Birds of Prey: Neotropical monkeys’ most fearsome predators

Check out this blog post featured on the Los Amigos Bird Observatory Blog about our latest publication!

April 5, 2018 | Author: Carla Mere |

Jaguars are without a doubt the top predators in Amazonia, but organisms flying above the canopy certainly have a big advantage and unique predation skills that make them respectable predators when compared to wild cats. Raptors are considered the major predators of new world primates, such as crested eagles (Morphnus guianensis) predation on infant tamarins (Leontocebus mystax & L. fuscicollis) and also squirrel monkeys (Saimiri sciureus); black-hawk eagles are also known to attack howler monkeys; and the largest and powerful harpy eagle (Harpia harpyja) predation on saki, capuchin and night monkeys. Current ecological knowledge of Neotropical raptors is scarce, thus filling in the gaps of information on this particular group of birds will allow us to understand their ecology and general biology, whether it is through anecdotal incidents or observations in the field.


Photo by Marc Fasol

The black-and-white hawk eagle (Spizaetus melanoleucus) is one of the 55 birds of prey found at Los Amigos. Compared to other well-known raptors such as the mighty harpy eagle or the crested eagle, the black-and-white hawk eagle is a small size bird (body mass: 780-1191 g; wingspan: 110-135 cm), feeding mainly on terrestrial and arboreal birds such as tinamous and guans, and some documents report small mammals and reptiles in their diet. However, successful predation on primates by this species was not described until 2014, when a group of researchers witnessed and described the mortal attack of the Rylands’ bald-faced saki monkey (Pithecia rylandsi) at Los Amigos.


Ryland’s bald-face saki carcass on the forest floor, and attacked by the black-and-white hawk eagle.         Photo: Adams & Williams, 2017

This fatal event was recorded on 23 July, 2014, during a long-term project assessing the anti-predation behavior and alarm calling of P. rylandsi at Los Amigos. While conducting the usual primate behavior monitoring, one of the research assistants heard a large bird flapping, followed by alarming calls of a group of sakis, which are whistle-like calls emitted when they detect an eagle’s presence. Upon the researcher’s return after a couple of hours, he heard wing’s flapping in the same location. After following the motion event, the researcher found out the black-and-white hawk eagle feeding on an adult saki’s carcass on the ground. The black-and-white hawk quickly flew away after detecting the researcher approaching. Most of the saki’s flesh, muscles and skin were removed, with fur scattered beside and along a 16.4 m path away from the carcass. Several puncture holes were noted on the body and skull, while the stomach lay untouched next to the body despite most of the soft tissue having been removed. Although the observers didn’t visually witness the attack, the described observations together with the physical injuries documented on the saki most likely indicate that it was the black-and-white hawk-eagle as its predator.

Black-and-white hawk eagles utilize the “soar and stoop” hunting tactic, compared to the “perch and wait” strategy used by large raptors, consisting of searching for preys above the canopy and forest edges and, upon prey detection, diving rapidly into the forest to attack them. This report suggested that smaller and lesser-known raptors, like the black-and-white hawk eagle, should also be considered important predators of Neotropical primates, principally those that occupy the mid to upper canopy given their hunting strategy. Identifying and providing evidence of predation events like this is key to learn more about less prominent raptors, so keep your eyes and ears open while walking in the forest!

For more references:

Adams, D., Williams, S. 2017. Fatal attack on a Ryland’s bald-faced saki monkey (Pithecia rylandsi) by a black-and-white hawk eagle (Spizaetus melanoleucus). Primates 58: 361-365.

Robinson, S. 1994. Habitat selection and foraging ecology of raptors in Amazonian Peru. Biotropica 26(4): 443-458.

Smart Sakis: A Spoonful of Termite Mound helps the Bitter Seeds Go Down

Primatologist Michelle Rodrigues posted a cool write-up of our most recent paper on geophagy in saki monkeys on her blog SpiderMonkeyTales. Check it out below!

Saki monkeys are a Neotropical primate found in Amazonia. They are seed predators, which means that rather than ingesting seeds and passing them whole (like spider monkeys), their teeth and digestive system destroy the seeds they eat. This is a good way to get maximum nutrition from those seeds, but the seeds contain high levels of secondary compounds like tannins. Tannins are the bitter, astringent compounds that give coffee, tea, and wine their unique flavors, but high levels of tannins (much higher than we consume), can be toxic.  Other Amazonian seed predators, like parrots, eat soil with clay and high cation exchange capacity, both of which neutralize the toxic effects. Seeds eaten by parrots in the same region have tannin levels toxic to most verterbrates. If the Sakis are eating the same seeds, how do they cope with those levels of toxins?

