FROM THE WARDENS DESK – OLIFANTS WEST September 2012
Figure 1. Boris the resident Ratel looks on as we type our reports. Well, this has been an eventful three months! There is so much to write and so little time to do it in. First I would like to announce that it is with a heavy hart that we have said good-by to Tim Girling who has worked with me for over three years now and has been a major asset to my team and OWNR. He has returned to help his farther manage their farm in the UK. Stefan has stepped up and taken it upon himself to tackle Tim‟s responsibilities and I wish him the very best of bushveldt Luck! You will learn to hate that fence and old tractor! Then we have had two fires in our region – one on the farm Nonwane and the other on Takazile. Tragic Black Rhino losses, anthrax scares and the usual tractor troubles. I do not have to say much here as I have already circulated reports on most of these incidents. There is currently an anthrax outbreak in the central Kruger National Park and has reached as far as Umbabat, which is close enough to spread into Balule. The loss of several buffalo and other high-value species in the east of the reserve led us to take precautions and have samples of their blood and bone-marrow sent to Skukuza for analysis. The results were negative for Anthrax which was a huge relief. Then we have been plagued by a spate of snared animals on the reserve in the past few months. This has led to huge costs to both wildlife as well as the reserve. Please read the detailed anti-poaching summary contained within the report. The problem is internal and
we have to share the responsibilities with landowners to reduce the threat of poaching on our reserve. Please look closely at the maps and see which properties are affected. The 28mm of rain that we enjoyed in mid September has transformed the bush overnight! The long-term forecast for our rainfall this year is that we will receive late rains and therefore will endure a dry period until after Christmas. So be it! Our resources and dams can carry us for many months still. Once again I have had the privilege of mentoring several university students and interns who have all contributed to the contents of this report. STATE OF THE ENVIRONMENT: We have received 394mm of rain since the beginning of this year and 28mm since the beginning of the 2012/2013 wet season.
Figure 2. 2012 rainfall in relation to monthly average since 1985.
Anti-poaching Francois van der Merwe; Transfrontier Africa: Staff member In the past quarter, the wardenâ€&#x;s team has responded to an abnormally high number of security breaches. Our anti-poaching unit is out every day, patrolling and doing what they can to prevent these event. Table 1 shows a brief summary of recent events. Table 1: Summary of incidences on OWNR Date:
Reason for activity:
Cambridge 7 and hardekool
Reported lion with a snare
Bated for animal, but suspect did not show up
Cambridge 7 and hardekool
Follow up on snared lion
Tried to track and bate animal, still could not find.
Cambridge 7 airstrip
Follow up on snared lion
Reports of lions roaring the area. Snared lion was not seen at bait.
Barnards/Van der Merwe fence line
Reported wild dog with a snare
Wild dog was darted and snare was removed. Part of foot was amputated and animal was sent to the Hoedspruit Endangered Species centre, for rehabilitation.
Cambridge 6, 7 and hardekool
Reported lion in snare
Baited for lion, no lion was found with a snare or any serious damage
Section of western boundary fence
Reported black rhino on fence
Fence was clear
Sherombirombi Cambridge 6
Report of a gunshot in the area
Accidental shot went off from land owner
Maroela road Servitude road
Tracks of people walking on Maroela road from last night
Tracks start at the juntion of two main roads and end on the fence near the gate possibly staff going on leave
Tracks of people walking on Maroela road, from last night.
Tracks start at the junction of two main roads and end on the fence near the gate unknown reason
Southern side of Cambridge 5/6 and olifant road
Report of a gunshot in the area
Western boundary fence - Hoedspruit
Fence alarm went off, reading is 0.3Kv
Buffalo ran into fence fixed broken strands
Follow up on last night‟s gunshot - person might have reserve through this section. Patrol picked up tracks on the neighbouring reserve the previous night in this section
Con van der Merwe/OWNR western boundary fence corner
Section of western boundry fence Hoedspruit side/Maroela road
Reported black rhino on fence
Fence was clear
Reported buffalo in snare
Buffalo was darted and snare was removed
Reported foot prints on maroela road
Lost tracks, unknown origin and destination.
Reported Zebra in snare
No snare was seen on leg, only a few cuts.
06:00 07:30 07:30 08:50
One the night of the 09th of August, one of the Olifants West pride males was reported to have snare around its back right leg. The warden‟s team responded immediately and arrived on the scene, but the lion eluded us. We could not relocate that night. Our antipoaching unit went out at first light with one of the trackers who first reported the animal. The tracks where lost and it was decided to bait for the animal at a nearby location. Two impala ram carcasses where tied to a tree with chain, to serve as bait, we then continued to play sounds of a dying wildebeest and buffalo to attract the lions to the bait. The bait served as a window for us to call the vet in and for the vet to arrive on the scene.
Figure 1: Wardens Team with lions on the bait. Lions where on the bait within 20 minutes, but none of them had a snare on them or shown any weakness (Figure 1). No lions where reported on the next day. Reports came through on the 12th of August for lions around the Cambridge 7 area. We baited again in the hopes that the snared lion would show up, with Peter Rogers (local vet) on standby. Once again, we had lions on the bait, but none of them had a snare on them or showed signs of injury. It was apparent that the snare either fell off or the animal is not in the area anymore. The decision was made to wait for the animal to be seen again and we would respond immediately. ď‚ˇ
Wild dog snare:
On the afternoon of the 11th of September, a report came through that a wild dog has a snare on itsback right foot. Stefan Bosman (Wardens team) responded immediately to the area. It was confirmed that the animal had a Figure 2: Wild dog with a snare. snare around the leg and was cutting in badly (Figure 2). Peter Rogers was immediately called to respond. Once the vet was on site, he darted the animal and removed the snare. Part of the foot had to be amputated and the animal was send to the Hoedspruit Endangered Species Centre for rehabilitation. On the night of the 15th of September, another report came through of a snared lion on the Cambridge 3 area. The anti-poaching team was on the tracks early the next morning. The
anti-poaching team did come across some lions, but none of them had a snare. Audio for more lions was noted in the area. It was then decided to bate for the animal. The same procedure was followed than the previous incident in regards to the bating procedure. None of the lions on the bait had a snare on it once again. It is suspected that the snare fell off. I am happy to report that we could account for all our lions (snare free) on the 21st of September. The last male lion was found on oxford, looking very healthy (figure 3).
Figure 3: Last of unaccounted male lion found on Oxford farm. Recently our black rhinos have been found more in the western sector of the reserve. As a result we have encountered them on our western boundary fence during our fence patrols. Reports from the rhino monitoring team has also pointed us into the right direction. Once these reports come through, we respond immediately and chase the animal off the fence line as this could become serious security risks for us and the animal. The first gun shot was an accidental shot that went off and was quickly resolved. The second reported gunshot on the night of the 28th of September ended without a conclusion. The wardenâ€&#x;s team was in the area within 10minutes of the shot, with jointed efforts from us and York Nature reserve we quickly swept the area and found no suspicious activity. The fences where patrolled the next the next day, at first light, to make sure that no tracks enter or leave the reserve through the fence. The anti-poaching unit has responded to numerous reports of tracks on Maroela road of tracks of people walking on the road from the night before. It would seem that the tracks would start on Maroela/Sable road junction and walk down Maroela road, towards the fence. The tracks are lost close to the fence, which might mean that the perpetrators have been picked up by a vehicle. On the 29th of September the western boundary fenceâ€&#x;s alarm went off, indicating that the voltage on the fence has dropped dramatically. Upon inspection it was clear that a small herd of buffalo ran into the fence. The fence was quickly fixed. ď‚ˇ
On the 30th of September we received a report of a buffalo with a snare around its foot. We responded immediately and were on the scene within 30 minutes. A snare was confirmed to be on the animal by the Warden and Peter Rogers was called immediately to
assist with the animal. The animal was darted and the snare was removed (Figure 4). Luckily the animal did not suffer any serious damage to the leg.
