Yesterday was my last day in the field with the monkeys here at Tiputini, and it ended in appropriate fashion for the rainforest: with a torrential downpour. Despite a rainy first two weeks, its been remarkably dry recently. The depth of the Rio Tiputini, which has been as high as 11 meters in the last few months and as high as 9 during my stay, is now just below five, which makes for a pretty remarkable change in the way the river and all the streams feeding into it look. To highlight the difference, you can see two pictures below taken from the exact same spot on one of the trails that goes right through titi territory. Just a few weeks ago, the water was so high that all that was visible of the bridge was the rope that serves as a handrail, and crossing the bridge meant going into water well over your boots. When its real bad the water can get up to chest level. As of now, however, you can stand on the bridge and look at least ten feet below you to an almost completely dry streambed, which to me is a pretty impressive demonstration of the rapid and massive fluctuations in the amount of water this environment can contain.
But on my last day with the titis, as I got my umbrella and rain jacket out in preparation for the hard rain that I could already hear hitting the canopy above me, I was thinking less about water levels and instead was sympathizing with the titis who were about to get drenched. The rain here can be intense. It was beginning to come down in sheets, and within a few minutes a pretty sizeable stream coming from the ridge behind me began forming I was hoping I would get a nice goodbye to the six members of group B whom I have become acquainted with these last five weeks as they all filed into their sleep tree, but given that it was already almost five in the afternoon (which isn’t far from their bedtime anyway) I figured I should take any opportunity I had to avoid getting soaked by heading back to camp as soon as the rain lightened, even if it meant foregoing a face to face farewell.
The last two weeks provided a handful of noteworthy events, both monkey and non-monkey related. The non-monkey related event doesn’t actually have anything to do with me, but instead was an incredible sighting by Pete Oxford, a professional photographer who is spending a month taking pictures at Tiputini. Just two weeks ago, Pete become the first person ever to shoot photographs of a black panther in the wild. He was canoeing down the Tiputini and caught site of the animal on the bank of the river, and remarkably had the fortune to spend well over an hour photographing it as it lazed about with very little concern for the human rapidly snapping pictures of it. The pictures are absolutely phenomenal, as the black panther (which is actually a mellanistic jaguar) is a beautifully sleek and powerful-looking animal, yet its gorgeous black coat has a few spotted imperfections from scars and the like that let you see just how wild it is. One of the sad things, however, is that when Pete sent the pictures to his agent hoping he would hear that national geographic and other wildlife magazines should be thrilled with the shots, he heard that there probably wouldn’t be a whole lot of interest because people have seen photos of captive black panthers so much. Even though it is one of the rarest animals to see in the world, and nobody to date has captured a wild one in a photo, magazines don’t expect the picture to sell to the public because people are used to seeing photos of perfectly formed animals that grow up in captivity, and they don’t much care if the picture is of a wild animal surrounded by the wild environment it naturally lives in. Hopefully something will work out and the photos will get the recognition they deserve, but it seems a real shame that something so cool might not be fully appreciated because of concerns about money and what the public has been trained to see.
Getting back to wild animals that I am working with, however, we did another playback experiment with group B, who hadn’t responded to the recorded calls in our previous two attempts. We play each call several times in order to get as much of a response as possible, and after the first two calls it looked as if yet again this group would foil our experiment. There was some slight moaning from Bongo and Banana, the adult male and female in the group, but Bongo initially seemed more interested in remaining with his youngest offspring, who was snuggling up against him trying to rest. Finally after the third call, Bongo moved toward Banana and they finally started dueting. They called only once, however, for about two minutes and didn’t move toward the source of the recorded calls or show any of the extreme agitation that we had seen with Kong and Katta in group K. Such a response fits with the lack of response seen from group B to our previous playbacks, and it may indicate something about the dynamics among the titi groups.
