Langurs: Bright-Orange Babies

You may think most newborn monkeys would blend in with their mothers. However, with silver-leaf langurs it is quite the opposite: their babies are a beautiful bright orange! There are several theories as to why this is; unfortunately, it is unknown which theory is accurate.

Theory 1: It makes it easy for the mothers to find them, as young langurs like to explore. They can sometimes travel a little too far away from their mothers. Being bright orange, their mothers can easily spot and retrieve them.

Theory 2: The orange actually helps the babies blend into their surroundings. It seems hard to believe that bright orange could be used as camouflage, unless maybe the orange would make them appear as a bright-colored flower on a tree. Most predators are color blind and cannot tell the difference between orange and green.

Theory 3: The coloration lets the other troop members know a new baby has arrived and they need to all share in the caring for the infant. A baby langur can wear a mother out, so having a troop full of babysitters allows Mom to rest. The babysitters can also relieve the mother so she can get something to eat.

The theories I have mentioned are a lot more detailed than what you have just read. It is a matter of opinion as to which theory you believe to be the most likely. Silver-leaf langur babies turn from orange to silver at about three months of age, slowly changing color starting as early as just under a month old.

We now have two orange additions to our troop: one born on February 26, 2009, to Tevy and Aden, and the other on April 13, 2009, to Adamena and Aden. Tevy’s baby is already changing color around her face. So to see two bright orange babies, you will have to hurry to the Zoo’s Sun Bear Forest habitat, because Adamena’s baby is following close behind. They will both be silver before we know it!

Beth McDonald is a senior keeper at the San Diego Zoo.

Read Beth’s previous blog, Silver-leaf Langurs.

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