Abstract
In
the beginning of this year, from January 6th to January 13th, a
unique experiment took place. Working with Alberto Pomares and members of his expedition team, a camera trapping pilot
study took place which followed a transect line survey of an area on
Auyan Tepui known as the Laime trail. The positive results of this
experiment demonstrate that camera trapping on the summit of Auyan
Tepui is not only possible, but can be used to obtain images of the
unique fauna of the summit. The application of such a study can be
used to monitor invasive faunal elements entering the tepui. I am
deeply indebted to the entire expedition crew for the realization of my pilot study; Alberto Pomares, Vittorio Assandria, Daniel Abgrall, Cedrig Abgrall, Dr. Douglas Olivares, Nelson Gonzalez, Richard Dittmar, Ana Cristina Fernandez, Dr. Carlos Acevedo,and Paul Stanley. I would also like to especially thank the Pemon guides who assisted with the completion of the camera trap: Santos Ugarte (the principle guide), Arturo Berti ( Guide and Camera Trap assistant) and Nixson (Camera trap assistant). Currently Alberto Pomares and his fellow team members are setting up a website for this and other work on Auyan Tepui.
Introduction
Camera
trapping is becoming a widespread practice in wildlife biology. It is
minimally invasive and when employed en mass over a large area can be
an effective tool in monitoring biodiversity, carrying capacity, and
species density.1
It has been used to identify new species and identify cryptic species.2
In this instance, a camera trap pilot study was utilized during an
expedition to the summit of Auyan Tepui in Venezuela. The
methodology of the pilot study differed from that of traditional
camera trapping in that it followed the progress of a transect walk
across a defined path in the southern access point of Auyan Tepui,
known as the Laime Trail. While not a traditional camera trapping
study due to its differential methodology, it did produce positive
results of multiple captures of the fox Cerdocyon thous. The
implications and data returned can be used to launch a larger more
comprehensive project to study an area of the world which may be
subject to significant ecosystem change over the next 100 years due
to anthropogenic climate change.
The
Laime Trail and Auyan Tepui
At
roughly 700 square kilometers in summit area and 200 square miles of
tallus slopes, the Auyan Tepui in Venezuela is the largest tepui
(flat topped sandstone mesas) in the Guiana Highlands. Officially
discovered in the mid 1930s and first explored in 1937, the summit
hosts the greatest diversity of ecosystems and animal life when
compared to the other tepui summits. The tepui summit has never been
completely surveyed over time, and its sum total biodiversity has not
been completely assessed. Auyan Tepui is host to four types of
vegetational assemblages; pioneer assemblages, tepui summit meadows
and woody scrub, evergreen forests (mostly along river systems and
areas with large soil deposits) and mountain forests on the tallus
slopes.3
The
Laime Trail is the southern access point on the tepui summit used by
Alexander Laime to access the summit of Auyan Tepui. Alexander Laime
was a well known explorer and local celebrity in Canaima. He was the
first westerner to reach Angel Falls by foot, and participated in the
1955 expedition to the summit of Auyan Tepui. He spent substantial
time on the summit of Angel Falls, and made numerous observations
regarding the fauna of the tepui summit, including observations of
undescribed animals on the summit. His extensive knowledge of the
Auyan Tepui allowed him to access the southern portion of the
plateau, which turned out to be a trail which with minimal climbing
allows for easy hiking access to the tepui summit. Mr. Laime has been
featured in a variety of travel logs and documentaries pertaining to
the Auyan Tepui. Sadly, this famous explorer died in 1994, a recent
documentary detailing his life can be found following this link4.
The 2012 Laime Trail expedition intended to set out from the bottom
of the trail and end in the central point of Auyan Tepui, where the a
series of rivers empty into the southern end of the Canon Del Diablo,
and the approximate location of the Salto Churun-meru. This trip
would cover a variety of habitats and floral assemblages, ending near
the collection camp of the 1994 AMNH-Terramar herpetological
expedition.5
Thus, the camera trapping would have followed this trail to its
conclusion, and time was set aside to scout a new camp site. The
intended course of the expedition is detailed below in figure 1.
Figure
1. Satelite image of Auyan Tepui with the positions of intended
camera trapping points for the 2012 Laime Trail expedition
represented by yellow pins.
Rationale
for camera trapping on the tepuis
Camera
trapping has not been documented as a research tool in the study of
tepui fauna this far. Although Auyan Tepui has been partly surveyed
since its formal discovery in the late 1930s, inconsistent
information regarding its vertebrate fauna has never been reconciled.
The vertebrate fauna of the tepui summit ecosystems is considered to
be composed of mostly small reptiles, amphibians, birds, and a
limited number of small endemic mammals. However, numerous sources
indicate that Auyan Tepui may be host to larger vertebrates.
Havelkova and Robovsky have documented the presence of coatis (Nasua
nasua) on the tepui summits.6
My previous blog posts deal with the presence of coatis on the summit
of Auyan, and Havelkova and Robovsky have detailed them on Roraima
and the Chimataná Massif, respectively. Other authors have mentioned
the presence of Panthera onca on the summit of Auyan Tepui,
and members of the Terramar expedition society have reported seeing
mountain lions on the summit of Auyan, in the eastern section of the
tepui.7
Tapirs have been reported on the summit of the Auyan Tepui by both
Otto Huber and Armando Michelangeli.8
Tamanduas were observed and documented by Tate, and photographed by Alberto Pomares, as well as coatis.9
“The
diversity of herpetofauna (frogs and reptiles) is about half that of
birds, but the level of endemism is higher, reaching 60% in some
tepuis. Mammals, most of them small, are also represented by even
lower number of species, mainly of bats, rodents, and some marsupials
(opossums). So far, felids, monkeys, and medium to large herbivores
have not been observed atop the tepuis. Insects have not been studied
systematically, but recently, a new genus of damselflies was
described (Tepuibasis),
with all its seven species being endemic to Pantepui”10
The
difference between the reported sightings and observations of medium
to large animals represent something of a knowledge gap in our
understanding of the tepuis in general, and their ecological carrying
capacity. I have addressed this in my previous blog posts by stating:
“The
presence of coatis and large vertebrates on the tepuis is now a
question natural range extension or climate
change induced invasion. Solutions to this question can be answered
with increased monitoring and scientific surveys. However, there is
an admitted research gap in the study of the Tepuis, stated in both
Rull et al 2009 and in Robovsky et al 2007. In Rull et al 2009 the
authors state “Scientific expeditions to the GH started 170 years
ago and continued in a regular fashion, until the late 1980s”, a
statement which mirrors Robovsky et al 2007 with the statement “The
aim of this paper is to bring new observations concerning the
distribution of this species (Nasua
nasua) on the
Chimanta Massif after 15 years (sic) long gap and also partially
describe its external appearance”.”