Figure 4: Stefan assisting with the darting process. What we are doing: Our anti-poaching unit is still going out every day on patrols. A total of 218 snares have been removed/recovered from the field since February 2010 until September 2012. Figure 5 illustrates how the poaching incidences have varied over the last three years. Although we are only in September of 2012, the graph already shows that we could expect less poaching attempts (Snaring) than last year.
Figure 5: Snaring incidences for the last three years. The number of snares recovered from our patrols has dropped since the previous year and at the rate or removal or discovery, it will not reach the level that we saw in 2011. However, the same old hot-spots remain and we will see an increase in the number of affected animals as they utilise more of the landscape every year (new waterholes opened in the west, new lion distribution patterns, etc.).
Our anti-poaching trackers are still patrolling every day, on the lookout for anything suspicious. Figure 6 is a map of our trackers movement for the week of 24 September 2012 to 30 September 2012.
Figure 6: Anti-poaching trackers movements in a week. As with all things in conservation, we have a shortage of resources and therefore it is critical that we share the responsibilities with land owners in OWNR. We cannot deny that with over 112 workers living on 46 properties, spread over 8 800ha and with numerous absentee landowners, there will be snaring! With figure 7, we can identify our „hot spots‟ for the last three months (July-September). With this we know on which areas to focus more on. „Hot spots‟ are marked with a red circle.
Figure 7: Snares for the period July 2012 – September 2012.
From this information we can see that the problems are primarily internal. The snares are set in close proximity to houses, compounds and waterholes, access roads and such that are known and used by internal workers daily.
Figure 8. The Western Hot-Spots in relation to compounds, roads and waterholes.
Figure 9. The central Hot-Spots in relation to compounds, roads and waterholes.
The major areas of concern are the western extremity of the reserve on Oxford and the central region of Takazile, Cambridge 7 and Hardekool (river front). There is also a strong correlation between live-on-site building projects and snaring activities. Due to the sudden surge in snaring activity again, we have solicited the assistance of Protrackâ€&#x;s, who currently have a small team on the reserve and are working closely with us to address this problem. People that are walking around on the reserve are always a security risk that is difficult to deal with. We ask from all landowners to please not let their staff walk around on the reserve. I would like to take this opportunity to thank everyone who has reported an animal in distress or any suspicious activity. The more eyes and ears we have out there, the better.
Analysis of Grass in the Olifants West Nature Reserve Alex Lin-Moore, Transfrontier Africa intern
Grass phytomass, or the amount of grass that grows above the soil, is an important indicator of ecosystem health. The amount (and quality) of grass in the Olifants West Nature Reserve determines carrying capacity of many animal species, regulates the plant community, and controls fire intensity, an essential factor in shaping the environment. Understanding changes in grass phytomass is fundamental to our working knowledge of the landscape. In 2012, the wardenâ€™s team continued a multi-year analysis of the grass phytomass in the OWNR. We sample the phytomass at the end of the dry winter season to provide an idea of what remains in the environment after grazing pressure. To calculate the reserveâ€™s aboveground phytomass, we sampled four regions: Rome 8 and 9, Impalabos East and West, Cambridge 5 and 6, and Rome 4 and 5. We collected a total of 28 samples along River Lodge main road, Huppel road, False Cutline, Mohlabetsi cutline, Sable road, Marula lane, and the Rome IV-V cutline. Each sample site was 1 km from the last site to avoid biases due to unusually dense or sparse patches of grass. At each sample site, ten 1m x 1m plots were randomly distributed, and all grass was removed from within the plot.
These samples were weighed on the day of collection and again every day (at the same time) for several weeks whilst drying in porous bags, until the grass has reached its minimum weight. The Impalabos West region had the highest phytomass, while the Cambridge 5 and 6 area had the lowest (Fig. 2).
Figure 2. Aboveground phytomass from the four sampled regions over four years.
This finding contrasts the results of previous years, in which the eastern border of the reserve had the highest phytomass. Also in contrast with previous years’ data is the amount of change in phytomass between years. Whereas between 2009 and 2010 the reserve’s phytomass increased by an average of 279% (202 kg to 765 kg), between 2011 and 2012 phytomass decreased by 4% (1180 in 2011 to 1130 in 2012). Figure 3 shows the trend in phytomass accumulation since 2009 and we suspect that the figures would have been higher this year if the January floods had not scoured the seasonal drainages as the banks of these drainages yielded a large sample every year and were lost to the floods this year. 6000
5000 River Lodge
Impalabos West 3000
Sable/Marula Rd. Rome IV
TOTAL Log. (TOTAL)
R² = 0.9413 0 2009
Figure 3. Aboveground phytomass sampled across four years. The total phytomass fits a logarithmic curve.
While the reserveâ€™s phytomass appears to fit a logarithmic curve, the factors determining how much grass grows in the reserve are unclear. To better understand the interactions between grass and the environment, we compared yearly phytomass to factors known to regulate the arid savanna. We specifically compared phytomass to annual rainfall and grazer populations. While fire is known to be an important determinant in grass growth, the lack of fires in the reserveâ€™s recent history (before this year) excludes it as a determining factor. Both rain and grazer numbers appear to have increased in the past few seasons (Fig. 4), but analysis showed that rainfall was not significantly correlated with phytomass. However, phytomass was significantly correlated with total grazer numbers (Pearson correlation, p=0.043). 5000 4500 4000
Total Phytomass (kg/ha) Rain (mm/year)
3500 3000 2500 2000
Total Grazer Numbers
1500 1000 500 0 1
Figure 4. Comparison of annual changes in phytomass, annual rainfall, and grazing herbivore populations. Increases in phytomass are significantly correlated with increases in grazer population (Pearson correlation, p=0.043).
The correlation between phytomass and grazer numbers highlights both the interconnectedness of animals and plants in the reserve and the importance of maintaining a sustainable population of grazing mammals. While keeping a sustainable population of game is important to maintaining healthy predator populations, these data show that a sustainable population of game is also necessary to keep the reserveâ€™s plant community healthy. It is clear from that above that both the climatic conditions as well as consumers (grazers) are important ecosystem drivers or ecological processes required to maintain a balance.
Analysis of Species Diversity at Water Holes in the western OWNR Alex Lin-Moore, Transfrontier Africa Intern
Figure 1. A black rhino (Khuza), a young bull elephant, and members of the Singwe pride were some animals captured on our camera traps between and 14 August and 1 October, 2012.
