Wildlife Handling: Primates | Field Projects International

Wildlife Handling: Primates

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Detailed Description

This volunteer training program targets participants with an interest in wildlife handling, zoology, or veterinary science. It program will provide training in the context of an annual mark-recapture program on tamarins in southeastern Peru.  Each participant will individually handle upwards of 25 animals of two species of primate, while gaining valuable knowledge on the natural history of the 9 other primate species present at this site.

The annual mark-recapture program at this site is unique in that it does not disturb habituation to the observer.  All capture events are conducted using a multi compartment trap into which the animals voluntarily enter – we do not coerce them in any way or tranquilize them using darts. Once captured, they are processed using verified protocols and released within a few hours of capture.  In addition to the invaluable information gleaned on the health of this wild population of tamarins, we are also able to provide each individual with a temporary tag that will drop off within a couple of months. This greatly facilitates the collection of detailed behavioral data that is individualized for all animals in the program.

Our protocol is comprehensive and puts the comforts and safety of the animals above our own. For example, to ensure the maximum security of the animals, we conduct all processing in the jungle, at the trap site. We work with a single group each day, checking every individual in the group as a whole, so that we do not alter their social dynamics. We begin very early, often setting up our processing tent before dawn and typically begin working with a group by 10 am. This ensures that our groups are released in a few hours on the same day they captured, thus causing as minimal a disruption of their lives as is possible. We are proud to say that our program does not cause the animals any noticeable harm, and that every animal that has been captured once through the program and that is present the next year, has been captured again.

All of this work is sanctioned by the Amazon Conservation Association, the Animal Care Committee of the University of Missouri, St. Louis, and the Ministry of Agriculture and Forestry in Perú.

There is a serious lack of available training for those interested in working with wild animals today. Due to our rigorous training protocols, we are a singular resource of training and opportunity in which trainees will gain a number of invaluable and unusual skills in this program that are not easy to come by.  Our applicants typically are zoology majors, anthropologists and veterinarians/pre-vet students, but all you really need is a willingness to work hard and a demonstrated interest in the project.

At the end of this program, research assistants will be able to:

  • Construct an animal field processing kit
  • Collect biological samples from the primates
  • Determine sex and appropriate age of individuals by morphological characters for two primate species
  • Learn appropriate handling techniques for wild primates
  • Record TPRs at regular intervals (temperature, pulse and respiration)
  • Manipulate a weighing scale to accurately record the body mass of subjects
  • Store and process biological samples for analyses of endocrinology, parasitology and reproductive physiology
  • Manage and work in a laboratory like no other.


We are currently recruiting participants with the following requirements.  If you are uncertain if you are eligible, contact us to confirm.

  • Participants must be at least 18 years of age by the time the training program begins
  • Participants must demonstrate a grounding or strong interest in animal handling and biology
  • Participants must be certain that they are not squeamish at the sight of medical equipment
  • Previous field experience is not required, but previous handling experience (or some contact with animals other than your pets) is a plus
  • Participants must justify why this program is important to them, and what they hope to gain from it
  • Participants must provide a letter of recommendation from a source that can substantiate the participant’s experience and skills
  • Participants must be in good physical condition, with the capability to walk 4 miles a day
  • Participants will not be discriminated against for medical conditions they might have, if we determine that being on this project will not pose an immediate risk to their health
  • Participants must sign waivers of liability for this project and for the field station before their participation in the project is finalized
  • Participants must be willing to maintain long hours in the field, and return to complete data entry in the evenings.
  • Sometimes we wait and are unsuccessful – this is the nature of the work. Participants must demonstrate patience
  • Participants must be reliable – when a team is assigned to work with a group of animals, days of planning go into the execution of the protocol. Carelessness and tardiness on the part of the participant could jeopardize the entire project.
  • Due to the nature of the work and weather constraints, participants MUST be willing to be flexible about their schedules
  • Participants must exhibit a willingness to adjust your schedule to primate daily activity patterns. This can require waking up early, sometimes by 4 or 5 am, and going to bed early, 8 or 9 pm.

