Land Conservation and Forest Restoration, Science and Research

Endless forest interactions

Blogpost by Jonathan Navarro Picado, Healthy Rivers Program Coordinator

Whether we perceive it or not, the forest is alive; there is movement, there is disorder, and—most importantly—there are endless interactions. This last word is the key to help make this hidden world clear to our human “worlds,” which are so short and tiny in comparison to the existence of these forests.

When you walk through the old growth and secondary forests of the Osa Verde BioStation (Piro), you can see everythimg from herbs, seedlings and shrubs to gigantic trees hundreds of years old. Commonly seen are a great diversity of birds and insects, and sometimes one can have the good fortune to observe peccaries or to spot a small wild cat.

Epiphytes crawl up the trunk of a mature rainforest tree. Photo: Jonathan Navarro Picado

Now, there are many other things that we cannot witness, either because they occur at scales unimaginable to the human being (at a microscopic level, like bacteria, or in the heights of treetops) or because it would take months or years to notice the patterns of a certain event. One way to notice these small scale changes that happen in the forest is through observing the difference between day and night. In the night, more sounds are heard, even different events or movements are observed.

Observing a higuerón seems impressive to us all, but the interactions are what fascinate biologists: the complexity of their pollination related to certain wasp species, the presence of hemiepiphytes (a plant that stays in another) that present the majority of fig trees (Ficusspp) and how they affect the development and biology of other plant species. In addition, there is a large number of birds that feed on the fruits of Ficus and are also their dispersers. The Fig tree is related to an endless number of animals and events. This is considering only a specific tree; therefore, the amount of interactions in the forest is unimaginable, more taking into account that over time new relationships will appear.

The sad thing about all this is that as you learn more about the complexity of a forest and the interdependence among all its components, when you hear that people are cutting down a forest, extracting endangered species, polluting of rivers, hunting and causing many other environmental problems, you realize that the impact is at the ecosystem level and that recovering the conditions of a forest with all its interactions will take years or even centuries.

Bats residing in the hallowed-out old Ajo tree (Caryocar costarricense). Photo: Elène Haave Audet

When a person for personal and economic interests cuts down a tree that is hundreds of years old and says “there are many other trees” or even plants a new one, perhaps he or she does not know or does not share the great feeling of entering the cave formed at the base of a great old garlic tree (Caryocar costarricense), of feel part of nature itself. More importantly, perhaps he or she does not see the amount of bats that depend on said cave, the facilitation in the dispersal of seeds, the great source of food for so many animals and all the storage of carbon during decades that helps us to be here today delighting in all these interactions.

That’s why I want to be part of those interactions in a positive way, through inducing positive change. As the change from being a Osa Conservation Restoration & Rewilding Field Course student to being the Coordinator of the Healthy Rivers program here, I hope that this challenge helps to conserve many interactions in the veins of our planet.

Jonathan, with fellow students in Restoration & Rewilding Field Course, identify aquatic insects as indicators of healthy river ecosystems. Photo: Hilary Brumberg

Aquatic Health, Community Outreach, Environmental Education

“Picnic in the River,” a nationwide celebration of rivers

Blogpost by Kristina Graves, Healthy Rivers Program Research Field Assistant and Masters Student at Imperial College London

Having just arrived at the start of the week, I was really excited to hear that Osa Conservation was hosting a “Picnic in the River” in celebration of Costa Rican rivers and their importance to people and wildlife. I thought it would be a great way to understand the context of rivers in the Osa and community and throw myself headfirst into learning some Spanish. 

“Picnic in the River” is an annual festival in which communities across Costa Rica celebrate rivers as part of the International Day of Action for Rivers. This year, we hosted the largest ever Osa Peninsula “Picnic en el River”, thanks to the 71 community members who come out to our Osa Verde BioStation (Piro) to celebrate rivers. 

The Osa Community celebrated Costa Rica’s rivers, along with 170 groups across Costa Rica, in honor of the International Day of River Action. Photo: Jo De Pauw

The day started off with a buzz in the air and a tangible excitement among the staff in anticipation of the day. It all kicked off when three buses arrived bringing children from local schools and their families to the station. 

