A Quick Update: Sapajus cay demographics paper now available!

The first publication to come from the Para La Tierra Primate Project is now available! "Using Camera Traps to Determine Group Demography in a Paraguayan Population of Sapajus cay" has been published in Issue 22(2) of Neotropical Primates!

If you would like to read the full article you can access the full article on my research gate profile (Rebecca L. Smith) or send me a message through this blog.

Emily and I would like to thank all the PLT staff, volunteers and interns who assisted with this project and all the people that donated to our YouCaring fundraising campaign that allowed us to buy the two HD camera traps used in the the study.

Thank you everyone!

Monkey Methods

Arguably the most widely known fact about capuchin monkey behaviour is that they use tools. Capuchins have been seen in both captivity and the wild using a wide variety of tools and it allows them to access food sources that they wouldn’t be able to normally exploit. There are lots of examples of different capuchin species (both Cebus and Sapajus) using various tools. Blonde and black-capped capuchins (Sapajus flavius and S. libidinosus) living in the Brazilian Caatinga use hammer stones and anvils to smash hard shelled nuts (Ferreira et al. 2009). An adult male white-faced capuchin (Cebus capucinus) in Costa Rica was observed using a branch as a club to kill a venomous snake (Bothrops asper) (Boinski 1988).

Credit: Barth W. Wright/Kansas City University

Profitt et al (2016) reported in Nature that black-capped capuchins in Brazil smash rocks, producing flakes and cores that have the same characteristics of the tools produced by our own ancestors - a huge discovery. Check out a great video and article on this behaviour here:

http://www.nature.com/news/monkey-tools-raise-questions-over-human-archaeological-record-1.20816?WT.mc_id=FBK_NatureNews

I haven’t yet seen full tool use in my capuchin groups in Laguna Blanca but we have seen complex object manipulation. The capuchins use “First Order” manipulation techniques. This means that they combine an object with a hard surface or another stationary object. In Laguna Blanca the capuchins smash the hard-shelled fruits of the Ka’I Ka’gua tree (Cariniana estrellensis) to loosen and access the seed inside.  The capuchins use two different techniques to open the fruits involving hammering the fruit using one hand or using two hands and the entire body weight to hit the fruit on the branch. The younger monkeys are not very good at opening the seeds and their attempts often ending up with the fruit flying unopened out of the tree as they rolled it along the branch and then let it go!

Adult capuchin selecting a fruit to hammer.

This information is the first description of this behaviour in wild Paraguayan capuchins and a full description of the techniques has recently been accepted for publication. Watch this space for information on when the article will be available!

This fascinating behaviour is something that we are keeping a close eye out for in our studies of the capuchins in Laguna Blanca. In the future I hope to be able to investigate whether this behaviour is a socially learned, like nut smashing in other capuchin species (Fragaszy et al. 2013) and how much variation there is in smashing technique between individuals of different age and sex classes.

Why habituate?

When you set out to study primates in the wild there are a lot of things to consider. What are you looking to find out? What species will best answer your question? What habitat do your primates live in? Is that country even safe to travel to? As you narrow down these choices you are narrowing down your choice of field site. Are you going to an established field where the primates are already habituated to the presence of people or are you going to establish a site and habituate a new population?

Habituation? What is that? Habituation is an on-going process whereby study animals lose their fear of humans through frequent neutral exposure to researchers. The loss of fear eventually leads to the study subject ignoring the observers. Behavioural studies of non-habituated primates yield very little results, since it is often not possible to observer natural behaviours, as they tend to flee as quickly as possible or only threaten observers.

How long this process takes is dependant on both the species of primate you are dealing with and the situation at your site. Bushbabies (Galago spp.) can be habituated in an hour, chacma baboons (Papio ursinus) in 2-5 months and lowland gorillas (Gorilla gorilla) can take anything from 5-15 years (Williamson & Fiestner, 2011). When I arrived at Laguna Blanca the capuchin monkeys were completely unhabituated and the older monkeys had almost definitely been hunted during their lifetimes. I knew it was not going to be easy, I didn’t know just how hard it would be!

