Breaking a coconut, the Pinocchio way

One of Cayo Santiago’s rhesus superstars, Pinocchio or 84J, made it to BBC News after Comins et al wrote a short article for the Journal of Ethology. The article recorded this particular macaque’s “innovative and highly beneficial foraging behavior.” They reported that this male rhesus has been able to open the coconut by tossing it on a cement dock or at any hard surface on the island until the hard shell cracks and the white flesh is exposed.

The researchers explained the mechanics of Pinocchio’s nut-cracking technique:

The coconut-opening behavior of 84 J has two notable components: a horizontal toss and an underhand vertical throw. The horizontal toss is used to transport the coconut as he moves towards the island’s dock. This is a useful technique since it is cumbersome for a largely quadrupedal rhesus to carry a coconut in one or both arms. The second component of the coconut-opening behavior occurs once 84 J has reached the rocky area near the island’s dock. Rearing back on his hind legs, he springs upward into a small hop while concurrently propelling his front arms upward in an underhand throw. Towards the peak trajectory of his hop and throw, 84 J releases the coconut from his front hands, projecting the coconut upwards and then allowing it to fall on the nearby cement or rocky terrain. This process is repeated until the shell cracks, allowing him access to the flesh inside.

ResearchBlogging.orgDespite the efficiency of 84J’s nut-cracking abilities, this innovation has not been transmitted to the Cayo Santiago macaques or to Pinocchio’s immediate group. Although Comins et al suggest a “systematic investigation” to understand this foraging behavior and its social learning implications, I would like to add my two cents anyway regarding the potential factors that may have prevented the transmission of  the nut-cracking skills from 84J to the rest of the troop:

Firstly, coconuts are high-energy expenditure food items requiring more effort on the part of the macaque forager (climbing, unhusking, throwing, breaking). Coconuts are said to be “plentiful” on the island, but may in fact be minimal if compared to the relative abundance of other low-energy expenditure food sources (e.g., monkey chow, leaves, clay, and mangrove saplings). The presence of these food items could be a factor in lessening the incentive for seeking out coconut as a food resource.

Besides in a small island like Cayo with a macaque population of around 1000, the number of actual coconut trees may not be enough to encourage coconut foraging unless, of course, if there is a food preference for coconuts over other food items. In this regard, given the relative scarcity of coconuts on the island, it would thus be interesting to investigate the frequency of 84J’s nut-cracking activities (ditto with the mention in the article of Berard’s account of two macaques opening a coconut in full view of conspecifics).

Secondly, one way to address the conundrum is to determine the position of 84J in the Cayo macaque social organization and his behavioral tendencies. For example, low-ranking males usually stay at the periphery with minimal interaction with most of the individuals while high-ranking males stay more (and get to interact more) with individuals in the group . Thus, the position of 84J in the dominance hierarchy (and the nature of male migration) may also have been factors in the non-transmission of this innovative behavior. An investigation into Pinocchio’s social behavior would also reveal the range of possibilities for transmission.

These blog ideas are mere shots from the hip. Comins et al’s recommendation for a systematic investigation into 84J’s behavior should thus be heeded in order to understand more thoroughly the nature of primate social learning and cognition.
Jordan A. Comins • Brian E. Russ •, & Kelley A. Humbert • Marc D. Hauser (2010). Innovative coconut-opening in a semi free-ranging rhesus monkey
(Macaca mulatta): a case report on behavioral propensities
J Ethol

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staring at them resting

Image courtesy of if in meditation, she sat on that gnarled mangrove branch with her head bowed, the chin almost reaching the top of her infant’s head. A sudden twitch and she pulled the baby closer to her chest, perhaps hoping that the throbbing of the heart would keep her from waking up. But, she was still sleeping. Or, at least, her eyes were closed. Then, the infant grasped the skin of her left breast, mouth closing in on the nipple, milking even more every square inch of the flesh that nursed an infant almost every year since her menarche.

About a foot away from the mother’s curved back, a juvenile curled on a horizontal branch made shiny by the constant rubbing of skin on bark. He looked comfortable: his head rested on crossed arms, legs hung limp, and the mouth slightly opened. He blended well with the earth-colored branches. It was a perfect resting spot–the branches descended to the ground like overgrown athritic fingers and the leaves were green, sometimes yellow, refracting the sun’s rays as stained glasses would.