After introductions, workshops were led by Hilary Brumberg (Healthy Rivers Program Coordinator), and Mariam Weyand (Sea Turtle Biologist), and Marlon Jiménez Castro (the local aqueduct administrator), to highlight the many uses people have for rivers and how rivers function as a connection between the land and the sea. Marco Hidalgo (Coordinator of Ecosystem Resilience and Community Outreach) explained how the iNaturalist application can be used to register the incredible wildlife found in the Osa. The children, who were initially shy, seemed really enthusiastic as they called out their ideas and got involved in the presentations. 

Participants learned about aquatic biodiversity and competed in a mini “BioBlitz” to find as much wildlife as they could. Photo: Osa Conservation

The children had two dances prepared for the day, and outfits to match! They came dressed as iconic forest creatures and plants and they looked fantastic. It was great to get involved with them at the end and share their enthusiasm for nature and the day in general. 

In the afternoon, families were split into two groups and led to either Piro River or the nearby Piro Beach, where Piro River meets the sea, to get an opportunity to experience first-hand the diversity and ecological importance of their country. The kids participated in a mini wildlife BioBlitz, each competing to find the most different types of wildlife to records on their iNaturalist “nametags.” Nature really showed off with some turtle hatchlings at the beach and lots of shrimp, fish and insect larva in the stream. There was also time for a quick dip in the stream afterwards to cool off!

To celebrate declaring Piro River “healthy” based on a high diversity of aquatic wildlife, the kids celebrated with a dip in the stream. Photo: Jo De Pauw

Overall, it felt great to be part of a “Picnic in the River” celebration on the same day as 170 groups across Costa Rica in honor of the International Day of River Action. I had a great first introduction to the community and streams in the Osa Peninsula and I am so excited to get stuck in to the projects and be a part of the work Osa Conservation are doing here.

Birds, Community Outreach, Land Conservation and Forest Restoration, Science and Research, Sea Turtles, Volunteers and Visitors

Repeat volunteers reflect on growth of restoration plots and science programs

Blogpost by Robin Morris and Steve Pearce, General Volunteers

It seems like yesterday when we walked through the gate to the Osa Verde BioStation (Piro) for the first time in January 2017 and were greeted by a group scarlet macaws in the trees snacking and squawking.  We’re here now for our third winter excursion, and I have to admit we’ve done some cool things the last couple years.  

Robin enjoying a two-year-old balsa forest. During Robin and Steve’s 2018 visit, they helped clear plants around the small balsa saplings, and in 2019, they helped preparing bird boxes to bring wildlife to the young balsa forest. Photo: Steve Pearce

One of the projects we’ve helped with here is reforesting abandoned farmland.  Seedlings of balsa trees have been planted, and on a previous stay we were given small machetes and told to clear the plants around the seedlings, a project we lovingly christened ¨Weeding the rainforest.¨ It felt somewhat silly and hopeless, but when we came this year, we found new forests of balsa on the former farmland, proving conservation work frequently requires patience to see results.  Part of the reforestation process is creating habitats for animals, so this year we helped set up bird boxes to encourage birds to move into the new forest, sort of like opening a piano bar to lure lounge lizards.  

“Conservation work frequently requires patience to see results.”

Robin helping Manuel relocate a sea turtle nest on a patrol with Manuel Sanchez. Photo: Steve Pearce

One of the great lures to volunteering here is the Sea Turtle Program.  A newly hatched green or Olive Ridley turtle could give cuteness-lessons to puppies or kittens. When we first came here two years ago, the program was led by local legendary naturalist and photographer Manuel Sanchez.  Last year we even got to checked on the hatchery in the afternoons so he could have a vacation.  The Sea Turtle Program, like much work in conservation, is a steady commitment. Now the program has several dedicated enthusiastic staff members, frequently assisted by volunteers like us.  But the work is still the same, patrolling the deserted beach on breathtaking mornings, finding and relocating nests to the hatchery, releasing the hatchlings to the sea, as well as excavating nests to determine mortality rates among the eggs.  And after releasing young turtles for three years, it’s fun to watch people melt.

“The Sea Turtle Program, like much work in conservation, is a steady commitment… And after releasing young turtles for three years, it’s fun to watch people melt.”

The Osa features a splendid variety of wildlife, from squirrel monkeys and scarlet macaws to cane toads and green turtles.  Each trip has brought new sightings or exciting moments of discovery.  But one creature has almost brought our marriage to an end each year.  No, a jaguar has not attacked us on a footpath.  Snakes have not ambushed us in the bathroom.  And no, a crocodile has never attacked us on the beach. The problem is that Steve always falls in love with the paraque.  

