In February, 2014 Biokryptos initiated Tepui Watch, the first systematic camera trap survey of the talus and summit of a tepui. The lofty goal of Tepui Watch is to survey and catalogue the sum total biodiversity of the tepui ecosystems, a goal which will require the use of camera traps, field expeditions, and cutting edge techniques for detecting and analyzing latent environmental DNA. A critical element of Tepui Watch is establishing if medium and large bodied lowland animals can penetrate the tepui summits. Thus far, we have identified the coati Nasua nasua vittata and the Tamandua anteaters (Tamandua tetradactyla) as being tepui invasives based on historical encounters and observational data, as well as data from our own camera traps. As of August, 2015, we are now able to add an additional lowland animal to the list: the Tayra (Eira Barbara), colloquially known as a “pero de agua”.
|Tayra recorded at Lecho,|
|Tayra camera trap details. Bottom right image clearly shows grey pelage covering the head and neck of the animal.|
On April 30, 2015 at 1600 meters Biokryptos camera traps recorded the Tayra Eira barbara policophala at Campo Lecho. This is the first photograph of a tayra on the summit of Auyan tepui, and we have captured Tayras on the talus slope near Penon during previous camera trapping surveys. This area is a heavily forested riparian ecosystem, bordered to the west by uplifted cliffs and rocks known as the “Second Wall”, and to the east by more low canopy forests which eventually give way to swamps and bogs, rocky areas and gallery forests below rock ridges.
|the sampling area location on Auyan- campo Lecho and campo Dragon|
Diagnosis and Ecology
Eira barbara is a long, slender, muscular mustelid with a long bushy tail, strong claws and a humped back. It is IUCN Redlisted as LC (least threatened) in Venezuela, with human generated habitat loss being the only recognized threat to the species. The animal is distributed across Venezuela, represented by two sub species: E. b. sinuensis in the west and up to the Venezuelan Andes, and E. b. policophala in the east through Guiana, Surinam, French Guiana and North East Brazil. The central portions of the Pantepui represent a dividing line between the two sub species. Although found up to 2400 metres, Tayras are uncommon above 1200 metres. Their feeding strategy is temporally diurnocrepuscular, solitary, and cover wide ranging territory. They have been observed in primary and secondary forests, gallery forests, cloud forests, dry scrub and near human agricultural and domiciles. Tayras are opportunistic mesopredators. In Venezuela, three species of reptiles, and four fruits were recorded from fecal samples, although there is no reason to rule out rodents, invertebrates, and carrion as food sources for Tayras. In captivity Tayras accept a wide variety of vegetables as well as prepared pet food and scraps.
Their feeding pattern is characterized by actively hunting and pursuing small animals at dawn and dusk, while foraging for fruits during the day. While primarily diurnal, nocturnal activity has been noted. Tayras tend to be unidirectional while foraging, and cover an average of 7 km per day. Tayras maintain overlapping home ranges, which can range from 16 to 24 km in area. Although not aquatic in captivity, Tayras possess webbed feet, and are able to enter the water in pursuit of prey.
Capturing images of E. b. policophala on the summit of Auyan was surprising to our lead field researcher Arturo, who has never seen this animal before on a tepui. Brief correspondence with Venezuelan experts who have spent time on Auyan in field research roles supports the observations and opinions of Arturo and the Tepui Watch team. This is the first image of a Tayra ever recorded on a tepui summit, and as such is academically relevant as a new distribution for this species. This animal represents the largest carnivore proven to be present on a tepui summit, although there have been a few reports mentioned in academic journals and popular publications indicating mountain lions or jaguars are present on Auyan. This is also the second time Biokryptos cameras have photographed a Tayra during the Tepui Watch program. The first instance was during the Penon camera trapping campaign, where we recorded a Tayra in the vicinity of Penon, between 1500 and 1800 meters. This encounter was also considered unusual to the Pemon experts. What we have now is evidence supporting the hypothesis that the tepui summits are susceptible to invasion by lowland animals, which raises a series of new research questions, as well as conservation and ecology issues. We can be certain, however, that these animals are established in certain areas of the tepui: campo Lecho and campo Dragon are far inland in the summit, and accessing them from the south means traversing terrain which is not conducive for foraging, such as bare rock and small swampy moors. Given the feeding strategy of E. barbara, large portions of Auyan should be ecologically open to this species, and food sources could range from reptiles to birds, small mammals (including the numerous squirrels photographed at Lecho), as well as large insects and fruits, if available. It is unknown at this time what the population size of the Tayra on Auyan is, or if they are concentrated in certain areas or not. However, given their preferred habitat I surmise that they will be present in gallery forests in and around Lecho and Dragon, following river systems where gallery forests grow along the riparian ecosystem. I would also expect that they will be present in forest in the north along the Camino Angel, and into to the Sima Aonda forests. Although there is little indication if Tayras are sympatric with coatis, we also captured two individual coatis at Lecho on May 5th, 2015. Coatis have been recorded on Auyan from Naranja in the south to the north into the Angel Falls area , and westward to the Valle Encantada. Given the history of sightings of coatis since the 1938 Phelps expedition to the current date, we can comfortably state that coatis are ubiquitous on the summit of Auyan Tepuy. At this point, their ecological interactions with the other fauna of the tepui summit ecosystem remain unknown, and requires in depth study.