Sakis eat termite mounds, which contains soil, clay, and nutrients. Adams and colleagues tested between two hypotheses: 1) Sakis eat the termite mounds because they provide nutritious minerals (like vitamins), or 2) to help counteract the potentially toxic effects of secondary compounds (like a detox supplement). If the soil they ate from termite mounds contained more micronutrients, that would support the vitamin hypothesis. If the soils contained that have more clay and and cation exchange properties, that would support the detox hypothesis.

They observed how long the monkeys ate termite mounds, which age/sex classes at the termite mounds, if there were termites present. They also collected samples from termite mounds that the Saki fed at, and compared to control soil samples and unvisited termite mounds.

About 2/3 of the termite mounds contained termites, and Sakis did eat termites at the active mounds. However, they fed from both active and inactive termite mounds, all age/sex classes fed on the mounds. Termite mounds did have higher levels of some minerals than topsoil, and those levels were similar in the both the Saki-eaten mounds and univisited mounds. The eaten- and uneaten-termite mounds did not differ in in clay content, but the termite mounds that were eaten had twice the cation exchange capacity. Adams and colleagues conclude that the Sakis are eating the termite mounds primarly because it helps counteract the effect of the tannins, supporting the detox hypothesis.

So basically, Sakis are wisely self-medicating with termite mounds to counteract the effects of their potentially toxic diet!

An important caveat: Adams and colleagues do not use terms like the “vitamin” or “detox” hypothesis–I use these terms only to simply the function of termite-mound eating. Also, humans are not seed predators, so we do not have the same need for detoxing. Most talk of “toxins” in human diets is pseudoscience, and unless you’re eating some strange things that are not suitable for human consumption, you should have no need for detoxing!

The Monkey Monster

By Christina Vojta (research assistant) & Dara Adams

Christina monitoring the nest

Christina observing the harpy nest through the spotting scope.

High in an ironwood tree, a pair of obsidian eyes peer watchfully from a ghost-gray face, majestically crowned with a fan of feathers. I spin the spotting scope into focus and the eyes meet mine; they lock my gaze, and I gasp. The power of the creature is palpable, even across the 100-meter distance that separates us. The bird’s plumage is striking, with dark steel gray wings and upper chest contrasting handsomely with its pure white torso. I watch transfixed as the creature slowly spreads its wings, revealing a wingspan of over two meters and a pair of hefty talons the size of butcher knives. This is the harpy eagle (Harpia harpyja), the spirit of the Amazon, the monkey’s nightmare.

As the largest raptor in the Amazon rainforest, the harpy eagle is built to impale and consume monkeys and sloths, some of which weigh up to 7 kg (17 pounds). Because of this predilection for monkey meat, Dara was interested in finding out which species of monkey harpies frequently ate and whether monkeys altered their behavior or travel paths in response to eagle presence. To answer these questions, field assistants and volunteers, including myself, took turns monitoring activity at a harpy eagle nest, with each assistant spending four hours a day for several weeks to two months, yielding near-continual monitoring from March through August 2015.

Although the harpy eagle is a monster for monkeys, it is hard to not admire its beauty and grace. Through the scope, I can see an intricate pattern down the length of its tail created from alternating wavy lines of steel gray and white, and its legs are patterned in gray and white like fashionable leggings. The wing shoulders of the harpy are powerful and thick, and are held a bit out from the body, like the arms of a thick-muscled weight trainer. Females are larger than males, and weigh up to 9 kg (20 lbs).


Adult female harpy near the nest. Photo credits: left, Gordon Ulmer; right, Fiorella A. Briceño

One of the most captivating aspects of the harpy eagle is the flexibility of its neck. Like extraterrestrial ET, it can elevate the neck, then twist it more than 180 degrees and peer down over its back. Whether looking forward or back, the eagle can shift its head from side to side like a Hindu temple dancer, a motion that increases depth perception and helps pinpoint an environmental sound. Between shifting its neck and raising and lowering its crown of head feathers, the harpy eagle is able to evoke a wide range of emotions, including curiosity, calmness, agitation, attentiveness, hunger, and annoyance (usually over the many flies attracted by rotting meat in the nest).

Harpy Nest

The nest seated on top of the main fork of an ironwood tree. Photo by Aaron Pomerantz.

A creature this size needs a huge nest and an enormous tree fork to support it. The nest that we observed was approximately 2 m (6 ft) wide and 1.3 m (4 ft) deep, created by the adults through an elaborate weaving of sticks. Across the globe, most raptors use the same nest for several seasons, possibly because of the effort required to build these large structures, and often because the nest tree has the best location and shape for the purpose. Harpy eagles select nest trees with widely-spaced branches to facilitate flights into and out of the nest with their wide wingspans.

Bird watching

Project assistants Carly Fitzpatrick (foreground) and Dani Couceiro observe the chick as Dara takes data (background).

