Are you my baby? Why males might care for infants that are not their own

Written by Laura Abondano

YASUNI BIOSPHERE RESERVE, Ecuador – Guava, a baby woolly monkey, jumps off her mother’s back and lands on the back of Gordon, a male from one of the groups of woolly monkeys living at the Tiputini Biodiversity Station deep in the Amazon rainforest. Gordon continues moving a few meters in the tree with Guava on top of him before he sits down to rest with the baby still on his back. Guava’s mom, Guayaba, approaches Gordon and while the adults sit down to rest from a long journey, the baby plays with Gordon’s tail over and over again.

Lowland woolly monkeys live in groups where females typically display sexual behaviors that invite males to copulate with them. In fact, it is not unusual to see a female mating with multiple males in the same day, making it difficult for males to be certain of who they are fathering. Interestingly, males are often seen carrying, playing, grooming, or socializing with young infants, just like Gordon with Guayaba’s daughter, Guava. But not only are males tolerant with young infants, they also seem to be interested in maintaining close proximity to females with infants. What is very intriguing is why males engage in these friendly behaviors with infants given that they are not guaranteed to be the father.

As part of my doctoral research, I am studying how adult male woolly monkeys interact with infants to understand why it may be advantageous for males to have these strong social bonds with the infants or their mothers. Among primates, baboon and macaque males are known to form ‘friendships’ with mothers in their social groups. Mothers may be interested in creating these friendships given that these so-called male ‘friends’ may be offer protection or share food with the female and her offspring. But what do males gain from investing time with these females? Shouldn’t they be looking for other females to mate with?

If a male suspects that they may be the father of the infant, a strong relationship with the infant or his mother may increase the chances of survival of their own offspring. However, woolly monkey males have low certainty of who they are fathers to given that females may have copulated with other males during the previous mating season. It is possible that males may be interested in forming strong social bonds with females who have infants that are not necessarily their own, in order to increase the chances of the male mating with that female afterwards. This behavior is often seen among males that use their friendships to compensate for their low ranking position in the dominance hierarchy or reduced attractiveness as mates.

Among woolly monkeys, however, it is still unclear whether male relationships with infants and their mothers represent care for their own offspring or whether it reflects a male strategy to strengthen social bonds with females in order to increase future mating opportunities. Establishing paternity relationships between males and infants is the next step for our woolly monkey research team at UT-Austin, which will clarify whether males are really caring for their offspring, or whether they doing so to ensure their future reproductive potential.

In this video a small male infant, Dax, transfers from his mom, Darlene, on to a small adult male, Dash, and crawls around for a few seconds before transferring back to mom.

 

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It’s Raining Monkeys!

Written by J. Mayo

In the four months that I have been working with the woollies here at Tiputini, I have seen seven monkeys fall out of trees. Thankfully all of them have been just fine, getting up and carrying on monkey business as usual. It’s not something I expected to encounter working here though, especially not at this rate. With their prehensile tails, incredible ability to judge distance and branch stability, and mad jumping skills, you would think they would have this arboreal thing down pat, right?

Photo of female woolly leaping through the trees. Photo was taken by Tim Laman from the canopy walkway at TBS. To read about how Tim took this picture follow this link https://www.worldwildlife.org/magazine/issues/summer-2015/articles/monkey-swinging-through-the-rain-forest

Photo of female woolly leaping through the trees. Photo was taken by Tim Laman from the canopy walkway at TBS. To read about how Tim took this picture click here.

Let’s take a second to think about reasons why woollies might fall out of trees:
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Intro to Woolly Monkey Identification

Written by R. Ellis

When I first arrived at Tiputini Biodiversity Station, I was confronted with a daunting reality: I was responsible for being able to individually recognize all 80 or so monkeys we observe. Of course, I knew this information coming in, but l didn’t understand how much of a challenge it would prove to be until the first time we followed a group. A recurring thought kept running through my head:  all of these monkeys look exactly the same! Telling the males apart from the females was easy enough, but distinguishing between individuals of the same sex seemed utterly impossible. To compound my fears, that first group was G, our largest group, with about 30 individuals. Briefly, I wondered what I had gotten myself into.

Chromeo has a broken finger on his left hand that remains straight at all times, helping us identify him from other large males in surrounding groups

Chromeo has a broken finger on his right hand that remains straight at all times, helping us identify him from other large males in surrounding groups.

Fortunately, Kelsey had faith that learning all the individuals could be done, as she, along with her other field assistants, had achieved it the season prior. This gave me some respite, but I was still anxious that I would never be able to tell these monkeys apart.