The
primary concern is that the inconsistent reporting of tepui
vertebrate fauna is hiding a phenomena which may be catastrophic to
tepui summit life; vertical migration and extinction caused by
anthropogenic climate change.11
Such a phenomena would be a devastating loss to local and global
biodiversity, and needs to be researched in depth and addressed with
the proper conservation strategies.
While
research methodologies to determine the realities of habitat loss on
the tepui summits are multidisciplinary and diverse, camera trapping
can be one tool used to determine elements of the current faunal
diversity of the tepuis. Thus a kind of impromptu pilot study was
initiated to test the use of camera traps following a single transect
walk across the Auyan Tepui. The theory behind this impromptu study
is that camera trapping is capable of producing more data regarding
cryptic animals (such as felids and tapirs) than the traditional
survey techniques used thus far. This experiment had four major
objectives:
- To record images of medium sized vertebrates, if encountered, along the Laime Trail.
- To conduct a reconnaissance of the Laime Trail for future camera trapping exercises on Auyan Tepui.
- To test the camera trapping equipment for durability in the tepui summit environment.
- To use the data collected to asses the feasibility of future tepui summit camera trapping activity
Survey
area
The
summit and escarpments of Auyan Tepui are the areas surveyed,
starting at a southern entrance point at camp Uruyen and proceeding
north into the interior of the summit. The area is interesting to
examine as it is a major entrance to the interior of Auyan Tepui; the
sloping topography allows for humans to enter the summit of the
tepui. The trail moves through a variety of different ecosystems from
the base of the tepui up the slopes to the summit; from mountain
forests to tepui meadows, leading into a slight increase of elevation at
the second wall near camp Dragon in the center of the tepui. The tepui
vegetational cover varies with altitude: submontane forests exist up
to 1200 meters, montane forests, scrub and swamp exists from 1200 to
3000 meters in elevation. The summit in the south is rocky and filled
with meadows and bogs, with the terminal point of the Laime Trail
composed of peat bogs, sandstone bluffs and some dense forests
following the river that drains into the Canon Del Diablo, just east
of the Salto Churun-meru. This portion of Auyan Tepui is also subject
to periodic tourist activity, so the location can be useful in
analyzing the impact of human presence on the tepui ecosystems.
Equally, it may act as an access point for invasive animals entering
the tepui summit, either as part of their natural range or vertical
migration due to global climate change.
Trapping
locations, tools and and methods
The
expedition occurred from 6th to the 13th of
January, 2012. The expeditions' intended route was to proceed from
Uruyen in the Kamarata Valley to Campo Guayaraca, and proceed north on the summit
of Auyan Tepui, moving past camp Dragon and the second wall of Auyan
Tepui to scout out a new camp site, as presented in figure 1.
Inclement weather limited the expeditions' progress and forced them
to end early at camp Naranja (2146 meters in elevation) detailed in
figure 2. While this represents only a small part of the entire
trail, the team did move through ecosystems ranging from the lower
elevation (approx 1000 meter) forests into the rocky and meadow
dominated portions of the Auyan Tepui summit. Unfortunately, the
gallery forests and dense vegetation which characterizes the the
northern portion of the trail after the second wall was left unvisited.
Figure
2 (A and B) Figure 2A is a satelite map of the Auyan Tepui with the
camps and camera trapping locations on the Laime Trail indicated by
yellow pins. Figure 2B is a close up of the camp and camera trap
locations.
Camera
traps specifications and notation
Two D55IR GameSpy digital cameras manufactured by Moultrie were utilized
with SD memory cards valued at 4 gigs each. Desiccant packs had been
placed within the housing to absorb moisture. The cameras were set
with the following custom modes:
Camera
name: biokpt01 Camera
name: biokpt02
Capture
mode: video Capture
mode: multiple stills
Quality:
low
Quality: medium
Delay:
15 seconds Delay:
15 seconds
Temperature:
Celsius Temperature:
Celsius
IR
test: off
IR test: off
Info
Strip: On
Info Strip: On
Default
settings: No Default settings: No
Delete
All : No
Delete All: No
Flash:
On.
Flash: On
The
second camera (biokpt02) was set with a capture mode of multiple
stills, with a quality (resolution) setting placed at medium. In all
other respects the settings were identical. These
cameras utilize a temperature sensor which triggers the camera when
an object with a higher temperature than the background ambient
temperature passes with in its range. The effective detection range
of the camera is 35 feet +/- five feet, with a 52 degree field view.
The camera system was selected due to weight, price and and capture
mode. Primarily, a camera system using an infrared trip sensor would
not have been effective to use in an opportunistic manner without
establishing specific sites for long term trapping.
Methodology
The
method utilized for the camera trapping study was a nocturnal set up
and use of the traps at each camp location, effectively preforming a
photographic nocturnal survey of the Laime Trail in multiple
locations. While the expedition team moved from camp to camp, they
preformed a default transect survey of the south of Auyan Tepui,
noting and recording vertebrates observed and recording possible
locations for future camera trapping exercises. The GPS coordinates
and elevation of each camera trap site was recorded, as were the
precise location of vertebrates observed, and suitable locations for
future camera trapping. The cameras were retrieved and deactivated
when camp was abandoned, and set up at the next camp location to
record from approximately dusk to dawn. The intention of this method
was to monitor faunal elements along the transect during time periods
which have never been monitored before. As the majority of camera
time was in indifferent locations, the data obtained produced a
limited account of nocturnal life along the Laime Trail during the
course of the expedition. The traps were set at approximately 60
centimeters from the ground, and attached to sufficiently large trees
or appropriate natural features. They were artificially triggered
after set up to verify they were functioning. The expedition crew
attempted when possible to set the traps along a trail or open area
which would tend to encourage animals to walk into the capture zone.