At the end of August, the wardenâ€™s team moved 10 camera traps from water holes in the eastern half of the OWNR to selected water holes in the western half of the reserve. Four earth dams, four concrete pans, and two raised reservoirs were selected as survey sites (Table 1, Figure 3). The purpose of moving these cameras was to better understand how the animals in the OWNR utilize water holes. Data from the traps were collected weekly, and has been used in multiple projects, including assessments of visits by elephants and black rhinos, as well as predator identification (Fig. 1, Fig. 2). Table 1. Water holes surveyed in the western half of the OWNR. Billy's Lodge Cambridge 7 Earth Dams Masodini Singwe Bushcamp Charly's Hide
Sausage Tree Camwild Koorts Pan 1 Sven's Dam Ingwe Walk
Figure 2.Top left, young bull elephants at Charlieâ€™s Hide. Top right, three black rhinos at Camwild pan. Bottom, a leopard drinking at Camwild pan.
Figure 3. qGIS map of water holes selected for the second phase of camera trap surveys. Water holes were selected not only by location, but also by type (earth dam, concrete pan, raised reservoir).
As with previous water holes in the eastern region of the OWNR, the wardenâ€™s team ran several tests to determine patterns of animal visitation to these water holes. The tests were used to determine both species richness and species diversity of the
water holes. Species richness is a simple count of how many species are recorded at the water hole. Species diversity is a combination of species richness and species evenness, which identifies how equal the abundances of different species are. Species richness was calculated for each of the surveyed water holes, and was compared to species richness of previously sampled water holes (Fig. 4, A). In addition to drinking water, many species visit water holes in order to wallow or cool themselves. Furthermore, water quality varies between artificial pans and natural earth dams, particularly in the dry season, during which only artificial dams are fed with fresh water. Because of these factors, we were interested to see if species richness is affected by water hole type. However, no significant differences were seen between species diversity and water hole type (Fig. 4, B). Species diversity was also calculated for all surveyed water holes. Three tests were used to determine diversity: Simpsonâ€™s Index, Simpsonâ€™s Index of Diversity, and Simpsonâ€™s Reciprocal Index. Simpsonâ€™s Index (D): Simpsonâ€™s Index calculates the probability that two individuals selected at random from the sample will belong to the same species. Values range from 0 to 1, with a lower value indicating higher diversity n= total number of organisms đ?‘›(đ?‘› âˆ’ 1) đ??ˇ= of a particular species đ?‘ (đ?‘ âˆ’ 1) N= total number of organisms of all species Simpsonâ€™s Index of Diversity (1-D): Simpson's Index of Diversity calculates the probability that two randomly selected individuals from the sample will belong to different species. The values range from 0 to 1, with a higher value indicating higher diversity. đ?‘›(đ?‘› âˆ’ 1) 1âˆ’đ??ˇ =1âˆ’ đ?‘ (đ?‘ âˆ’ 1) Simpsonâ€™s Reciprocal Index (1/D): The Simpson's Reciprocal Index calculates the diversity (both richness and evenness) of the species in the sample. The lowest value is 1, while the greatest possible value is the species richness of the sample. A higher value indicates greater diversity. 1 1 = đ?‘›(đ?‘› âˆ’ 1) đ??ˇ đ?‘ (đ?‘ âˆ’ 1) These three indices were calculated for each of the sampled waterholes (Table 2). Masodini Earth Dam and Koorts Pan 1 were the most diverse of the surveyed dams, while Billyâ€™s Lodge Skywalk Earth Dam and Sausage Tree (despite recording the highest species richness) were the least diverse. Neither Simpsonâ€™s Index of Diversity nor Simpsonâ€™s Reciprocal Index were significantly different between water hole types (Fig. 5), implying that water hole type does not affect visitation by animals.
B Figure 4. Species richness at surveyed water holes. A) Of the most recently surveyed water holes (in red), species richness was lowest at Charly’s Hide Pan (8 species). Highest species richness was recorded at Sausage Tree Pan (13 species). B) Average species richness was not significantly different between water hole types, suggesting that water hole type does not determine the entire suite of species that visit. However, individual species (such as elephants) may still prefer different waterhole types. Table 2. Simpson’s Index, Simpson’s Index of Diversity, and Simpson’s Reciprocal Index for sampled water holes.
Concrete Pans Raised
Simpson's Index of Diversity
Simpson's Reciprocal Index
Billy's Lodge Cambridge 7 Masodini Singwe Bushcamp Charly's Hide
0.401595745 0.180881424 0.141192141 0.226420298 0.265667166
0.598404255 0.819118576 0.858807859 0.773579702 0.734332834
2.490066225 5.528483681 7.08254717 4.416565164 3.764108352
Sausage Tree Camwild Koorts Pan 1 Sven's Dam
0.333954355 0.303394124 0.133173724 0.305272109
0.666045645 0.696605876 0.866826276 0.694727891
2.994421199 3.296042745 7.508988764 3.275766017
B Figure 5. A) Simpsonâ€™s Index of Diversity for all surveyed water holes in the OWNR. B) Simpsonâ€™s Reciprocal Index and Species Richness for all surveyed water holes in the OWNR. No significant differences between earth dams and concrete pans were observed for either index although concrete pans scored higher than all the other demographics. Furthermore, raised reservoirs scored the lowest of all the demographics of waterholes. However, this does not account for the different uses that waterhole types will provide for different animals. IE. Elephants, rhino, buffalo and warthog like to wallow in mud and cool down on hot days. Only certain demographics of waterholes will provide for these important activities.
How the elephant got its trunk!
Animal population trends in Balule and the Olifants West Nature Reserve Alex Lin-Moore, Transfrontier Africa intern
Animals were counted again this year using helicopter counts across Balule.. Helicopter counts were done by flying a grid across the reserve. Animals were counted when spotted within 200m of the helicopter. When possible, age and gender were also recorded. While this strategy cannot account for every individual in the reserve, by keeping a consistent method, we can compare data across years, and get a more or less accurate understanding of population trends within the reserve for the majority of game species. This year, a total of 1446 animals, comprising 22 different species, were recorded from the helicopter counts in the OWNR (Table 1), almost identical to last yearâ€™s 1446 individuals, comprising 20 species. Table 1. Data from the 2012 helicopter counts across Balule Nature Reserve and within the OWNR, including species density per hectare.
Black Rhino Bushbuck Duiker Giraffe Klipspringer Kudu Nyala Sharpeâ€™s Grysbok Steenbok
11 68 38 216 5 640 17 6 20
0.000297297 0.001837838 0.001027027 0.005837838 0.000135135 0.017297297 0.000459459 0.000162162 0.000540541
3 8 3 55 1 119 0 0 3
0.000340909 0.000909091 0.000340909 0.00625 0.000113636 0.013522727 0 0 0.000340909
Cheetah Crocodile Ground Hornbill Hyena Leopard Lion Raptor Nest Vulture Nest Buffalo Hippo Ostrich Rhino Warthog Waterbuck Wildebeest Zebra Elephant Impala Baboon Jackal Monkey Troops
2 77 5 5 3 20 2 16 540 123 5 41 325 472 145 320 243 5714 25 12 8
0.0000540541 0.002081081 0.000135135 0.000135135 0.000081081 0.000540541 0.0000540541 0.000432432 0.014594595 0.003324324 0.000135135 0.001108108 0.008783784 0.012756757 0.003918919 0.008648649 0.006567568 0.154432432 0.000675676 0.000324324 0.000216216
0 14 0 0 1 17 0 0 13 37 0 4 44 68 8 57 6 978 4 2 1
0 0.001590909 0 0 0.000113636 0.001931818 0 0 0.001477273 0.004204545 0 0.000454545 0.005 0.007727273 0.000909091 0.006477273 0.000681818 0.111136364 0.000454545 0.000227273 0.000113636
Grazers Grazer populations decreased slightly both in the OWNR and throughout the Balule region since 1999. In the Balule region, grazers showed an increased between 2011 and 2012. However, in the OWNR average grazer population decreased between 2011 and 2012. (Fig. 1 A, Fig. 2A). Several species in particular experienced notable decreases in population: waterbuck decreased by 24% in the OWNR (44 in 2011, 37 in 2012), and 13% in Balule (534 in 2011, 472 in 2012). Blue wildebeest populations also decreased by 33% in the OWNR (12 in 2011, 8 in 2012) and 20% in Balule (181 in 2011, 145 in 2012) (Fig. 1B, 2B). However, other species increased in population between 2011 and 2012, most notably warthog and buffalo (Fig. 1B, 2B).
