Wider World for Sun Bear Cubs

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Things continue to go well in the den for sun bear Marcella and her twin cubs (see previous blog, Sun Bears: Growing Up Great). The youngsters are now nearly 2.5 months old and have grown by literal leaps and bounds. Their eyes have long since fully opened, and the cubs are able to take in the world around them. Now that they are becoming more mobile, they are able to interact with that world as well.

Two weeks ago I recorded the cubs crawling about on the den floor. They dragged their bellies as they pushed with their feet, not always moving about in a straight line. Often the early attempts at crawling resulted in a cub flipping over onto its back unceremoniously, squawking and squirming as it tried to right itself. Last week, I saw some of their first clumsy steps with their bellies held up off the floor. They stumbled and fumbled about, tripping over each other and the nesting material in the den. This week – look out! They are moving quickly around the den and clearing a full adult body length of distance in mere seconds.

Along with this burgeoning motor development comes rapid cognitive leaps. Last week I saw the first signs of social play from the cubs. One would paw or bite at its mother or sibling, and at times Marcella would respond with very gentle nipping or nudging. Today I witnessed the cubs playing with each other for a few moments before getting distracted by other things in their environment. But what could be more enticing than a playmate?

The mouth of the den, that’s what! Beyond the entrance to the dark, warm cave they have always called home lay the big wide world, and the bright lights and noises coming from the mouth of the den are calling to the cubs. Today, they kept wandering to the den opening, standing at the threshold, peering about the adjoining bedroom. Marcella, for her part, isn’t ready for her babies to be so grown up: she repeatedly pulled them back from the den entrance and into the dark recesses of their shelter. As soon as she let go, they would race back to the mouth and stare out. Again and again she pulled them back as they howled and squawked their protests. Finally, she enticed them with a nursing session and they fell asleep against her warm body.

You dodged the bullet this time, Marcella, but the cubs won’t let you get away with it for long. Soon these babies will be charging about the bedrooms and stealing your food. With any luck they will enjoying playing with each other more than tormenting you with their firm bites to your toes and ears.

Suzanne Hall is a senior research techinican at the San Diego Zoo.