Results
(as delivered verbatim from Alberto Pomares)
First
Trap setup: GUAYARACA
Results: POSITIVE CAPTURE OF A FOX
Food: Vegetables
Operator: Alberto Pomares
Assistant: Arturo Berti (Pemón Guide)
Location: At 50 m from Guayaraca Camp on a forest trail
Fotos and Videos: DROPBOX\2012\CAMERA TRAP\2012-01-06-NEAR GUAYARACA
Date: From 2012 Jan 06, 17:20 to 2012 Jan 07 07:16 (Local Time)
Position: N 5º 41.084' & W62º 31.483'
Altitude: 1010m (over sea level)
Location Photos: DROPBOX\2012\CAMERA TRAP\2012-01-06-NEAR GUAYARACA\CAMERA-PLACEMENT
Height position: aprox 2 feet from ground
Noted: Easy to position due to the trees in the forest
Second Trap setup: Peñón
Results: Negative (Cameras not fired at all)
Food: Dinner leftovers
Operator: Alberto Pomares
Assistant: Arturo Berti (Pemón Guide)
Location: At 10 m from Peñón Camp in the bushes (no forest)
Fotos and Videos: NO IMAGE RECORDED
Date: From 2012 Jan 07, 19:14 to 2012 Jan 08 06:41 (Local Time)
Position: N 5º 44.665' & W62º 32.452'
Altitude: 1838m (over sea level)
Location Photos: NO PHOTOS TAKEN DUE TO THE INTRICATE OF BUSHES AND RAINY WEATHER
Height position: aprox 1 feet from ground
Noted: Difficult to position, no trees, just small logs and rocks. Camera belts are adequate just for tree setting up and not good for anything else. (Don´t know why no images were taking during setups?)
Recommendations: Next time there is the need for a pre-build support for bush setups.
Third Trap setup: Naranja (Orange)
Results: Negative (Cameras fired just during setup)
Food: First Cereal, then Dinner leftovers, 3rth day vegetables
Operator: Alberto Pomares
Assistant: Arturo Berti (Pemón Guide)
Location: At 264 m south from Naranja Camp in a trail among the bushes (no forest)
Fotos and Videos: DROPBOX\2012\CAMERA TRAP\2012-01-10-NARANJA
Date: From 2012 Jan 10, 16:17 to 2012 Jan 13 15:22 (Local Time)
Position: N 5º 46.415' & W62º 31.969'
Altitude: 2161m (over sea level)
Location Photos: DROPBOX\2012\CAMERA TRAP\2012-01-10-NARANJA\CAMERA-PLACEMENT
Height position: aprox 2 feet from ground
Noted: Difficult to position, no trees, just small logs and rocks. Camera belts are adequate just for tree setting up and not good for anything else.
Recommendations: Next time there is the need for a pre-build support for bush setups.
Fourth Trap setup: Naranja Camp (Orange)
Results: Negative (Cameras fired but no capture)
Food: Dinner leftovers
Operator: Alberto Pomares
Assistant: Arturo Berti (Pemón Guide)
Location: Right at the camp near the fireplace were we saw small mice eating leftovers
Fotos and Videos: DROPBOX\2012\CAMERA TRAP\2012-01-13-NARANJA-CAMP
Date: From 2012 Jan 10, 16:17 to 2012 Jan 13 15:22 (Local Time)
Position: N 5º 46.528' & W62º 32.075'
Altitude: 2130m (over sea level)
Location Photos: NO PHOTOS TAKEN DUE TO RAINY WEATHER
Height position: aprox 2 feet from ground
Noted: Difficult to position, no trees, just small logs and rocks. Camera belts are adequate just for tree setting up and not good for anything else.
Recommendations: Next time there is the need for a pre-build support for bush setups, including placement on rocks.
Fauna Sighting:
In this expedition we had the opportunity to see:
2 Birds (maybe a couple) at the Naranja Camp. They were all day long lurking for food left overs
1 black vulture (Zamuro) all black, flying over the Naranja Camp in several days
1 Royal vulture (Zamuro Real), black with white and red head, flying over the Naranja Camp in several days
1 frog on a tree at Guayaraca Camp
1 Small Lizard at Orange camp.
1 Spider at Oso camp
1 Little frog at Naranja camp
Results: POSITIVE CAPTURE OF A FOX
Food: Vegetables
Operator: Alberto Pomares
Assistant: Arturo Berti (Pemón Guide)
Location: At 50 m from Guayaraca Camp on a forest trail
Fotos and Videos: DROPBOX\2012\CAMERA TRAP\2012-01-06-NEAR GUAYARACA
Date: From 2012 Jan 06, 17:20 to 2012 Jan 07 07:16 (Local Time)
Position: N 5º 41.084' & W62º 31.483'
Altitude: 1010m (over sea level)
Location Photos: DROPBOX\2012\CAMERA TRAP\2012-01-06-NEAR GUAYARACA\CAMERA-PLACEMENT
Height position: aprox 2 feet from ground
Noted: Easy to position due to the trees in the forest
Second Trap setup: Peñón
Results: Negative (Cameras not fired at all)
Food: Dinner leftovers
Operator: Alberto Pomares
Assistant: Arturo Berti (Pemón Guide)
Location: At 10 m from Peñón Camp in the bushes (no forest)
Fotos and Videos: NO IMAGE RECORDED
Date: From 2012 Jan 07, 19:14 to 2012 Jan 08 06:41 (Local Time)
Position: N 5º 44.665' & W62º 32.452'
Altitude: 1838m (over sea level)
Location Photos: NO PHOTOS TAKEN DUE TO THE INTRICATE OF BUSHES AND RAINY WEATHER
Height position: aprox 1 feet from ground
Noted: Difficult to position, no trees, just small logs and rocks. Camera belts are adequate just for tree setting up and not good for anything else. (Don´t know why no images were taking during setups?)