Grazer Populations by Year (Balule NR)
Blue Wildebeest Plains Zebra Waterbuck
# Individuals per hectare
White Rhinoceros 0.005
0 1999 2001 2003 2005 2006 2007 2008 2009 2011 2012
Average Grazer Population (Balule NR) Log10 of population
2.5 2 y = -0.047x + 2.379 RÂ˛ = 0.6109
1.5 1 0.5 0 1999
Figure 1. A) Population density changes in important grazer species in the Balule Nature Reserve. Several species (waterbuck, blue wildebeest, plains zebra) have decreased, while other species (buffalo, warthog, hippopotamus) have increased. B) Average grazer population in the Balule Nature Reserve over the past 13 years. Grazers have overall decreased slightly, but have increased between 2011 and 2012. Log10 of population was used in both cases to avoid biases in the data due to particularly large or small populations.
Observer bias can account for the fluctuations between 2011 and 2012 as well as the emigration of species across borders. The trend however is still downward for the whole of Balule but long term monitoring is required to show if this is of significants.
Grazer Populations by Year (OWNR)
# individuals per hectare
Average grazer population (OWNR)
Log10 of population
y = -0.0119x + 1.4856 RÂ˛ = 0.024
1 0.5 0 2007
Figure 2. A) Population density changes in important grazer species in the OWNR. All populations underwent decreases in density within the reserve from 2011. B) Average grazer population in the OWNR over the past 13 years. Grazers have decreased slightly overall, and dropped significantly between 2011 and 2012. Log10 of population was used in both cases to avoid biases in the data due to particularly large or small populations.
When species such as buffalo are added to the graph, it can cause bias if regions are evaluated in isolation from their neighbours. Large herds of buffalo are shared between regions and therefore should be monitored over the entire Balule spectrum. Browsers Like grazer density, browser density in both the Balule Nature Reserve and the OWNR has decreased in the past years. However, in the past few years the browser population has stabilized Fig. 3A, 4A). Giraffe, one of the most abundant browsers, decreased in density both in the Balule region and the OWNR between 2011 and 2012 (Fig. 3B, 4B). In contrast, kudu increased across Balule, although they also decreased in the OWNR (Fig. 3B, 4B). All other recorded browser species increased in density across Balule, while in the OWNR browser densities either increased slightly or did not change
(Fig. 3B, 4B). Most other browsers underwent negligible increases or decreases in density in the OWNR (Fig 4B). A Giraffe
# Individuals per hectare
Browser Populations by Year (Balule NR) 0.02 0.018 0.016 0.014 0.012 0.01 0.008 0.006 0.004 0.002 0
Kudu Sharpe's Grysbok Bushbuck Common Duiker Nyala Steenbok Klipspringer 1999
Average Browser Population (Balule NR) Log10 of population
y = -0.1122x + 2.4074 RÂ˛ = 0.6919
1.5 1 0.5 0 1999
Figure 3. A) Population density changes in important browser species in the Balule Nature Reserve. Giraffe was the only species that decreased in density between 2011 and 2012. All other speices increased in density, with kudu undergoing the most significant increases. B) Average browser population in the Balule Nature Reserve over the past 5 years. Browsers have overall decreased slightly, but have stabilized between 2010 and 2012. Log10 of population was used in both cases to avoid biases in the data due to particularly large or small populations.
A Black Rhinoceros Bushbuck
Browser Populations by Year (OWNR) # Individuals per hectare
Common Duiker Giraffe
Sharpe's Grysbok Steenbok
Log10 of population
Average Browser Population (OWNR) 1.5 1
y = -0.0303x + 1.0891 RÂ˛ = 0.3413
0.5 0 2007
Figure 4. A) Population density changes in important browser species in the OWNR. Giraffe and kudu population densities both decreased between 2011 and 2012, while other browser species either increased in density or remained unchanged. B) Average browser population in the OWNR over the past 5 years. Browsers have decreased slightly overall, but appear to have stabilized between 2011 and 2012. Log10 of population was used in both cases to avoid biases in the data due to particularly large or small populations.
Mixed Feeders Impala and elephants were placed in their own category because their dietary restrictions are not as specific as with other herbivore species. Their populations have increased in Balule since recording began in 1999, but appear to be stabilizing (Fig. 5). This stabilization could indicate that these species are near their carrying capacity in the reserve. However, it could also indicate that their populations are being limited by human activities. This possibility is supported by the population density changes observed in the OWNR. Impala population density increased by 50% between 2011 and 2012, while elephant population density dropped during the same period (Fig. 6). These fluctuations and contradictions in the data are not consistent with a stable environment, and imply that external factors are affecting population.
# Individuals per hectare
Mixed Feeder Populations by Year (Balule NR) 0.2 0.15 0.1
0.05 0 1999
Log10 of population
Average Mixed Feeder Population (Balule NR) 4 3
y = 0.2467ln(x) + 2.5959 RÂ˛ = 0.7121
2 1 0 1999
Figure 5.Impala and elephant populations in the Balule Nature Reserve, 1999-2012. Impala populations appear to be increasing, but average density of mixed feeders appears to have stabilized in the past 5 years.
Mixed Feeder Populations by Year (OWNR) # Individuals per hectare
0.15 0.1 Impala 0.05
Average Mixed Feder Population (OWNR)
0.03 Log10 of population
0.02 y = -0.202ln(x) + 2.0893 RÂ˛ = 0.2254
0.02 0.01 0.01 0.00 2007
Figure 6. Impala and elephant populations in the Olifants West Nature Reserve, 2007-2012. Impala populations appear to be increasing, but average density of mixed feeders, as well as elephant populations, have decreased in the last five years.
Carnivores Carnivore population densities have followed similar trends to common prey, which is not too surprising, since their populations are partly regulated by prey availability (Fig. 7). However, certain species have showed alarming decreases in density. Leopard populations in Balule decreased by 63% between 2011 and 2012 (Fig. 8), although this figure is probably exaggerated by the fact that leopard are difficult to spot from helicopters. In Olifants West, carnivore populations appear to be increasing slightly (Fig. 9). This could be because these species are still recovering from persecution in the area, or could be a response to habitat changes.
