why do bears eat their cubs cruelly sometimes?  

hi,lilaclady! i've watched a record about polarbear done by BBC. it showed that sometimes the male bear would track down the female bear with some babies in the winter(i'm not sure whether its winter or not for bears often hibernate in winter). if the babies got sick and are not able to keep up with its mom, they will be eaten by the male bear behind. but i saw another film about blackbears. there is nothing wrong with the baby bear, but it was eaten by several male bears, more shocking that eaters includes his father...

well, thank u for professional answer ,monkeyrose!