We spent most of our time observing the behavior of the chick that hatched in January or February. It quickly grew into a fluffy white version of its parents, with the same onyx eyes, black hooked beak, and feathered crown. There is nothing like a baby to warm our hearts, and the harpy chick was no exception. The chick was five months old when I began my month-long observation period, and I never tired of watching it learn about its body and its environment. By 6 months, it was nearly full-grown and had begun to develop adult plumage, but still had many characteristics of a chick, including a huge bundle of down that still persisted under the base of its tail. We were never sure if the chick was a male or female, but the fact that it rapidly attained a large size made us feel that it was a female. Nevertheless, in the absence of evidence, I will use the neutral pronoun.


Development of the chick over a five month period. The first picture shows the chick with all white down feathers in mid-March. The second photo was taken late May just before the chick left the nest. The last photo was taken in early August as the chick was making short flights in and around the nesting tree (note the change in plumage color and development of the crest). Photos from left to right taken by: Gordon Ulmer, Aaron Pomerantz, and Christina Vojta.

As with most animals, raptor behavior is a combination of genetically-programmed responses coupled with environmental learning. Many actions made by the harpy eagle chick made me realize the important role of learning during its youth, and I wondered if sufficient time for learning is one reason that harpy eagle chicks usually stay near the nest for 10 months or more. They are born with innate abilities to fly, hunt, eat, build nests, and rear young, but these instincts must be honed through learning and practice for several months.

Sleeping chick

The chick taking a mid-day snooze. Photo by Christina Vojta

For example, when the chick was ready to explore beyond the nest, its balance was unsteady and it rocked back and forth, learning to control its movements like any toddler. The first flights were only a meter or two, and required several minutes of contemplation and shuffling around before the wings were spread into flight. The chick learned about gravity by tearing off small sticks from the tree with its beak and watching them fall to the ground. The chick became increasingly aware of sounds in its environment, and often raised its crest with interest to the sounds of certain bird species, particularly flocks of macaws and parrots.

One day I watched the chick experimenting with different perch sizes, and it quickly learned that the really tiny branches would not hold its weight, as it flapped and struggled to stay perched on a 3-cm branch that flexed dangerously before the chick moved to a safer perch.

Even eating was partially learned. At first, the adults (mostly the female) fed the chick by tearing small pieces from a carcass in the nest and placing them in the chick’s mouth. However, once the chick began to feed from the carcass by itself, it made the error of attempting to ingest a huge chunk of meat in one piece, so that the meat was stuck halfway down its throat while still hanging out its mouth. After several minutes, the chick managed to wriggle the whole slab into its mouth, but it must have been an uncomfortable process because I never saw it do that again.


The adult female tears up a fresh kill and feeds it to the chick. Gif created by biologist Aaron Pomerantz. You can read more about harpies in Aaron’s article in The Huffington Post here.

Our total observation time of approx. 400 hours yielded abundant information about the importance of monkeys in raising a harpy eagle chick. Coupled with results of a previous local study of harpy eagle diet, the most frequent food items were sloths, howler monkeys, and brown capuchins, but squirrel monkeys were also significant prey along with an occasional macaw. Saddleback tamarins were present in the study area, but to our knowledge, they were never part of the harpy eagle diet, perhaps because they tend to stay in the lower canopy, move quickly, and are quite small-bodied (offering little meat).

Harpy with howler

Adult female bringing a howler monkey back to the nest. Photo by biologist Chris A. Johns. Check out more of Chris’ amazing photography here.

As the chick moved into its 6th month, the adult eagles brought fresh food less often. One day I watched the chick pluck fur from the tail of a squirrel monkey and eat the meager tail meat, and I wondered whether an adult would eventually appear with food. The chick was not able to hunt on its own but it could fly to adjacent trees, and we often could not find it for hours when it was perched silently. However, there were other days when the chick seemed to need fresh provisions, as evidenced through incessant begging cries. On my last evening watching the chick, it crouched into the begging pose of a nestling, squatting in the nest with wings held out, beak pointed skyward, emitting plaintive begging cries until dusk. I returned the next day, but there was still no fresh food. I knew that the female eventually would arrive, perhaps with another sloth, but in a month or two, our chick would need to learn to hunt by itself. And when it did, the monkeys of Tambopata would serve to carry the chick into adulthood, and perhaps into the realm of raising its own chick someday.

To learn more about our study subjects and see amazing harpy footage, check out the video below filmed and created by biologist Aaron Pomerantz and wildlife photographer Jeff Cremer.

Predator Experiments: Patience Pays Off

By Missy Painter (Research Assistant)

titis calling

Titis alarm calling during an experiment. Photo by Denise Peterson.

How does a monkey react to an ocelot prowling beneath its tree, or to an eagle circling above? Observing monkeys in the presence of predators is a great way to learn more about their anti-predator strategies. However, we can’t count on stumbling across these rare predator-prey interactions in the forest to observe them firsthand. So, we are conducting field experiments through which we present saki and titi monkeys with realistic models of three predator types – ocelot, harpy eagle, and boa constrictor – and document their responses.