Average predator-prey populations 3
Log10 of population
2.5 y = 0.0347x + 2.0623 R² = 0.6175
y = 0.056x + 0.2256 R² = 0.512
Figure 7. Average populations of predators in Balule. Data from the 2010 helicopter count was excluded because no predators were recorded that year. However, the complete absence of predators was probably due to lack of visibility during aerial counts, rather than the animals’ absence. The population of “common prey” was calculated from the sum of counts for giraffe, kudu, warthog, buffalo, blue wildebeest, plains zebra, nyala, impala, and steenbok, the most common mammal prey taken by lions and leopards in the OWNR.
Carnivore Populations by Year (Balule NR)
0.0025 Nile Crocodile
# Individuals per hectare
African Rock Python
Southern Ground-Hornbill 0 1999
Pel's Fishing Owl
Average Carnivore Population (Balule NR)
1.5 Log10 of population
y = -0.0151x + 1.0579 R² = 0.0976
Figure 8. Carnivore populations in Balule, 1999-2012.Average populations appear to be relatively stable, although individual species’ densities fluctuate significantly.
Average Carnivore Population (OWNR) 1.5 1 y = 0.0052x + 0.7 R² = 0.0005
0.5 0 2007
Figure 9. Average carnivore populations in the OWNR, 2007-2012. A slight increase in average population could be due to multiple factors, including reduced hunting pressure or landscape changes.
Summary Densities for many species have changed significantly since monitoring began, both in the Olifants West Nature Reserve and Balule as a whole. How densities of both individual species and different guilds of animals change over time is the result of many different factors, including human activity. Further research and long-term monitoring is needed to better understand how our own behavior may affect animal species in the reserve. Predator-prey interactions Compiled by Indlovu West Conservation Research Intern: Matthew Detjen: University of Minnesota Duluth
Interns observing a large male lion, aka â€œBig Boyâ€? at an Impala kill
Predators are essential to OWNR not only from management perspective, but for tourism as well. To keep the balance between predator and prey species at equilibrium requires extensive research throughout Balule (OWNR cannot be seen in isolation), requiring a collaborative effort by everyone on the reserve. In order to determine how to keep the ecosystem stable, we have spent a great deal of time studying the relationship predators and prey have on the ecosystem. We have been trying to devise a formula that will help us manage the needs of both predators as well as hunting and tourism. We know a single adult lion needs to eat 10 kg of meat a day on average, and that one of their favorite prey is the giraffe which weighs an average of 900kg as an adult. We currently have 18 lions, meaning they have the potential to eat a large adult giraffe every
five days, or seventy-three in a single year (thank heavens that they have a varied diet). This means that if a single lion was killed on the reserve, there would be an obvious effect on the number of prey species. If too many prey species were killed, hunted or poached, predator species would have a difficulty surviving on the reserve, which could cause them to spend more time in neighboring areas. This could create a problem for the tourist industry who came here to see the Big Five, not the Big Three! Lion Population The OWNR pride has remained relatively stable since 2011, aside from infants becoming juveniles (Table #1). The Singwe pride on the other hand has recently shown us it is beginning to bounce back since it was dispersed a few years back. Our camera traps and witness reports have concluded a sub-adult female has become an adult, giving the pride three hunting females. Along with this we have seen three infant cubs with this pride, meaning the females are beginning to replenish their ranks with the help from a male in the OWNR pride (Table #2 and Picture #1). Table #1 Lions in the OWNR pride from 2010-2012 Male Year Adult Sub-adult Juv. Infant 2010 2 0 6 0 2011 1 4 0 0 2012 7 0 0 0 Table #2 Lions in the Singwe Pride from 2010-2012 Male Year Adult Sub-adult Juv. Infant 2010 3 0 0 0 2011 0 0 0 0 2012 0 0 0 0
Adult 3 1 6
Female Sub-adult Juv. 0 5 5 0 2
Sub-adult 2 1 3
Female Juv. 0 1 2 0 0 0
Infant 0 2 0
Table 1 and 2 show that we have managed to account for the 2 sub-adult male lions that we could not find when the June report was released. Therefore the only notable changes are the addition of the three cubs in the Singwe.
Total 16 13 15
Total 0 1 3
6 4 6
Picture #1 Camera trap photo of Singwe females and cubs
Lion-Prey Relationship In order to better understand the lions and determine how to manage hunting quotas, we must first focus on their prey. If we are able to determine which species is the most vital source of food for the lions, which animals act as buffer species and which are most vulnerable, we can adjust things such as hunting quotas in order to give the lions an adequate choice of prey species. This is essential to understand the balance between hunters and the tourism industry. Below are the recent recorded kills by lions, which is vital in determining healthy hunting quotas (Fig #1).
Figure #2: Lion kills made January through August in 2012
Every year since we have recorded lion prey data has yielded different results, which confirms our faith in the Jacobs Index. The Jacobs Index basically states that if a certain species of prey animal is in a shortage, then lions will select the next easiest or prolific prey species. With that we are also beginning to see trends in certain species that seem to be more vital to the lions on OWNR diet, compared to other reserves.
Figure #3: lion kills January through August 2012
So far in 2012 we have seen a significant increase in the percentage of Warthog killed by lions on the reserve (Fig #3). Aside from this, most categories show that we are on a similar pace from what we saw in 2011, aside from the high amount of Giraffe kills last year (Fig #4). Kudu, 8%
Buffalo Wildbeest Waterbuck, 3%
Buffalo, 17% Warthog, 3% Figure #4: Prey killed by lions in 2011
Figures 3 & 4 show a 16% increase in Warthog kills from last year. Warthog might have temporarily taken the place of giraffe as the other prey species have remained comparably similar between the last two years. The recent game-count figures show that the warthog population for OWNR has dropped in the past 12 months and this we attribute to the predator pressure. Perhaps this can be explained by the 6 sub-adult male lions that started to hunt for themselves or that, according to the Jacobs Index, it may be easier for lions to find the smaller prey species such as warthog. We expect this to shift again in favour of the bigger prey species. Injured Lions We are happy to inform the reserve that the male lion from the OW Pride, which was recently seen with a snare on his right rear leg, is doing much better and will undoubtedly make a full recovery. The young female from the Singwe Pride with the front right leg injury has been monitored and is coping well. This is a natural injury and therefore we are compelled to allow nature to take its course. She, with her adult female companion was seen on 2 October 2012 on Ukhizi, east of Rome 9 â€“ in good condition.
Leopard Current population We currently have an estimated nine leopardsâ€&#x; visiting the reserve, of which seven are thought to be permanent residents on OWNR. Leopard-prey relationships It is vital to separate leopard from lions as kills in our reports, with the reasoning for this being a leopard tends to have a drastically different diet than that of a lion. Leopards often take out smaller prey such as Impala and birds, animals we have found lions rarely target due to their small size. Our figures show a difference in leopard prey selection in relation to lions.
Figure #5 Leopard kills January through August 2012
The gaps in the data-set is due to a lack of information (January and May) as we rely on the game rangers from the various lodges. Despite this, the trends still remain the same. Notice how the variety on the menu of the leopards increases in the winter months as animals disperse and become more difficult for an ambush-predator to hunt.
