How many accounts of american black bears killing boars are available?
Predation. In general, predation is a minor mortality factor, particularly in the removal of adult hogs. Alligator (Alligator mississippiensis). Black bears, and mountain lions (Puma [Fellis] concolor) have all been reported as predators of an occasional adult feral bog (Hamilton 1941; Hanson and Karstad 1959, Wood and Brenneman 1977). Bobcats and coyotes (Canus latrans) have been reported as potentially significant predators in some cases on feral hogs (Hanson and Karstad 1959; Wood and Brenneman 1977; Barrett 1978), but much of this may be consumption of carrion rather than predation.
Sweeney et. al, Feral Hogs Sus scrofa, (2003) in Wild mammals of North America: biology, management, and conservation.
Survival of the Fittest. Feral pigs are fierce fighters, as their tusks, tough hide and shoulder capes attest. Although biologists in other parts of the United States report that mountain lions, bobcats and black bears occasionally prey on young feral pigs, it is highly unlikely that Wisconsin's native predators would have a very big impact on an exotic animal with a high reproductive potential.
There are also stable isotope data of Tennessee black bear which show wild boar signatures.
This question/subject is interesting, there are a several states where these two animals coexist; perhaps later in the year (time permitting) I can dig up more relating (my guess is such data is limited) literature.
. Black Bear – The black bear is known to prey on feral hogs of all ages; however, the impact of predation by this bear on feral hog populations is not known. Some researchers have speculated that black bears probably kill few if any feral hogs, especially given that an adult hog would represent a formidable adversary for a black bear. In fact, in the 1920s a feral boar in the Okefenokee Swamp was reported to have killed a black bear in a fight between the two animals. Similar accounts of feral boars killing bears during fights in the Ozark Mountains of Arkansas were reported in the 1880s. Being opportunistic, black bears have been reported to raid nylon net live traps used for feral hog control at high elevations in the to obtain any trapped hogs contained within these devices.
Rakov, N.V. (1970) Causes of mortality of the wild boar and its interrelation with predators in the Amur territory. Zoologicheskii Zhurnal
"In years of crop failure, brown bears are well adapted to the hunt wild boars.Bears do kill boar of all ages and classes.(Including adult and prime male wild boar)"
To be continued...
Some remarks and corrections :
Outer Manchuria (formerly known as Priamurye Приаму́рье in Russia), is the territory ceded by China to Russia in the Treaty of Aigun in 1858 and the Treaty of Peking in 1860. ( See Amur Annexation ). The northern part of the area was also in dispute between 1643 and 1689 (see Russian–Manchu border conflicts). The area comprises the present-day Russian areas of Primorsky Krai, southern Khabarovsk Krai, the Jewish Autonomous Oblast and Amur Oblast. Another interpretation also adds the island of Sakhalin
Outer Manchuria is in light red on this map. Some also consider the island of Sakhalin to be part of Outer Manchuria