Annual Game Count Olifants West Nature Reserve Balule Nature Reserve 2020

Annual Game Count Olifants West Nature Reserve Balule Nature Reserve 2020 Report Compiled by Paul Allin Annual game counts are conducted in order to obtain the most accurate representation of the species within Balule Nature Reserve. For many years the same methodology has been employed allowing for consistency in the data and the ability to detect trends over time. In 2019 only half of the regions in Balule opted to do the game count. This year all regions were counted again, however this was done using a different team and following a slightly different methodology. This report is based on the data from the aerial game count and will address the differences that appear compared to previous years. The area of Boston was included this year in the count, and therefore the total size of the reserve increased. Without know populations in the area prior to inclusion it is hard to know the net effect of adding a new area. For this purpose it is key to look at densities per ha and biomass per ha. These data can then be compared to primary vegetation production to help understand why species increase or decrease in a given year. Conditions during the count were good, with clear weather and the count was conducted before the first rains. The flight path is shown on the following page in figure 1 (data from the helicopter) and figure 2 (data of counted animals). Figure 2 shows which part of the reserve was flown per day, gaps can be attributed to no animals being counted in a specific location. A predator call up was conducted across much of the reserve. Olifants West Nature Reserve (OWNR) chose not to participate in the call up due to the limited reliability in gathering accurate data and avoiding counting the same individual multiple times. Furthermore there is research to support the call-ups have a disruptive effect on the spatial distribution of predators across the landscape. For these reasons OWNR collated the predator numbers from the lodges across the region, providing detailed break-downs of the demographics and locations. Figure 1. Flight path recorded by the helicopter. Figure 2. Flight path based on the location and date each animal was recorded during the game count. OWNR BNR All Species # kg/ha #/ha # kg/ha #/ha African Wild Cat 0.000 0.000 1 0.000 Buffalo 0.000 0.000 266 2.589 0.005 Bushbuck 9 0.031 0.001 40 0.021 0.001 Crocodile 15 0.000 0.002 29 0.001 Duiker - Grey 6 0.013 0.001 32 0.011 0.001 Elephant 183 79.538 0.021 883 58.449 0.016 Giraffe 43 5.034 0.005 249 4.440 0.004 Hippo 89 15.119 0.010 131 3.389 0.002 Hyena - Spotted 6 0.000 0.001 10 0.000 Impala 1623 8.701 0.188 8326 6.798 0.147 Kudu 64 1.372 0.007 479 1.563 0.008 Leopard 1 1 Lion 0.000 0.000 16 0.000 Nyala 4 0.039 0.000 35 0.052 0.001 Raptor nests 6 0.000 0.001 36 0.001 Rhino - Black 3 0.348 0.000 17 0.300 0.000 Rhino - White 0.000 0.000 41 1.375 0.001 Sable 0.000 0.000 11 0.043 0.000 Sharps Grysbok 0.000 0.000 1 0.000 0.000 Steenbok 4 0.005 0.000 24 0.005 0.000 Warthog 21 0.166 0.002 124 0.149 0.002 Waterbuck 49 1.164 0.006 261 0.944 0.005 Wildebeest - Blue 0.000 0.000 101 0.416 0.002 Zebra 70 2.496 0.008 271 1.471 0.005 TOTAL 2196 114.026 0.255 11385 82.016 0.201 Table 1. Overview of all game counted during the aerial survey in OWNR and BNR. Table 1 shows the animal numbers counted during the aerial surveys in 2020 in OWNR and BNR respectively, densities in biomass (kg/ha) and individuals (#/ha) are given to be able to compare areas with different sizes. The mean animal mass is taken from Smithers and Skinners (2005). As the aerial census in 2019 only included half of BNR trends over time are only done using these densities as extrapolation of figures is not possible due to very different vegetation types, rainfall and soils. Within any ecosystem to ensure long-term sustainability, vegetation, herbivores and carnivores need to remain in balance. The data (number, location, and sex of each animal) that these game counts provide is analysed and compared to the veld condition and rainfall to identify imbalances within the ecosystem functioning. Following 4 years of very dry and drought conditions last season was again slightly above average in rainfall and the veld remained stable. The late rains in April ensured an above average biomass to persist during the winter. Figure 3 shows the slight decline in carrying capacity from 825.85 in 2019 to 784.57in 2020, with a strong correlation to the precipitation. The increase in floral biomass will have had a significant impact in general health of herbivores and one would expect an increase in populations of most species. 