Recommendations: Next time there is the need for a pre-build support for bush setups.
Third Trap setup: Naranja (Orange)
Results: Negative (Cameras fired just during setup)
Food: First Cereal, then Dinner leftovers, 3rth day vegetables
Operator: Alberto Pomares
Assistant: Arturo Berti (Pemón Guide)
Location: At 264 m south from Naranja Camp in a trail among the bushes (no forest)
Fotos and Videos: DROPBOX\2012\CAMERA TRAP\2012-01-10-NARANJA
Date: From 2012 Jan 10, 16:17 to 2012 Jan 13 15:22 (Local Time)
Position: N 5º 46.415' & W62º 31.969'
Altitude: 2161m (over sea level)
Location Photos: DROPBOX\2012\CAMERA TRAP\2012-01-10-NARANJA\CAMERA-PLACEMENT
Height position: aprox 2 feet from ground
Noted: Difficult to position, no trees, just small logs and rocks. Camera belts are adequate just for tree setting up and not good for anything else.
Recommendations: Next time there is the need for a pre-build support for bush setups.
Fourth Trap setup: Naranja Camp (Orange)
Results: Negative (Cameras fired but no capture)
Food: Dinner leftovers
Operator: Alberto Pomares
Assistant: Arturo Berti (Pemón Guide)
Location: Right at the camp near the fireplace were we saw small mice eating leftovers
Fotos and Videos: DROPBOX\2012\CAMERA TRAP\2012-01-13-NARANJA-CAMP
Date: From 2012 Jan 10, 16:17 to 2012 Jan 13 15:22 (Local Time)
Position: N 5º 46.528' & W62º 32.075'
Altitude: 2130m (over sea level)
Location Photos: NO PHOTOS TAKEN DUE TO RAINY WEATHER
Height position: aprox 2 feet from ground
Noted: Difficult to position, no trees, just small logs and rocks. Camera belts are adequate just for tree setting up and not good for anything else.
Recommendations: Next time there is the need for a pre-build support for bush setups, including placement on rocks.
Fauna Sighting:
In this expedition we had the opportunity to see:
2 Birds (maybe a couple) at the Naranja Camp. They were all day long lurking for food left overs
1 black vulture (Zamuro) all black, flying over the Naranja Camp in several days
1 Royal vulture (Zamuro Real), black with white and red head, flying over the Naranja Camp in several days
1 frog on a tree at Guayaraca Camp
1 Small Lizard at Orange camp.
1 Spider at Oso camp
1 Little frog at Naranja camp
summary of results
Biokpt 1 was equipped to record still images and 5 seconds of video. Out of 45 shots, seven are of fauna (Cerdocyon thous), and four appear to be misfires of the camera. The remaining images are of expedition members setting up the cameras or moving around them. Biokpt 2 was configured to capture still images and no video. Of 81 images, 6 are of fauna, again Cerdocyon thous. 34 shots are misfires (three appear blank, and may be a mechanical failure), and the remaining shots are of expedition members. These results indicate that the video function of the cameras is far superior in producing images of wildlife, whereas the still image setting alone produces more misfires, and records less usable data. Each camera was operational for 166 hours in the field, producing 332 camera hours, or approximately 13.8 camera days (a “camera day” is the number of cameras multiplied by the number of days they are operational.) This information is summarized in chart 1 below.
camera
|
Total number of shots
|
Number of captures
|
Number of misfires
|
Expedition members recorded
|
Positive capture rate
|
Capture in Photo/hour
|
Biokpt1
|
45
|
7
|
4
|
34
|
0.155
|
0.0421
|
Biokpt2
|
81
|
6
|
34
|
41
|
0.074
|
0.0361
|
Chart
1; summary of the results of camera trapping the Laime Trail.
Camera
trapping results analysis
The
camera trapping experiment was successful; it recorded images of the
fox Cerdocyon thous, and
images from the summit (expedition members moving in front of the
camera). It was, however, not perfect. At camp Penon from the 7th
to the 8th
of January, the cameras failed to fire, and subsequent capture of
images were mostly of expedition members. The failure of the
cameras to properly fire at the second location may be due to a
variety of factors. The most obvious factor is that the no animal of
sufficient size to trigger the cameras passed in front of the
cameras. Given the limited time the traps were active, their failure
to capture further images of larger vertebrates at camp Pemon and
Naranja is not entirely surprising. Furthermore, the inclement
weather and extremely heavy rain which halted the expedition at
Naranja may have discouraged animals from moving around at night
during the time the cameras were active. The rain may also have
produced interference which prevented the cameras from operating by
drowning out the temperature variations which trigger the operation
of the camera. The expedition members who set up the camera traps
noted the presence of moisture build up around the lenses and
infrared lens; this phenomena is known to interfere with camera
traps.
At
Penon, the trap failed to fire from the initial set up. Though it
remains unknown what caused the failure, the problem was temporary
and the traps fired at the Naranja camp, although they apparently did
not capture anything other than their own initial set up. In effect,
after photographing a fox at on the forested talus slopes, the
cameras did not capture any other animals. At both Penon and Naranja,
the expedition team had difficulty setting up the cameras due to a
lack of suitable locations to attach the units. The D55IR Gamespy
cameras come with straps to attach the camera unit to tree trunks- an
optimal set up to both camouflage the cameras and properly anchor
them. On tepui summits, suitable trees are generally restricted to
gallery forests which exist along stream margins, or are located in
slime forests. In open tepui meadows, there are few suitable trees to
attach the cameras to. The expedition crew noted that the traps were
“Difficult to position, no trees, just small logs and rocks.
Camera belts are adequate just for tree setting up and not good for
anything else”, and recommend that “Next time there is the
need for a pre-build support for bush setups, including placement on
rocks.” This lack of mounting structures may have contributed
to the lack of camera trap captures on the tepui summit.
This
assessment is defiantly accurate; for the topographically complex and
floristically diverse tepui summits, future camera trapping efforts
will require specialized pre-built structures for mounting camera
traps. Such structures, perhaps similar to tripods, can be disguised
with local plants, placed in dense herbaceous settings, or covered in
camouflage material to make them inconspicuous to local wildlife.
