It's easy to find examples of humans introducing non-native species to solve some problem (e.g. for food, to control the population of a pest), but later regretting it as the introduced species upsets the ecosystem.

Are there any examples of this going as expected?

I guess, since I'm really interested in how well humans can predict this sort of thing, what I'm looking for is examples of a situation where there were no unintended consequences. (Rather than beneficial, but unintended, consequences).

  • $\begingroup$ Would species that were introduced by humans with out a specific purpose (except Oh, that one looks nice. Let's take it with us.) count as an answer? Or would you limit your question to problem solving (food, pest control) as stated in your first sentence? $\endgroup$
    – Arsak
    Commented Aug 23, 2018 at 9:49
  • $\begingroup$ Probably most major food crops (other than corn/maize) in the Americas. Cows seem to have worked out fairly well (I mean open-range or pastured cattle, not the problems associated with industrial feedlots). Horses are a bit more problematic, but I'd argue that most of the problems actually stem from the decimation of potential predators. $\endgroup$
    – jamesqf
    Commented Aug 23, 2018 at 18:10
  • $\begingroup$ Almost all domestic species would count, the intention was to replace the native ecosystem and that is what happened. The problem with "unintentional" is you have who's intentions. The people who introduced wild boar to the US didn't care what damage they caused, they wanted to be able to hunt boar. $\endgroup$
    – John
    Commented Aug 23, 2018 at 22:59

1 Answer 1


The best examples are for when non-native pest species arrive, and then a search for their natural enemies in their native countries is undertaken to bring them back and control the invaders. This is called "biocontrol", and there are many examples of it going well, under carefully controlled conditions. https://biocontrol.entomology.cornell.edu/success.php However, you are right to note that it is very difficult to predict.

  • $\begingroup$ Fascinating to hear about this working well all the way back in 1889! $\endgroup$
    – Eli Rose
    Commented Aug 24, 2018 at 8:42

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