Behaviour of European wild boar (Sus scrofa) in connection with farrowing in an enclosure

Abstract

Wild boars (Sus scrofa) are often kept in enclosures for hunting or meat production purposes in Sweden. The sows are known to undergo behavioural changes in connection with farrowing and their natural behaviours may be compromised by the limited area of the enclosure. The aim of this study was to quantitatively describe wild boar sows' behaviour when farrowing in an enclosure. A field study was carried out in a hunting enclosure, where 1200 hours of behavioural recordings and data from 22 farrowings were collected. According to the results, the farrowing period could be divided into 3 phases: pre-farrowing, isolation and sociality phases (in relation to farrowing: day -14 to -1, day 1 to 8, day 9 to 14 respectively). The activity decreased during isolation and increased in the sociality phase (p<0.05), whereas the average distance to other individuals increased during isolation and decreased in the sociality phase (p<0.05). Nose contacts with other individuals increased in the isolation phase (p<0.05) and habitat use changed towards more protective habitats after farrowing. 68 % of the nests were situated in edges between 2 habitats of different vegetation density and 73% had some kind of protection to the north. We conclude that farrowing induces a number of changes in the activity, social behaviour and habitat preference in captive European wild boars. This may need attention when enclosures for this species are designed.

Extensive infanticide in enclosed European wild boars (Sus scrofa)

“…Although the sows spent a large portion of their active time at the feeding area (Andersson et al, 2011), we did not find any effect of distance between farrowing nest and feeding areas on the infanticide, which again may indicate some limitations of the studied enclosure.…”

“…Our data suggest that infanticide is wide-spread among captive wild boars, and also allow some hypotheses to be formulated regarding the functional background. Furthermore, we suggest that infanticide may have been a significant aspect of the evolution of the maternal behaviour of the species (for example isolation and nest site choice; Andersson et al, 2011) and hence also of the domestic pig (Gundlach, 1968;Jensen, 1988). Importantly, it may constitute a major welfare problem for wild boars in captivity.…”

“…Since natural home ranges can be 1000 ha and more (Dardaillon, 1986), the restricted area in many of these enclosures could possibly limit the ability of sows to isolate during farrowing which may influence piglet mortality in connection with farrowing as shown in domestic pigs by Jensen (1988). Preliminary observations during studies of the maternal behaviour in captive wild boars (Andersson et al, 2011) showed a frequent occurrence of non-maternal infanticide. Based on this, the present paper reports a closer investigation on this behaviour.…”

“…dense forests and in the edge between open and dense areas (Andersson et al, 2011;Dardaillon, 1986;Janeau and Spitz, 1984). The sow and her piglets stay in the nest for up to two weeks during an isolation phase considered necessary to establish bonds between the sow and her piglets and decrease risk of predation (Fernández-Llario, 2004;Jensen et al, 1987).…”

Sow communication with piglets while being active is a good predictor of maternal skills, piglet survival and litter quality in three different breeds of domestic pigs (Sus scrofa domesticus)

“…Although sows do not establish bonds to their young by licking their offspring such as ruminants [ 15 – 17 ], the attachment is rather established by isolating from the conspecifics in a nest, and through communication by olfactory (sniffing), vocal (grunting) and tactile (nudging) cues [ 18 , 19 ]. Maternal communication strengthens offspring recognition and attention [ 20 ], and is crucial for keeping the piglets in close proximity and to protect them from danger [ 10 , 21 , 22 ].…”