During the course of the experiment, (though the expedition crew made
an effort to position the cameras where they would intercept
wildlife) camera placement near the camp and in human traveled areas
may have had resulted in a decreased likelihood of encounters with
local fauna. In future camera trapping endeavors on tepui summits
pre-built structures would have to be used and the cameras would be
placed for maximum encounter possibility in appropriate environments,
for longer periods of time.
Some literature indicates that camera trapping can be more successful
than transect line surveys for a variety of reasons, and more
appropriate in conducting long term surveys.12
The viability of camera trapping vs transect line surveying for
recording medium sized or larger vertebrates is evident with regards
to the fauna encountered on the the Laime Trail during the
expedition. In this case, we have a clear dichotomy between the
effectiveness of a transect survey and a camera trap survey during a
short expedition: a medium sized carnivorous mammal was camera
trapped but not physically observed. The transect survey managed to
produce observations of a limited number of organisms: two small
birds, two species of vultures, two amphibians, one small reptile and
one spider. What is interesting to note is that at the Guayaraca
camp, only a spider was observed, whereas the camera trap managed to
photograph Cerdocyon thous. Thus, it appears that camera
trapping is possibly a more effective method of recording and
surveying the larger vertebrates of the Guiana Highlands,
particularly over longer periods of time. Transect survey methods are
by definition useful in recording smaller organisms or arboreal
animals which the cameras may miss, although possible solutions to
this may be found with strategic camera placement and proper use of
bait.13
Based on the success of this camera trapping pilot study, it would
seem that there is some strong evidence to propose the use of camera
trapping in future surveys of certain tepui summits. Larger tepuis
that maintain a greater diversity of summit ecosystems and that a
have topographical connection to the lowlands should be the primary
focus.
Cerdocyon
thous Analysis
1)
Description and ecology
At
Campo Guayaraca, the camera traps successfully recorded images of a
Venezuelan fox, identified in this case as Cerdocyon thous,
the crab eating fox. The images and video below are from the camera traps at Guayaraca. The fox enters the capture area of the camera traps presumably to feed on the food scraps that have been left as bait.
The classification of the fox is based upon the physical features of the fox, as well as the known distribution of foxes in this region.14 A medium sized canid, Cerdocyon thous is known as the zorro comun, zorro de monte, or zorro sabanero in Spanish. Cerdocyon thous weighs on average 5-7 kg, and is identifiable by a moderately bushy tail with a black or dark tip, narrow pointed head, dark pelage from the dorsum to the midline, and generally light colored ventral pelage, although significant pelage color variation is known. Five subspecies are known, the Venezuelan subspecies being C. t thous. The range and distribution if Cerdocyon thous is shown below.
(The map of the distribution for Cerdocyon thous can be found here and at the IUCN website.)
The classification of the fox is based upon the physical features of the fox, as well as the known distribution of foxes in this region.14 A medium sized canid, Cerdocyon thous is known as the zorro comun, zorro de monte, or zorro sabanero in Spanish. Cerdocyon thous weighs on average 5-7 kg, and is identifiable by a moderately bushy tail with a black or dark tip, narrow pointed head, dark pelage from the dorsum to the midline, and generally light colored ventral pelage, although significant pelage color variation is known. Five subspecies are known, the Venezuelan subspecies being C. t thous. The range and distribution if Cerdocyon thous is shown below.
(The map of the distribution for Cerdocyon thous can be found here and at the IUCN website.)
Cerdocyon
thous has been noted as being sympatric with several other
species of fox, including the pampas fox Pseudalopex gymnocercus,
Pseudalopex culpaeus and P. vetulus in Brazil.15
The population density varies depending on location and environment;
in the scrub mosaics of Brazil the average population density is 0.55
animals per square kilometer, whereas the population density for C.
thous in the Venezuelan llanos is 4 animals per square kilometer.
The population density is not known in the Venezuelan highlands,
Suriname, French Guiana, or the lowland Amazon forests. Habitat
varies considerably throughout the animals range, from scrub to
woodlands and forests, and C. thous has been recorded up to
3000 meters. Range varies with abundance, season, and availability of
prey items as well as social status of individual foxes. Range varies
greatly across south America, from an estimated 5.3 km2 in
Marajo Brazil to 1km2 in the Venezuelan llanos, with dry
season ranges greater than wet season ranges. C. thous is
hyopcarnivorous, and omnivory is well established. Prey items vary
with availability; in the Venezuelan llanos, the majority of prey
items were small mammals, followed by fruit, amphibians and insects.
In Argentina, aquatic birds made up the majority of the prey items,
and in Colombia vertebrates were the favorite food items, while in
Marajo Brazil insects appear to be the primary food item. Foraging
behavior of C. thous is characterized by individual or pair
hunting, with adults accompanied by 1 to 3 grown offspring. Hunting
method of C. thous is primarily pouncing when hunting
vertebrates, and lateral head movements when hunting insects. C.
thous may act as a seed disperser of Acacia aroma,
Celtis tala, different varieties of fig species, and presumably
other cultivated and wild plants. Studies conducted on the feeding
habits of C. thous found that the majority of ingested food
was plant based (fruits and leaves), followed by insects and finally
vertebrates.16
Social
behavior is categorized by monogamy and social interactions in small
groups of offspring. Dispersed offspring form territories in
proximity to their parents ranges. Breeding pairs produce a litter of
approximately 2.6 offspring between December and February. Parents
and offspring are sociable throughout their lives, and there is no
sexual division of labor in cub rearing. With such a comparatively
large population density, the presence of foxes in the areas around
the tepui talus slopes is not surprising. An fairly high population
density of C. thous (at 0.78 individuals per square kilometer)
was found in Itapua National Park in Brazil. This population density
was partly attributed to the variety of feeding habitats in the area,
where diverse ecosystems offered a myriad of feeding opportunities.17
The GH and the tepui ecosystems (including the talus slopes) offer
an high diversity in ecosystems; potential feeding opportunities
should abound for C. thous in the region. Therefore, while the
precise population density of C. thous is not recorded for
tepui slopes, it should be fairly high. Only future studies using
methods like long term camera trapping will determine the reality of
this assertion.