More information is available on travel requirements and the Los Amigos Field Station, as well as Frequently Asked Questions.


Quick Info

Program dates: May 27 – June 30
Start date: May 27, June 3, June 10
Minimum commitment: 4 weeks
Application deadline: April 15, 2018
Program fee: $1800 (includes food and lodging, transportation to the field station from Puerto Maldonado and back, training and use of field equipment)

Primary Investigators

This project has been running since 2008, and the primary investigators working on it currently are Gideon Erkenswick, Efstathia Robakis and Mrinalini Watsa.  They have extensive experience handling primates, and have conducted a capture-and-release program at this site with the tamarins for eight years (as of 2016).  They have also conducted over  2000 hours of behavioral observation on the callitrichids at this site, and trained over fifty students on these techniques.  The data analyses are presented here by Mrinalini, and are an offshoot of her doctoral thesis.

Background Information

The Callitrichidae are a family of small New World primates with a suite of distinctive morphological and behavioral adaptations that set them apart from other primates.  Of primary interest is their reproductive system that includes compulsive twinning (>80% of births) and cooperative care of offspring by individuals other than biological parents (termed alloparenting).  Further, hematopoietic tissues in callitrichids display signals of both self and sibling DNA, due to an exchange of stem cells early in gestation that renders twin callitrichids as cellular mosaics of each other. This phenomenon is known as genetic chimerism, which increases genetic relatedness between individuals and is likely maintained by cooperative breeding systems.

The Callitrichidae are thought to be phyletic dwarfs that exhibit habitual twinning as a derived feature, and accompanied by their tolerance for genetic chimerism, are an important clade to study the evolution of primate reproductive system that has adapted to increased reproductive outputs. They are suspected to be highly polyandrous, where additional male mates assist in the care of a dominant female’s reproduction, and subdominant females are reproductively suppressed so that all efforts at alloparenting are directed towards offsetting the high energetic costs of raising a single set of infants of the dominant female.

To better understand the evolutionary advantages of this system of reproduction, it is important to document group structure and membership, as well as individual dispersal, reproductive success, and the development of offspring across callitrichid species.

Project Outline

The goal of this study is to examine group structure, reproductive success and individual growth and development to assess two sympatric Saguinus spp.   All data are evaluated in light of the reproductive system proposed for these callitrichids – strict polyandry, cooperative breeding, reproductive suppression, and single reproducing females – in the context of future genetic studies.  As such, we attempt to achieve three specific goals:

  • an examination of morphological variation between two sympatric callitrichid species to classify individuals into precise developmental classes
  • an evaluation of age and reproductive status per individual
  • a comparison of group compositions, mating systems and dispersal patterns of both species to the expected callitrichid reproductive pattern.

How we work with very small monkeys

We monitor two sympatric species of callitrichids in southeastern Perú at the Los Amigos Field Station, and have been doing so since 2008.  Over the course of this study, we have worked with nearly 180+ individual saddleback tamarins (Saguinus weddelli, also Leontocebus weddelli, see Garbino et al. 2015 ) and emperor tamarins (S. imperator) to date. We use a modified trapping protocol for capturing callitrichids with a dual- step anesthetization protocol that increases animal safety and preserves habituation, resulting in nearly 100% recapture rates. We record 19 measures of morphology and dental condition for all subjects.

We use dental morphology to estimate age for animals < 1 y old (via dental eruption timings) and are developing age categories for animals > 1 y old via analyses of molar occlusal wear. We assess changes in morphology with age and sex for both species, and use reproductive morphology to assign developmental status to adults, identifying mature, immature, and non-breeders for both sexes (preprint of our paper, Watsa et al. 2015). We then identify the predominant mating systems present, based on the number and sex of adults of different developmental classes in groups of both species.