Figure #6 Leopard prey counts
As we can see by these graphs, impala made up over half of the diet of the leopardsâ€&#x; in this area (Fig 5 and 6). In order to keep them happy and hunters, we must make sure they have plenty of opportunities to make a kill, which is why the management of impala is so important on the reserve. Total predator counts Although we donâ€&#x;t know as much about the crocodilesâ€&#x; on the reserve, we can still learn a lot by studying the kills they make. Below is our total percentage of kills by the three main predators that have been recorded on the reserve.
Figure #7 Predator responsibility for kills in 2012
It is only through the cooperation of game rangers, lodge owners, and the wardenâ€&#x;s team that we are able to collect this vital data. We would like to thank everyone who helped us obtain this information, whether it was through pictures, locations of kills, or just a quick radio call. All information is vital to keeping the ecosystem in a balance that not only helps the predator species, but to everything living on the reserve. We hope for the continued support from everyone so we can continue to collect vital data to help insure the future of the reserve.
Impact of the Rhino Fence on the Elephant Population within OWNR --Hannah Malin: Liverpool John Moores University, School of Natural Sciences In recent months the lack of Elephants in the OWNR has been very obvious, particularly the absence of breeding herds since May/June. One noticeable feature within the past year that could have had an effect on the population within the OWNR is the construction of the Rhino Fence, which was erected in October 2011 and taken down four months later in January 2012. The fenceâ€&#x;s presence would have made it more difficult for elephants outside of the reserve to enter, theoretically resulting in a drop in local population. To test if seasonal changes were also having an impact on the number of elephant sightings, the data were first compared to the average amount of rainfall per month to see if water availability had a significant effect. The result was negative, showing no significance between the two (F[21,14]=0.869, p=0.624). An Analysis Of Variance with a suitable post hoc test was then used to determine if there were significant changes throughout the year by grouping the data into three four-month categories based around the months that the Rhino Fence was in place (June-September, October-January, February-May). For the total number of sightings this also showed no significance (F[2,45]=0.458, p=0.635), however, there was a significant difference between the fourmonth categories for both bull sightings and breeding herds separately, influencing the later in particular (bulls: F[2,45]=3.370, p=0.043; breeding herds: F[2,45]=4.693, p=0.014). One of the explanations for this is that a small resident herd of bulls will be seen regularly by rangers and therefore bias the data-set to show a higher number of bull sightings, but in fact it is the same bulls seen every time. The post hoc Tukey HSD test showed that the breeding herds tended to increase during the dry season (June-September) and decrease during the wet season (October-January) across years, and vice versa for males (shown in Figure 1). The increase in male only sightings during the summer months as the cows decrease may be because the bulls split from the breeding group as the cows return to the Kruger National Park when water becomes freely available during this time of the year. Young bulls on their own are possibly recorded as bull sightings where previously their presence may have been incorporated as part of a breeding herd. Again we must be aware of the small group of bulls that frequent the OWNR (Shoshangan and Ezulwini Bulls) and are seen on a high frequency.
40.0 30.0 20.0 10.0 0.0 Jun-Sep Oct-Jan Feb-May Jun-Sep Oct-Jan Feb-May Jun-Sep Oct-Jan Feb-May Jun-Sep Oct-Jan Feb-May 2008-09
2009-10 Breeding Herd
Figure 1 Chart showing the average number of sightings per month for Bulls and Breeding Herds between June 2008 and May 2012 within three four-month periods (Jun-Sep, Oct-Jan, Feb-May), including Oct-Jan 2012 when the Rhino Fence was in place (marked)
To test whether the fence had a significant impact on the elephant population in OWNR the total number of sightings between 2011 and 2012 were taken and split into three categories: Pre-fence, Fence, and Post-fence. The analysis suggested a high significance of variability between the three categories (F[2,45]=4.742, p=0.014), and a post hoc Tukey test confirmed this significance to be the decrease between the pre-fence period and the time in which the fence was still in place. The extent of this can be seen in Figures 1 & 2. The test was repeated after the data had been split into bull and breeding herd sightings to view the impact on individual genders. The results showed that there was a high significance on breeding herd numbers (F[2,45]=3.684, p=0.033), but none for bulls (F[2,45]1.103, p=0.341). The post hoc Tukey HSD test again suggested that this significance was between the dry months (Jun-Sep) and the wet months (Oct-Jan). Whilst the fence did seem to have a significant effect on the number of elephants within the OWNR, the post hoc Tukey HSD tests showed no significance between the postfence period (Feb-May) and the other two categories, for neither the total number of sightings nor the individual bull/breeding herd sightings. This suggests that the population was recovering from a temporary barrier once it was removed, before experiencing another decrease in April/May (Figure 2). Because of this, it is unlikely that the fence is the sole cause of the recent decrease of elephant sightings in the OWNR, but it is very possible that it has intensified the effect of another factor, particularly towards the loss of breeding herd sighting, as there seems to be an obvious trend between the presence of the fence and their decline. It is also important to note that the number of breeding herd sightings took longer to recover than the bull sightings, which substantiates the literature that breeding herds are more susceptible to disturbance.
50 No. Sightings
40 30 20 10 0 Jun
Apr May Jun
Figure 2. Graph showing the number of sightings of Bulls and Breeding Herds per month between June 2011 and August 2012, including Oct-Jan when the Rhino Fence was in place. (NOTE: Although the data is discreet, it has been presented as continuous for clarification of the effect of the fence)
When dealing with the elephants, we still have no conclusive results as we are still waiting for some data to add into the model. However, we have used the findings of the Vortex model which is a stochastic simulation of the extinction process (version 9.50). In the paper â€œIs Elephant trophy hunting Sustainable? A case Study from the Greater Mapungubwe Transfrontier Conservation Areaâ€? (Selier, J., Page, B., Slotow, R. 2012). The findings of this model show the same trends as we have identified in our elephant populations in the west. IE. the hunting of adult bulls resulted in the indirect disturbance effect that caused them to move out of the areas that are affected by hunting. Further results showed that the return intervals were shorter for bulls than for females. IE. bulls returned before females and breeding herds.
Foraging Analysis and Habitat Selection of Reintroduced Black Rhinos Preliminary Results Compiled by: John Clark, Western Kentucky University, United States
As the following are only the preliminary results, reporting on the findings thus far, the data has yet to be analyzed statistically and has not all been collected. Vegetation Sampling A total of 12 transects were laid out across Olifants West Nature Reserve. Within each transect one 10m X 10m plot was placed every kilometer. The species, height class, and phenology of each woody species present were recorded for each plot. The number of plots sampled at each interval is as follows: seven were sampled along the river, seven at 1Km from the river, seven at 2Km, seven at 3Km, six at 4Km, six at 5Km , nine at 6Km, seven at 7Km, and six at 8Km, for a total of 62 plots and 832 plants sampled. The locations of each plot, along with minimum convex polygon home ranges of the six black rhino routinely on Olifants West are shown in figure 1 below.
Figure 1: Home Ranges and Sample Plots ď‚ˇ Phenology All of the data were recorded either prior to the first rains, or prior to any visible response from the system to the first rains to fall in September. Thus, the phenologies were recorded during their highest point of water stress and represent the point at which the vegetation will be the sparsest across the study area. The percentage of plants with leaves remaining at each distance from the river is shown in figure 2 below.