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The Big Bad Clash

Written by R. Ellis

It isn’t often that New World monkeys depart from the safety of the towering trees they call home. In fact, when studying Neotropical primates, researchers spend most of their day looking up 20-30 meters into the canopy, watching the animals go about their lives in the skies.  Some monkeys, like spiders and howlers, will come down to eat the mineral rich clay of salt licks, but it is very uncommon to see a woolly come down deliberately (falling out of the tree on accident, on the other hand, is a different story). Accordingly, it’s always exciting to see any arboreal monkey plant its toes into the terrestrial environment, but on this day, it was an extraordinary and exhilarating experience. Continue reading

R.I.P. Dear Digit

Written by K. Ellis

I got some pretty heavy news my first day back to the station. While searching for a few of our radio-collared animals, I heard one of my favorite monkeys on mortality (when there is no activity the collar will pulse much faster than the normal rate to alert the researcher that either the animal has died or that the collar has fallen off).  We pinpointed the collar to a large tree fall in the middle of D’s home range, but were unable to actually locate the collar before nightfall. I had the highest of hopes that Digit had managed to rip off the radio-collar and was now roaming the forest a free man. However, this fantasy would never play out as we found what remained of Digit and his collar under the tree fall the next morning. Digit’s cranium was intact and many of his bones were concentrated in one area, directly under the tree that had fallen. Thus, we have ruled out predation as the cause of death. The question remains, however, was Digit snoozing away when the tree went and he somehow got pinned under the tree as it fell or was he already injured and unable to move quickly enough to get out of harms way in time? Only poor Digit will know.

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Digit was first identified as a subadult male in 2008 and noted to have two missing digits on his right hand for which he later acquired his name. In July of 2014 he was fashioned with a radio-collar allowing us to track him and his group. By this time, Digit had grown into a strapping adult male. Over several months of observation, Digit was noted to be a kind monkey and an integral member of the group. While he could often be found socializing with the moms and infants of the group, his true passion was to gallivant through the jungle on his own or with his trusty sidekick Docket (another adult male of the same age). And, although he was not much of a ladies man, he did have some successful copulations while under observation. Who knows maybe come summer we’ll have some little Digits running around (and Digit, or at least his genes, will live on)…

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Primatologist’s Field Gear Guide For TBS

Written by: K. Ellis

Prior to each long field season, I send out an email to my research assistants covering the clothing items and gear that they will need for a successful trip to the Amazon. To save myself time looking for that email over and over again I decided to keep a modified version of it posted here. Keep in mind that this post is tailored specifically to our field site (the Tiputini Biodiversity Station), a remote field site in Amazonian Ecuador with some key amenities (i.e., laundry is done at least once a week and we generally have access to electricity for several hours each day).

Necessary Field Items

  • Day Pack. If you already have a day pack that you don’t mind getting covered in mold and monkey poop, bring that…We really only need our packs to carry our food, water and telemetry equipment. I currently use a 24 liter pack and that seems to fit everything well. I also prefer packs that are able to accommodate water bladders (e.g., camelback, platypus) so that I can drink whenever I want and don’t have to stop to grab my water bottle.
  • Water bladder or water bottles that can hold at least 2 liters of water (this seems to be the average amount of water people go through in a day when following the monkeys).
  • Rubber boots. These can be purchased in Ecuador if so desired, however, there are often boots of various sizes that we can loan from the station for field work.
    • In-soles (optional) if you tend to get achy feet.
  • Binoculars. Waterproof binoculars, with 8 to 10X magnification and 40 to 50 mm forward barrel diameter are preferred.

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Entry #5: The Trek to Maquisapa

Written by: R. Reeder

Well, time is winding down. We are in the final stretch, as much as we are trying to deny it. One of our fellow researchers, Sebastian, was the first to leave the station, after working with the spider monkeys for a year. To make the most out of his last day, we all took the day off and hiked the Maquisapa trail. None of us had ever done the entire trail before. It is four kilometers, the longest trail here in the trail system. It’s a beautiful trail, with high elevation points where the forest thins out a little more so you can see further into the distance, and low points where the trail can flood if there is a substantial amount of rain. The trail meets the Puma plot on the eastern and western sides, which is a well-known area for the spider monkey researchers, as it is an area the spider group MQ-1 frequents. Sebastian was hoping, of course, to see some spider monkeys along the way to say one last goodbye. Unfortunately, they were nowhere to be found. We heard woolly monkeys; saw some sakis, and also some howlers, but no spiders. It wasn’t a big deal though; Sebastian had visited several members of the group in the days prior to this last day and had said his goodbyes. Once we reached a lagoon, which touches the southwestern side of the trail, we decided it would be a great adventure if we could canoe out of the lagoon to the Rio Tiputini, and then float down to camp. The other option was simply to walk back down the Lago trail, about another two kilometers, to camp. It should come as no surprise that we thought about the options for maybe a minute, and in the next minute all seven of us were all clambering into the rickety wooden canoe tied to the dock. Continue reading