Wildlife Utilisation of Artificial Waterholes and the Effects on Habitat Integrity

We are still investigating the consequences of the plethora of waterholes on our landscape in OWNR. The University of South Africa is a partner to the Balule Research Facility and has appointed Eilidh Smith (MSc student) to continue our investigations that were initiated last year and presented at the Kruger Science Network Meeting. This is a short summary of the early results. No conclusions can be generated yet as we still have many months of work ahead!

We are hoping to demonstrate the effects of the different types of waterholes on OWNR as well as if there have been negative impacts associated with the numerous waterholes available to animals.

In February 2013, camera traps were deployed on 9 water holes of specific demographics in the Olifants West Nature Reserve in an on-going project to assess the value and effects of artificial waterholes. 

The photographs taken by the camera traps are used to quantify the numbers, group composition and behaviour of species using the waterholes. This data can then be used to assess which demographics of waterhole are most productive according to species diversity and function as some waterholes are primarily sources for drinking whereas others may be used for cooling and wallowing as well. In addition to this, certain waterholes are restricted to particular species, for example reservoirs are predominantly utilised by elephants. Using a combination of data collected from the camera traps and vegetation surveys around the waterholes, it will be possible to determine the influence of waterholes on surrounding habitat integrity and establish which demographics of waterhole have the greatest effect. This will aid reserve management when manipulating water sources by providing an understanding of wildlife requirements and the effects this has on the wider environment.

Table 1: Waterholes at which camera traps are currently deployed

 Name of Waterhole

 Type of Waterhole

 Source of water

 Size

1.      Singwe Big Dam

 Earth dam

 Drainage/manual pump

 Large

2.      Ngala Dam

 Earth dam

 Solar pump

 Medium

3.      Oxford  Big Dam

 Earth dam

 Wind pump

 Large

4.      Nzuwini

 Reservoir

 Manual pump

 Medium

5.      Tony’s dam

 Pan

 Manual pump

 Small

6.      Leopard’s View

 Pan

 Electric pump

 Small

7.      Singwe Bush Camp

 Pan

 Wind pump

 Small

8.      Nyala

 Reservoir/trough

 Solar/wind pump

 Medium/small

9.      Van Wyk

 Reservoir/trough

 Wind pump

 Medium/small

Camera trap analysis on species diversity and utilisation

Methodology

Camera traps are positioned at 9 waterholes across the OWNR. They are positioned in order to capture as much of the water edge as possible and so there are more camera traps at the larger waterholes. Singwe Big Dam and Oxford Big Dam are the largest waterholes in the study with between three and four camera traps positioned throughout the study period. These cameras are repositioned according to changes in the water’s edge as the dams dry up.

The data is collected on a weekly basis and entered onto a spreadsheet which records the time of day the waterhole was visited, the duration of the visit, activity undertaken and the numbers and demographics of the animals utilising the waterhole.

Results

Species Richness

Species richness is determined by the total number of different species that have been record at a waterhole. It indicates which waterholes are utilised by the largest range of species.

Figure 1: Species richness at each waterhole determined by total number of different species visiting

Figure 1 shows that Singwe Big Dam has the highest number of different species visiting, this is followed by Ngala and Tony’s Dam. The lowest species richness can be seen at Nyala and Nzulwini which are both reservoirs. Certain demographics of waterhole have greater productivity in terms of species richness – this can be seen in Figure 2.

Figure 2: Species richness according to waterhole demographic

Figure 2 shows that the most productive demographic of waterhole in terms of species richness is, on average, the earth dams. However, there is a difference of less than one between earth dams and pans. Reservoirs have the lowest species richness due to their relative inaccessibility, even when associated with troughs which tend to hold only small amounts of water.

Variations in species richness may be attributed to size of waterhole. Singwe Big Dam and Oxford Big Dam are the largest waterholes in the study and are both earth dams. This may distort the species richness values in favour of them as a larger waterhole can cater to more species. With this in mind, a species diversity index can be used in future analysis to establish a species diversity value that considers the number of visitations separately.

Habitat Integrity surrounding waterholes

Methodology

Habitat integrity was measured around each of the study waterholes using a unique scoring system. This scoring system incorporates indicators such as prevalence of increaser versus decreaser grass species, the occurrence and diversity of woody species and the level of wildlife effects such as broken branches, bark stripping and pushed over trees.

At each of the study waterholes transects were marked out using Quantum GIS. Each waterhole has a North, South, East and West transect consisting of 5 plots each at 200m intervals from the centre of the waterhole (Figure 6).

Figure 3: Map showing study waterholes marked by red dots and surrounding transects with each plot represented by blue dots

A drop method was used in plots sized 10X10m to assess the grass component by recording the species touching a stick which was placed 100 times in a grid pattern across the plot. Each of the 100 hits generated a score according to whether or not the grass was an increaser or decreaser. Forbs were also included and scored the same as an increaser (Table 2). A hit where no species was touching was recorded as a ‘miss’ and received a score of zero.

Table 2: Table showing the scoring system for measuring habitat integrity

 

 Identification

Grass

 Increaser/forb =0.5

 Decreaser = 1

 

Results

Preliminary results were obtained by scoring the grass component of the vegetation surveys in order to assess which waterholes are the most grazed.

Figure 4: Graph showing the difference in grass scores between waterholes with a higher value indicating a higher grazing quality

It can be seen in Figure 4 that Toni’s dam has the highest accumulative grazing quality across all transects and Singwe Big Dam has the lowest. Figure 5 shows that earth dams have the lowest scoring plots and concrete pans the highest. This may be related to the functions of the waterholes if waterholes such as the earth dams that scored poorly cater for species requirements beyond merely drinking, for example providing wallowing sites. These waterholes may then encourage species to inhabit the areas more consistently and therefore increase the level of grazing impact seen in the surveys. Size may also be a contributing factor as larger waterholes such as the earth dams can be expected to have more animal visitations and the methodology does not account for the wider radius of impact expected.

Figure 5: Average grazing quality per demographic of waterhole

The grazing quality of the areas surrounding the study waterholes may be influenced by a number of factors and further analysis is necessary the extricate these. The scores are highly impacted by anomalous data such as that collected in areas near drainage lines where high scoring decreasers such as Panicum maximum are in abundance.