Going back to August for this series on a day in Waterton Canyon when I was observing a Black Bear sow and her two cubs. The trio had worked their way down to the South Platte River and while the female and one of the cubs crossed the river without a problem, one of the little ones was hesitant to cross.
Not realizing this, mom and the one cub continued on their journey further up the river. The scared one did finally cross the river but by the time it did, mom was nowhere in sight due to the thick growth along the river banks. Clearly scared, the cub began calling for its mom over and over.
The sow heard the cries and took off running, backtracking to find her offspring. They did eventually find each other and Mom led the lost one along, undoubtedly paying a bit more attention to where her little ones were at.