The mother must be around 12, in her middle years if she was human. A few weeks from now, she will be pregnant again. Her face got the mask of estrous–swollen with blotches of crimson, like an embossed Cold War-era map. The back of her legs and the buttocks were swollen and deep red too, obvious signals for sexual receptivity. The males at this time hover around her–stalking and observing who she is with. Many times, higher ranking males chase her around if seen mating or in proximity with a low-ranking male. She would try to escape, shrieking and running; and if she is slower, the male’s inch-long canines would dig into her skin, sometimes ripping through her flesh. If she has enough females close to her (i.e., friends and relatives), then she has a better chance of escaping–the females in a series of feints and dashes will try to intimidate the attacking male, giving her space for a getaway.

Despite all the guarding that high-ranking males do however, researchers have found out that “male dominance rank was not associated with reproductive success” (Berard et al 1993). The study by Berard et al revealed that,

High-ranking resident males (N=5) sired 27% of the infants born during a one-year study. Four of the 11 infants of known paternity were sired by males of other social groups. The four infants of unknown paternity were sired either by males not observed mating with the females or the low-ranking male who was not fingerprinted.

Rhesus females also prefer novel males for mating. This female mate selection is thought to be one of the primary factors why males migrate out of their natal group. The migrating males, who are at the very bottom of the hierarchy, have to be in constant high alert, especially so during the mating season when high ranking males are on guard (i.e., those who are on top are particularly protective of their position on this period).

Only a few survive the ordeal and get accepted to the receiving group. Many of these migrating males prefer to hang out with the other males (an all-boys gang, so to speak), living on the fringes of macaque society (e.g., they only get to eat when the established groups are done and gone). They occasionally sneak into the group for a quick rump with the females but, if found, they get chased by everyone and quite a few have been seen jumping off from cliffs or to the water for dear life.

So, I sat there thinking about these while staring at the sleeping monkeys. These brood of three, motionless except for an occasional scratch or the movement of their bellies as they breathe, will wake up soon. In a little while, a male monkey will sneak in. And again, all hell will break loose.

On Island Tourists and Science

Today, a boatload of curious tourists went into Cayo Santiago, a government-run primate research island off the east coast of Puerto Rico. They surreptitiously entered right under the glaring NO ENTRY sign posted near the shore. With camera on hand and shouts of “Are there monkeys in here?!”, they disembarked from their speedboat and waded through waist-deep water. Probably thinking that the island was deserted because the CPRC lancha had left (i.e., it ferries the employees back to Punta for the lunchbreak), their guide let them through the mangroves and smack into a crowd of free-ranging monkeys.

I was partially hidden by the foliage while recording behavioral data on a sleeping monkey when I heard them coming. It is customary to have visitors snorkeling around the island, so hearing voices was not that surprising. Tourists usually come in rented boats and kayaks anchored about 20 meters from the shore. The sea around Cayo Santiago has beautiful sea grass beds and reefs festooned with all sorts of Caribbean marine life. Just a couple of days ago, a juvenile black tip reef shark swam along the cay, its dorsal fin jutting out of the glassy sea. I also saw three manatees a while back, bobbing their snouts in the air to catch breath while foraging on the lush sea grasses. The place does beckon nature lovers. And some of the riskier bent are just too reckless to ignore the danger signage posted everywhere on the island.

Seeing barefooted tourists on the island is unnerving, considering the risk of disease transmission between humans and rhesus macaques. CPRC sets a series of health and safety protocols to prevent the risk of zoonotic diseases. Failure to take even one test (of a host of other tests) means being denied from entering the island, even if your last name is Obama. Aside from this, researchers, students, and all those who come into contact with the primates have to pass a lengthy IACUC certification exam detailing the appropriate handling of the animals.

The safety measures are put in place precisely because of the real danger of zoonoses. Consider this excerpt from Jensen et al on the herpes B virus found in these free-ranging colony:

Whereas the effects of the virus are mild in macaque hosts, it causes a serious and frequently fatal disease in other primates, including humans. Once transmitted to a human, B virus infection has a nearly 80% case-fatality rate.

Tuberculosis, Shigella, and other pathogens, which might not be as lethal to humans, are very deadly to the macaques. Primate Info Net has an excellent list of zoonotic diseases recorded in the medical and primate literature. Primate Info Net:

Mycobacteria are responsible for tuberculosis, the scourge of the primate owner and veterinarian. Tuberculosis has been recognized as a common disease of captive primates for many years. Early outbreaks were devastating, causing the loss of hundreds of primates of many species.

