Foraging behaviour in domestic pigs (Sus scrofa): remembering and prioritizing food sites of different value

Abstract

This experiment investigated whether domestic pigs can remember the locations of food sites of different relative value, and how a restricted retrieval choice affects their foraging behaviour. Nine juvenile female pigs were trained to relocate two food sites out of a possible eight in a spatial memory task. The two baited sites contained different amounts of food and an obstacle was added to the smaller amount to increase handling time. On each trial, a pig searched for the two baited sites (search visit). Once it had found and eaten the bait, it returned for a second (relocation) visit, in which the two same sites were baited. Baited sites were changed between trials. All subjects learnt the task. When allowed to retrieve both baits, the subjects showed no preference for retrieving a particular one first (experiment 1). When they were allowed to retrieve only one bait, a significant overall preference for retrieving the larger amount emerged across subjects (experiment 2). To test whether this preference reflected an avoidance of the obstacle with the smaller bait, 15 choice-restricted control trials were conducted. In control trials obstacles were present with both baits. Pigs continued to retrieve the larger bait, indicating they had discriminated between the two food sites on the basis of quantity or profitability and adjusted their behaviour accordingly when the relocation choice was restricted. This suggests for the first time that domestic pigs have the ability to discriminate between food sites of different relative value and to remember their respective locations.

Spatial learning in pigs: effects of environmental enrichment and individual characteristics on behaviour and performance

“…Wild boars and feral pigs forage in large home ranges in which they can exploit an enormous variety of food sources (Gundlach 1986;Schley and Roper 2003). Under such conditions, individuals would beneWt from good spatial memory skills and a high Xexibility in behaviour (Held et al 2005). Indeed, studies on cognitive abilities in domestic pigs have demonstrated good spatial memory skills (e.g.…”

Spontaneous Object Recognition in Animals: A Test of Episodic Memory

“…Similar to rats, pigs naturally tend to explore novel aspects of their environment (Wood-Gush & Vestergaard, 1991). Pigs also have good spatial memory abilities and they are able to learn tasks quickly (e.g., Croney, 1999;Held et al, 2002;Held et al, 2005;Puppe et al, 2007; reviewed in Gieling et al, 2011). As well, wild and feral pigs have a life history in which memory is valuable; particularly because they live socially, have large foraging ranges, and have foraging habits/movement patterns/nesting sites that change with season and food availability (Graves, 1984).…”

Development of pigs raised in a group housing system for lactating sows and their litters

“…For both I and NI pigs, revisits to buckets were assessed as a measure of impaired working memory (van der Staay et al, 2012). Pairs of I/NI pigs proceeded to phase 2 when the I pig reached the criterion of visiting a maximum of 2 unbaited buckets during the relocation visits in at least 6 out of 8 consecutive trials (Held et al, 2005;Held et al, 2010).…”

“…Alternatively, non-informed MS pigs may have adopted a scrounger role -where the submissive pig is exploitedonly if more profitable bait could be obtained. The social organisation of wild boar is characterised by cooperation, rather than competition (Focardi et al, 2015), and domestic pigs can alter their foraging behaviour in response to the quantity of bait that can be retrieved (Held et al, 2005).…”

“…When food is distributed in patches, as is the case for wild boar (Meynhardt, 1980), the most dominant animals within a group can benefit from exploiting submissive producers, whereas the latter may best forage alone or find tactics to avoid exploitation . Previous studies have shown that domestic pigs can flexibly adapt their behaviour to optimise their foraging strategy, depending on the type of food reward and the behaviour of other pigs (Held et al, , 2002Held et al, 2005;Held et al, 2010). In the IFT, pigs are directed to adopt a certain forager role, by training pairs consisting of a submissive 'informed' pig, which has knowledge about the location of a food reward in an arena with hidden buckets, and a dominant 'non-informed' pig, which is unaware of the reward's location.…”