Steve’s girlfriend, a paraque, resting in the pavilion. Photo: Steve Pearce

A nocturnal species, the paraque birds frequently sit along the paths of the research station and even in the pavilion, occasionally sweeping through to feed on insects drawn by the light.   They make an assortment of whistles to other paraques in the area and flop about when people walk near.  They sometimes make cooing ¨bwot¨ sounds.  Local folklore includes tales of the paraque calling travelers into the forest to get them or their children lost.  A paraque sometimes follows us to our cabina and bwots to lure me outside.  Attempts to photograph them at night usually yield nothing but a red dot in the darkness, further evidence of their supernatural nature.  

The paraque is a heartbreaker though, for when we asked another volunteer what her favorite mammal and bird of the Osa were, she replied ¨squirrel monkeys and Steve’s girlfriend.¨  We hope to leave at the end of the week without Steve pining for his girlfriend at the airport.

Land Conservation and Forest Restoration, Science and Research, Sustainable agriculture

New plant record for the Osa Peninsula: Cipura campanulata

By Marvin Lopez Morales, Botanic Assistant

Not long ago, the Costa Rican ethnobotanist Jorge Luis Poveda visited Osa Conservation. For me, it was an honor and pleasure to meet him. 

Luis Poveda in the forest during his visit to our Conservation campus. Photo credit: Osa Conservation

A simple and very friendly person, he has so many stories to tell about his personal experiences, plants, and teaching a wide variety of people. Poveda has devoted many years of his professional career to projects against cancer, Costa Rican Trees, and Manual of Plants of Costa Rica, among others. In addition, he is a passionate naturalist, and he writes poems inspired by nature itself. 

In one of his walks through Cerro Osa, he saw a small plant that caught his attention that he had not seen before in the Osa Peninsula, Cipura campanulata. It was the first report of this species for the area. Our botanist friend, Reinaldo Aguilar, who lives in Puerto Jiménez, confirmed the discovery.

View of Cerro Osa, natural habitat of this beautiful plant. Photo credit: Osa Conservation

It is a Monocotyledonous plant, belonging to the family of Iridaceae plants. For the country, Costa Rica, there are 6 generaand 14 species registered, among them the genus Cipura, which consists of 5 species in total. 

This plant is found only in the continent of America, with a wide distribution range that extends from Mexico to Colombia and Venezuela and Antilles. In Costa Rica, it is found mainly to the north of the Pacific slope and in the plains of Guanacaste between 0 to 300 meters above sea level. They reach a height of about 20 to 60 cm high, and their leaves have a resemblance to rice plants with white flowers in the shape of a small bell that open very early in the morning and also close in a short time. Because of their small size, they are ideal to have as ornamentals.

Cipura campanulata in its natural environment. This plant has the potential to be used in our gardens as an ornamental plant. Photo credit: Rich Hoyer

This plant flowers once a day. If you get to own one of these wonderful plants, you can be sure every morning that this grass-shaped, bushy plant will have a small flower to brighten the morning, wishing you good morning. Sit with a good coffee and admire the beauty of this fragile and helpless little plant.

One of Poveda’s poems:

La Montaña Mágica

Sí, eres mágica, eres hontanar de sabiduría, eres pan nuestro de cada día.

Oh Montaña Sagrada que nutres nuestras vidas,

joyel de aventuras, sacrosanto vergel,

estancia de mi vejez.

–Jorge Luis Poveda Álvares”

Aves, Birds, Community Outreach, Science and Research

Descubriendo la ecología de un ave endémica y en peligro en Osa: Habia atrimaxillaris

Blogpost por Arlet Quiros-Calvo, ganador de la Beca Alvaro Ugalde y estudiante de maestría en la Universidad de Costa Rica

Macho y hembra de izquierda a derecha de tangara hormiguera carinegra (H. atrimaxillaris). Fotos: Arlet Quiros-Calvo

 Me llamo Arlet, trabajo con una especie en peligro de extinción, especial porque se encuentra en un único lugar del mundo. La tangara hormiguera carinegra, Habia atrimaxillaris, habita solamente en la Península de Osa y en el Refugio Nacional de Vida Silvestre Golfito-Parque Nacional Piedras Blancas en Costa Rica.

 Se cree que su población está disminuyendo rápidamente dentro de su pequeño rango geográfico debido a una gran reducción de su hábitat, resultante de la deforestación y la expansión de la frontera agrícola en el Pacífico Sur.