2)
Discussion of C. thous in proximity to the tepuis
In
the Guiana Shield (GH), there are two primary species of Canids;
Cerdocyon thous and Speothos venaticus, commonly known
in English as the bush dog.18
The order Carnivora is represented in the Guiana Shield by two
canids, six felids, five mustelids, and four procyonids.19
In terms of our present knowledge of the mammals of the region, the
first systematic efforts to collect the mammals of the GH were
undertaken by Robert and Richard Schomburgk
in the 1840s.20
Analysis and collecting of both the flora and fauna were later
conducted between 1937 and 1938 with the famous Phelps/ American
Museum of Natural History expeditions, funded by W.H Phelps and led
by G.H.H Tate. A comprehensive list of the mammalian fauna of the
Guiana Shield was latter compiled by Tate based on these expeditions
and previous work, while Phelps Senior and Junior continued
ornithological expeditions in the tepuis of Venezuela.21
Further comprehensive inventories and species lists were made by the
Smithsonian Venezuelan Project, and by Ochoa et al in 1993, with
complete inventories of Canaima National Park.22
In the region as a whole, (ie the entire Guiana Shield) the vast
majority of mammalian diversity is made made up by chioptera (bats),
which represent 148 out of the 282 known mammal species. This is
followed by Rodentia at 58 described species, Didelphimorphia
(opossums) with 22 species, and Carnivora at 17 species. Given the
body sizes and behavior of these groups, one can assume that the
majority of the mammalian fauna in the Guiana Highlands and the
Guiana Shield will be difficult not only to camera trap, but also to
identify and classify during a short term expedition or transect
survey, particularly for non-specialists.
To
my knowledge there exists no study of the general capture frequency
for crab eating foxes in the Guiana Highlands. There are some studies
involving camera trapping that did included C. thous captures
that were carried out in other parts of South America. In the
Bolivian Chaco, four years of camera trapping (2001-2005) resulted in
215 photos of Cerdocyon thous .23
A similar study in the Emas National Park in Brazil, again over an
extended period of time and with multiple camera traps, recorded a
capture rate of 93 captures out of 157968 camera trap hours, with a
calculated photographic rate defined in photographs/hour at between
0.000106 to 0.000980 depending on habitat.24
My capture per camera hour rate is comparatively impressive at
between 0.0421 and 0.0361 for the two cameras, though the brevity of
the study makes any statistical comparison with other studies
virtually irrelevant. Only a longer study or series of short term
studies would yield enough data to make valid and useful comparisons.
It is unfortunate that this is the first instance of camera trapping
and investigation into the fox population of the tepui slopes; a
contemporary analysis would give at least a baseline to compare my
results to. Despite the knowledge gap regarding the distribution of
larger carnivores on the tepui summits, C. thous has been
noted as being a resident of the area by Tate in the late 1930s, in
his report the “Mammals of the Guiana Highlands”. Regarding the
foxes of the Auyan Tepui Tate writes that they have certain features
which differentiate them from the foxes of the Colombian Andes:
“The
audital bullae, though fuller, more rounded and deeper than those of
the high Andean fox reissi,
are far less full than those of the foxes of Mt. Auyan-Tepui and the
Cotiga savannas north of the Rio Branco.”
He
differentiates the Auyan tepui foxes further from foxes found in
other parts of the highlands, stating that:
“The
specimens from the Cuyuni are slightly aberrant-perhaps transitional
with Auyan-Tepui specimens-in the reduction of the black dorsal hairs
of their tails to a small area at the tip. The audital bullae,
however, differ from those of Auyan-Tepui.”25
Speaking
specifically about the morphology of Auyan Tepui foxes, Tate makes
several anatomical observations:
“The
foxes from the Auyan Tepui area and those of the Cotiga savannas
differ markedly from Orinoco foxes in the enlargement and
proportional approximation of their bullae and in the accompanying
narrowness of the basi-occipital. In animals from the Auyan-Tepui the
teeth are slightly smaller…Auyan Tepui specimens, furthermore,
differ Cotinga animals in possessing small, short haired tails with
black markings limited to the tip….”26
Tate
asserts that C. thous can be differentiated by the size of
their dentition; where the Auyan Tepui animals representing a
transitional form between the northern Brazilian foxes and those
found in the Venezuelan llanos. Although this camera trapping
experiment did not obtain enough information to verify Tate's
observations regarding the derivation of foxes across Northern South
America, it does confirm his observations regarding the distribution
of foxes into the upper elevations of Auyan Tepui. Interestingly,
Tate's investigations of the fauna of Mt. Duida failed to produce
evidence of foxes, and upon further investigation he confirmed with
the indigenous people that C. thous is unknown in the region.
This could speak to the fact that higher elevation tepuis do not
maintain the same levels of faunal diversity, possibly due to their
carrying capacity. If this is the case, then the distribution of C.
thous in the Pantepui region should include the Chimantá Massif,
and other large tepuis with lower elevations, greater surface area
and diversity of ecosystems. Establishing the range and populations
of C. thous in the Pantepui region is extremely important for
a variety of reasons, but for our purposes here the role of C.
thous in the ecosystem need to be established as it effects not
only the endemic fauna, but also the flora. C. thous is a
potential seed disperser, and its gut may encourage the germination
of certain plant seeds. 27
Similar phenomena has been observed in coatis, which should be
considered as regular members of Tepui summit biota.28
This could effect the potential change in tepui summit floral
composition if global climate change effects the tepui summits as
disastrously as predicted. C. thous and N. nausa may
change the distribution of current and future floral assemblages by
introducing non-endemic or indigenous plant species by acting as seed
dispersers.