Percentage of Plants with leaves
Leaves vs. Distance from River 70.00% 60.00% 50.00% 40.00% 30.00% 20.00% 10.00% 0.00% 0K
Distance from Olifants River Figure 2: Leaves vs. Distance from River
Vegetation Structure Of the 62 plots included in these results, 44 of those sampled did not fall within the minimum convex polygon home ranges that have been established by the six black rhinos that frequent Olifants West Nature Reserve. Four plots have fallen within one animalâ€&#x;s home range, and 14 have fallen into two or more home ranges. The following graph shows the percent difference between plots that fall into home ranges and plots that do not for each woody species recorded. The percentage of each species present is shown in figure 3.
Percent Comparisons 50 40 30 20 10 0
Percent 2 or more HR
Percent 0 HR
Figure 3: Vegetation comparisons between Home Range and Non Home Range Plots Additional plots within home ranges will be selected and surveyed for the final results. Density An average of 16.29 woody species have been found in IHR plots, compared to an average of 12.56 woody species in OHR plots per 100 square meters. Foraging Analysis Thus far the data collection for the foraging analysis has been accomplished through following and backtracking from actively feeding animals, and through the collection of older damage that researchers are highly confident is the result of black rhinos, due to their characteristic feeding method and other sign. Old damage has not been collected from the same sites multiple times in order to prevent re-sampling the same damage. Thus far 1696 standard bites have been recorded, from a minimum of 16 total species. Figure 4 represents the data collected.
1% 1% 3% 1%
Black Rhino Forage 2% <1%
Euclea crispa--12% 18% 13%
Euclea divinoru--18% Euclea undulata--<1%
Euphorbia sp--11% <1%
Figure 4: Black Rhino Forage
Number of Bites
Black Rhino Forage 600 500 400 300 200 100 0
Plant Species Targeted Figure 4: Black Rhino Forage
Black Rhino Field Report Complied by Stefan Bosman
Figure 1: Lima 27th July 2012
Introduction: There have been many developments with regard to black rhinos in the OWNR and within the rest of Balule. Since the last report, we have upgraded our equipment with the help of the University of Western Kentucky, (UWK). However, we have also suffered from technical issues concerning several rhinosâ€&#x; transmitters. They have either been failing entirely to send a signal or only sending signals intermittently. This has affected the accuracy of many home range estimates, although the core ranges are well known to us.
Rhinos and their transmitter status: Rhino Sex Horn Transmitter
Aphella Zulu Deena Dutchess Khuza Ntombizana
Good Signal No Collar Good Signal Weak Signal No Signal Good Signal
Male Male Female Female Female Female
Good Signal No Signal Good Signal Intermittent Good Signal No Horn Transmitter
Rhinos and their frequency of sightings: Rhino
Aphella Zulu Deena Dutchess Ntombizana Khuza Thokombisa Zoliswe
20 20 19 18 24 23 0 3
B (Close proximity) 4 2 2 3 2 2 0 0
C (Triangulation) 7 1 14 8 8 8 5 4
Black Rhino movements between July and Sept After the devestating loss of Lima, one of our female rhinos in OWNR on August 1st we suffered major displacemnet of black rhinos from Rome 4 to River Lodge property. This displacement effect is often seen after the loss of a black rhino. Ntombizana has now moved to Ukhozi for the most part though, although she occasionally moves to Ngala Dam where she was once often found.
Figure 2: Black Rhino Sightings June Sept.
Figure 3: Black Rhino pre Limas death
Figure 3: Black Rhino displacement after Lima died The other black rhinos that were typically found between Rome 2 and River Lodge have now moved west, closer to the river in less traversed areas. Khuza and Zulu are still together for the most part and have been seen pseudo-mating on a number of sightings. They are still raising concern, as they have been bouncing off the Western boundary fence regularly.
Figure 3: Zulu And Khuza Movements Towards the Western Boundary Thanks to John and Rachel for all the hard work they have been putting in getting extra data including night surveillance of the black rhinos. ANTHROPOGENIC INFLUENCES ON EASTERN BLACK RHINO DISTRIBUTION IN BALULE A BRIEF SUMMARY OF RESULTS Rachel Beyke Western Kentuky University - USA I am currently doing research on the Eastern Black rhino located on the Olifants West section of Balule. I am looking to see if the current black rhino population is avoiding certain areas of the reserve due to man-made disturbances. The data being collected will be used to determine whether the estimated carrying capacity for black rhino on Ofliants West differs from the theorized carrying capacity. My hypothesis states that the Eastern Black rhino located on Olifants West Nature Reserve have a lower true carrying capacity than therorized carrying capacity because they are avoiding man-made areas or areas of high human disturbances. As one of the variables, I have been monitoring the road usage and land usage through gate entrance books, as well as camera traps. I have completed the years 2009-2010 of the gate books. I am currently working on the year 2011. This information will show me which properties are experiencing the most human activity related to tourism, construction, and deliveries. Of my camera traps set up I am looking to see what roads are being utilized the most. This will help me determine further where the highest human disturbance regimes are. Unfortunately, two of my camera traps, located along Marolea road, were stolen. Therefore, I am creating a new plan for the remaining camera traps to ensure that I am still collecting the data that is needed. These camera traps set up along road are not just for monitoring traffic. They are vital in the collection of home range data on the black
rhino. I have been able to catch the rhino on the camera traps which adds new locations for their home ranges. An example of this is shown in figure 1.
Figure 1. Khuza and Zulu walking on Maroela Road near Hardekool and heading toward Cambridge 7.
Furthermore, in collaboration with Transfrontier Africa, we have camera traps set up at various dams throughout the reserve which provides valuable information regarding which dams are being utilized by which animals. I will be specifically looking to see which dams are being used most frequently by the black rhino. When looking at the dams, the location, visibility index, vegetation, and proximity to man-made structures will be taken into account. I have had my camera traps set up at Oxford East Dam, Oxford West Dam, Hardekool Dam, Elephants Dam, and Khuza Dam. The most frequently visited dam is Hardekool Dam (figure 2). I am looking to see if dam usage will change with the changing of seasons.
Figure 2. Black Rhino at Hardekool Dam.
We have been going out on average 2-3 times a week to collect locations for the rhino using triangulations and biangulations. We have compiled the data previously collected on the rhino home ranges and inserted our own data giving us a more complete estimate of their home ranges. We are looking to see if the theory of decolonization will take place after the death of Lima. We have home ranges for before her death, and we are now collecting home range data for after her death and have also begun night triangulation and biangulations as rhino are most active from between dusk and dawn. Therefore, it is important for our home range data to collect locations at night. Night scans happen twice a week. All of this information will assist us in determining how the rhinos use space in relation to areas of concentrated human activity.
Entrance Times 2009 Frequency
800 600 400 200 0 00:0002:0004:0006:0008:0010:0012:0014:0016:0018:0020:0022:00
Figure 3. Chart showing the time most traffic passed through the gate in 2009
Entrance Times 2010 600 Frequency
500 400 300 200 100 00:00 01:00 02:00 03:00 04:00 05:00 06:00 07:00 08:00 09:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00
Figure 4. Chart showing the time more traffic passed through the gate in 2010 Figures 3 & 4 show that the majority of traffic through the reserve is between sunrise and sunset when the black rhino are dormant. At a quick glance, the traffic on our servitude roads should therefore not interfere with the energy budget of the black rhino. Figures 4 & 5. Traffic volumes over the year is relatively consistent.
