Mantled Howler Monkeys

Notice anything strange in this picture?  ....if you guessed my worst nightmare you're right.  I often bore my friends with all of the things I'd rather do, or eat, or have than a bot fly larvae living inside of me.  I even refuse to show my students video of bot fly extractions during my weekly Strange Behavior videos.  This poor fella kept scratching what looked like at least three of them.  That's all I'm saying about the bot fly.

This is a Mantled Howler Monkey, one of 15 species of this type (genus) of New World monkey .  From Mexico to Ecuador there are three subspecies of the Mantled Howlers. I think the ones we see here are the Golden-mantled Howler monkeys.  They are differentiated by skull shape with their northern cousins and fur color with their southern cousins.  They feed mainly on young leaves so don't get a lot of calories and try to conserve energy by resting a lot.  These monkeys also have a low-pitched howl or grunt to help them locate other troops or to communicate disturbances, another energy-saving adaptation which prevents them from having to move around too much.

Howlers eat leaves, fruit, and flowers but manage to avoid dangerous plant toxins like alkaloids and cardiac glycosides by focusing on sampling small quantities of younger leaves with lower concentrations and by learning to recognize and find the safer trees.  They are thought to create mental libraries and maps to help them distinguish between these closely related species.   Kenneth Glander found that howlers will avoid the leaves of 146 Madero negro trees while eating from the only three without the toxins.  He hypothesized that the evolution of higher intelligence in primates may have been sparked by this need for this complex discrimination of food sources.

They seemed to be pretty indifferent to our presence but apparently are really good at using humans for defecation target practice.  : /