 Según investigaciones en la Gamba de Golfito, esta especie tiene una preferencia por los bosques primarios y bosques secundarios maduros. Al ser una especie que forrajea en el sotobosque, es decir, en la vegetación que se encuentra por debajo del dosel, puede ser muy sensible a las fragmentaciones del bosque. Aún así, el estado de conservación actual de la especie y el conocimiento sobre sus preferencias de hábitat es muy limitado en la Península de Osa, por lo que decidí ampliar la información existente sobre esta ave con la beca Álvaro Ugalde de Conservación Osa.

Los asistentes monitoreando día a día los nidos (izquierda). Realizando mediciones de las parcelas en Dos Brazos del Rio Tigre y la Tarde (derecha). Fotos: Arlet Quiros-Calvo

Desarrollamos esta investigación en sitios ubicados en la comunidad llamada La Tarde y la comunidad Dos Brazos de Rio Tigre, donde localizamos individuos en dos parcelas. Cuando nos dispusimos a monitorearlos, día a día, ¡descubrimos algunos secretos de su reproducción! 

Hasta el momento, hemos descubierto información muy valiosa para la conservación de esta peculiar especie. En los meses de época reproductiva (febrero-abril), observamos su comportamiento de cortejo y apareamiento, la selección del sitio de anidación, preferencia de hábitat, el número de huevos, su alimentación, e incluso anotamos datos de polluelos depredados. Además, mediante videos, llegamos a ver actividades cotidianas como forrajeo, búsqueda de alimento e incubación, lo cual nos ayuda a entender la complejidad reproductiva de la especie y su adaptabilidad en Osa. Adicionalmente, el comportamiento reproductivo es diferente en Dos Brazos de Rio Tigre y la Tarde, por la misma razón: la fragmentación de propiedades vecinas al Parque Nacional Corcovado.

Nido encontrado en la palma suita Asterogyne martiana en Dos Brazos de Río Tigre. Foto: Arlet Quiros-Calvo

A pesar de que en la literatura se menciona que la distribución de la especie se limita a hábitat maduro, nosotros ubicamos nidos en bosques de galería (bosques en los bordes de cuerpos de agua), áreas abiertas, bosques en regeneración y zonas de pendiente.

Al visualizar todos estos datos obtenidos, podemos generar información clave para proteger los bosques de Osa, sus aves y en general toda la biodiversidad presente en esta pequeña área de Costa Rica.

Diseño del nido de H. atrimaxillaris encontrado en Dos Brazos de Rio Tigre. Foto: Arlet Quiros-Calvo

Land Conservation and Forest Restoration, Science and Research, Uncategorized

“Restoring forests for bats” and beyond: NASBR 2018

Blogpost by Elene Haave Audet, Restoration & Rewilding Research Field Assistant

This October, I ventured out of the sanctity of the jungle to present at the 48thNorth American Symposium on Bat Research (NASBR) in Puerto Vallarta, Mexico. Over 300 researchers from across the globe gathered to share bat stories, communicate their research, and further our understanding of this hugely diverse mammalian group. Because of its location, the conference offered many opportunities to discuss the conservation of bats in the tropics, presenting a great opportunity to share Osa Conservation’s work on surveying bats in the restoration plots.

The Osa Bat Family, Priscila Chaverri, Gloriana Chaverri, Beatriz Lopez, Elene Haave Audet and Doris Audet, at NASBR. Photo: Elene Haave Audet

It was very exciting to see our Restoration and Rewilding efforts so well received by a bat-savvy audience. Researchers were curious to hear about the ways in which Osa Conservation is “restoring forests for bats”. This project is focussed on attracting bats to areas that are actively being restored, for example by planting flowering trees like the balsa, and installing two-meter-tall bat boxes, all with the aim of restoring bat diversity whilst the forest is regenerating.

Micronycteris microstis bats are feeling at home in this bat box, installed by Dr. Chaverri’s team at Osa Conservation. Photo: Elene Haave Audet

Excitingly, the bats of the Osa Peninsula were able to reach the audience in Puerto Vallarta beyond the scope of the restoration project, by researchers conducting work at and around the Osa Verde BioStation. Beatriz Lopez, from the University of Florida, discussed gathering bat echolocation calls on the Osa Peninsula to document species diversity, and Dr. Doris Audet from the University of Alberta, shared her research on bat exploratory behavior in the field. The conference was also a wonderful opportunity to discuss advances in bat research in Costa Rica with Dr. Gloriana Chaverri from the University of Costa Rica, who has planted deep roots of bat research on the peninsula over the course of her career. 