Missy recording alarm calls. Photo by Denise Peterson

When the team heads out to conduct these experiments, we need a few things in our bag of monkey tricks: a predator model to present to the monkeys, a camouflaged sheet to cover the model until just the right time to reveal the predator, an audio recorder to capture the monkeys’ vocalizations, and, perhaps most importantly, patience! Coming across the perfect conditions for these experiments can take some time. First, we have to find the monkeys. They can be elusive! Then, we follow the monkeys until they are low in the canopy in an area without too much undergrowth. If there is a lot of vegetation between the monkeys and where we place the predator model, or if the monkeys are high in the canopy and the predator model is near the ground, they won’t be able to see it. And of course, once we have the monkeys where we want them, we cross our fingers and hope it doesn’t rain. Eventually, the stars align and we are able to present the monkeys with a predator model, and our patience pays off.

Boa in swamp

Boa decoy placed on the ground for a low risk experiment.

The monkeys show some surprising differences in their reactions to the different types of predator models. When presented with the boa constrictor model, one group of titi monkeys vocalized quietly before quickly retreating. When presented with the ocelot model, another group of titi monkeys immediately climbed higher in the canopy and vocalized loudly. The group members spread out into a few different trees around the model and continued to vocalize loudly for almost an hour. It was clear that each member of the group saw the ocelot model and was aware of the potential threat. So, why would the monkeys continue to vocalize for so long before retreating? These prolonged calls may communicate to cat predators, which rely on sneaking up on their prey, that they have been spotted. In other words, the monkeys may be communicating to the cat that the jig is up. If a cat knows its prey is aware of its presence, it may give up the hunt sooner, which would certainly benefit the monkeys.

Ocelot decoy

Ocelot decoy on the ground during a ‘low’ risk experiment.

What I find even more interesting is that the monkeys respond differently based on the predator model’s location. When we presented titi monkeys with a harpy eagle model perched on a branch about two meters off the ground, the group reacted quite strongly. The adult male and female vocalized loudly for almost half an hour before the adult female and the juvenile retreated. The adult male hung back for another 20 minutes, hiding in thick vegetation and keeping an eye on the harpy model before finally retreating. When we presented another group of titis with a harpy eagle model on the ground, the monkeys’ response was relatively mild. They dared to come a bit closer to the model, briefly emitted some quiet vocalizations, traveled directly above the model, and then settled into a fruit tree not even 10 meters away to enjoy an afternoon snack. It seems the monkeys perceive a harpy eagle a few meters in the air to be a greater threat than a harpy eagle on the ground. Harpy eagles hunt in the canopy of the forest, flying from branch to branch as opposed to soaring above the trees, so the monkeys’ reaction to the harpy model perched on a branch is certainly warranted!

harpy recording missy dara

Missy and Dara practice recording alarm calls and behavioral data during a high risk harpy eagle experiment. Photo by Denise Peterson

Conducting these predator experiments has by far been my favorite aspect of the research project so far. With just a little patience (okay, A LOT of patience), we are able to replicate predator-prey encounters that very few people have the opportunity to witness in the wild.

Saki Monkey Business

By Dara Adams

While we’ve had much exciting ocelot news to share, the majority of our time on the project is spent with the saki monkeys, locally called ‘huapos.’ We typically conduct day-long follows on our two behavioral groups for 10 to 15 days per month and spend the rest of the month locating and carrying out experiments on our four experimental monkey groups or collecting data on habitat variables (e.g., fruit availability, forest density, etc.) in the monkeys’ home ranges. Given that we follow the monkeys from the time they wake up until they go to sleep, we see a lot of interesting behaviors and events. Side note: Saki bedtime is quite early in the monkey world – they often enter their sleep tree around 2 or 2:30 in the afternoon, which is quite nice for us humans!

huapo y bebe

An infant saki resting on the back of its mother. Photo by Marlon Guerra

One such interesting behavior occurred about three weeks after the arrival of a new baby, “Zetsu,” in the Otorongo group (‘Otorongo’ is the local word for jaguar- the group is aptly named after the trail that runs directly through the middle of the sakis’ home range). Marlon and Alberto, local assistants working on the project, returned from the field one afternoon after a full day follow and told me that the adult male of the group had been harassing the infant all throughout the day. The male approached the female, who was carrying her newborn snuggly under her belly, and grabbed at the infant aggressively. The infant shrieked repeatedly until the female moved away. In the seven years I’ve been studying sakis at the field site, I have never seen seemingly aggressive behavior from an adult male toward an infant. My first thought was that perhaps the male was just curious and trying to inspect or carry the infant.