Photo Credit: Anna O'Riodan

Finding the capuchins was challenge number one. There are several different ways to search for your primates. You can sit and wait in an area that you know they will pass through; you can walk around their home range looking for them or provision animals at selected locations (although this has its own risks and should be done with care). The forest fragment in Laguna Blanca has a trail system that allows us access through the dense, spiky vegetation. Capuchins are not the quietest of creatures. They are very destructive foragers and can be heard at quite a distance crashing around in the trees. The noise of the capuchins moving in the trees was my auditory cue, alerting me to their presence long before I saw them. Once I had located the capuchins it was always tempting to hide from them and watch their fascinating behaviour but to achieve habituation you have to be seen, even when you know it means they will probably run away. 

The trail system of Laguna Blanca Atlantic Forest.

Subadult capuchin foraging in a Ka'i KaGua tree

During my first few months, when I did manage to find them, they always fled. It was frustrating to say the least. As time passed, I began spending longer and longer with them. The adults would threaten me and break branches and try and drop them on me while the juveniles played chicken to see who could get closest to me. Now it is nearly 4 years later. O Group is much more habituated to my presence than F Group and slowly getting to know their personalities has been so rewarding. I still get threatened every now and again and, when they get really mad, sticks thrown at me. However, now they tolerate my presence and let me have glimpses into their lives. It has been a long road to get to this point but when I see the monkeys feeding or grooming one another it feels like a privilege and I am amazed at how lucky I am to get to spend so much time with these fascinating creatures.  

My boy Damien. He will always be my favourite.

A Quick Update: Guess Who's Back....

In June 2013 myself and two volunteers stumbled across something amazing: two adult female Black and Gold Howler monkeys and a small juvenile. It had been years since this species had been seen on the property. I reacted pretty well, basically collapsing again a tree and starting to cry! As there were no males we never got to hear their distinctive roaring every morning and they very quickly disappeared again. That is...until today!

While sitting on a log waiting for the capuchins to come back we were startled by a loud crash directly behind us and a noise that could only be one thing! Three adult females and a juvenile howler monkey hanging out at the top of the flooded forest! Here are some photos of our furry friends.

All my photos are my own.

Benefits of Bad Table Manners?

When you work with capuchins you notice very quickly as you creep around the forest that when they feed in a fruiting tree, they tend to leave behind an absolute disaster. Capuchin monkeys are incredibly messing eaters. They waste a lot of fruit, which ends up mostly lying on the forest floor. Maybe waste is too strong a word. At the very least, the nutrients from the fruits go back into the soil, enriching it for other plants or ants and other insects get to enjoy a feast. But the primate team at Para La Tierra wanted to know if anything a little bigger than insects was benefitting from the remains of capuchin dinnertime.

Interspecific associations have been observed between several species of capuchins and other large mammals including peccaries, coatis, tayras and howler monkeys. In 2014, Tortato et al. released a short article documenting collared peccaries following groups of hooded capuchin (Sapajus cay) and eating the leftover palm fruits in the Brazilian Pantanal. Collared peccaries are a species that we have in Laguna Blanca and we decided it would be interesting to find out whether or not there would be any such interspecific interactions here.

Intern Kelly joined the primate team in May 2016 to carry out data collection on the dietary diversity of the capuchin groups for her masters project. During her internship we decided to pilot the interspecific associations study. Armed with camera traps, she began spontaneous data collection to test the theory that other mammals eat capuchin leftovers. During her monkey follows, she would set up the cameras facing the bases of the fruiting trees that the monkeys had recently visited. The cameras remained out for three or four days.

Almost immediately the cameras yielded exciting and often surprising results! Actually eating the fruit we filmed 6 different species: the crab-eating fox, Azara’s agouti, an unidentified Didelphid opossum, brown rats (unfortunately!), the Brazilian rabbit and the South-American coati. The most frequent visitors were definitely the agoutis! Appearances were also made by other species that didn’t eat the left over fruit including red brocket deer, nine-banded armadillos and, most excitingly, an oncilla and the reserve’s first record of a margay! The two cats are extremely similar and were very difficult to tell apart in the videos and photographs that we have but we are now sure judging from tail length in relation to body length!

Some of the camera trap photos we have snapped so far.

This project is now going to continue under the care of new primate intern Gabriel. Hopefully we continue to get such exciting results!