The presence of bat research on the Osa Peninsula, and Osa Conservation’s important contributions to supporting that research, was very well represented at NASBR 2018. The Osa Verde Biostation is truly a gem for bat diversity, with over 50 recorded species of bats to date, and sharing Osa Conservation’s involvement in conserving and restoring habitats for bats ensures that those contributions are recognized and appreciated by the bat community at large. 

Elene, identifying a bat by measuring its forearm, as part of the diversity surveys in the restoration plots. Photo: Elene Haave Audet

Aquatic Health, Volunteers and Visitors

Pumas en el sendero

Blog por Lucía Vargas Araya, Coordinadora de Experiencia de Conservación.

La autora Lucía Vargas Araya disfruta de la búsqueda de vida silvestre en el sendero. Photo: Laurien Dwars

“Hay dos pumas en el sendero”- me dijo mi compañero Leiner por un mensaje que recibí estando sentada en mi oficina en la Estación Biológica Osa Verde el otro día. Emocionada, le avisé a los compañeros que estaban cerca mío, nos pusimos zapatos y salimos rápidamente hacia El Sendero Las Tortugas, donde esperábamos encontrar a los felinos.

La entrada del sendero está justo al costado de La Estación y continúa hasta llegar a Playa Piro. Como Leiner no especificó en qué parte del sendero estaban los animales, desde que entramos al mismo y nos encontramos rodeados del bosque, el corazón latía fuerte; podían estar ahí camuflados detrás de cualquier árbol.

Rayos de luz solar caen en el camino cerca de la estación de investigación. Foto: Lucia Vargas Araya

Continuamos a un punto del sendero donde se debe de cruzar el Río Piro y entonces, el suspenso aumentó. Caminaba poniendo mucha atención a mi alrededor, cerca y hacia la distancia, tratando de detectar a los pumas, pero también viendo el barro que pisaba para no resbalarme.

Quienes estábamos en búsqueda de los pumas, íbamos con los ojos alertas y nos hablábamos en un tono muy bajo, casi como un susurro, para no espantar la ilusión de verlos de cerca. Continuamos el sendero, paralelo al río, hasta llegar a un cruce. ¿Cuál camino debíamos escoger? Ahí nos quedamos unos segundos hasta que decidimos tomar el de la izquierda, el que se aproxima al vivero de huevos de tortuga en Playa Piro. Nuestro caminar se volvió más pausado y esperamos a que Leiner respondiera el celular para saber si aún teníamos esperanza, pero no respondió.

Finalmente, nos topamos con quienes habían tenido la oportunidad de verlos y nos dijeron que ya los habían perdido de vista, se habían ido. Sin embargo, se sabía que estaban cerca porque escuchábamos aún el aullido típico de un mono que está observando a su potencial depredador.

Sereno Río Piro, el río que pasa por la estación de investigación. Photo: Lucia Vargas Araya

Esa tarde no encontré al puma, pero sentí una profunda gratitud de que el bosque de Osa se hubiera convertido en mi nuevo hogar. En este rincón palpitante de vida las posibilidades son infinitas. Aquí cada día estamos a la merced de la naturaleza; cada día puedo ver algo que nunca había visto antes. Y, además, aquí todos los días aprendo.

Esa tarde tuve una excusa para distraerme en el bosque y visitar el río Piro un rato. Además, iba en compañía de espíritus aventureros, que luchan por proteger lo que aman: la naturaleza; de la cual son parte. 

Land Conservation and Forest Restoration, Science and Research, Uncategorized

Variety is the spice of life: Monitoring the wildlife in our ecological restoration and rewilding plots

Blogpost by Alice Connell, Restoration and Rewilding Research Field Assistant

Alice monitoring the effectiveness of log piles in attracting amphibian and reptile species to the restoration and rewilding plots. Photo: Sophie Blow

My work is never the same from one day to the next on the Restoration and Rewilding Program, which encompasses many diverse projects that require frequent monitoring. There is plenty to do, I always arrive at lunch hungry and satisfied after mornings of hard work. I want to give you an insight into my first month of being a Restoration and Rewilding Research Field Assistant.