The following day, I went out with Marlon and Alberto and sure enough the adult male periodically approached the female and grabbed and pulled at her infant. At first she moved away but by the end of the day she quit turning away and refrained from trying to prevent the male from touching the infant. The behavior continued intermittently for several more days and we became quite familiar with the loud shrieks of this tiny new group member. By mid-month the behavior was becoming more frequent but we had to stop following the group to collect monthly habitat data. It is impossible to say what the male’s intentions were but the behavior appeared to be more aggressive than curious.

huapo vigilating

Vigilant male from the Otorongo group scans the horizon. Photo by Marlon Guerra

By the time we returned to collecting behavioral data on the Otorongo group the following month, the infant had grown quite a bit and had migrated onto its mother’s back. It frequently reached out and grasped at branches or other nearby objects and the male’s interest in the infant seemed to have lessened. We left the Otorongo group at the end of the month and started following the Yungunturo group (named after trail Yungunturo, which is the local name for the Priodontes, or giant armadillo). We were pleasantly surprised to see that the Yungunturo group had also recently welcomed a new group member. We were eager to get back to the Otorongo group later in the month to see how much their infant had grown. To our shock, the infant, which would now be around three months old, was nowhere in sight. Instead, we were greeted by a brand new infant that could not have been more than a few days old securely tucked into the underside of a different adult female.

The team was a bit saddened by the disappearance of Zetsu, as we had been documenting its development and were quite fond of the little one. Each person had his or her own ideas as to what happened – everything from infanticide (intentional killing) by the male to perhaps a lethal fall from the canopy. While infanticide is documented in a number of primate species, such as langurs and howler monkeys, it is extremely rare among ‘socially monogamous’ or pair bonded primates and it has never been documented in saki monkeys. Thus, it is unlikely that this was the fate of the little one; however, it is also rare for multiple births to be documented so close in time in one saki group.

Male food mouth

Playful juvenile saki swinging in the trees. Photo by Marlon Guerra

On the other hand, we have witnessed quite a few close calls with infants and juveniles falling from the canopy. For example, back in September I was following the Yungunturo group one day when the adult female descended to the ground to feed on army ants. Saki monkeys at the field site love to feed on army ants and will often spend upwards of one hour or more on the ground preferentially selecting the soldier ants from the steady stream of ants to feed on. While the female saki was feeding on ants, the adult male of the group rested nearby and the juvenile male decided to make Rufo, one of my assistants, and I his playmates! The juvenile started swinging down low in the trees towards us, batting his hands at us, and emitting gleeful grunts. He became so carried away at one point that he fell about 10 meters and managed to grasp onto a sapling at the last minute, which prevented him from hitting the ground. He emitted one short shriek and eye-balled us like we were responsible for his fall.


Adult female forages for ants on the ground. Photo by Dara Adams

A few months later we were following the Otorongo group and taking data while the group was feeding in the crown of an emergent tree. The infant was just starting to move around independently, occasionally leaving its mother’s back to explore. Out of nowhere we saw the infant free falling in the canopy from about 30 meters up. I emitted a high-pitched cry because I was certain the infant was going to hit the ground – and from that height – I couldn’t imagine it would survive. But somehow the infant managed to grab onto a small branch with one hand just 10 meters from the ground. The infant sat there in a stunned state while the rest of the group jumped down in the canopy toward it. The female quickly grabbed the infant and placed it on her back where it remained safely for the remainder of the day.

The adult male exhibited the same seemingly aggressive behavior toward the new infant in the first few months, albeit less frequently. The newer infant is now about seven months old and has started to venture off its mothers back to forage and explore. The male has taken a new but much friendlier interest in the infant. They frequently play or rest together and occasionally the male carries the infant for short periods. We look forward to the next few months as we continue to document the infants growth and development!

Houdini Meets his Match

Written by Marlon Guerra (translated and edited by Dara Adams)

It was a dreary, rainy day and the team’s spirit was down after Zeus had mysteriously escaped from the trap the night prior. After seeing video after video of Zeus securely trapped, it seemed that he disappeared as if by magic, like the infamous illusionist Houdini. By afternoon, the rain had finally passed but the forest was wet and water droplets loudly fell from the canopy to the forest floor. We were making our afternoon rounds to check traps and I was heading to the traps on Aguajina trail where Zeus had escaped the previous night. I was feeling a little sad because I knew it was impossible that we would trap Zeus again, especially during the day time.

Megan, a volunteer at the station, asked if she could accompany me. As we came within 25 meters of the farthest trap on my route, we heard a noise. I started running toward the trap and as I approached I could see the door was bending at the safety latch. I couldn’t believe my eyes – Zeus was in the trap!!! I could see his head poking out from the bend in the door. How incredible, the force of this cat! I had nothing on me to secure the door but I spotted a huge branch nearby that had fallen from the heavy rains. I quickly grabbed the branch and placed it against the door. I started yelling for Megan, who had lagged behind. She was incredibly excited as she approached and realized Zeus was in the trap – it was her first time seeing a wild ocelot! I wasn’t able to move because the door latch was broken and I was determined to make sure the door was secured. I yelled at Megan to run back to the station to alert the team that there is an ocelot in the trap.

