Since their formal description by western scientists over a century ago, the dramatic tepuis of the Guiana Highlands (GH) have been a source of fascination and continuing scientific research starting with Roraima Tepui and proceeding to Auyan Tepui in the 1930s. After nearly a 80 years of exploration and surveying, the scholarly concensus is that larger mammals are absent from the tepui summits. However, consistent reports of larger anaimals sighted on the tepui summits (almost exclusively lowland organisms), continues. The 2008 photographing and sighting of the Southern Tamandua Tamandua tetradactyla on the summit of Auyan Tepui represents an interesting case of medium sized exclusively insectivorous mammal living on the summit of a tepui. Diagnosed as Tamandua tetradactyla nigra, this animal is mentioned to inhabit the summits of Auyan Tepui by Tate in the late 1930s. Other forms of the order Pilosa mentioned to inhabit the tepuis are the giant anteater Myrmecophaga tridactyla and the pale throated sloth Bradypus tridactylus. The presence of these animals on the tepui summits raises questions about tepui carrying capacity, gaps in our knowledge about tepui ecology and fauna, and how these ecosystems will change with future anthropogenic climate change. To address these questions, I recommend a meta-analysis of scientific documentation concerning tepui ecology and ecosystems to determine what animals on the tepui summits would be considered anomalous and what animals are already known to invade the summits. Once this is completed, a system for the future monitoring of the tepui summits using expeditionary surveying, GIS analysis and camera trapping will help determine the dynamics of tepui summit ecosystems and biota.
The exploration of the tepuis in the Guiana Highlands has yielded a plethora of information regarding the distribution and endemicity of unique tepui summit life, but has produced some contradictory results regarding the distribution of large vertebrates. The first list of the mammals of the Guiana Highlands was compiled by G.H.H Tate in 1939, based on three expeditions: the 1927-28 Day expedition to Roraima, the 1928-29 Tyler expedition to Duida, and the 1937-38 Phelps expedition to Auyan Tepui. The recent history of the exploration of Auyan Tepui has been characterized by periodic expeditions, long gaps in surveying, and a few target oriented searches by local explorers.
Auyan Tepui was explored by Terramar S.C during the mid 1980s, and in 1994 by the AMNH and
Terramar. There was a significant increase in the exploration of the tepuis in the 1980s and early 1990s by the American Museum of Natural History (AMNH); five separate expeditions in total which surveyed and explored a variety of different tepuis summits, however the field work tapered off due to a lack of funding, public disinterest, and bureaucratic complications. Auyan Tepui has not been explored entirely, with the possible exception of the work of Alexander Laime, who lived on Auyan Tepui for a considerable amount of time, and had the opportunity to extensively observe its wildlife in great detail. Unfortunately, Laimes' observations have never been systematically recorded, and are subsequently mostly lost. There have been sightings by Terramar expedition members of larger vertebrates on the tepui summits (such as Tapirus terrestris and Panthera onca), but no confirmed reports, and no long term studies have been undertaken so far to confirm or refute these sightings.1 The consensus is that the tepui summit lack the diversity of ecosystems and resources to sustain medium sized mammals. Thus, the limited number of mammals sighted during periodic expeditions have been considered anomalous.
While the tepuis were initially considered to be “lost worlds” where archaic lazarus taxon reside, research and exploration in the 1970s challenged this assumption. Recent molecular and paleoecological studies have further challenged the long term isolation of the tepui summits, demonstrating that their vegetational assemblages are the result of post Pleistocene warming, and that their herpetological make up is mostly composed of recent species immigrations, as opposed to vicariant evolution based on the fragmentation of paleofaunal populations.2
Despite our current knowledge of the floristic make up of the tepuis and partial phylogeny of its herpetofauna, there has been a lack of studies on the carrying capacity of the tepui summit ecosystems. This gap in our knowledge regarding the potential for tepui ecosystems has limited our understanding of the possible pathways for lowland colonization of the tepui summits, and what organisms in the future may be expected to invade the summits during periods of climate change.