Conclusion
From an epistemological stand point, the photographic capture of C.
thous is not surprising, but its lack of documentation on the
tepui summits is. As of the writing of this paper, I have been unable
to find records of C. thous on the tepui summits or talus
slopes with the exception of the 1939 work by Tate previously
referenced. This is unusual, as C. thous seems to be highly
adaptable predator and is present in the Guiana Highlands and
Canaima National park. Despite the fact that the animal was recorded
on the slopes leading up to the summit rather than the summit proper,
the altitude of the capture was still within the higher elevations of
the tepuis. At 1010 meters in elevation, the camp Guayaraca photo
and video captures place C. thous in the proper location and
niche to be present on the summits of low-lying tepuis. The feeding
behavior of C. thous is consistent with what would be expected
from a tepui summit invasive animal; omnivory, adaptability and the
capability of feeding on a variety of available food sources. The
diet and niche of C. thous compares favorably to that of Nasua
nasua; a mesopredator already known to range into the summits of
low elevation tepuis,.29
I covered in detail the phenomena of coatis on the summit if Auyan
Tepui; the presence of these animals on Roraima and Chimantá was
considered noteworthy enough to generate two short scholarly
articles, which did a great deal to illuminate the carrying capacity
of the tepuis and the biogeography of Nasua nasua.30
The lack of scholarly information on the presence of C. thous
on the tepui summits presents something of a mystery, given the
relative ease of camera trapping these animals on the slopes of Auyan
Tepui. It could be that there have been no sightings of C. thous
on the tepui summits as a result of summit avoiding behavior.
Perhaps there is a lack of long term food sources on the summits, or
maybe the topography of the tepuis represents a challenge to C.
thous. This seems unlikely, as the area in which the fox was
photographed grants humans relatively easy access to the summit; it
seems logical that an agile fox could make the hike from camp
Guayaraca to the summit of Auyan Tepui. It could also be that the
absence of C. thous on the summit is the result of a sampling
error; C. thous is mostly active during the night and at dawn,
and therefore unlikely to be encountered during a transect walk or
under the usual conditions of daytime scientific field activity. In
this case, when a survey methodology was used that was biased towards
nocturnal organisms, (ie nocturnal camera trapping), the presence C.
thous was recorded successfully. In all likelihood this nocturnal
carnivore would have not been recorded without the camera trapping
experiment. Finally, as I mentioned in part 1 of the Auyan Tepui
coati post, it may simply be that local scientists and foreign
scientists do not have a identical understanding of the precise
distribution of vertebrates in the Guiana highlands.
Projecting
forward- future endeavors
This
camera trapping experiment was a successful proof of concept. Given
that the methodology differed from standard camera trapping, and
taking into account poor weather and extremely limited duration,
this experiment was wildly successful. Based on this fact alone, it
would seem that camera trapping the Auyan Tepui and its sister tepuis
would be useful in deducing the sum total biodiversity of the tepui
summits, bearing in mind that camera trapping would be biased toward
larger bodied endothermic vertebrates to trigger the camera. Camera
trapping has worked all over the world to catalog known species and
has managed to uncover new species.31
Traditional transect surveys and site collection methodologies should
be used in conjunction with camera trapping. An excellent methodology
for integrating theses systems can be found in the Tropical Ecology
Assessment and Monitoring Network (TEAM), with specific guidelines on
camera trapping systems and procedures. There are a few general
recommendations that can be made based on this work:
- A mapping analysis of Auyan Tepui focusing on both key regions of interest and entrance points along the talus slopes which can be camera trapped.
- An increase in both the number of camera traps used and and their duration of time in the field. TEAM methodology recommends 32 cameras per survey, 2 per site with a total of 16 sites. Such as large number of cameras would only be possible with a well funded expedition, in cooperation with local organizations in Canaima and Venezuela.
- Complete georeferencing of all camera locations, as well as specimens photographed or collected by recognized scientists.32
- Proper post camera trapping data analysis, again following TEAM protocols. Protocols are outlined and available for download at http://www.teamnetwork.org/protocols
- Following the recommendations of Captain Pomares and his expedition team ( waterproofed housing, use of tripods or prebuilt mounts, moisture control).
These
five recommendation are just a few things that need to be done in
order to camera trap the tepui summits successfully and competently.
The recommendations are easily enough implemented in future camera
trapping experiments. At this point in time, based on what was
learned from this camera trapping experiment, Auyan Tepui needs to be
the focus of a new, more involved and more detailed camera trapping
study. The time for such studies is now, as we come to understand
that global climate change will alter the tepui ecosystems forever.
.
1Carbone,
C. et al “The use of photographic rates to estimate the densities
of tigers and other cryptic mammals” Animal Conservation #
4 2001.
2
“First images of newly discovered primate”
http://www.fauna-flora.org/news/first-images-of-newly-discovered-primate/
3
McDiarmid and Donnelly, “The herpetofauna of the Guayana
Highlands; amphibians of the lost world”. Ecology and evolution
in the tropics: a herpetological perspective. pp. 461-560
Donnelly, Maureen A., Crother, Brian I., Guyer, Craig, Wake,
Marvalee H. and White, Mary E. (eds.)
4
http://www.screenvision.lv/index.php/en/?option=com_k2&view=item&id=327:aleksandr-laime-dimonds-of-angel-falls&Itemid=493&lang=en
5Myers
& Donnelly, “The summit herpetofauna of Auyantepui, Venezuela:
report from the Robert G. Goelet American Museum-Terramar
expedition” Bulletin of the AMNH # 308, 2008
6Havelkova
et al, “Brown-nosed coati (Nasua nasua vittata on the Roraima
tepui, (Carnivora: Procyonidae)” Lynx (Praha) 2006,
Robovsky et al “Additional report of the brown-nosed Coati (Nasua
nasua vittata) on the tepuis- the Chimantá Massif, Churi Tepui
Venezuela” Lynx (Praha) 38, 2007
7
1)Havelkova et al, “Brown-nosed coati (Nasua nasua vittata on the
Roraima tepui, (Carnivora: Procyonidae)” Lynx (Praha) 2006,
Havelkova summarizes limited sightings and reports of larger mammals
on tepui summits. 2)Uwe, George “Tepuis, Venezuelas Islands in
Time” National Geographic, May 1989.
8
Huber, Otto “Guayana Highlands versus Guayana Lowlands, a
reappraisal” Taxon, 37 1988 , Michelangeli, Armando
“Tepuis, los colossus de la tierra”, Uwe, George “Tepuis,
Venezuelas Islands in Time” National Geographic, May 1989
9Tate
G.H.H “Mammals of the Guiana region”. Bulletin AMNH vol
79 1939
10
Rull, V “Pantepui” Encyclopedia of islands Rosemary
Gillespie and David Clague eds University of California Press, 2009.
