats, cattle). The whole has been simplified to fit into a game system and is not a fully accurate representation – but it is close enough for a certain amount of verisimilitude.


Herbivores: The number of herbivores that can subsist in a given territory size is based on several factors – the most important one being the size (weight) of the herbivore. Other factors also come into play, such as room to roam, rivers, barren patches, inefficient grazing, etc. From a gaming perspective this can be reduced to X kilograms worth of herbivores within each square kilometer of area. The total weight of the herbivores in a given area includes everything from large herbivores (such as elephants) down to smaller herbivores (such as rabbits).  As such the following guideline can be used.

  •  -- Average yield (25,000 kg per km2): This would include grasslands for bison to graze with jackrabbits, gophers and birds in abundance.
  • -- Good yield (50,000 kg per km2): This would include temperate forests with deer, boar, rabbits, salmon in the rivers and many birds in the trees. 
  • -- Abundant yield (75,000 kg per km2): This would include lush jungles and tropical forests.

Example: a herd of 30 horses, each weighing on average 500 kg (15,000 kg total), would need 0.6 km2 (150 acres) of land to live in an Average yield location. Assuming the smaller herbivores don’t add much weight to the total. 

Carnivores & Omnivores: A carnivore’s hunting area is based on the amount of prey it can hunt. For gaming purposes, treat omnivores (i.e., bears) as carnivores. As a general guideline assume that 1 kg worth of predator needs 2000 kg worth of prey.

Example: In a 10 km2 area of Average yield, you would have 250,000 kg worth of herbivores. This would be enough to feed 125 kg worth of predators.

Although multiple predators can share the same territory, there is competition within the same size category (i.e., excluding creatures within a pack which share a territory) but rarely between size categories; larger predators hunt the larger prey, whereas the smaller predators hunt the smaller prey. As such, assume that within a given area, the total weight of the predators is divided roughly into 1/3 weight by size category (small, medium, large) roaming within it.

Example: In a 50 km2 area of Abundant yield, you would have 1875 kg worth of predators: a liger (600 kg, large creature), a pack of 8 hyenas (55 kg each, medium sized), four cheetahs (50 kg each, medium sized), and around 100 Small sized predators (jackals, eagles, caracal, vultures, snakes, etc). In addition to the list above, there are numerous Little, Tiny and Minute (swarm) sized creatures. Although each of the predators listed would live within the 50 km2 of area, the area would be split into smaller domains for each successive smaller sized creature (i.e., the hyenas and cheetahs would not share a territory).

Magical beasts and Monsters: These creature’s biology can be different than that of “Earthly” animals. As such, the amount of food they require and territory needed to survive is purely speculative. The GM to adjudicate based on their own preferences and guided by the previous suggestions. 


This article comes from Canonfire!

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