Tepui Summit Mammals
This characterization of the tepui summits as being devoid of larger mammals is consistent with the work of authors such as Perez-Zapata, Pokorney, and Havelkova. The lack of larger mammals is due to difficulty in accessing the topographically isolated tepuis, as well as the limited sources of food and suitable surface area on the tepui summits. As an example, in Havelkova et al the authors state “Mammals on the tepuis are scarce and probably represent stray animals (e.g. Panthera onca in Auyan Tepui) or extremely rare endemic taxa (e.g. Podoxymys roraimae).”3 Despite this characterization, coatis can added to the list of mammals known to inhabit the tepui summits based on the work of Havelkova et al in 2006, supported in Robovsky et al 2007, Barkoczy 2009, and detailed in my blog entitled Brown-nosed Coati on Auyan-Tepuy, parts 1 & 2.4 With the addition of coatis to the summit fauna of certain tepuis, one would expect that other medium sized mammals may also inhabit or regularly invade the tepui summits. This appears now to be the case.
In 2008, a Southern Anteater (Tamandua tetradactyla nigra) was sighted and photographed on the summit of Auyan Tepui, adding yet another species of medium sized lowland mammal to the short list of vertebrates known to at least invade the tepuis. This is possibly the first time a Tamandua has been photographed on a tepui summit, and its presence here is interesting for a variety of reasons. First and foremost, its presence confirms the statements by Tate during the initial explorations of the summit of Auyan Tepui regarding the summit fauna. Secondly, its presence on the Auyan Tepui indicates that Auyan Tepui and possibly its sister tepui the Chimanta Massif may have a greater ecological carrying capacity than previously thought. Third, it indicates that lowland animals have seemingly little problem invading tepui summits to forage when there is sufficient enticement to do so.
Location of the sighting. January 5th 2008, on top of the second wall near the monument of Jimmy Angels landing in 1937. Altitude is 1841 meters. Approximate time 20.00 GMT. Located in a plain composed of extremely moist soils and bogs, among herbaceous vegetation. Exact coordinates are N5 56.182 W62 35.985
Figure 1. Map of Auyan Tepui, where the yellow pin mark indicates the location of the Tamandua sighted.
Behavior: Engaged in foraging among herbaceous plants, the tamandua immediately adopted a defensive position with its arms extended and claws pointed outward. The animal resumed foraging when the human photographers walked away from it.
Observers: Alberto Pomares and the 2008 expedition crew observed and photographed the animal. The presence of a tamandua on the summit of Auyan Tepui was not considered unusual as “there are many ant colonies on Auyan Tepuy, his main or only food”.5
Physical description: Adult tamandua, sex undetermined. Snout is black color, which extends and terminates at the animals eyes. Pleage color is two toned, light cream colored pelage with a light v shaped black marking on the dorsum and ventral side of the animal. Neck is a darker coloration of light orange. Pelage coloration is consistent with Tates description of “Auyan-Tepui” tamanduas. Photographs of the ventral and dorsal side of the tamandua are below in figure 2
Fig 2. Tamandua photographed in 2008. Top image facing the tamandua, bottom image is a photograph of the dorsal view of the animal. Photographs courtesy of Alberto Pomares can be found on the Alberto Pomares website.
The tamandua photographed is the southern tamandua species Tamandua tetradactyla nigra, based on the geographic location of the tamandua species.6 Tamanduas are common in diverse habitats across South America, and exist at variety of elevations. They exist in Venezuela primarily in thorn forests, in dry areas, and spend most of their day in trees. Their home range in Venezuela is 375 ha with an average daily movement of 3000 meters.7 However, their average range can vary with location; in Brazil the range of multiple animals has been recorded at 100 ha.8 Their diet is primarily social insects; with an approximate ratio of 50% ants and 50% termites.9 Tate notes the presence of tamanduas on the summit of three tepuis; Roraima, Auyan Tepui and Duida Tepui. He states that the pelage of the tamanduas in the Guiana Highlands and the tepui summits is unstripped and straw colored.10 Regarding Tamandua tetradactyla, Tate states:
“ the occurrence of that pallid form, though in a general way regional, seems unrelated to the conditions of climate or forestation. It is equally prevalent among the dwarfed woods of the Auyan-Tepui plateau, in the arid cactus belt at the Rio Tocuyo, and in the heavy rain forests of eastern Ecuador.”11
Tamanduas give birth to a single offspring after a gestation of 4-5 months, with a mean of 160 days. Juvenile tamanduas ride on their mothers back for up to a year learning how to forage. The general behavior of tamanduas is that of solitary nocturnal or diurnal behavior. Their range in the Patanal of Brazil is estimated at 350 to 400 ha, with a population density of .20 to .34 individuals per kilometer.12
Other forms of Pilosa on the tepui summits13
The giant anteater Myrmecophaga tridactyla has also been noted on Auyan Tepui.14 According to Tate the material for Myrmecophaga on Auyan tepui includes 1 animal and on “pick-up skull”.15Tate states:
“A full-grown giant anteater was seen at “Tree Savannas” foot of Mt. Duida, but not captured. These animals apparently range all over the Guianan savanna region up to 5000 feet. They are met with in forests, though usually near savannas. Thomas records a specimen from 'Mount Roraima, 5000 feet”.