So, there. For potential tourists who are reading this blog, the health risks are


The cultural anthropologist in me is amazed at the constant overlap of interests on the island.  It seems to me that there is a continuing tug-of-war with regards to the meaning of Cayo Santiago. For the scientists, the island is home to the free-ranging macaques, a repository of biological and behavioral knowledge for the past 70 years. For the tourist industry, Cayo Santiago is part of the Puerto Rico ecotourism package, the island of enchantment as they say. Tourism is what keeps the Puerto Rican economy afloat and Cayo Santiago does appear in tourist brochure as the enchanted monkey island. For the local fishers, the island is a crabbers’ paradise where they trap mantou crabs under the cover of darkness. They would catch the crabs, keep them for months to get the crabs “clean,” and sometimes sell them to roadside customers (who are mostly tourists too).

Before I got involved in a primatological research (of the biological bent), my original intention was to conduct an ethnoprimatological project as my dissertation. I wanted to investigate the social history of primates in Puerto Rico, with the purpose of understanding the axis of science, colonial politics, and primates in the island. There is a substantial glut about this in ethnoprimatological and anthropology literature and I thought this would be a nice dissertation topic. But I am on the verge of abandoning this project as I became more enamored by the biological side of primatology–a training that is almost absent in the Philippines (I got a few via a short Fulbright exchange program with New Mexico State University,  my involvement with the Philippine Tarsier Foundation, and with University of San Carlos, my home university).

Seeing the opportunity to learn more about anthropology and primates in general, I applied for the research job and got accepted. I believe, after this, I will be your typical Swiss knife anthropologist–not quite a specialist but got enough knowledge to teach anthropology students back home. I am hoping that once the research project is over I’ll get back to my home university and inspire students once again to get more interested in anthropology. Perhaps through this, the Philippines will have its own Jane Goodall or Louis Leakey in the future. Who knows really, right?


Before I leave, let me share these youtube videos of tourists in Cayo Santiago. I chanced on them while cybersurfing about the island.

Tourist hitting a male macaque after presumably feeding it

Tourists on the island (p.s. listen closely to the audio).

Iguana catching on the island. Puerto Rican iguanas are not scared of humans. You can actually pick them up without any hassle because the feral pet iguanas in Puerto Rico got no natural predators.

Jensen K, Alvarado-Ramy F, González-Martínez J, Kraiselburd E, & Rullán J (2004). B-virus and free-ranging macaques, Puerto Rico. Emerging infectious diseases, 10 (3), 494-6 PMID: 15109420

Learning Monkeys

I have been learning individual monkeys for the past few months. It is very challenging considering that the species I am more familiar with are the Philippine tarsiers and, cursorily, the long-tailed macaques. The only time I saw a live rhesus was during a visit to a zoo in Albuquerque, NM. Now, I have around 150 rhesus monkeys roaming in a 15-hectare island to learn from and identify.

The first few days were a real challenge. The monkeys looked no different from the other macaques elsewhere: quadrupedal, diurnal, sexually dimorphic, a hair ball with a human-like face.  The difficulty of learning the monkeys was compounded by my initial fear of the primate. Not so much that they are potential carriers of several pathogens, Herpes B among them, but the possibility that they might charge and rip the flesh off my leg–like that neighbor’s dog that crunched my behind when I was a kid.

The male rhesus weren’t interested in taming my wild imagination at all. A male monkey would cross my path from time to time, a  foot away or less, sometimes stepping on my shoe, as if letting me know that he can invade my personal bubble whenever he wants to. This constant flaunting of male rhesus authority in the island however made me immune to this display of power.

Almost often too, the beauty of the island diverts my attention away from the macaques. Cayo Santiago is composed of two small islands connected by a narrow semi-circle shaped sandy isthmus. The island is embraced by the emerald sea from all sides flourishing with all sorts of marine life. Manatees sometimes forage on the abundant sea grasses growing along the littoral zone. A lone osprey haunts the skyscape of the island. Iguanas–descendants of feral reptilian pets–also reside there together with a solitary Puerto Rican boa and a host of mantou crabs, egrets, pelicans, herons, etc.

Learning the monkeys was a painstaking process of gaining the census takers’ perspective. The census takers–our primary mentors–were tasked to teach us the basics of memorizing individual monkey IDs (Us here means Jackie and I. Jackie had experience working with baboons. A dive instructor and a primatologist, she has worked in both terrestrial and marine contexts). We went out with them as they take the census of each animal on the island. The census takers, with years upon years of experience, can identify each rhesus on the island with ease (around 1300 individuals). I suppose a shadow of the monkey’s tail from the bushes is quite enough for them to identify.

