Return to the lagoons: 3000+ photos, and a new distribution for Mustela frenata

Introduction and background

On August 7, Biokryptos chief investigator Arturo Berti and his field team returned to the lagoon near Angel Falls to service the camera traps which we placed there in January 2016. The January 2016 trip was a milestone for Biokryptos; it marked the beginning of Phase Three of the Tepui Watch programme. The January 2016 expedition was the result of two years of planning, surveying, and cartography on the part of Biokryptos board members Laszlo Barkoczy, Alberto Pomares, and Vittorio Assandria. During this expedition, a number of unusual events took place on the summit, including sounds of large animals in the forest near the lagoons, as well as the discovery of jaguar claw marks on tree trunks in the vicinity. After our expedition, the El Nino phenomena caused intense drought that affected the Guiana Highlands and Venezuela as a whole. When the rainy season did come, it came late, and was fairly intense on the highlands, as anticipated.

The August 2016 follow up was scheduled for July, however extreme river flooding at campo Guayaraca caused the team to postpone the mission and return to Uruyen. Once the rain let up, Arturo led the team to the summit for the 15 field days needed to access the lagoon area.. During this time, it rained constantly on the summit of Auyan, making field surveying partially impossible, and limiting movement to areas immediately around the shores of the lagoon. The major objective of the expedition was simply to service the traps and replace their batteries, which were running low. Data from the traps was recovered, although we are currently with out access to SD card # 7, and are attempting to retrieve data from cameras one and two, which were flooded at campo Lecho. The recovered SD cards contain 3300 + images, with a trivial number of false captures.  The high number of positive captures demonstrates a dramatic improvement over previous surveys with the camera traps, with all functional cameras preforming well.

Survey area: Lagoons.

The survey area during this expedition was primarily the northern lagoons on Auyan, within 2 km of Angel Falls. During this expedition, Arturo borrowed a GPS unit which was able to log both his path and the camera trap sites. The data from the GPS was translated from a .GPX file in to a .KML file, and loaded into Google Earth.

camera trap locations on Auyan. Note: file translation off set route and locations by several meters south from actual location

An overflight of the lagoon areas was conducted post expedition to examine the location during the rainy season. Vittorio Assandria overflew the location, while Alberto Pomares took high resolution photographs of the area. The structure of the lagoon is almost identical during the rainy season as it is during the dry season, proving that seasonal flooding does not change a great deal of the surface topography of this area.
August 2016 images of the lagoon. Structure remains the same, though heavy water flow makes rapids and treacherous crossing around rocks bordering the lagoon. 

Arturo verifying the absence of fish from this portion of Auyan. 
The team surveyed the lagoons for approximately 3 days, during which the the aquatic ecosystem was examined. Although no fish have been formally described on any tepui summit, information concerning their presence near the Aonda forest has come to my attention by explorers who have seen two species of small fish. At my behest, Arturo attempted fishing from the shore of the lagoon, however the results were negative. The only observable aquatic animals in the lagoon were large swimming beetles, which can be found across Auyan.

Expedition results- Camera trap data.

The objective of this expedition was to collect camera trap data while servicing the camera traps, as well as to place two additional camera traps in the lagoon area. As it is the height of the rainy season, no other actions were expected to be undertaken, and field survey efforts were minimal. No animals or trace evidence were positively identified during this expedition. The team was instructed to look for additional evidence of big cats on Auyan, but and no evidence was found.

The camera traps produced 3300+ photos of mammals and birds, with very few false positives. The most frequent triggers were caused by small rodents and the opossum Didelphis imperfecta attempting to access suet bait enclosed in cages. This occurred with such frequency that it may in fact be disruptive to our camera trap survey.
The camera traps also recorded the ubiquitous coati, squirrel, and tamandua, which have now been photographed at all summit locations. We equally have a number of photographs of various song birds, a tinamou, and doves walking in pairs. Finally, we can add a new species of animal to the growing list of tepui invasive, the long tailed weasle Mustela frenata.


Tamandua tetradactyla

Again, we find that tamanduas are present in the lagoon ecosystem in fairly high concentrations. We photographed two different individuals based on pelage markings and size. This animal has been photographed in Naranja, north into campo Lecho, and central Auyan. It seems that tamanduas are ubiquitous on the summit of Auyan.
The smaller of the two tamanduas photographed at the lagoons. Photo selected for ascetic and diagnostic reasons.

