Editing v0.34:Extinction

{{quality|Exceptional|23:53, 11 July 2013 (UTC)}}
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'''Extinction''' means one of two things in Dwarf Fortress.

== Sapient extinction ==
The first meaning of the word pertains to [[world generation]]: fighting between different sapient species may be so intense that a particular sapient species is wiped out entirely, going extinct in the process. Extinction events are exceedingly rare in larger worlds, but surprisingly common in pocket ones, where inter-species competition is at its fiercest.  Sapient species that go extinct will obviously no longer [[caravan|trade]] with your dwarves, nor threaten them with [[ambush]]es or [[siege]]s. You can somehow still start a fortress mode game in a map vacated of any dwarves, but you will not receive any [[migrant]]s beyond the first two (hard-coded) waves.

On a smaller scale, landmass-specific extinctions can also occur, and although they are not nearly so dramatic as ''mass'' extinctions, and are in fact quite common, they can still affect your game. This usually happens on separated landmasses and [[island]]s inhabited by more than one sapient species below a certain area. Since [[civilization]]s cannot yet cross 
bodies of water that don't freeze over, such extinctions will affect your gameplay should you chose to settle on such a landmass. The effect of settling someplace inaccessible to dwarves is the same as starting a fortress when they are extinct: only two, hard-coded, migrant waves.

[[Calendar#Ages|Calendar ages]] are greatly influenced by the relative lack or abundance of sapient life in your world, and so provide an at-a-glance view of the state of civilization on your lonely planet (if you know what they stand for, of course). Two calendar ages are more directly associated with extinction: the ''Age of Death'' and the ''Age of Emptiness'', in which all civilizations have been wiped out. Actually getting these to happen can be difficult - thel atter can only be achieved by killing every civilized creature in a world in Adventurer mode, then committing suicide, then [[embark]]ing on the same map in fortress mode, then committing suicide with all of ''those'' dwarves. Once all of this is done, you will finally get an [[announcement]] telling you of the passing of the age. [http://www.bay12forums.com/smf/index.php?topic=46033.0 It's been done before].

It should be noted that due to a bug, carnivorous sapient civilizations (those with the <tt>[CARNIVORE]</tt> or <tt>[BONECARN]</tt> [[creature token|token]] in their [[raw file]]s) will go extinct near immediately. This is both a blessing and a curse for [[modding|modders]]: a blessing because it allows the forceful extinction of modded civilizations, a curve because it prevents you from modding in and playing a purely carnivorous race.

== Site extinction ==
The second, more nuanced form of extinction has to do with the wildlife in your [[surroundings]]. Every [[site]] can have a certain number of [[creature]]s appear in it; ''which'' creatures depends on the site's [[biome]]s, ''how often'' depends on the <tt>[FREQUENCY]</tt> [[creature token]] in their [[raw file]]s,  ''how many'' depends on the number of biomes you abridge and on the creature's <tt>[CLUSTER_NUMBER:#]</tt>, and ''how many before none will ever appear in the wild again'' depends on a somewhat randomized token in specific creatures' definitions, the <tt>[POPULATION_NUMBER:#:#]</tt> tag. That is, if as many (wild, non-[[mount|siege mount]]) creatures die or are [[cage trap|captured]] and kept upon visiting your fortress as <tt>[POPULATION_NUMBER]</tt> is set to, they will be considered locally extinct, and will have their range clipped from your fortress surroundings.

This cap will not limit any [[breeding]] you do once you have captured the creature, and will obviously not affect any creatures visiting your [[site]] that are allowed to leave. It ''will'' affect the maximum number of non-breeding creatures that you can have at your fortress, however, and will not allow the appearance of creatures in clusters larger than are allowed by the cap. Note that the cap is biome-specific: even though [[sea serpent]]s are capped at one serpent per site, it is possible to get multiples, and even [http://www.bay12forums.com/smf/index.php?topic=75780.0 start a breeding program], if your fortress abridges multiple valid biomes - note that such a breeding program wouldn't work in the current version, as sea serpents are now egg-laying and aquatic egg-layers don't breed due to a bug)

Every time a species becomes locally extinct it is (obviously) taken out of the wildlife visitation rotation. Rendering a policy of mass genocide on the countryside can thus eventually force the appearance of a sought-after species of wildlife, if you push hard enough. However, for the most part the number of creatures that can appear in the biome is so large, and the population caps are set so high, that it doesn't seriously affect gameplay. Aggressively hunting the local wildlife ''will'' eventually restrict its variety, however, and eventually you can prevent ''any'' wildlife from spawning at all from spawning on your map.

The cap does have important ramifications for a few specific species, however. Wildlife appearances on [[glacier]]s are heavily restricted, for instance, so the particularly aggressive [[yeti]], which only appears five to ten times, is often made extinct very quickly. Because of a bug, aquatic vermin do not restock when fished, resulting in guaranteed eventual extinction.{{bug|2780}} [http://www.bay12forums.com/smf/index.php?topic=84112.msg2252463#msg2252463 A certain nuance] of the tag's implementation allows maintained hunting of certain species, with some micromanagement: if a cluster (or pack) of animals appears on the map, as long as at least one animal in that cluster is allowed to leave, the species will not have been considered depleted. This obviously does not work on solitary creatures.