Extensive infanticide in enclosed European wild boars (Sus scrofa)

Abstract

Infanticidal behaviour, behaviour with wide welfare implications, is wide-spread among animals of various taxonomic groups, but has not previously been systematically studied in European wild boars, which are commonly kept in enclosures in Sweden and Finland for meat and recreation hunting. We studied the behaviour of wild boars in one enclosure during three reproductive seasons. Non-maternal infanticide was documented in 14 out of 22 litters, causing the deaths of all piglets in all but one affected litters. Infanticide was typically performed during or shortly after parturition by a sow which was older (P<0.05) and tended to be larger (P=0.068) than the victimised sow, and was not affected by whether or not the involved females were mother-daughter pairs. A questionnaire sent to 112 owners of a total of 116 enclosures in Sweden and Finland resulted in 62 valid responses. Non-maternal infanticide was reported to be the most common cause of piglet pre-weaning mortality, which in total (including all causes) was estimated to be 29.1 %.The occurrence of infanticide was unrelated to size of enclosure (less or more than 20 ha) and to variations in supplementary feeding routines (less or more than once a week) (P>0.05), which may suggest that the behaviour could be a part of the normal behavioural repertoire in European wild boars. The observed levels of infanticide constitute a major welfare problem in captive wild boars.3

Post‐mortem examination of the reproductive organs of female wild boars (Sus scrofa) in Sweden

“…In addition, infanticide (killing of an infant by a conspecific) might be another reason behind these observations. In wild boars kept in enclosure, a high degree of non-maternal infanticide has been reported and hence a common cause of newborn piglet mortality (Andersson, Valros, Rombin, & Jensen, 2011). Yet, the extent of infanticides in freeranging wild boars is not known.…”

Predation by Red Foxes (Vulpes vulpes) at an Outdoor Piggery

“…We also observed ravens on camera harassing piglets and grabbing them by the tail. Ravens or foxes were implicated in 18% (75 of 412) of piglet deaths in European wild boars kept in external enclosures [17]. Ravens are known to scavenge dead lambs ( Ovis aries ) and placentas, but have also been observed predating a small number of healthy, as well as sick, and dying lambs [18].…”

A Case of Adult Cannibalism in the Gray Mouse Lemur,Microcebus murinus

“…The cases in captivity are quite rare, with a few events seen yearly in a large study population of M. murinus. Whereas captive cannibalism (including the killing of conspecifics) has sometimes been connected to crowding, high-stress conditions, or insufficient diet [Andersson et al, 2011;Fox, 1975;Marlar et al, 2000;Tartabini, 1991], none of these factors are likely causes of the cases observed in the mouse lemur colony in question: lethal aggression toward cage-mates has not been reported and the lemurs are normally fed a balanced diet ad libitum.…”

“…In the vast majority of cases, the victims of intraspecific predation are subadults, but killing and eating of adults (although of usually smaller body size than the attacker) has also been described for instance in some species of insects, fish, amphibians, birds, and mammalian carnivores [Amstrup et al, 2006;Andersen, 2004;Polis, 1981;Rogers, 1983]. Many of the documented cases of cannibalism are from captivity or areas disturbed by humans, where the conditions (such as stress, crowding, or insufficient nutrition) may increase the frequency of the phenomenon and where it is easier to observe [Andersson et al, 2011;Angst and Thommen, 1977;Bartlett et al, 1993;Dellatore et al, 2009;Fox, 1975;Tartabini, 1991].…”