Howler Sunset

In birds, the hyoid bone is a flexible Y-fork anchoring the tongue. In humans, it's a forgettable little scrap at the back of the tongue. In howler monkeys, it's really something else. 

 I had an excellent conversation with this male howler near the dining room at La Ensenada, an eco-dude ranch in Guanacaste, Costa Rica's cowboy country up north. We ooked and grunted and talked.  I don't know what I was saying, but it sure was a thrill to make contact with him. I started the conversation with an ook or two, imitating him, and he plopped down right there and had a good chat with me. Ook. Ook. Owwww. Owwwwwwwwwww ook ook ook. OOK!

As I wrote in the previous post, howlers use their voices to mark and hold territory--yelling takes a lot less energy than, say, chasing and fighting off other monkey troops. Which is good if you eat nothing but leaves and a little fruit. Pardon the blur. I got excited when he opened up that big ol' chamber at close range.

Male howlers are charged with the job of holding feeding territory for their troop; females busy themselves raising young. So males have some special equipment, other than the swag you can see. The hyoid bone is enlarged into a bony bulla, or sac, which makes a resonating chamber for his voice. It's as if he has a megaphone right in his throat. He's got one of the loudest voices in the animal kingdom. And as far as we know, this is the only mammal with a hyoid bulla made of bone, rather than esophageal tissue. Lots of monkeys and apes have large fleshy elastic laryngeal pouches (think gibbons and orangs) but only howlers have bony bullae.

1.These are the skulls of red howler monkeys (Alouatta seniculus). Female is on the left, and the male on the right.  

2. is the rear view of the skulls. A female howler has a nice bulla, too, but the male's is almost three times its size. So it's the males who can really roar.

Check out the incredibly deep and massive jaw bone on both sexes (3). That tells me I do not want to get bitten by a howler monkey. With masseter muscle inserts like that, they must have some tremendous crushing power! Let's face it. Nobody wants to get bitten by a monkey. So I try to be polite when talking with them, and not escalate things with empty rhetoric.

I've borrowed these photos from the University of Edinburgh Natural History Collections. You can read more at their page.  There's also a highly detailed discussion (condensed to a couple of sentences here) by Darren Naish at the excellent science blog, Tetrapod Zoology. 

I thank both sources for publishing such cool stuff online, where pikers like me can share it. They're welcome to my photos of the live creatures!

Are you going to grow up to have a bony bulla in your throat? What does that feel like, little monklet?

How is it to trip so lightly over a palm frond? To have a tail that reaches out like a fifth hand to grab whatever's nearest? To know you're not going to fall?

It feels good to be a howler, hanging with my troop in the dry forest, waiting for sunset. We're going to sleep down the slope tonight, where the bougainvilleas are blooming. I'll wrap my tail around a limb and drift off, blinking at the moon.

I was blessed--blessed!! to have a lovely group of travelers on Costa Rica 2016. And my dear friend Ann Hoffert came along which pretty much made my year. We had a lot of catching up to do, many stories to tell. I've known Ann for 13 years; she hand-crafted the Potholes and Prairie festival that Bill and I worked for 11 years. With Ann, we crafted uniquely North Dakotan experiences for festival goers like Pipits and Pie and the Prairie Ramble. Bill and I gave talks, played live music, and joyfully soaked up and shared the richness of the Potholes region, where all the ducks are born.

Ann and Ernie have watched our babies grow up. This is my favorite photo of her. Yep, that's Liam, when he was under 4' tall. Two platinum blondes in the June prairie sunshine.

It was a beautiful thing, an impossibly rich mix of social events, bird appreciation, prairie rambling,  sumptuous gardens, home-made food, and music. I hold those memories close in my heart.

After all that, to get to travel with Ann, and share some of the things I love about the Neotropics,  which is  yin to North Dakota's yang, was a great and precious gift. 

On this trip, Ann and I got to tell each other some of the untold stories of our abundant lives. Something best done as the full moon rises over the Golfo de Nicoya. Hard to believe it was already a month ago: I look and the moon is full again, Jupiter and his moons cuddling up next to her at sundown.

In this little clip, Ann and I stand beneath a tree where a howler troup is bivouacking for the night. You'll hear their song, that storm in the treetops. Come--stand there with us. Listen to them sing the moon up at La Ensenada.