Giant anteaters are mostly present in grasslands where they feed on social insects such as termites and ants. Generally solitary in behavior, giant anteaters socialize during courtship, aggressive encounters, and in the case of females caring for their offspring. Their general population density varies. Some authors suggest a home range between 9 and 25 kilometers, while other authors suggest that they are nomadic.16
The pale-throated three toed sloth, Bradypus tridactylus, is listed as being present on the tepui summits. 17 Although this reference gives no indication as to the specific tepui on which B. tridactylus has been sighted, its presence on the tepuis is in the established literature regarding its distribution and conservation. Its distribution is within the areas of the Guianan shield and highlands that include the tepuis of Venezuela ie. the neotropics of Venezuela, Guayana, Suriname and French Guiana.18 It is entirely arboreal and primarily inactive, sleeping the majority of the day. Its diet is based upon the leaves of trees.
The presence of tamanduas on the summit of Auyan Tepui represents something a quandary in terms of the academic knowledge of tepui summit fauna. First and foremost, the presence of this animal was not surprising to the expedition members who photographed it. They were pleased that this animal was present to pose for the camera and show its defensive posture; the display resulted in excellent photographs. In this respect, the presence of such an animal was expected to some degree. This is not entirely surprising; Tate records the Phelps expedition encountering tamanduas on the summit of Auyan Tepui, although they have for some reason been omitted from more recent surveys.
With regard to the presence of giant anteaters on Auyan Tepui, at this point the only reference to these animals comes from Tates “Mammals of the Guiana region”. Compounding this lack of information is the ambiguity of his entry, which gives no indication as to the location or altitude on Auyan Tepui at which either the individual or the skull was located. It is interesting to note that while giant anteaters are found across the llanos, their ability to climb structures has been recently noted. Young, Coelho and Wieloch reviewed the climbing ability of the giant anteater Myrmecophaga tridactyla in their 2003 article, and conclude that tridactyla is in fact fully capable of scaling not only termite mounds in search of food, but also trees upwards of 5 meters in height and artificial enclosure barriers 2 meters in height.19 This ability of giant anteaters to climb obstacles demonstrates their ability to theoretically access the summit of the Venezuelan tepuis given the proper incentive, lending credence to Tates work.
Interestingly a partial analogue to the summit of Auyan Tepui can be found in the Serra Canastra National Park in Brazil, which has a comparable area of the summit of Auyan Tepui ( approx 715 square km and 700 square km, respectively). While obviously phytologically different, both locals are semi isolated and higher in altitude than the surrounding lowlands ( average elevation of Serra de Canastra is 1400 m), and maintain patches of brush lands and gallery forests. Results from a survey of of Serra Canastra carried out between November 1979 and June 1980 indicated a population density of 1.3 animals per square kilometer, much higher than that recorded elsewhere in South America. The existence of such an analogue, with a high density of Myrmecophaga tridactyla present, indicates that giant anteaters might indeed be present on some of the larger more accessible tepui summits.
The only thing which restricts animals such as tamanduas and giant anteaters from the summits of the tepuis is the topography and intrinsic carrying capacity of a given tepui. Certainly, tepuis with small summit areas harbor fewer available resources than the larger ones. In the case of Auyan,the largest tepui interms of continuous summit area, the carring capacity may be unusually high. In this case, it may be useful to diagnose the summit biota of Auyan tepui less in terms of its similarity to other tepuis, and more in terms of its unique characteristics.
