August 2018

The rainy afternoons this time of year create some amazing rich green colors in the forest.  As the rainy season continues there is good reason to visit this area if you don’t mind a little moisture.  The lushness of the forest, swelling rivers, and dramatic waterfalls are all a sight to see.


Research and Volunteers:

Cléa Lefevbre from AgroParisTech in France just finished a forestry internship with us where she was examining the differences in forest structure between planted and naturally regenerating (NR) forest of the same age. She also did some general comparisons with old growth forest. She found that planted forest had a linear relationship when plotting tree height against diameter at breast height (DBH), while NR forest had an exponential relationship. She thought this was because the trees in the planted area are planted at least 2 m from each other and the vegetation cleared so the young trees don’t have to compete with each other or other plants so can can grow at a steady rate. In the NR forest, the young trees have to compete for light so focus initially on growing tall to capture the light. Once that is achieved they then will start to increase their girth.

She then looked at the distribution of trees across 5 size classes (seedling, sapling, small tree, medium tree, and large tree). She found that the plantation forest had a large number of trees in the sapling category, no large trees, and few seedlings. While the NR forest also had a large number of sapling trees, it had a much larger number of seedlings and a few large trees, a structure more similar to the old growth. This means that recruitment is lower in the plantation area, which could lead to issues in the event of a disturbance in the forest (ex. blow-down, landslide, etc.).

She also found significant differences in DBH (greater in plantation), wood volume (greater in plantation), carbon storage (higher in plantation), and canopy closure (less light in NR), and no significant difference in tree height or wood density between planted and natural regeneration.
She concluded that while the naturally regenerating forest looks closer to the old growth in terms of overall forest structure, the planted forest is storing more carbon which is of benefit to combat climate change.

Her plots will be used in future years to continue to monitor the differences between the two forest types as they age and it will be interesting to see how things change over time!

In July, Una Williams completed her research on avian flight initiation distances (FID) (the distance at which a bird will move away from a threat (i.e. hiker)) on trails with different human activity levels. Increased FID’s and vigilance behaviour can lead to significant alteration in energy expenditure for the birds. Larger FIDs may indicate increased sensitivity and reduced tolerance to disturbance.
Study trails were grouped into 3 different activity levels: low (<5 visitors/day), medium (5-15 visitors/day), and high (>15 visitors/day + horses). Overall, across all bird species, she found that FID increased as trail activity level increased, although differences were not significant (p=0.117). There were 3 species found on all of the study trails: Common Chlorospingus (Chlorospingus flavopectus), Black Guan (Chamaepetes unicolor), and Slate-throated Redstart (Myioborus miniatus). Of these three, the Slate-throated Redstart showed a significant difference in FID between the trails, with much larger FIDs on the high traffic trail (Chirripó), and the shortest FIDs on one of the low traffic trails (Gavilan). This may indicate that the Slate-throated Redstart has become sensitized to the high traffic on the Chirripó Trail.
She is still completing her analyses so we look forward to seeing her final results!  Una is from Queen’s University, Belfast in Northern Ireland.


Catherine Walker, Elle Boone, Kelsey Davies, and Harriet Tyson from Exeter university in the United Kingdom finished a 6 week study on ant diversity and distribution in Cloudbridge. They wanted to study ants as they are the forest’s caretaker’s, cleaning up dead material, and can be used as bioindicator’s of reforestation success. Using pitfall and baited traps (tuna and sugar water) to collect the ants, they studied 3 forest types: planted (<15 years), natural regeneration (>30 years old), and old growth forest (70+ years old). They were able to identify the ants down to at least genus and many also to species. When comparing overall abundance and species richness, there was no significant difference between the habitats, which is a good sign for the effectiveness of our reforestation efforts. However, when looking at the similarity of the abundance of each genera present in the different habitat types (Bray-Curtis), they found that the planted and naturally regenerated habitats were moderately similar (0.5), while natural regen compared to old growth was lower (0.3), and planted compared to old growth was the least similar (0.1). Further analysis is being done to see if there were certain genera specific to each habitat and what that means for our forests.

They also compared the effectiveness of the different trap types they used and found that the baited traps were significantly more effective than the pitfall traps, in both abundance and species richness, but the baited traps were not significantly different from each other.
They did some great work and identified a lot of new genera and species for our species list. Here are some of their favourites.
Eciton burchellii parvispinum  (an army ant)


Eciton burchellii parvispinum  (an army ant)

















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Acromyrmex coronatus (a leaf-cutter ant) worker


Acromyrmex coronatus (a leaf-cutter ant) Queen
Pachycondyla impressa (largest species found, >7mm)
Carebara reina (smallest species found 1-2mm)

Alena Frehner from Van Hall Larenstein in the Netherlands completed her camera trap study in July. She used camera trap data (6 locations) and habitat data she collected to examine habitat factors that may affect the abundance and species richness of animals around the camera traps. The habitat factors she looked at included: habitat type (old growth, naturally regenerating, or planted forest), canopy closure, difference in slope of trail compared to the surrounding landscape, and tree size (when looking at arboreal and semi-arboreal species only).

She found that while species richness was not significantly different between the camera trap locations, abundance was, both when looked at as individual locations (with two of the sites showing higher than expected abundance and the rest lower, p=0.00) and when locations were grouped into habitats (with natural regenerated and planted forest having greater abundance than expected and the old growth lower, p=0.00). When examining the other habitat factors, none of them were found to have significant relationships to either species richness or abundance on the camera traps.

