Man of the Forest – Flanged or Unflanged

An Orangutan in the Fragile Forest (October 19, 2007) Orangutan means “man of the forest” in the Malay language.

In my reading about orangutans today I came across something I either never heard before or I heard but never processed.

I have always loved orangutans but could not decide if I liked the looks of male orangutans because of their “ugly” faces.  After checking out these fantastic pictures I made up my mind that they are adorable in their own way.  In fact, I can see why perhaps some female orangutan would be attracted to them.  (Some have those bedroom eyes.) 

Back to what I learned today.

Flanged and unflanged – male orangutans that is.  I thought all male orangutans had those cheek pads (flanges) but only the flanged orangutans have them.

The flanged adult males after about 15 years old may start showing what is called secondary sexual characteristics (physical characteristics that differentiate male and females that are not directly related to reproduction and usually appear at sexual maturity).  In male orangutans this includes having a throat pouch, long hair and the ability to make long, loud calls.  In the wild — of which we know is disappearing quickly — flanged males have established territories they protect.

Flanged males establish their territories and then advertise to the ladies to come to them.  They do this with their physical characteristics that make them attractive to a female and with what is called “long calls” that carry a long way in the forests.  Their throat sac lets them advertise with a long, loud call to the ladies while at the same time telling other male orangutans to keep their distance.  Then the ladies come calling.  Obviously, they want babies by this beautiful, large and dominant male so their babies have all of the advantages of becoming like him.  Also, they like the protection he provides them against the advances of unflanged males.

Orangutan Male   What female orangutan could resist this guys looks?  I told you they have bedroom eyes.

Unflanged males do not have established territories.  They are able to reproduce but instead of letting the ladies know they around and available they go to the ladies.  Unfortunately for them they usually have to force the ladies since ladies are much more interested in the “pretty guy” who has his own territory.

But there is hope for those unflanged male orangutans.  It appears they can become flanged within a few months of establishing and defending their own territory.  Then they too can sit back and make those long calls to lure the ladies in.
Age Before Beauty, Male Orangutan

Obviously, there are flanged male orangutans in zoos and I have no idea how that works.  Unless, their territory is the habitat we force them to live in — hopefully, it is more than a cage of bars.

Kind Regards,

April & Kesi

Check out this cool site:

This is a great video:

These have fantastic pictures of male orangutans:


2 Responses

  1. […] Only flanged (see my blog on Man of the Forest – Flanged or Unflanged) perform the long-call.  This may be heard over several miles sometimes and lasts for one to two […]

  2. I like the valuable information you provide in your articles.
    I will bookmark your weblog and check again here regularly.
    I’m quite sure I will learn many new stuff right here! Good luck for the next!

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