Ants of Auyan Tepui
A critical limiting factor for the distribution of both Tamandua tetradactyla and Myrmecophaga tridactyla is the availability of social insects which are their principle food source. Ants and other social insects have been surveyed to some extent the tepui summits. Jaffe, Lattke, and Perez Hernandes produced a survey of the various ants of the tepui summits in which they compare the distribution of tepui summit ants, their lowland counterparts, and the apparent richness of ant diversity on the tepui summits.20 They found that ants are most abundant at an altitude of 800 meters; altitudinal diversity decline was attributed to the difficulty in colonizing the tepui summit ecosystems. This is a trend with the tepui summits, and extends to insects as well as higher animals. For our purposes, the analysis of Auyan Tepui is particularly interesting. According to their findings, Auyan tepui contained the highest divesity of ant species, (14) second only to the Chimanta massif (10 species). The stated reasons for this high diversity is the comparatively “Moderately harsh climate conditions (less altitude)” of Auyan and Chimanta. This hints at the fact that Auyan Tepui may have the highest ecological carrying capacity of any of the tepuis, due to its climate, size, and the availability of micro-habitats and the diversity of ecosystems it contains. The authors characterized:
“a direct relationship between area and diversity is confluent with is land biogeography theories...although in the case of tepuies, part of the fauna is derived from the surrounding lowland forests rather than some distant mountain source. The larger summits offer a greater diversity of habitats and this should translate into more opportunities for colonization”.21
Indeed this seems to be the case; Auyan Tepui and the Chimanta Massif share he greatest diversity of ant species at 14 and 10 respectively. The next highest diversity of ants are found on Huachamakari Tepui and Aparaman Tepui at 5 species. The majority of tepuis sampled harbor no more than 1 to 2 species. Auyan Tepuy is a statistical outlier in the distribution of tepui ant populations, lying outside of two standard deviations from the sampled tepui ant populations. Jaffe, Lattke and Perez-Hernandez conclude that 1) ant distribution on the tepuis can be explained if the tepuis are treated as biogeographical islands ie climate, altitude and niche abundance (expressed partialy as surface area) limit the colonization of ant species 2) the distribution of the species of ants suggest different colonization methods, which do not conform to a single theory but rather represent a complex history of colonization following island biogepgraphy and panbiogeography. The work of the authors suggests a complex history of climate related alterations and changes in the summit biota, expressed by Rull in his analysis of the effects of climate change on the tepui summits. The authors tentatively date the vicarriant speciation of the ant genus Selenopsis at 8000 kya, based on a change in climate from an arid ecology to a more humid one at the start of the Holocene. It would be interesting to see if the various ant species on the tepui summits are old enough to have existed in their present locations during the theoretical tepui paramo period suggested by Rull as being the dominant tepui summit Pleistocene vegetational assemblage.22
The Meaning of tamanduas and members of the order Pilosa on the tepui summits
The presence of Tamandua tetradactyla on the summit of Auyan Tepui may be surprising given a broad characterization of tepui summit fauna, but is certainly not unusual to indigenous scientists and has been noted since the initial explorations of Auyan Tepui. The presence of giant anteaters on the summit of Auyan Tepui has only to my knowledge been noted by Tate, and supporting evidence for Myrmecophaga tridactyla on the tepui summits after Tates publication has not been noted to my knowledge. It is known that both the giant anteater and the southern tamandua share habitats, they occur in the same range, and the two groups appear to coexist well in the same ecosystem.23 Thus, evidence for one does not preclude the presence of the other, due to competition for resources. The presence of Bradypus tridactylus in a tepui environment is unusual, given the distribution of B. tridactylus and composition of tepui summit flora, not to mention the difficulty in accessing the summit of a tepui. Due to the behavior of this animal, being almost entirely sedentary, and dependent on extensive canopy cover for both food and protection, I am inclined to dismiss the notion of Bradypus tridactylus on any tepui summit. The limited presence of gallery forests and the preponderance of herbaceous assemblages, combined with the impoverished soils of the tepui summits which limit the growth of extensive gallery forests should render the tepui summits off limits to this sloth species.
The presence of three members of the order Pilosa on the tepuis raises questions about the distribution of mammals on the tepui summits, tepui carrying capacity, and the scientific knowledge produced by tepui research. In terms of mammalian distribution, it indicates that medium sized mammals are indeed present on tepui summits; exactly what species are present, their range, population density, and how they fit into tepui ecology is unknown. From a stand point of carrying capacity, the presence of at least Tamandua tetradactyla on Auyan Tepui indicates that larger tepuis will have a correspondingly larger ecological diversity, and may be host to more species of mammals than previously thought.
