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Amphibians and Reptiles

A comprehensive study of behavior in a community with 5 species of poison dart frogs

Authors: Salazar-Zuñiga, J.A. Chaves-Acuña, W. Mora-Camac, G.Gutierrez-Vannucchi. A.C. Brenes-Andrade, J. Gutierrez, J. Ossenabach, I. Abarca, J.I. Bolaños, F.

Some of the species of frogs of the Dendrobatidae and Aromobatidae families show bright warning colors associated with the high level of toxins in their skin, while others have cryptic colors. In addition, most of them are characterized by aggressive behavior for defending their territory.

Due to the immense diversity of diurnal frogs from the Dendrobatidae and Aromobatidae family in the park, this project attempts to understand how a community of 5 species of these frogs interact. The project aims to determine the peak activity of each species, the sizes of the territories of each speciesthe overlapping edges of the acoustic interferences between males of the same and alternate species, as well as to analyze whether there are other types of interaction within and between species.

This project will be divided into several aspects in order to deal with each species separately, work will be done simultaneously to overlap the data generated for each species in an attempt to understand the behavior of a community of frogs.


Multimodal stimulus that enhance aggressive responses in rocket frogs

Authors: Salazar-Zuñiga, J.A. & W. Chaves-Acuña

Rocket frog species (Anura: Aromobatidae) are highly territorial and many have been reported to display aggressive behaviors towards co-specific and hetero-specific intruders. In case of an invasion towards a male´s territory, the resident can respond back by attacking the intruder either physically or acoustically. These type of agonistic responses have been accurately measured with multimodal stimuli, which enhances aggressive behaviors in dendrobatoid males (Fig. 1). Throughout several experimental designs, we have come up with a real-size artificial model that can be manipulated in order to mimic an intrusion of a co-specific (e.g. vocal sac movement, rotatory movements, playback calls, and colors). However, territorial behaviors might be influenced by anti-predatory strategies that may benefit more conspicuous species to broaden their movement patterns (e.g. approaching an intruder).

The Talamancan rocket-frog is a cryptic species that continuously calls during the day and have been observed to present aggressive behaviors during field surveys. For this study, we recorded males in order to get a mean value for the population´s temporal and spectral acoustic parameters. We also carefully painted models considering the same coloration patterns of the species to be tested. When applying multimodal stimuli to males, we recorded their agonistic encounter calls during experimental treatments, and videotaped all male responses during a 10-minute interval.

We intend to describe specific aggressive responses from this cryptic species and any bio-acoustical variations during agonistic encounters. In this project, we also mean to test whether inter-note interval elicits dishonest calling cues and/or more phonotactic displays by males of A. talamancae.


Figure 1. Rocket-frog male approaching the multimodal stimulus during field trials.

Visual and acoustic signals during agonistic encounters of the strawberry poison-dart frog against progressive co-specific intrusions

Authors: Chaves-Acuña, W., E. Moreno, A. García, L. Sandoval, G. Barrantes & P. Paul-Biton

Since multimodal signals (visual and acoustic) mediate over reproductive and territorial aspects of poison dart frogs (Anura: Dendrobatidae), warning signals are expected to function on co-specific interactions. Recently, a strong phylogenetic approach by Santos et al. (2014) concluded that advertisement calls diversify in response to aposematism. Hence, selective pressures should act towards mechanisms of co-specific signals.

This study aims to determine the effect of visual and acoustic signals over the aggressive responses of Oophaga pumilio males when being faced with a progressive invasion of a co-specific intruder. In order to improve the visual stimulus of the real-size model, we previously measured color parameters with a spectrogram, which allow us to accurately paint the puppets with the mean color value for the population to be tested. Furthermore, the acoustic stimuli will be played using Bluetooth connected to a specialized loudspeaker placed beneath the artificial puppet.

Given the fact that males´ agonistic responses are probably affected by the size and shape of their territory, we mean to manipulate the invasion of a co-specific intruder by moving the puppet with a pulley that pulls a stripe, attached to the puppet, back and forth . In this case, when facing a progressive co-specific invasion, urging agonistic responses in dendrobatids will indicate the extent to which males expose themselves to predators. We suggest the hypothesis that conspicuous colorations (color-brightness) affect aggressive responses in O. pumilio males. After trials, males will be measured according to their snout-vent-length and their coloration values. We expect two independent results regarding phonotactic and acoustic responses, in which brighter males are to be more aggressive (Fig. 1).



Figure 1. Male of Oophaga pumilio from La Selva displaying phonotactic responses during field trials.


Santos, J.C., M. Baquero, C. Barrio-Amorós, L.A. Coloma, L.K. Erdtmann, A.P. Lima & D.C. Cannatella. 2014. Aposematism increases acoustic diversification and speciation in poison frogs. Proceedings of Royal Society B 281, 20141761.

Conservation project of the tiger frog.

Authors: Salazar-Zuñiga, J.A. Brenes-Andrade, J. Gutierrez-Vannucchi. A.C. Chaves-Acuña, W. Azuguru, N. Gutierrez, J. Abarca, J.I. Bolaños-Vives, F.

The tiger frog is considered very rare in the country and according to the IUCN there is little information on the species. We decided to begin a study of natural breeding sites and discovered that it uses very specific sites which are disappearing, owing to the destruction of habitat in recent years. Each site consist of a medium-sized hole in a tree, where small amounts of water accumulate and where the hatching of tadpoles occurs.  Because of this situation we created artificial sites within the forest where the species could reproduce. The project was very successful and within a year and a half we have data on more than 200 egg masses.