While the monkeys have ear notches and tattoos to aid researchers in recognizing individuals, it was the constant interaction with the macaques that allowed us to identify individuals. Anything particular and unique of each monkey became more noticeable. The scars, which were previously absent from my gaze, became primordial signposts for monkey identity along with other distinguishing characteristics like color of pelage, brow shape, crest shape, injuries, etc. Our little names for the monkeys also helped in many ways, perhaps because by anthropomorphizing, we render their traits comprehensible to our human experience. For example, I named one monkey Andy Garcia because his eyes droop, making him look like a guilt-ridden macaque mafiosi. Another was named as The Grinch because her face is similar to that classic Dr. Seuss character. There is one we call Feets because he has an extra set of toes jutting out of his left foot.

As the days went by, we moved from recognizing appearances to sensing individual temperaments. Similar to their human cousins, every monkey is an individual in their own right. One old male monkey, Leaf Boy, caught our attention because of his penchant for sticking a leaf under his upper lip. He would go around the island walking with a leaf dangling from his mouth. It does not matter what kind of leaf it is as long as it hangs there. Admittedly, he looks pretty cool with it (in the human sense, that is). But the youngsters haven’t quite got the hang of it. So this leaf habit might end with him. Another is Pinocchio–he got his name from an old nasal injury–who is the only monkey on the island  able to figure out how to open a coconut. He would unhusk the coconut, throw it up in the air repeatedly until the nut cracks. This behavior too has not caught on with the troop.

Right now, we are recording each individual’s behaviors in the Psion. Hopefully, our effort will contribute more to the understanding of this species.

**note: all images are taken from various websites.

The Dolphins of Punta Santiago

Dolphins followed our boat as we navigated the narrow stretch of sea that separates Cayo Santiago from the rest of Puerto Rico. They slid up to the surface, showed their glistening backs, and then dove back to the placid water. After a few minutes, they repeated the same maneuver, a bit closer to the boat this time. Their bodies sliced through the calm sea without any ripple, as if their slow jumps were just the occasional ebbs of the Caribbean Sea.

They blended perfectly into the marine environment that sometimes I forget that dolphins aren’t fishes. Instead of moving their tails sideways like their gilled neighbors, dolphins move their tails up and down, akin to the stride of a galloping horse. While fishes drop their eggs, spreading bubbles to the sea, dolphins suckle their young. In their distant evolutionary past, a dolphin ancestor, the mesonychidae, once lived inland–foraging in the shores of what is now Africa. Scientists suggest that this ancestral family lived close to the banks of rivers, feeding on mollusks and slow fishes. As the competition for resources grew fiercer, adaptive traits for catching faster fishes were selected for–slowly moving them to a more aquatic lifestyle and evolving a morphology fit to such an environment. Gradually, through millions of years, characteristics unfit for marine life were lost. The nostrils moved to the top of their heads to facilitate breathing, together with a host of other adaptive mechanisms, such as a fusiform body for fast swimming.

These dolphins have gone a long ways indeed. Yet, the years of evolutionary selection have not prepared them enough from the impact of human activities.  Nathalie Ward of the Eastern Caribbean Cetacean Network (ECCN) reported that, “The growing exploitation of coastal resources, degradation of habitat, accidental capture, contamination, acoustic pollution and tourism are serious threats to whales and dolphins in the Wider Caribbean, which extends from the Gulf of Mexico, across the Caribbean, to the adjacent Atlantic.”

I stood up from the lancha as I watched the dolphins disappear from sight. They swam away towards the open ocean, breaking the surface once in a while, as we approached the dock of Cayo Santiago. They swam farther until their backs were like shadows of sea waves, completely unaware of that oil slick that drapes the seas  of the neighboring Gulf of Mexico.

how the day started

BBC’s Faulty Tarsier Video

Here is a video from BBC on the tarsiers of Bohol. Nice but faulty.

The nice part. I am glad to see Nong Lito Pizarras being interviewed. He knows these primates better than anyone. He has no graduate degree to his credit but his knowledge about the primate is worth a library of books. His experience working with tarsiers has proved indispensable in the conservation efforts of the Philippine Tarsier Foundation, Inc. Absolutely no tarsier research project has ever been done in Bohol without the help of Nong Lito. While graduate students have moved on, Nong Lito remains in Bohol, dutifully attending to the conservation demands of this primate species.