When it comes to our scientific knowledge of the summit fauna of the tepuis, the presence of members of Pilosa on the summit can be viewed from a few different angles. If we base our knowledge of tepui summit mammals on the work of Tate and the knowledge of local Venezuelan scientists and explorers, then the existence of Tamandua tretradactyla (and to a lesser extent possibly Myrmecophaga tridactyla) on the tepui summits is within the norm of their geographic distribution. If, on the other hand, we base our knowledge of tepui summit mammals on current literature regarding the tepui summit fauna, then the presence of these animals would be considered anomalous. With regard to Bradypus tridactylus as a tepui summit mammal, there is no record of its presence mentioned by Tate, and as of this writing the source material which places this sloth on the tepui summits is not available. Given the ecological niche of Bradypus tridactylus, it is very unlikely that this animal is present on any tepui summit at all. I would consider that the sloth B. tridactylus is possibly not present on the tepui summits until sufficient data is obtained to indicate that it is. In this case, sufficient data would be diagnostic evidence of its presence (photographic or physical), or reliable visual observations of B. tridactylus on a tepui summit with the specific tepui name recorded as well the GPS coordinates of the sighting.24 This evidence needs to be produced to avoid errors in the recording of tepui species and which could complicate future conservation efforts.
The presence of at least one member of Pilosa (Tamandua tertradactyla) on the summit of Auyan Tepui indicates that Tate's observations are correct, and by implication we may expect to see other members of this order present as well. When these observations are compared to the presence of coatis on the tepui summits (documented in my previous blog) the image that emerges is that certain tepui summits are host to a greater diversity of larger vertebrates than currently thought. This situation has been documented in the form of observational data by Michelangeli and the Terramar organization during their expeditions during the 1980s. This confusion over the status of lowland vertebrates on the tepui summits needs to resolved.
The best way to solve the gaps in our scientific knowledge of the tepui summits is to attempt to fill them. An obvious course of action would be an extensive series of expeditions to survey and monitor the tepui summits over time, using the latest technologies available in geospatial science and wildlife biology (such as extensive camera trapping). This grand endeavor would be very expensive, and is not feasible outside of large non-profit groups (such as Conservation International and the Nature Conservancy) or the Venezuelan government and Venezuelan universities.
What is feasible right now is the dissemination of current knowledge of the tepui ecosystems, collected in a single source to aid future research processes. In order to compile all the existing knowledge of the tepui ecosystems, a kind of meta-analysis must be produced which is up to date with current theories. A meta-analysis will help determine where “anomalous” fauna and normative fauna diverge, exemplified in this case with the distribution of Tamandua tretradactyla and Bradypus tridactylus on the tepui summits. Once a meta-analysis is produced, if it can be combined with a review of tepui summit flora and topography, a crude carrying capasity evaluation for individual tepui summits can be created. This could then be used to further test predictive models for the projected impact of climate change on the tepui summits. Furthermore, carrying capacity analysis and meta-analysis of the entire pan-tepui region would be very useful in justifying the need for future expeditionary research.
11)Teouy, Colosos de la tierra. A. Michelangeli ed, Altolithos, Caracas Venezuela 2005, 2) George, Uwe. “Tepuys, Venezuelas Islands in Time”, National Geographic May 1989
2 1)Salerno, P. E. et al, D. C. (2012), “Ancient tepui summits harbor young rather than old lineages of endemic frogs”. Evolution. doi: 10.1111/j.1558-5646.2012.01666.x, 2)Garvish et al, “Ancient vicariance or recent long distance dispersal? Inferences about phylogeny and South American-African disjunctions in Rapateaceae and Bromeliaceae based on ndhF sequence data” International Journal of Plant Science. 2004
3Havelkova, Pavla et al, “Brown-nosed coati (Nasua nasua vittata) on the Roraima tepui (Carnivora: Procyonidae)” Lynx 37, 2006.