At each site we put a camera and sound recorders to monitor activity and to answer questions such as: When are the peaks of activity? What are the environmental variables that affect the reproduction activity? Does the moon affect the reproduction activity? and, Is competition between males a given?

We also took a systematic control of each egg mass that prompted the following questions: How many eggs per female? How long is the development? Who are the predators of the egg masses? What is the hatching success?

Also, a sample of embryos was collected from each egg mass for DNA testing to give us an idea of the state of the population and answer the questions: Who is the alpha male? and,  How often are the same guys playing? Through this project it was easy to see predation by snakes, interaction between males (fighting, competition), parasitism in the egg masses, and tadpole competition in the water.


Understanding the reproductive ecology of Talamanca glass frog

Authors: Chaves-Acuña, W. Salazar-Zúñiga, J.A. Bolaños, F. Chaves, G.

In the Tropics, amphibians are known for their wide variety of reproduction modes. Among these, glass frogs emerge as a unique and delicate group, endemic to the New World, that lack pigmentation on their belly, making internal organs such as the heart and liver to become visible through their skin. These interesting anurans can be found along the vegetation surrounding streams, where the calls of different species can be located during nocturnal surveys.

One of the most interesting projects being conducted by the Veragua Rainforest`s Research Team deals with the reproductive ecology of the Talamancan glass frog, an almost unknown and endangered species. This work provides details on how the males take care of the egg masses, as well as it also analyzes how efficient is this behavior towards the embryo`s survival rate. This natural phenomenon, also referred to as paternal care, can be found in some species of the genus Hyalinobatrachium, although the Talamancan glass frog`s (Hyalinobatrachium talamancae) males happen to vary the way they protect their newborns. In contrast to other species that sporadically protect their egg masses during night time only, the Talamancan glass frog presents paternal care on both, day and night time. This species is not only characterized by having a green dorsal line going through the middle of the back, but also because it presents yellow spots on their back too. This morphological description comes to be critical when understanding why males can almost blend in perfectly with the egg mass (eggs are yellow during the first larval stages), avoiding predation events by animals that locate by visual cues.

Given the fact that these frogs actually call from the underside of the leaf, eggs are exposed to dehydrating conditions due to the fact that they would lack the rain drops that would keep them moist. In order to solve this problem, males are likely to display a multi task performance by positioning themselves on top of the egg mass, while they also call for potential mates. Many authors have suggested that, when males directly touch the egg mass, a hydrating mechanism is enhanced between the male body fluids and the jelly matrix surrounding the eggs.

Although this behavior is essential when interpreting the evolutionary implications of reproductive modes among anurans, much is still unknown in regards to many aspects of the glass frogs` behavior. Therefore, the most recent study with the Talamancan glass frog seeks to analyze how the condition of taking care of an egg mass affects the calling acoustic activity of the males. Although paternal care is quite common among this species, when taking night walks, lonely males can be seen calling from either the upper side or lower side of the leave. With this on mind, we decided to compare several calling features of the males` vocalizations in order to determine if both groups differ in terms of frequencies, notes intervals and calling rate. At the same time, a formal description of the Talamancan glass frog vocalization is being reported, as well as some notes on how males seem to distribute themselves along a stream.

HT-5 (04-05-2012) (6)

Advertisement call of the silent frog Craugastor noblei: another calling species of the Craugastor gollmeri group. Pdf

Authors: José Andrés Salazar-Zúñiga and Adrían García Rodríguez                            Phyllomedusa 13(1), 67-70                                                              

Anuran communication is dominated by acoustic signals; consequently, most species have well developed vocal systems that can produce a variety of sounds in different situations (Duellman and Trueb 1986). The advertisement call is the most commonly emitted sound in this repertoire; males produce this vocalization in both reproductive and territorial contexts (Gerhardt 1994, Wells 2007), and it usually is accompanied by the inflation of a vocal sac with pulmonary air (Pauly et al. 2006).

Vocal sacs occur widely in anurans and are thought to be involved in both acoustic and visual communication (Narins et al. 2003, Rosenthal et al. 2004). Despite this relevance, vocal sacs are absent in many groups such as the basal genera: Alytes, Bombina and Discoglossus (Cannatella 2006), as well as in more derived groups including some New World direct-developing frogs. An example is the Craugastor gollmeri Group that contains seven forest-floor frog species distributed from southern Mexico to Panama (Savage 2002). These species were thought not to vocalize because they lacked vocal sacs and vocal slits (Savage 1987). However, Ibañez et al. (2012) described the advertisement call of Craugastor gollmeri in Panama, providing the first evidence of vocalization in this clade.

Here we describe the previously unknown advertisement call of Craugastor noblei, another representative of the Craugastor gollmeri Group. This is the second species known to vocalize of the three in the group (C. gollmeri, C. noblei, C. mimus that occur in lower Central America (Savage 2002). Other aspects of the species, such as habitat use, daily calling activity and calling season are also briefly assessed as a contribution to the poorly known biology of this species.

Key words: advertisement call, calling activity, Costa Rica, vocal sac, vocal slits


We thank Wagner Chaves Acuña and José Brenes Andrade for their help while recording the frogs, as well as Gerardo Chaves and Rafael Márquez for valuable comments and suggestions on early versions of the manuscript. Field work was conducted under permission No. 001-2012-SINAC. This is a contribution of Programa Institucional del Laboratorio de Autómatas y Sistemas Inteligentes en Biodiversidad (PILASIB) funded by Agencia Española de Cooperación Internacional y de desarrollo (AECID funds D/027406/09 (2010) and D/033858 (2011).

Figure 1

Fig 1. Spectrogram view of the advertisement call of Craugastor noblei.


Fig 2. The Craugastor noblei