However, when looking at tree size (average, median, and max tree height; and median DBH) and abundance of arboreal and semi-arboreal species, with the exception of one outlier, there appeared to be a positive relationship between abundance and height, and a negative relationship between abundance and median DBH. The outlier was location E1, which also had a much higher abundance of animals than expected, and was by far the most productive camera trap location. E1 is located at a pinch-point along a ridge trail, where a large boulder and dense vegetation force most animals to walk along the trail, and therefore in front of the camera, making it more likely that the camera will capture images of animals in the area. Because of this, E1 may be skewing the data and not be a true representation of habitat choice as the animals in that location have little choice but to walk in front of the camera. As such, the examination of tree size and presence of arboreal and semi-arboreal animals on the camera traps warrants further investigation.

Some of Alena’s camera trap photos  (Puma, Ocelot, and Hog-nosed Skunk) :
Janina Harms of Van Hall Larenstein in the Netherlands, finished up a study this month looking at the feasibility of using the reserve as a sloth release site. Building on the work of Ramon te Beek who did a sloth habitat suitability study earlier in 2018, Janina spent some time at an active sloth release site and then looked at the practicality of setting up a release site at various locations around the reserve. She developed a suitability index based on: habitat suitability, presence of wild cats, site accessibility, slope of the site, set-up costs, and human disturbance. Different to the habitat suitability index which found planted sites as the 3rd most suitable, she found that the planted areas were generally most suited to setting up a release site, with the other habitat types being fairly similar. The planted sites came out on top mostly because they were more accessible and flatter than a lot of the other habitat types. Janina also found information gaps that we would need to fill before we could proceed with a possible release site, which will be very helpful for us moving forward.

As part of her work on the index, she collected samples from trees to better identify potential sloth trees and took them to the national herbarium for help confirming the identifications. As a result of this work, they identified 3 new species for the reserve!


Brunellia darienensis
Styrax glabrescens
Meliosma allenii
Janina’s final presentation also included some interesting facts about sloths and a look at her time spent at the Sloth Institute at Manual Antonio.
Janina at the The Sloth Institute
Elisa Yang finished up her birding internship at Cloudbridge this month and presented her results on the last three months of the bird monitoring study. After calculating Simpson’s Index of Diversity for the different habitat types, Elisa noted that the old growth (or primary) forest had one of the lowest diversities. She wondered why this was as old growth forest is considered to be of higher value than secondary (or regenerating) forest. After looking closer she found that while overall diversity was lower, all four of the Near Threatened and Vulnerable bird species found at Cloudbridge have their highest abundances in the old growth. In addition, the furnarids (an uncommon group at lower elevations) reached their peak diversity in the old growth as well. This is in contrast to the naturally regenerated and planted habitats which had a higher presence of common and widespread birds like Common Chlorospingus and Slate-throated Redstart. This shows the importance of the old growth habitat for vulnerable and sensitive species.
Elisa also brought a unique perspective to the bird study as she is skilled at identifying birds by their calls, which is very hard to do. Birds identified only by audio are typically excluded from analysis in the bird study as it is difficult to do accurately or to standardize between researcher due to widely varying skill levels. After readjusting the Simpson’s Index to include birds identified by audio only, she found the old growth diversity was one of the highest, rather than one of the lowest. The difference between the two is due to the difficulty of visually identifying birds in the dense and high canopy of the old growth.

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Introducing a new volunteer – Marissa Romp

Hola amigos y amigas,

‘The earth has music for those who listen.’ This quote is one of my favorite quotes of all time because it catches my thoughts and inspires me to take decisions in life that contribute to this ability and creates that possibility. My name is Marissa, I am 27 springs young and am currently studying Wildlife Management in my home country – The Netherlands.  Although I am still wondering ánd wandering about what profession I want to engage in, I am the happiest surrounded by forest, its inhabitants and the beautiful music they make. As part of my study I have worked at an Animal Ambulance to transport wounded or neglected animals. Last year I conducted a behavioral study on Samango monkeys in the province of Limpopo, South-Africa. After returning back to the Netherlands I knew something was missing. This experience of living in basic conditions – compared to my Western upbringing – and surrounded by the beauty of the forest has ignited a little spark of wanting to go abroad again. Hence next adventure; Costa Rica. I choose to do my internship at Cloudbridge because of the remoteness, the presence of two of my favorite species (White-faced capuchin monkey and the Geoffroy’s spider monkey) and the chance to surround myself with people passionate about the conservation of the forest and its wildlife. Here, I am currently engaged in a new mammal study which recently started for a period of five months. The aim is to set up a mammal species list and to see whether there might be any differences in mammalian species diversity between the different habitats present at Cloudbridge Nature Reserve. I am extremely excited to find out what the results will be. Pura vida!

Marissa in the jungle.




New Research Report Now on Our Website:

Two new reports have been added to the website this month. Check them out and many other reports on the research done at Cloudbridge on our publications page (

Ramon te Beek’s report “A habitat suitability study for sloth species Bradypus variegates and Choloepus hoffmanni in Cloudbridge Nature Reserve, Costa Rica. “ (

Cloudbridge Fun:

We do like to have fun.  Its not all work.  Sometimes there is a little rumble in the jungle for birthdays on the reserve.


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