The faulty part. There are glaring errors in the BBC tarsier report. While the tarsier is indeed a fascinating primate, it is not the world’s smallest nor the oldest primate species as BBC contends. With regards to the claim that the tarsier is the smallest primate, Philippine tarsiers’ head and body length is 11.7-12.7 cm while its average weight is 67-112 g. Compare this for example to a mouse lemur species (M. jollyae), its average head and body length is at 5.3 cm and average weight is 61.3 g. Is the Philippine tarsier the oldest primate? A cursory look at fossil primates automatically disqualifies the tarsier as the oldest primate. Besides, primatologists are of the consensus that the Philippine tarsiers are more recent than the other tarsier species from Borneo and Indonesia. In a previous post, we noted that ” Philippine tarsiers may have migrated from Borneo through the Sulu archipelago, arriving sometime in the late Miocene to mid-Pleistocene.” Furthermore, there were a bunch of primate species whose existence can be traced back to the late Eocene like the lemurs of Madagascar.

The worst offense in the BBC video report is classifying tarsiers as marsupials. This completely removes the T. syrichta from the primate order. Tarsiers do not put their infants in a pouch but “park” their infants. Relative to the mother’s size, tarsiers have one of the largest infants in the entire animal kingdom (30% of the mother’s body weight). Mothers have to leave their infants in order to forage and then return to pick the infant up (this is called “parking”). I cannot imagine tarsiers having an over-sized infant inside a marsupium. This would render the primate immobile and break all the ankle bones of this vertical leaper and climber if it attempts to jump to the next branch. Suffice it to say that BBC, please, not all animals that leap are kangaroos.

Here is BBC’s video:

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more about “BBC’s Tarsier Video“, posted with vodpod

Ethnoprimatology in Sulawesi: Macaques in Farms and Folklore

Ethnoprimatology is a relatively new field that looks into the interaction between humans and nonhuman primates. Les Sponsel (2008) describes the ethnoprimatological approach as emphasizing on the “behavioral and ecological interactions between populations of human and nonhuman primate species inhabiting the same ecosystems. It serves an integrative function at the interface of anthropology and biology on the one hand, and the interface of biological and cultural anthropology on the other.”

Erin Riley and Nancy Priston’s  paper on the Indonesian macaques is a great addition to the growing literature on ethnoprimatology, an approach introduced by Les Sponsel and later on expounded and refined by Agustin Fuentes and other primatologists. The authors investigated the cultural location of the macaques in Indonesian cosmology as well as the human-macaque resource use overlap in Central and South Sulawesi and in the island of Buton using ethnographic and ecological methods.

They ascertained the impact of macaques on cash crops, specifically cacao (an important Indonesian export), by comparing the crop loss data caused by the macaques, squirrels (Prosciurillus sp.), and rats (Taeromys sp.). Semi-structured interviews and focus group discussions were also conducted on elders, farmers, and plantation owners regarding local perceptions and folklore related to macaques.

Their research suggested that “although humans and Sulawesi macaques exhibit considerable overlap in their uses of cultivated resources, the current level of resulting conflict is relatively low.” This is because macaques figure prominently in ecological and religious narratives for many of the ethnic groups in the island. The authors posited that “Tonkean macaques are seen as kin and guardians of adat (traditional law); noted as biologically similar, and hence of human origin; and are recognized as key members of their shared ecological environments.” The consumption of macaques is considered as haram among Muslim residents while Balinese Hindu were more likely to kill monkeys opportunistically. Some farmers in Sulawesi also view monkeys as beneficial because they help harvest without damaging the seeds.

Moreover, Riley and Priston said that  cacao crop damage due to macaques is much lesser than that of the rats. They however cautioned that macaque crop raiding may intensify in the future and will pose conservation management problems. The shift from traditional agriculture to cash crop production will intensify human-macaque conflicts, because “macaques raid cacao regardless of levels of forest fruit availability and that frequency of guarding by farmers had no effect on crop raiding levels.”

Riley and Priston’s research pointed at the importance of using anthropology’s holistic approach in primatological studies and conservation management. Culturally-sensitive studies, such as this, help thwart conservation plans that often do not involve local communities. Conservation agents can learn more by integrating indigenous knowledges into their plans. Ethnographic studies are rife with examples indicating that inscribed in the local culture is an ecological knowledge useful for conservation.


Riley, E., & Priston, N. (2010). Macaques in farms and folklore: exploring the human-nonhuman primate interface in Sulawesi, Indonesia American Journal of Primatology DOI: 10.1002/ajp.20798

Sponsel, Les. 2008. Ethnoprimatology from the Amazon to Thailand and Beyond: Engaging the Inspiration of Kenneth A. R. Kennedy in Pursuing the Four Field Approach. Paper for annual convention of the American Anthropological Association in San Francisco, CA, November 19-23, 2008


Special thanks to Raymond Ho of Prancing Papio for generously sending me this paper.