2500 2000 1500 1000 500 0 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 Grazing Capacity (LAU in Olifants West) Rainfall (mm) Figure 3. Grazing capacity for Olifants West vs rainfall for the past 11 years. Herbivore demographics Balule Herbivore demographics can be used as an indicator of the health of an ecosystem. Herbivores can be divided into four classes based on the nature of their feeding strategies: bulk feeders, grazers, browsers and mixed feeders, in line with all ARC reports. A fifth category is also added showing all mega-herbivores, as they are important drivers of ecosystem functioning and change. Each of the mega-herbivores is already included in one of the feeding classes so figure 2 and 3 do not show the mega herbivores separately The ratios between the feeding classes should be taken into consideration, so as to maintain the balance or correct an imbalance. 10.46% 0.70% 7.93% 80.91% Bulk grazers Selective grazers Browsers Mixed feeders Figure 4. Distribution of 2020 herbivores numbers in BNR across the feeding classes. Appendix 1a and 1b give an overview of all the animals per feeding class per region for the 2020 count. Figure 5 shows the same as figure 2, now animal numbers have been replaced with animal biomass as a more comparable metric between feeding classes. It is clear that there is a huge imbalance between the feeding classes and this has been shown over time in figure 6, including the guideline provided by the ARC. The ration of bulk grazers has continued to drop, mainly as a result of far fewer buffalo this year. Ideally ratio would be manipulated by management using introductions of underrepresented classes and offtakes of the overrepresented classes. 10.46% 0.70% 7.93% 80.91% Bulk grazers Selective grazers Browsers Mixed feeders Figure 5. Distribution of herbivores density (ton/Ha) in Balule across the feeding classes. % of biomass/feeding class 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 2012 2013 2014* 2015 2016 2017 2018 2019 2020 Guidline Bulk grazers Selective grazers Mixed feeders Browsers Figure 6. Ratio of feeding classes over time in Balule. *in 2014 only mega herbivores were counted. Megaherbivores Megaherbivore species counted during the census are elephant (Loxodonta africana), white rhinoceros (Ceratotherium simum), black rhinoceros (Diceros bicornis), buffalo (Syncerus caffer) and hippopotamus (Hippopotamus amphibious). A total of 690 megaherbivores were counted across the regions of Balule, up 24.32 % from 2018, Table 3. When looking at biomass, figure 4, there is an increase of 99.04%, predominately due to the high increase in elephant counted, that make up just over 82% of the mega herbivore biomass. Given the fact that both elephant and buffalo are highly mobile species, these changes will need to be compared to the mega herbivore fixed wing data and preferably also to the APNR data, neither of which were available when writing this report. Mega herbivores Density #/ha Biomass kg/ha 2017 0.0224 59.4963 2018 0.0173 44.7588 2019 0.0137 38.3695 2020 0.0236 66.1028 Table 2. Total mega-herbivore counts per region in Balule. Mega herbivores 70.0000 0.0250 60.0000 0.0200 50.0000 40.0000 0.0150 30.0000 0.0100 #/ha Biomass kg/ha 20.0000 0.0050 10.0000 0.0000 0.0000 2017 2018 2019 2020 Biomass kg/ha Density #/ha Figure 7. Total mega-herbivore biomass (kg/ha) and density (#/ha) in Balule. The downward trend has reversed drastically, as a result of a large increase in elephant numbers. Elephant are a highly mobile species that travel significant distances in the open system and population figures should be viewed in conjuncture with the rest of the APNR. Unfortunately data are not available for the rest of the APNR. Given the life history, elephants under ideal circumstances can increase 3-5% per annum. They are not really susceptible to predators and therefore any increase beyond this can only be attributed to migration, off-takes or disease. Looking at the long-term trends, figure 5, shows a significantly different picture to last year, this the result of the sharp increase in elephant and buffalo numbers. Long-term trends are given as numbers per ha to show population density increases rather than biomass increase.

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