Figures 6 â€“ 9. Traffic times at each station on the servitude roads. Trap 4 = Sable / Olifants Junction Trap 3 = Maroela Road Trap 2 = Maroela Road Trap 1 = Maroela road
Time of Traffic Camera Trap 4 Frequency
80 60 40 20 22:00
Figure 6. Sable/Olifants intersection
Time of Traffic Camera Trap 3
15 10 5 00:00 02:00 04:00 06:00 08:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00
40 20 0 00:00
Time of Traffic Camera Trap 2
80 70 60 50 40 30 20 10 0
Series1 00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00
Time of Traffic Camera Trap 1
Figures 6 â€“ 9 shows that there is still a significant frequency of traffic on the servitude roads after dark. This is attributed to the high density of residences and lodges in the Maroela and Sable road areas and could have an effect on the usage of this area by black rhino.
Progress on clearing alien cactus species in the Olifants West Nature Reserve Alex Lin-Moore, Transfrontier Africa Intern
Figure 1.The three most important invasive alien cactus species in the OWNR, from left to right: Prickly pear (Opuntia ficus-indica), the Harrisia cactus (Harrisia martinii), and the queen of the night (Cereus jamacaru).
Since the last report, the wardenâ€™s team has made major progress in the clearing and control of alien cactus species in the reserve. The three main species of concern are
the prickly pear (Opuntia ficus-indica), the Harrisia cactus (Harrisia martinii), and the queen of the night cactus (Cereus jamacaru) (Fig. 1).In the past quarter, we have developed effective methods of eliminating each of these dangerous species. Prickly Pear Despite our extensive efforts, the prickly pear infestation in the Balule region is still very serious. Patches of prickly pear have been found across the reserve, and despite our studies, it is difficult to determine how they are spread, and how widespread the actual invasion is. However, clusters of prickly pear tend to be found near residential compounds, so human activity may have something to do with the spread of the cactus (Fig. 2). We encourage anyone who finds prickly pear nearby their buildings to report them to the wardenâ€™s department or, if possible, eliminate them on site. By March 2012 we had already eliminated nearly 200 prickly pears in the reserve, with particular focus given to lower Cambridge 2-4 and Impalabos West. We have since shifted our focus to the Cambridge 7 and Rome 4-5 riverfront. The majority of prickly pears found along roads in the reserve have either been treated or recorded by the wardenâ€™s department, and are confident that these individuals will be eradicated. However, areas far from the road may still have high numbers of prickly pears, and we are continuing our practice of walking these blocks in search of the cactus. Furthermore, any information about locations of high prickly pear density would be very helpful in our campaign to remove this invasive alien species from the reserve. The most effective way to kill the prickly pear cactus is to spray the plant with a mixture of water, dish soap, and the poison MSMA, with the MSMA making up only 2% of the liquid. This small percentage of poison is still usually enough to kill the plant, but does not leave much poison in the area, making it a safe practice for the native species in the area.
Figure 2. Untreated prickly pear cactus in the reserve. Insets (A and B) show association between prickly pears (red) and buildings (blue).
Harrisia cactus The Harrisia cactus invasion of the OWNR was noticed first in late 2011. Since then, the warden’s department has led a very successful campaign against the invaders, and now only a few isolated cactus remain on the reserve. However, these few cactus are still of high concern, because each one has the ability to start a new invasion. Like the prickly pear and queen of the night, the Harrisia cactus can reproduce in two ways: the first is through animals eating their fruits, which grow after significant rains. Once the fruits grow, the animals spread the fruit throughout the reserve, spreading the cactus. Since we have already had several rains in September, it is vitally important that we eliminate these cactus before they have a chance to grow fruit. The second way that the invasive cactus reproduce is through “vegetative growth,” which means that any piece of the cactus that is removed and left on the ground can grow into an entirely new plant. This is a major cause for concern, because it means that every centimeter of a plant must be treated, cut down, burned or removed in order to ensure that it does not grow back. Thoroughly covering the plant in the MSMA spray is a good way to ensure that regrowth cannot happen. Like the prickly pear, the Harrisia cactus can be treated with a 2% MSMA spray around the plant. However, another effective method of treatment for the Harrisia cactus is by injecting MSMA directly into the flesh of the plant. Both methods of poisoning have been shown to be effective at killing the plant. Queen of the night The queen of the night infestation of the OWNR is still in its early stages, which means that this time period is critical if we want to prevent the alien species from becoming established in the reserve. Compared to the other cactus species, the queen of the night is still relatively rare in the reserve (Fig. 3), and most plants show nosigns of reproduction. However, plants from multiple age classes have been found on the reserve (Fig. 4), which means that the alien plant may have been on the reserve for a long time before being recognized as a problem.
Figure 3.Known queen of the night in the OWNR. Cactus are found in the highest density around the Rome 4-5 riverfront, while no cactus have yet been found south of Olifants Rd.
Figure 4.Different age classes of queen of the night on the OWNR. Cactus have been found on the reserve ranging from 1.5m tall (left) to over 6m tall (right, reluctant warden for scale). The cactus cannot reproduce until it is at least 3m tall, so many plants on the reserve can be eliminated before they have the ability to spread.
Unlike the Harrisia cactus and prickly pear, queen of the night cannot easily be eliminated by spraying with 2% MSMA, since it is covered in a thick waxy coating that protects it from harm. Instead, the best way to eliminate the alien cactus is by injecting a mixture of 50% MSMA, 50% water directly into the plant (Fig. 5). Tests in the OWNR show that injecting the queen of the night with approximately 1mL solution per cubic meter of tissue is sufficient to kill the cactus. An easy formula to calculate volume of cactus is:
0.494486**(/2) where=height in cactus in meters, and =number of branches, assuming that the average branch is approximately half as tall as the main trunk. 0.494486 is the volume in cubic meters of a 1cm cross-section of a queen of the night branch.
Figure 5. Injecting a queen of the night cactus with 50% MSMA directly into the trunk.
The poison works by killing the cactus’ external layer of cells, depriving the plant of the ability to perform photosynthesis (Fig. 6). In order to ensure the complete death of the cactus, all branches must be injected. Otherwise, the surviving branches will regenerate into new plants. Summary Invasive alien plant species present a serious risk to the native wildlife in the OWNR. While each different species of invasive alien cactus has a different method of treatment (Table 1), by controlling their spread, we can both improve the aesthetic of the reserve and maintain the diversity that makes this region of Africa so unique.
Figure 6. Injecting queen of the night with 50% MSMA results in the decay of the outer layer. A) Branch of cactus cut from a plant. The right-hand section was injected with 50% MSMA on 3 August 2012. B) The same cut branch on 14 August. The injected section has begun to rot, while the uninjected section remains healthy, despite being removed from the main plant. C) A queen of the night with some branches injected and other intact. The injected branches will rot and die, but the poison-free branches will continue to grow and the plant will recover. Table 1. Preferred treatment methods for three invasive alien cactus found in the OWNR.
Density in OWNR
Queen of the Night
2% MSMA spray Effective Somewhat effective Ineffective
50% MSMA injection Effective Effective Effective
CONCLUSION: And so concludes another quarter and the next time that I write a formal report, it will be Christmas! Thank you once again for all the assistance that you have given to our team and the goodwill that we enjoy on OWNR.
Craig Spencer Warden: Olifants West