 Nasua nasua vittata

Multiple coatis were again photographed at the lagoons, and with greater frequency than tamanduas. Pelage color varies as it did at Naranja and Lecho. We have  found the same pelage pattern as found on the coati documented on Roraima in Havelkova et al 2006 in one individual animal. This indicates that coati pelage patterns are not restricted to any one color, although different bands may have higher or lower frequencies of certain colors.
individual coati, black head yellow pelage similar to coati reported on Roraima in 2006 in Havelkova et al
Two coatis with similar pelage.

 At this point in our investigation, we can say that coatis are going to be completely ubiqutous on the summit of Auyan Tepui.

Didephis  imperfecta

The VAST majority of animals photographed were the opossum Didelphis imperfecta. So man were photographed, in fact, that it actually interfered with our study. The main problem causing this is our baiting system, and the low placement of the traps facing the bait. Based on the results of this initial survey of the lagoons, I conclude that we are going to have to explore adjacent areas to photograph summit vertebrates, or rethink our system of surveillance.

Mustela frenata

We have, for the first time, identified a second species of mustelid on Auyan Tepui, the long tailed weasle Mustela frenata. M. frenata IUCN listed least concern (LC) due to its wide distribution across North America and northern South America, and is well established in Venezuela. Its is a major predator of small mammals such as rodents, although it will attack prey animals larger than itself. Unlike omnivorous coatis and raccoons, M. frenata is an obligate carnivore, and requires a supply of live prey in its range. It is not possible for this animal to act as a seed disperser, although it will seek out carrion opportunistically. In terms of altitudinal distribution, the highest elevation the long tailed weasel is found in is 3800 meters asl (Escobar-Lasso and Gil-Fernandez, Mammalogy Notes 2014), so the approx 2400 masl elevation of Auyan does not pose an altitudinal barrier. As the distribution of this animal varies from alpine to tropical zones across the U.S. and Canada and it is present throughout Central America, M. frenata should have no difficulty in adapting to tepui environments and establishing a population on any tepui with sufficient prey species. Its preferred habitat is a location with abundant prey species to satisfy its high metabolic rate, with numerous dens and large populations of birds. M. frenata will also use waterways for dispersal, and its den locations seem correlated with avaliable standing water (Sheffield and Thomas, Mammalian Species 1997).  This habitat preference a perfect description of the northern lagoon area, which has abundant rodents, rodent burrows, a high densities of birds, and is a riparian ecosystem with pools of sanding water in erroded sandstone basins.  The major predators of M. frenata in North America are foxes and raptors, although larger snakes and cats are also possible predators to a lesser degree (Sheffield and Thomas, Mammalian Species 1997). 

The long tailed weasel Mustela frenata investigates suet cake bait on Auyan Tepui. Another new distribution for this little carnivore on a tepui. 

Based on the behaviour and and ecological niche of M. frenata, I expect that this species is going to be distributed across the dense forests and riparian ecosystems of Auyan, following the larger waterways and into areas with enough substrate to form forests. As the biodiversity of larger mammals on Auyan seems to increase with the presence of forests, I expect that we will locate predators of M. frenata, which may include both tayras as well as crab eating foxes. 


With the discovery of Mustela frenata on Auyan, we now have two species of mustelids living on the summit of this tepui. This brings the count of verified members of the order carnivora on the summit of Auyan up to four: 1) Nasua nasua vittata, 2) Procyon cancrivorus 3) Eira barbara, 4) and Mustela frenata. Still awaiting exact photographic verification on the summit itself are Cerdocyon thous and either Panthera onca or Panthera concolor, although both are found on the talus and both have been sighted on Auyan in the past. Every past camera trap phase has resulted in photographs of coatis and tamanduas, as well as various members of rodentia and didelphimorphia including D. imperfecta, and unidentified mouse opossums. These will be considered ubiquitous on Auyan at this point, as they are present in both low substrate bogs, meadows, and forests. The trick is now to relocate the traps to new locations, and further survey the aquatic ecosystem of this tepui. As the Aonda region seems to be an epicenter for sightings of other larger animals, we will begin to plan for a survey in that areas as well.