There's locomotion, for one thing. Chiquito's position in the photo (referred to as a "tail-hindlimb assisted posture" in academic circles) is impossible if you don't have a tail and/or opposable thumbs on your feet. But not only are Paul and I challenged in the trees...we have trouble maintaining our own natural upright bipedal balance when we're walking around the jungle floor. [See the March 13th diary entry "Telling Monkey Tales."] Fortunately, Chiquito seems to come by his spider monkey moves instinctively.
Then there's communication. We can mimic Lolita's "eh eh eh eh eh" giggling sound, and the contented little exhaling noises she makes when she's snuggling (which are even more endearing when they're accompanied by her breath in my ear). But the quintessential spider monkey "whinny" vocalization eludes me. I know this because I attempted it once, and the dumfounded expression on Chiquito's face was...mortifying.
A happy spider monkey makes a noise that's called a whinny, presumably because the sound is reminiscent of a (squeaky) horse neighing. In more technical terms, "whinnies consist of a series of 2-12 rapid rises and falls in pitch, about 100 ms from peak to peak, with a fundamental frequency moving from about 1000 Hz to about 2300 Hz and back" [Gabriel Ramos-Fernandez]. And I discovered something about the whinny that I haven't read in any scientific literature. It's a developmental milestone, like a human baby's first steps. Chiquito has whinnied since we got him at twenty-two months of age, but Lolita made her first - and subsequent - whinnies this week at nine months of age! (Even more notable is that most of her whinnies are in response to rock music from the 70's on Pandora, when a new song starts - whereas Chiquito's are almost always in response to food.)
So (getting back on topic), I'm confident that duplicating spider monkey locomotion and communication aren't prerequisites for successful surrogate parenting, even if I still feel inadequate. But what about environment? From the beginning I was convinced that rehabilitation was dependent on the monkeys spending time exploring and playing in the jungle, and thankfully they've done just that...disproving advice that it was impossible for a spider monkey to be alternately free-ranging and caged. But the cage is still a cage, which makes me feel badly enough. And then I read a well-intentioned sentence in Gloria Yeatman's wonderful article yesterday that said: "Lolita is an adorable female, about eight months old, who currently lives inside the house with Michele and Paul until she is old enough to share the monkey cage with Chiquito." http://retireforlessincostarica.com/2012/07/monkey-love-and-monkey-yoga/
LIVES INSIDE THE HOUSE??? Those words aren't found in any North American wildlife rehabilitation book or training manual. In fact, that literature stresses how critical it is not to allow wildlife to become habituated to humans and pets. Habituated animals have no fear of people or dogs in general...which is almost a guarantee that they'll be killed after they're released.
If Lolita was living in the house, was "I" living in denial?
I've spent a restless 24 hours, but the soul-searching was enlightening. I'm not in North America. And orphaned primates require physical contact with a surrogate mother or they become psychotic. Like numerous orangutans, and howler monkeys, and spider monkeys, and other primates before them - successfully released after being rehabilitated by human surrogates who didn't sleep in trees - Chiquito and Lolita can be, too.