Our results (as of 2012)

Age-structures, or the pattern of the number of individuals in each age-class for a species, that were predicted by dental wear did not differ significantly between species, or between the sexes for each species. Further sampling of younger adults in the study population is one of our future goals, so we can conduct population viability analyses. Adult Saguinus imperator (533 ± SD 79 g females vs. 495 ± SD 45 g males) are significantly heavier than adult S. weddelli (395 ± SD 30 g females vs. 385 ± SD 35 g males), with and without pooled sexes. Among S. imperator, significantly thicker limbs, but not an overall increase in body size account for this increased weight. No sexual dimorphism was recorded for either species, save in upper arm lengths among S. weddelli (slightly longer in females) and waist circumferences in S. imperator (slightly larger in females, but unrelated to pregnancy).

There are no significant differences between the species in the size of their genitalia or scent glands, despite differing markedly in their physical appearance (i.e shape and pigmentation).  No significant effect of month was found on testicular volume, vulvar indices or suprapubic gland areas (Kruskal-Wallis rank sum test, p ≥ 0.05). Suprapubic scent gland areas are significantly higher among females than males for both species (e.g. in S. weddelli, gland area =267.5± 143 mm for females and 117.1±72.4 mm for males). Vulvar indices explain ca. 70% of variation in suprapubic gland area for females of both S. weddelli (R2 = 0.70, P ≤ 0.001) and S. imperator (R2 = 0.76, P ≤ 0.001), while testicular volumes explain suprapubic gland areas only among male S. weddelli (R2 = 0.63, P ≤ 0.001). Male S. imperator have undifferentiated glands in general, unrelated to age or breeding status.

While vulvar indices initially appear to grow faster than testicular volumes in both species, by 1.5 years of age, males have fully developed genitalia while females still appear underdeveloped. Morphological scores assigned to genitalia and glands encompass their range of variation, and can be used to distinguish infants from adults, but not other age classes (scores are too variable among adults). This highlights the singular importance of evaluating age based on dentition and not reproductive measures for either species, as reproductive suppression can be misleading and cause animals to appear younger than they actually are.

Twinning and strong birth seasonality were observed in both species, with overlapping birth peaks influenced by the environment occurring during the wet season (ca. September to March). Primary breeding males had higher testicular volumes than secondary breeding males (44-287% higher in S. weddelli and 24-80% higher in S. imperator), indicating possible subtle reproductive suppression of males. Secondary breeding females had lower vulvar indices and suprapubic scent gland areas than primary breeding females, and required 2-3 y to acquire secondary breeding status compared to 1 y for males.

This is evidence of reproductive suppression of females, but it was not as strict as expected, as evidenced by multiple instances of two primary breeding females reproducing in the same group. Groups of both species display group compositions that encompass multiple adults of both sexes. Their mating systems, however, tend to be polyandrous among S. imperator and polygynandrous among S. weddelli. Overall, no sex ratio biases were observed at the level of the population or group; although operational sex ratios indicate that male S. imperator have to share their mate with more males than do male S. weddelli.

Immigration events are significantly less common than emigration events, with breeding females having extended tenures in both species. Cold fronts known as friajes create breeding vacancies among groups, which were filled by individuals from outside the group. Overall, Saguinus imperator appears to be more similar in terms infant survivorship and mean reproductive output to both the CICRA and Cocha Cashu populations of S. weddelli, than it is to S. mystax at other long-term study sites. However, S. weddelli has a slightly higher reproductive output likely achieved by its polygynandrous mating system, maintained by reduced reproductive suppression, in which multiple females breed successfully in a group. Therefore, it does not appear that groups of these two species conform to one, invariable mating system or group structure. It is likely that this variability may apply to other callitrichid species as well.

There appear to be more ways than one to be a successful callitrichid. Further years of study, including an investigation of endocrine profiles, genetic population structure, feeding ecology, parasitism and genetic chimerism are also underway at this site, and will lend further insight into the range of variation among callitrichid reproductive systems in the wild.

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