Ficus trees fruit asynchronously. Rather than fruiting around the same time, each Ficus fruits on its own schedule. This particular tree fruits twice a year, once in the winter and once in the summer, but its hard to predict exactly when. However, if you periodically monitor it, you'll see when little unripe pinkish-white fruits appear. These figs ripen to a deeper pink, and when they do, it's party time! Figs are a keystone resource among primates in many locations, and are found throughout the tropics (there are a number of different species, so the fruit varies between species and among habitats--while this tree produces small pink fruits, other Ficus trees in this forest produce large green fruit). When the fruit ripens, it's a good source of sugar and carbohydrates (essential for highly frugivorous spider monkeys!). But, figs also contain protein (due to the presence of fig wasps that have a symbiotic relationship with the fruits) and calcium, which isn't present in a lot of fruits. So, they are a great resource, and when a fig tree fruits, it's absolutely laden with fruit--until the hungry frugivores completely deplete it (the figs on this tree only last for a few days once they ripen--after that, it's pretty picked through, and then usually howler monkeys and other less picky eaters consume the fruit that didn't properly ripen).
I call this tree the "party tree" for several reasons. First, because when it is fruiting, it attracts all three species of monkeys, as well as coatis, birds, and other frugivores, and it tends to be a noisy and festive attraction. Second, subgroups of spider monkeys are also known as parties, and I like the play on words when I talk about spider monkey parties. Also, my friend Stacy and I had a running joke about trying to identify the community members. Because spider monkeys are in dispersed, fission-fusion communities, the whole community is rarely (if ever) together as a whole. Instead, community members travel in flexible subgroups that are always changing. These subgroups are usually fairly small (mean subgroup size is usually 2-3 individuals, excluding infants who travel on their mothers), but occasionally can be larger, particularly when multiple subgroups converge at key fruiting trees. This community has approximately 35-40 individuals. However, the largest subgroup I've seen was about 15-20 individuals. This makes it really difficult to assess how many communities are present at El Zota, and identify the boundaries of the different communities territories. Furthermore, Stacy and I were both studying females and juveniles--which don't frequent the edges of territories as frequently as the males. So, Stacy and I had a running joke about how we would identify community membership--we talked about throwing a spider monkey block party, where we'd serve fermented fruit, and give the spider monkeys name tags and sharpies, so that they could write their names and community identify with their prehensile tails.
Okay, so obviously, that was a bit of anthropomorphic silliness that could never happen. However, on my first trip to El Zota, we had the next best thing. We were only there for a few weeks, over winter break (Dec 2005-Jan 2006--seven years ago!). During that time, I was trying to collect pilot data for my masters project. I didn't know the forest that well, and I had not yet mastered the art of following spider monkeys and navigating swamps. And... I didn't have the best binoculars (I got new ones that spring before returning to El Zota in the summer). All of these factors made identifying individuals and collecting data quite challenging. But then, the figs ripened. And for several days, subgroups of spider monkeys fed, rested, and socialized in the tree for most of the day (and slept in the tree--Stacy could hear them at night/early morning from the cabin closest to the tree). Occasionally they would retreat into nearby trees or travel away briefly (usually when the tree was taken over by a raucous capuchin group), but for most of the day they stayed there (some of them--party composition changed over the course of the day, with some individuals coming and going), affording me great opportunities to see them well, identify females and juveniles, and conduct focal observations. Additionally, it also gave Stacy and me some great opportunities to take pictures! Some of the best pictures of juvenile male Tristan were taken that day.