|coati at Lecho|
Developing an Agenda
Until now, the academic consensus has been that tepui summits do not maintain medium sized or large mammals, due to topographic isolation and depauperate ecosystems. We now have a unique situation in terms of tepui biodiversity epistemology- two medium sized mesopredators have been documented on a tepui summit, in the same area, both of which seem distributed continuously from the lowlands up to the summit. We have also documented summit tamanduas, a specialized medium sized insectivore, which seems absent from the talus but abundant on the summit. The question is how these animals fit into the tepui ecosystems, and how they access the summit. There are two possibilities regarding these animals: 1) They are established on the tepuis as a semi isolated population, or 2) they are invasive individuals that exist with a range that includes access to lower elevations. In either scenario, there is one central question: how are these animals accessing the summit?
Tepuis are often described as islands, sometimes with romantic hyperbole, (“Islands in time”, “Islands in the sky”, etc), other times within the scientific scope of island biogeography. They have been treated as biogeographic islands from a scientific point of view, as they maintain a high level of endemic vascular plants, and partially endemic herpetofauna. In recent years, molecular phylogentic analysis has challenged this concept of endemism and paleofaunal refuge, and paleoclimatological analysis has led to a complex interplay of climate change causing vertical migration and summit extinctions. However, the fact remains that the tepuis are isolated from the surrounding lowlands, even if they are not as isolated as previously thought. The human navigable access point, Libertador, would be a barrier to lowland animals- it is steep, rocky, and requires ropes to access. The reasons humans go to this point is because it is comparatively easy to access for humans; mostly barren of vegetation, and the hike in is both spectacular and within reach of human settlements. Potential faunal access points are far from indigenous settlements, and covered with large forests and swamps, and lack known trails- but they are topographically easier to move into. There are a few possible entrance points to Auyan which may be accessible to lowland animals.
The first such location is in the Canyon Del Diablo, in which a more gradual increase in elevation is found near the entrance to an isolated river valley which penetrates the tepui for some 12 kilometers. The topography at the entrance to this valley is complex, and hosts a series of short talus cliffs, and a sinkhole some four hundred meters in depth near the entrance from the Canyon del Diablo valley floor. A more gradual increase in elevation can be found in the valley southwards as it penetrates Auyan. This may be a corridor for lowland animals to access the summit.
|Possible topographic access point from the Canyon del Diablo. The access point goes from the canyon floor at 900 meters into the eastern section of Auyan at 1400 meters.|
The second location is far to the north east of Auyan, along a contour which contains the two small peaks of Cerro el Sol and Cerro la Luna, which is partly continuous with Auyan at 1200 meters, and interfaces with Auyan at a 100 meter talus cliff, permeated with several more gradual cliffs.
|Ridge line access point, gentle topographic slope up to the eastern portion of Auyan, The 800 meter contour has a gentle slope up to broken escarpments.|
The third possible location for fauna access is in the north of the tepui, along the rivers which flow into the Rio Ahonda. This area is topographically complex, however the altitudinal increase is gradual enough that it may be an area of influx to Auyan. Immediately to the south east a large basin is present, as well as many permanent lagoons and rivers.
At this point, these three areas are merely the best possible candidates in terms of a topographic and vegetational corridor into the summit; they are far from proven entrance points. Going forward, they are areas of interest for future camera trapping surveys, however a good deal of research and GIS work will need to be conducted before any field expeditions or camera trap surveys are undertaken. It is a fact that certain lowland animals are able to access tepui summits- determining how, where, and why is critically important in both understanding the natural history and ecology of the tepuis, and how to best design conservation efforts to maintain their unique biodiversity. We need to know if having larger lowland mammals on the tepui summits is a matter of long term natural history, or if their migration to the summits is driven by Anthropogenic Climate Change.