Marlon Zeus

Marlon using a branch from a fallen tree to secure the trap door until the team arrived to help (still frame from a camera trap video).

Megan ran 3 kilometers back to the station and up a 250 meter steep, muddy embankment. I can only imagine the amazement and chaos back at the station as the team heard the news. Dara, Renata, Alice, and Alberto had to quickly grab everything needed and run 3 kilometers to the trap site. Meanwhile, I was still holding the branch against the door while the forest became dark and the mosquitos started biting. Zeus had calmed down with my presence and was no longer trying to escape. By the time the team arrived it was completely dark so Renata and Dara decided that it was unsafe to work and release Zeus in the middle of the night. But Dara was concerned Zeus might get hurt trying to escape from the trap in the middle of the night so it was decided that I would camp beside the trap to make sure he remained calm and safe.

Marlon and Renata Weighing Zeus

Marlon and Renata weigh Zeus.


I returned to the station to retrieve a tent, sleeping bag, and dinner while Alice, my wife, and Alberto stayed by the trap. I increased my walking speed as the sky was threatening rain. When I returned, Alice decided that she would stay with me and sleep next to Zeus. We put our tent six meters away to give him space but close enough so that we could make sure he was safe. We could occassionally hear Zeus growling but it seemed that our presence calmed him quite a bit. We certainly did not get much sleep but it was very cool to be able to hear and smell a wet cat all night!


Neck spines

Renata removing porcupine quills from Zeus’ neck.

The team arrived with all the necessary equipment at daybreak so that we could anesthesize Zeus and fit him with a GPS collar. While Zeus had no injuries from the trapping, his neck was filled with porcupine quills! We had anticipated this because we had seen the quills on the camera traps the week prior but luckily they were much smaller than they appeared on the cameras and were easy to remove. Zeus had quite a few ticks and large botflys, which we removed, but overall he seemed to be in great health.

Later that day, after we released Zeus with his new GPS collar, we watched the camera trap video and saw that I had arrived to the trap less than one minute after Zeus had arrived. He must have been spooked when I came up behind him and ran right into the trap! In the end, it was Zeus’ over-confidence and a little bit of luck in timing that allowed us to finally capture this magnificent creature.

Group with Zeus

The Team: Megan, Dara, Marlon, Alberto, Alice, and Renata

Overall it was an intense but amazing experience – thanks Zeus!

Zues blue

Zeus appears on a camera trap a few days after his release. Photo courtesy of Carlos Quispe, the Science Coordinator of Los Amigos Biological Station.

The Saga Continues

By Dara Adams

Apologies for the long radio silence but we’ve had our hands full with monkeys, cats, and more! Wildlife veterinarian Renata Leite Pitman returned to the field site in September to assist on our project. Renata lived at the field site with her husband Nigel, who was CICRA’s Scientific Director, and her two young girls until 2008. During this time, Renata captured, radio collared, and studied a variety of mammal species, including short-eared dogs, giant armadillos, jaguars, and…ocelots! When our project took a turn to include predator behavior we didn’t hesitate to consult Renata. Our goal during her two-week visit was to capture and place a GPS collar on Zeus, the male ocelot that became an expert at evading our traps back in August.

The first week of Renata’s arrival we were met with a new challenge preventing us from successfully capturing Zeus – Chaska, the first ocelot we trapped! Chaska began visiting the traps in the early evening and, mimicking Zeus’ behavior, would leave her back leg in the doorway as she stretched her body as far as possible to the back of the trap. This resulted in the door coming down and bouncing off her foot, which gave her just enough time to slip under the door. Each morning the team crowded around the computer to watch footage from the camera traps placed outside each box trap. With great despair (and slight amusement) we watched as Zeus approached the traps late in the evenings and curiously tried to open the doors that had been left shut after prior visits by Chaska.


Two of our field assistants, Marlon and Alberto, became determined to outsmart Zeus. On one particular day, they spent over 6 hours constructing their own modified traps, each convinced that their own trap design would be the one to finally capture Zeus. Marlon’s design involved removing the door from one box trap and connecting that trap to a second trap, thus creating one very long trap. Surely Zeus would be enticed to the back of the trap (thus unable to leave his foot in the doorway) where a speaker broadcasting baby chick calls and the smell of chicken would greet him! Alberto decided to remove the push plate from his trap and instead thread the wire connected to the door to the back of the trap where a small piece of chicken fat hung at the end. Alberto was convinced that Zeus would be so concentrated on removing the bait at the back of the trap that he would forget about the door and it would close securely behind him.

marlon inside trap

Marlon modifying one of the traps in hopes of finally capturing Zeus.