We are employing a variety of approaches and techniques across the rewilding plots in order to “rewild” an array of animals to return to recently reforested abandoned grassland. Our idea is that as the overall species diversity increases, inter- and intra-species interactions within the regenerating areas will begin to re-establish. With some patience and continuous monitoring, we the aim to demonstrate a restored harmonic ecosystem functioning of the Osa Peninsula, and its associated key ecosystem services.

A medium bird box installed to offer shelter for birds. Photo: Alice Connell

One project in the restoration plots is the installation of nesting and roosting boxes to attract birds and bats. To accommodate a variety of species, there are 5 bird box designs, each differing in dimension of the entry hole and the box itself. The frugivorous species belonging to both birds and bats play a vital role in increasing the rate of seed rain, and consequently, the rate of seed dispersal and reforestation.

One day of my week is dedicated to surveying the wonderfully diverse bats that are choosing to use the rewilding plots. The morning’s duty involves erecting mist nets in preparation for the evening’s bat survey. Come the evening time, the team heads back out into the field to open the nets. When the clock strikes six, the monitoring begins, and the excitement of the possibility of catching a new species record ripples through the team.

The species, Micronycteris hirsuta, was recently caught for the first time in one of the rewilding plots. Photo: Alice Connell

The following morning, decaying log piles and epiphytes (such as bromeliads) are translocated to the rewilding plots to increase microhabitat availability, in an effort to rewild amphibians and reptiles. Such microhabitats occur naturally in the primary forests, usually providing refuge for different invertebrates, such as centipedes and millipedes, and for amphibians and reptiles, such as leaf-litter frogs and sun-basking lizards. It is always a pleasure to find a fer-de-lance coiled peacefully within a log pile in a rewilding plot. While the log pile project is relatively new, we have already observed a rapid return and colonization of several amphibian and reptile species within a short period of time, which is highly encouraging.

Undeniably, a huge effort, in terms of time and determination, is required to create a biodiverse and ecologically restored forest ecosystem. Fortunately, the team of highly-motivated and enthusiastic people that constitute the Restoration and Rewilding Program indicates a promising future for Osa’s forests.

A Northern Cat Eyed Snake coiled peacefully within a log pile in a rewilding plot. Photo: Alice Connell

Science and Research

Massive treefrog breeding aggregations at Shampoo Pond

Blog Post by Brandon André Güell, NSF Pre-doctoral Fellow and Ph.D. Student, Warkentin Lab, Boston University

Brandon Güell observing a breeding aggregation at Shampoo Pond. Photo: Brandon Güell

It was about 06:00 after night-long heavy rains ended a short dry spell, and already you could hear a deafening chorus of creatures gathering at the pond. Though sleepless and mosquito-ridden, we trudged chest-deep through the murky swamp waters with notebook and camera in hand to reach the source of the chaos. That’s when we saw it: One of the largest aggregations of treefrogs likely ever to be witnessed.

Tens of thousands of adult gliding treefrogs (Agalychnis spurrelli) literally poured over each other in attempt to breed and lay eggs. And for two Costa Rican tropical biologists and herpetologists, this rare biblical magnitude of frogs was like heaven on earth. This is Costa Rica. This is Osa. This is “Shampoo Pond”.

Agalychnis spurrelli breeding aggregation on palm leaf at Shampoo Pond. Photo: Brandon Güell

 

Since 2015, I have been studying how frog embryos use environmental cues to change their behavior. My current Ph.D. research in the Osa aims to understand how specific reproductive strategies interact with both environmental cues and development to affect embryo behavior and survival. For these gliding treefrogs, tens of thousands of reproducing adult frogs mean hundreds of thousands of frog eggs and embryos. And in this species, embryos are left alone to fend for themselves after they are laid. That means this event leaves behind a massive all you can eat frog-egg buffet for hungry predators

Why have a massive population lay their helpless eggs all at once in one location? That’s a great question, and it’s one I hope to answer!

In some cases, an overwhelming amount of prey can function as an antipredator adaptation if, for example, the overabundance of frog eggs decreases the probability of any one egg’s chance of being eaten. Basically, it can serve as a form of “safety in numbers”. This is known as predator swamping (or predator satiation). Shampoo Pond offers a pristine ecosystem where this hypothesis can be tested using these treefrogs.