This is the opinion of a variety of scientists regarding the general
level of tepui summit fauna. See also Ochoa & Gorzula “Los
Mamiferos del macizo de Chimantá. Con algunos comentarios sobre las
comunidades de las cumbres tepuyanas” in Huber (ed) El Macizo
del Chimantá, Escudo de Guayana Venezuela, Un Ensayo Ecologico
Tepuyano, Caracas, 1992
11Rull,
V. et al (2006) “Unexpected biodiversity loss under global
warming in the neotropical Guayana Highlands: a preliminary
appraisal” Global Change Biology 12:
1-6, Rull, V(2007) “The Guayana
Highlands: a promised (but threatened) land for ecological and
evolutionary science” Biotropica 39:
31-3,Rull, Villarrubia,, Nogue, Huber,
(2009) “Conservation of the unique neotropical vascular
flora from the Guayana Highlands in the face of global warming”
Conservation Biology 23: 1323-1327
12
Trolle, M. et al “Brazilian
Tapir Density in the Pantanal: A Comparison of Systematic
Camera-Trapping and Line-Transect Surveys” Biotropica,
vol 40, issue 2 2008, Silvera, L et al “camera trap, line transect
census and track surveys: a comparative evaluation”. Biological
Conservation, 114, 2003
13
Schipper J “Camera trap avoidance by Kinkajous Potos flavus,
rethinging the “non-invasive” paradigm”, Small carnivore
conservation vol 36April 2007
14
Identification based upon long bushy tail, appearance of black line
on the dorsum, as well as the known canids of the Guanyana
highlands. See 1)“Checklist of the Terrestrial Vertebrates of the
Guiana Shield” Bulletin of the Biological society of Washington
no 13, December 2005 2) Berta A “Cerdocyon thous” Mammalian
species # 86, 1982 3) IUCN Canid Specialist Group “Crab-eating
fox (Cerdocyon thous)”
http://www.canids.org/species/Cerdocyon_thous.htm
15
IUCN Canid Specialist Group “Crab-eating fox (Cerdocyon thous)”
http://www.canids.org/species/Cerdocyon_thous.htm
16
Rocha, V. J et al “feeding habits of the Crab eating fox Cerdocyon
thous in a mosaic area with native and exotic vegetation in Southern
Brazil,” Revista Brasileira de Zoologica, 24(4) Dec 2008
17
Faria- Correa, M, et al “Activity, habitat use, density, and
reproductive biology of the crab-eating fox (Cerdocyon thous)
and comparison with the pampas fox (Lycalopex gymnocercus) in
a resting area in the southern Brazilian Atlantic Forest”
Mammalian biology 74, 2009
18Burton
K et al “Mammals: Checklist of the Terrestrial Vertebrates of the
Guiana Shield” Bulletin of the Biological Society of Washington
# 13 2005
19Burton
K et al “Mammals: Checklist of the Terrestrial Vertebrates of the
Guiana Shield” Bulletin of the Biological Society of Washington
# 13 2005
20
Burton K et al “Mammals: Checklist of the Terrestrial Vertebrates
of the Guiana Shield” Bulletin of the Biological Society of
Washington # 13 2005
21Myers,
Charles W. “A history of Herpetology at the American Museum of
Natural history”, Bulletin of the AMNH no 252, 2000.
22Ochoa
et al “Inventario y estudio communitario de los mamiferos del
Parque National Canaima, con una lista de las especies registradas
para la Guayana Venezolana Acta Cientifica Venezolana # 44, 1993
23
Maffei et al 2007 Home range and activity of two sympatric fox
species in the Bolivian Dry Chaco. Canid news 10.4
24De
Almeida Jacomo A.T. Et al “Niche separation between the maned wolf
(Chrysocyon brachyurus), the crab-eating fox (Dusicyon
thous) and the hoary fox (Dusicyon ventulus) in central
Brazil” London Journal of Zoology, 262, 2004. It should be
noted that Dusicyon thous is
a synonym of Cerdocyon thous.
25Tate
G.H.H Mammals of the Guiana region. Bulletin AMNH vol 79 1939
26Tate
G.H.H Mammals of the Guiana region. Bulletin AMNH vol 79 1939
27
1)The Crab-eating Fox (Cerdocyon thous) as a secondary seed
disperser of Eugenia umbelliflora (Myrtaceae) in a Restinga forest
of southeastern Brazil Biota Neotrop., vol. 9, no. 2 Eliana
Cazetta1,2,3 & Mauro Galetti12) Seed dispersal of Solanum
thomasiifolium Sendtner (Solanaceae) in the Linhares Forest,
Espírito Santo state, Brazil Acta bot. bras. 23(4): 1171-1179. 2009
João Vasconcellos-Neto et al
28
Cecília P. Alves-Costa “Seed dispersal services by coatis (Nasua
nasua, Procyonidae) and their redundancy with other frugivores in
southeastern Brazil” Acta Ecologica, vol 32 issue 1 2007
29
Aguiar, Lucas M et el “Diet of
brown-nosed coatis and crab-eating raccoons from a mosaic landscape
with exotic plantations in southern Brazil” Studies
on Neotropical Fauna and Environment
vol 46, issue 3 2011.
30
Havelkova et al, “Brown-nosed coati (Nasua nasua vittata on the
Roraima tepui, (Carnivora: Procyonidae)” Lynx (Praha) 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, 2007
31Rovero,
F. “A new species of giant sengi or elephant-shrew (genus
Rhynchocyon) highlights the exceptional biodiversity of the Udzungwa
mountains of Tanzania” Journal Of Zoology 274 2008.
32See
Garcia and Funk “Improving the use of information from museum
specimens: Using Google Earth (c) to georeference Guiana Shield
specimens in the U.S. National Herbarium” Frontiers of
Biogeography 2.3 2010
Great work on this post Laszlo. It was a pleasure participating in this pilot study. We are ready to help you out for the next one on the Auyan Tepuy.
ReplyDeleteRegards.
Alberto Pomares