The following observations has been made by researchers studying captive animals within Farm systems and in Zoos:
*A Predator generally make the stereotypies before feeding and has a tendency to prefer Locomotory types, e.g. Pacing.
* A Herbivore generally engage in stereotypies after feeding, and have a tendency to prefer oral types of this behaviour.
Domesticated animals have to a far extent maintained their ancestor's behavioural patterns and this can be seen if placed in natural, or semi-natural surroundings.
Wild pigs natural way of feeding is to root around in the ground with its snout. If the pig finds a suitable food item it can pay to root around in the vicinity since the preferred food is typically lumped distributed. After a thorough search the pig will wander to a new nearby locality and repeat the procedure. Wild pigs can spend up to 50% of their activity foraging.
Wild Mink on contrary can walk long stretched in the search for prey - in excess of 2 km during a hunting session. Once the prey is taken down the mink will typically eat, rest, engage in other activities and then start hunting again when hungry. It is not worth the effort to look for another prey immediately after the kill since it is unlikely that such will be around.
These observations has encouraged the following hypothesis to explain the difference in timing of stereotypies between pigs and minks:
Hypothesis: "Different foraging strategy is adaptive; an expression of past selection (now genetically founded) and is reflected in the present timing of stereotypies during captivity."
This is at first glance an appealing hypothesis that seems to be able to explain the observed differences in stereotypies between these two species. Naturally, it has spawned a counter-hypothesis that claims to be able to explain this difference otherwise. However, first it will be necessary to touch upon another subject - namely motivational systems.