 Other studies in Europe and North America indicate only limited success in the consumption of wild boar, deer and other ungulates, however it could not be determined if this was predation or scavenging on carcasses.Studies have observed feral dogs conducting brief, uncoordinated chases of small game with constant barking - a technique without success.In 2004, a study reviewed 5 other studies of feral dogs published between 1975 and 1995 and concluded that their pack structure is very loose and rarely involves any cooperative behavior, either in raising young or in obtaining food.