4Havelkova, Pavla et al, “Brown-nosed coati (Nasua nasua vittata) on the Roraima tepui (Carnivora: Procyonidae)” Lynx 37, 2006. Robovsky et al, “Additional report of the Brown nosed Coati (Nasua nasua vittata) on the tepuis- The Chimanta Massif, Churi Tepui, Venezuela” Lynx (Praha) 38, 115-117 2007, Barkoczy, Laszlo “Globalizing a Lost world: Beauty or Benefit, what drives conservation? The International Relations Journal, San Francisco State University, Vol 28, 2009. http://biokryptos.blogspot.com/2011_10_01_archive.html
5Personal communication with Alberto Pomares regarding the presence of tamanduas on the summit of Auyan Tepui.
6V. Hayssen “Tamandua tetradactyla (Pilosa: Myrmecophagidae)” Mammalian Species 43 (875): 64-74, May 2011.
7Montgomery, G. G.. “Movements, foraging and food habits of the four extant species of Neotropical vermilinguas (Mammalia: Myrmecophagidae)”. Pp. 365–377 in The evolution and ecology of armadillos, sloths, and vermilinguas (G. G. Montgomery, ed.). Smithsonian Institution Press, Washington, D.C. 1985
8F.H Rodrigues et al “Anteater behavior and ecology” Pp. 257–268 in The biology of the Xenarthra (S. F. Vizcaıno and W. J. Loughry, eds.). University Press of Florida, Gainesville 2008
9Wetzel R. M. 1985. “The identification and distribution of recent Xenarthra ( Edentata)”. Pp. 5–21 in The evolution and ecology of armadillos, sloths, and vermilinguas (G. G. Montgomery, ed.). Smithsonian Institution Press, Washington, D.C.
10Tate, “Mammals of the Guiana Region,” The bulletin of the American Museum of Natural History, October, 1939.
11Tate, “Mammals of the Guiana Region”, The bulletin of the American Museum of Natural History, page 171
121) Panera A Los Mamíferos de la Argentina y la Región Austral de Sudamérica - Editorial El Ateneo,
2002 2) Desbiez ALJ, Medri Im “Density and Habitat Use by Giant Anteaters (Myrmecophaga tridactyla) and
Southern Tamanduas (Tamandua tetradactyla) in the Pantanal Wetland, Brazil” - Edentata 11: p4-10.
13Pilosa is an order of mammals which includes South American anteaters as well as extant and extinct sloths. The origin of the order is unclear, but it seems to date from the early tertiary in South America.
14 At the time of this writing, it is unclear to me of Tate means that Myrmecophaga was sighted on the summit or near the summit on the slopes of Auyan Tepui
15Tate, Mammals of the Guiana Region, The bulkletin of the american museum of natural history, october, 1939. page 171
16Pinto da Silvera, “Historia natural do tamanduad-banderia, Myrmecophaga tridactyla. Myrmecophagidae” Velozia No 7, Rio de Janerio 1969, Montgomery and Lubin “Prey influences on movements of neotropical anteaters. In Proceedings of the 1975 predator symposium, pgs 103-131. Montana forest and Conservation Experiment station, Montana USA.
18 Hayssen, V. “Bradypus tridactylus (Pilosa: Bradypodidae)” Mammalian Species, 839 2009
19Young et al “A note on the climbing abilities of giant anteaters, Myrmecophaga tridactyla (Xenarthra, Myrmecophagidae)” Bulletin of the Museum Biological Mello Letao, 15, June 2003
20 Jaffe, Klaus et al “Ants on the tepuis of the Guiana Shield, a zoogeographic study” Ecotropicos, vol 6 # 1 1993
21 Jaffe, Klaus et al “Ants on the tepuis of the Guiana Shield, a zoogeographic study” Ecotropicos, vol 6 # 1 1993
22 Rull, V., “The Guayana Highlands: A Promised (but Threatened) Land for Ecological and Evolutionary Science”. Biotropica, 39: 31–34. 2007
23Arnaud L et al “Density and Habitat Use by Giant Anteaters (Myrmecophaga tridactyla) and Southern Tamanduas (Tamandua tetradactyla) in the Pantanal Wetland, Brazil” Edentata no 11, 2010
24 This requirement is based on the evidentiary standards described in McKlevin et al “Using anecdotal occurrence data for rare or elusive species:the illusion of reality and a call for evidentiary standards” Bioscience vol 58, no 6 June 2008.