Later that day, I was following B’s neighbors to the east, group L, while Amy stuck with Bongo, Banana and company, and we witnessed the two groups come to within 50 meters of each other at their territory’s edge. Vocalizations were coming from both sides, but again Bongo seemed much less agitated and vocalized less frequently, while Lucifer, the adult male in group L was doing the majority of the calling. Group B has the largest territory among their neighbors, and the most individuals in the group (the two adults also interestingly seem to be the most wary of human presence), and it could be that there is a hierarchy among the titi groups in the area, and because of their numbers or some other reason, they are dominant. As a result their neighbors are much more concerned with what group B is doing than the other way around, hence the higher levels of agitation and more frequent vocalizations by L and K when compared to B. This is of course rather speculative, as not that much is known about intergroup interaction among titis and more data would be needed to show that these patterns are consistent, but it makes for an interesting hypothesis. Furthermore, these differences in group responses add a layer of complexity to the present research questions about the maintenance of social monogamy, since the differences among titi groups suggests some variation exists even among a single species in the behavior surrounding male and female contributions to mate guarding and territory protection.
Another notable behavior I observed with the titis which is probably less significant but cool nonetheless occurred the same day as the playback. I saw the juvenile from group L, accompanied briefly by its mother, come all the way to the ground to feed on a fruit that had fallen from a nearby tree. Its not uncommon to see titis come low (like head-height), often to feed on insects, but for them to come all the way to the ground is very rare. Just to see a monkey whose home is so obviously the trees above you on terra firma seemed bizarre, and to have the juvenile do it when I was within 20 feet was really surprising. He just seemed so exposed. The next day I got a sense of why he and his mother might have been willing to leave the safety of the trees to eat that fruit, as I saw how much they absolutely love it. I found out its called a tagua fruit, and it comes from a palm tree encased in a hard spiky shell. For the second day in a row I saw Infant 10 and his mother feeding on it, this time on the tree itself. It was an adorable demonstration of parental care, as Infant 10 needed his mother to take piece of the shell off, after which she would often bite a piece of fruit off and hold it in her mouth for Infant 10 to take. They both were clearly thrilled to be eating tagua though, as they excitedly munched on it for over a half hour. The juvenile would often get particularly excited and try to take things into his own hands by grabbing the fruit (which was about half the size of his body) at his mothers protest. Lulu (the mother) proved to be wise in protesting, for as soon as Infant 10 finally did get the fruit away from her, he dropped it to the ground. This didn’t stop Infant 10 though, as he cautiously made his way down the tree over the next couple of minutes before finally reaching the ground and his prize, the remainder of a de-shelled tagua fruit all to himself. While the day before he spent only about two minutes on the ground, twice retreating back up the tree to check out his surroundings, this time he stayed there happily eating away for over ten minutes, even though I was closer to him than the day before. Perhaps going to the ground isn’t as big of a risk as it might seem, since most of the animals that could prey on the titis could catch them in the trees as well as the ground, but it still is quite unusual. And notably, group L has had a lot of offspring die before reaching adulthood recently, which could potentially be related to the young engaging in similarly bold behavior.
At any rate, as I reflect on my experience here at Tiputini as a whole, it doesn’t quite seem like I’ve been here for six weeks, but at the same time I feel as if I have done a ton of work. I have completed over 200 twenty-minute focal samples and spent around 175 hours with the titi and saki monkeys here at Tiputini, watching them fly through the trees, do nothing for hours on end, eat, pee, poop, groom each other, tail-twine, have sex, duet, eat again, rest again, rest some more and so on. Even though it feels like its been a lot of work, its also a fairly miniscule amount in comparison to what needs to be done in order to have data that can definitively say something about social behavior. So while I was drawn into this project because I was interested in studying the reasons why monogamy makes for an adaptive social system, the fieldwork has taught me more about what it takes to study something like that rather than given me much in the way of answers. I think that’s still pretty valuable, and I suppose that so far it has also provided lesson about the nature of research (especially behavioral research on animals in the wild). And one important thing that I have seen through the field work is the differences in social monogamy across species, showing how monogamy is really a broad term that encompasses slightly different social organizations that are likely adaptive for slightly different reasons. In a few weeks, I’ll get to start observing another monogamous species in a completely different environment in Argentina, the owl monkey. Even though their social behavior is very similar to titis, I’m quite interested to get a sense of the sorts of differences that might nonetheless exist.
(Note: I’m uploading this blog back in Quito where the internet isn’t painfully slow, so I’m including a lot more pictures that I wasn’t able to upload before.)