The following morning we split up into three teams to check traps. Marlon eagerly volunteered to check the route where the two modified traps were located. I could tell by the look on Marlon’s face that he was certain Zeus would be waiting in his modified trap. When I arrived back to the station Marlon was sulking in the lab — both of the modified traps were closed with nothing inside. We inserted the camera trap SD card in the computer and were astonished by the first video, in which Zeus was inside Marlon’s long trap with the door securely shut behind him! After skimming through an hour’s worth of video, all showing Zeus sitting inside the very closed trap, the camera suddenly stopped working. A flood of thoughts rushed through me and everyone on the team suddenly began talking at once. How in the world did he escape? Why did the camera stop working? What if he is hurt? My number one goal was finding Zeus (remotely via spotting him on other camera traps) to make sure he was uninjured. I was also certain that our chances of getting a GPS collar on him were zero, as he would never enter a trap again.

To distract myself, I started showing Renata videos and photos of Chaska. I was describing to Renata how comfortable Chaska appeared with our team and the traps – she seemed completely at ease and not at all scared. In one camera trap video taken after she was captured but before our team arrived to the trap site, Chaska is seen stretched out on her back lounging comfortably with her feet in the air. In another video, she causally bats at a leaf poking into the trap. Renata commented that she had collared an adult female ocelot, Moro, several years ago only 200 meters from where we captured Chaska and that female exhibited a similar laid back behavior. A couple of hours later Renata showed me photos from her capture of Moro in 2008. I casually commented that Moro looked a lot like Chaska. We started to compare photos of Moro with photos of Chaska and could not believe our eyes. The two ocelots had the same exact spot patterns! As we compared various photos, we realized that indeed we were looking at the same ocelot.

Moro is Chaska

Renata’s photo of Moro is shown on the left. Our photo of Chaska from August is shown on the right. Ocelots have unique spot patterns that can be used to identify individuals. The highlighted sections show that Moro and Chaska are actually the same cat!

This is incredibly exciting news for several reasons. In 2008, Renata estimated Moro’s age to be around 2.5 to 3 years (based on body measurements, canine length, and dental wear), which means her age is now estimated around 8.5 to 9 years old! Ocelot lifespan in captivity can exceed 20 years but in the wild they are said to live from 8 to 13 years of age. While Chaska (or shall we call her Moro?) is getting up there in age, her blood panel results indicate she is in good health. Even more exciting, we can now compare Chaska’s ranging behavior and activity from 2008-2009 with our current data from 2014-2015. Chaska wasn’t done doling out surprises just yet. Not long after capturing her, she appeared on our camera traps with a beautiful female kitten! There was no evidence that Chaska was lactating at the time of her capture and the presence of the kitten out on the trail system suggests it is already a few months old. We’ve been able to monitor the kitten over the past few months via camera traps and it has been exciting to see her grow!

Read on to our next post to find out what became of Zeus!

Erica’s Do and Don’t Guide to Following Sakis

By Erica Charnock (volunteer research assistant)

It’s pretty impossible to say what a day following a group of sakis is like because each day is completely different; however, a guide can be useful.

When following sakis DO:

  • P1040085

    Erica and Emily after an attempt to follow sakis during a torrential downpour.

    Make sure that what you’re looking at is actually a saki: termite mounds and knots in trees can be deceiving. Binoculars come in handy for that.

  • Keep your eyes on the monkeys as often as possible. They could be sitting motionless for five minutes but chances are that as soon as you take your eyes off of them, they will have moved away silently.
  • Watch out for falling objects. It could be poop or discarded fruit, either way it’s unpleasant when it lands on you from 30m up.
  • Always bring a camera. You never know what other animals will show up or when the sakis will decide to become photogenic.
  • Watch out for spikey things. Ferns, palms, vines, and trees all have potentially lethal spikes and are all found in saki home ranges.
  • Come prepared. Rain can come in without notice, batteries die quickly, pens get lost, etc.

When following sakis DO NOT:

  • Monkey watching

    Erica watching huapos.

    Confuse other monkeys for the sakis that you’re following. It’s easy to start following a movement in the canopy or a crash on a branch but when you finally realize it’s a capuchin or tamarin or even just falling leaves, your saki will be far away.

  • Worry about falling/sliding down the cliff-side. If they’re going down to the palm swamp, so are you. Falling on your butt is the fastest way down and there is no shame in that!
  • Forget snacks. Following sakis takes a lot of energy so you’ll need to replenish. Watching sakis feed for hours at a time can also make you hungry. Vanilla Dia’s somehow taste better out in the field while following sakis than when you eat them in the comedor.

