A newborn cub — now thought to be dead — sits by the paws of its mother at Nuremberg Zoo. Credit: NUREMBERG ZOO

Polar bear cubs born at Nuremberg Zoo in southern Germany will not be hand-reared, but will instead be left to die if their mothers reject them. Zoo officials said last week that they wanted ?at all costs? to avoid the media and public attention surrounding Knut, the 13-month-old polar bear cub that was originally hand-reared at Berlin Zoo.

Nuremberg Zoo's two bears, Vera and Wilma, each gave birth to an estimated two cubs a few weeks ago in a cave in their enclosure. The cubs can be heard crying loudly, but Wilma has been observed occasionally strolling out of the cave, sparking fears that she might be about to reject her cubs, like Knut's mother Tosca. It is believed that Vera's two cubs have already died and been eaten by their mother, although zookeepers have not been in the cave to check, for fear of disturbing the inexperienced mothers.

Breeding polar bears in captivity is extremely difficult. The zoo hopes that, if their babies were to die this time, having had this experience, the young females will be more likely to bring up healthy cubs the next time they give birth.