In 2018, with the assistance of Katherine González, a Costa Rican tropical biologist, we conducted initial egg clutch monitoring studies in the hopes of determining whether this reproductive strategy has any impact on offspring survival. But this system has even more to it!

If undisturbed, gliding treefrog embryos develop and hatch into the pond as tadpoles in 6 days. But with so many threats, many wouldn’t survive that long.

Brandon Güell and Katherine Gonzalez headed out to the field from the research station. Photo: Brandon Güell

How can frog heaven get any more interesting, you say? Well, what makes these treefrogs particularly interesting is their ability to respond to threats by hatching prematurely!

That’s right! These embryos can hatch almost 40% early to escape the jaws of a hungry predator like snakes, wasps, and even monkeys! However, many of them don’t hatch early, and thus will die during predator attacks. We know the embryos have the ability to hatch early, but sometimes they don’t. Why?!

In addition to predation, these embryos are susceptible to desiccation, fungal infection, and flooding. These threats provide unique cues, which the embryos use to inform their decision of when best to hatch. This is called environmentally cued hatching, and it’s presumable a very adaptive embryo behavior— it increases their survival and fitness. But for the gliding treefrog, this behavior may not be as plastic or adaptive as in other species. Here in the Osa, another focus of my research is understanding the mechanisms which cause these embryos to hatch or not to hatch in these contexts at different developmental stages.

Our work has only begun at Shampoo Pond, and we hope that it will elucidate the conservation importance of this fragile ecosystem and its inhabitants, particularly amidst the current anthropogenic environmental changes in Neotropical rainforests.

 

Above: A series of gliding treefrog (Agalychnis spurrelli) embryo developmental stages. After embryos undergo early and late cleavages (cell divisions with visible nuclei), they form the dorsal lip and the yolk plug becomes visible. Later, embryo bodies rise and begin to show muscular response as the external gills form. Then, their hearts begin to pump blood throughout the body and external gills, and they begin to develop pigmentation. At three and four days, embryos begin to respond to environmental cues and can hatch prematurely to escape flooding and predators respectively. In the last picture, Brandon collects eggs in the swamp to study. 

 

Land Conservation and Forest Restoration, Science and Research

Restoration’s exciting night life

Blog Post by Elène Haave Audet, Restoration and Rewilding Research Field Assistant

 

Elène holding a Noctilio leporinus, the Greater bulldog bat, which fishes from streams. Photo: Doris Audet

For many of us, the creatures of the tropical forest that dare venture at night remain elusive and mysterious beings, their ways of life foreign to us daytime dwellers. Among these enigmatic animals are bats, the group of mammals with the second largest number of species in the world, whose charismatic presence in the tropics will not go un-noticed to the keen nocturnal observer.

Like many sensitive animals, bats are particularly special as a group, since many species require natural areas that have not been disturbed by human activity to find food and places to live. Thus, the presence of many different bat species can provide information about the health of an area. For this reason, Osa Conservation has started sampling the diversity of bats in areas that are being actively restored into forest, after years of use by humans. Overtime, the presence of different types of bats in these areas will help determine the success of restoration.

Vampyrodes caracciolli, the Great striped-faced bat, the second of two new fruit eating bats on the OC property, enjoying a well- deserved fig. Photo: Hilary Brumberg

After seeing the restoration plots for the first time this May, I was convinced that the bat diversity in these areas would not be exciting: that is, I expected to find very little diversity, since the restoration areas are in their infancy and have very little forest cover.

Was I ever wrong! The bat life in the restoration plots is teaming with diversity. After four months of sampling, we have recorded 24 different species of bats, ranging from those that eat insects, fruits, nectar, fish, and yes, even blood. To add to this excitement, two species of fruit eating bats recorded in the restoration areas had not been previously detected on the Osa Conservation property!

Why, then, has the bat nightlife been much more exciting than anticipated? Although the restoration areas have very few trees, the surrounding areas are lush with tropical forest, providing ideal habitat for these endearing creatures. This is very encouraging news for restoration initiatives, as connecting the surrounding forests with restored habitats will continue to support the diverse lifestyles of our nocturnal friends, so they may continue hunting insects, fishing bats, and snacking on figs.

Now every night of sampling is an adventure, and I cannot wait to see what other bats we will encounter in these deceptively rich areas!

Chiroderma villosum, the Hairy big-eyed bat, one of two new fruit eating bats encountered on OC property, posing handsomely. Photo: Elene Haave Audet

 

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