A day of following sakis will always be an adventure. It can be extremely fun but also difficult. My best advice would be to always remind yourself that you’re in the Amazon and exceptionally lucky to get to see what you see and do what you do.


Meet Zeus, a male ocelot that our team has been trying to capture and radio collar since August. Zeus has outsmarted us time and time again by activating our traps without getting captured. We have modified our traps in various ways to no avail. Notice in the second clip that the door on the trap behind him is closed!

Introducing the predators: Chaska, Nina, and Zeus!

By Dara Adams

Our team has been attempting to trap and place radio collars on ocelots since May. The goal is to use camera trap and telemetry data on felids in conjunction with data on saki monkey behavior and movement to determine whether sakis are perceptive of felid movement and activity patterns. In July we were very close to capturing a female ocelot we named ‘Chaska,’ which means ‘star’ in Quechua. During our last night of trapping with our vet Jesús Lescano, Chaska finally entered a trap and triggered the door but she bolted out so rapidly that she barely escaped under the trap door as it closed shut. We placed camera traps (which are triggered by movement) outside of each box trap and it was excruciating for our team to watch the video of Chaska’s escape!

Chaska in trap

Chaska calmly waiting in the trap before immobilization.

In August a veterinarian named Nancy Carlos arrived to oversee the capture and immobilization of ocelots. We opened all the trap doors around 4 o’clock in the afternoon the day Nancy arrived and only four hours later Chaska was staring back at us from inside a trap! She was sitting calmly and was quite beautiful! We briefly immobilized her so that we could examine her body, take blood samples to assess health, and fit her with a VHF collar. Since then we have been tracking her movement via radio telemetry and she thus far spends more than 85% of her time within the home ranges of our two saki focal groups.

The team working on Nina

The team (Marlon, Alberto, Nancy, and Dara) taking blood samples to assess Nina’s health and fitting her with a radio collar.

A few days later I was sitting in the lab with Nancy reviewing camera trap footage as the team was out on their morning routine checking box traps. Alberto Escudero, a local assistant to our project, calmly entered the lab and very casually said, “There is an ocelot in the trap on trail Huaperito.” For a split moment Nancy and I thought he was joking because of his nonchalant demeanor but we quickly realized he was serious when we saw the beads of sweat on his forehead (he must have dashed back to camp after finding a cat in the trap).

The team with Nina

The team with Nina (From left to right: Nancy Carlos, Alberto Escudero, Kailin Olufs, Dara Adams, Marlon Guerra, and Gordon Ulmer).

I sprang from my chair and ran out of the lab to locate the rest of the team when I saw Kailin, a student volunteer, and yelled for her to get ready because there was an ocelot in a trap. She responded, “Yeah, I know. Wait…how did you know?!” As it turned out, Kailin also checked a trap that had an ocelot inside, so there were TWO ocelots trapped that morning, and they were located only 300 meters apart. One of the ocelots was Chaska (again) and the other was a new female. While Chaska appeared calm and laid back, this new female was feisty, growling at anyone who dared to advance toward the trap! Fittingly, we named her Nina, which means ‘fire’ in Quechua.

We were able to follow the newly collared Nina for a couple of days and then lost her signal. We became increasingly concerned after a week of searching with no luck. Finally, Marlon Guerra, the other local assistant working on the project, located Nina’s signal late in the afternoon in a swamp not far from camp. Her signal was within 50 meters of Eleanor, a nearly 20-foot anaconda that also has a radio transmitter and has been monitored since May. The next morning Marlon located Nina’s signal again in the same location. He was extremely concerned that Nina had become an anaconda snack, but fortunately her signal started moving later in the morning and all is fine! We now have a better idea where Nina ranges and have been able to locate her much more easily.

During the last week of trapping, a male ocelot we named ‘Zeus’ started visiting some of our traps. He appears to be much larger than the females and is incredibly smart and agile. Zeus first figured out how to trigger the trap doors by pulling the push plate up (as opposed to stepping on it to push it down, which triggers the trap door).  As a result, the doors do not shut properly and he is able to escape. He then figured out that if he stretches his elastic body as far as possible he can inspect the trap and leave one foot in the doorway, preventing the door from shutting completely. As a result, our team was welcomed by closed trap doors every morning with nothing inside them!

We have also discovered that Chaska and Zeus have been ‘hooking up.’ Our camera traps have recorded hours of camera trap footage spanning over several nights of Chaska and Zeus taking turns sitting in front of camera traps. Every few minutes a different cat appears in front of the camera! Chaska is vocalizing in almost all of the videos so we are fairly certain she is in heat. With luck, maybe there will be a little Chaskita running around on the camera traps in a few short months!

Renata Leite Pitman, a wildlife veterinarian that has over 10 years of experience trapping felids, arrives today and we will begin our last trapping initiative. We are hoping to finally capture and collar Zeus, so stay tuned!