African Wildcat Breeding & Release Program
Previously listed as endangered, the African Wildcat has recently been “down listed” to species “unknown”, simply because little information exists on these animals, particularly in a savannah system. The greatest threat to these cats is loss of habitat and hybridisation with domestic cats. As a result, it is feared that few “pure” Wildcats remain in the wild. As the true African Wildcat resembles the domestic cat, the only accurate method of distinguishing the two is by DNA testing. The primary objective of this project was to release the offspring of DNA tested African Wildcat breeding pairs back into their natural environment where they could breed with those cats already on the reserve, thereby enhancing the genetic variability. To date, 10 offspring have been successfully reintroduced into the Greater Makalali Private Game Reserve. Makalali aims to engage in a long-term monitoring program to acquire data on the ranging, foraging and reproductive behaviour of these animals in a savannah environment.
Predicting Grazer Distribution
PREDICTING GRAZER DISTRIBUTION WITH GRASS QUALITY AND QUANTITY PARAMETERS
Maarten van Strien, MSc
Wageningen University, The Netherlands
Predicting species distribution is an important part of ecology. There are numerous factors influencing the distribution of herbivores in an ecosystem. The distribution of food resources within an ecosystem is an important explanatory factor for herbivore distribution. Hence, the distribution of grass quality and quantity parameters (GQQPs) could explain grazer distribution. The goal of this study is to (i) explore the possibility of predicting grazer distribution with grass quality and quantity parameters, making use of new statistical modeling techniques, (ii) explore which parameters have most influence on grazer distribution in the wet and the dry season and (iii) create resource maps for grazer species for practical purposes. The study area is the Greater Makalali Private Game Reserve (GMPGR), South Africa. Maps of GQQPs (grass species abundance, herbaceous biomass, grass species richness and herbaceous coverage) are created by relating field measurements with Landsat ETM+ bands and variables derived from a digital elevation model using Generalized Additive Modeling (GAM). The accuracy of the GQQP maps was not very high, which could be caused by the date the Landsat ETM+ image was taken. The GAM method proved to be a flexible and empirical method. In 2005 and 2006 sighting locations of grazers were recorded throughout the GMPGR. The maps of the GQQPs are used to predict zebra (Equus burchelli) and wildebeest (Connochaetes taurinus) distribution in the wet and the dry season making use of Ecological Niche Factor Analysis (ENFA).
By applying a quantile reclassification to the values of the GQQP maps, so that the GQQP values have a uniform distribution, the grazer distribution was reliably predicted for the wet season. Predicting grazer distribution in the dry season wasn’t successful, which could be because other factors than the GQQPs determine the distribution in the dry season, or be a result of the sampling method of the grazer locations, or be caused by a possible change in the values of the GQQPs in the dry season. From the results of the ENFA, ‘resource maps’ were calculated that mapped the habitat suitability for the grazers. One of the findings is that the only factors positively influencing the distribution of both zebra and wildebeest in the wet season, is a high abundance of Urochloa mossambicensis and in lesser extent a high herbaceous biomass. All other GQQPs had a negative influence on grazer distribution, which could be because the environment a certain grass species grows in is of more influence on grazer distribution than the grazing value of the grass species. This study describes a method that is suited to obtain grazer resource preference in a specific area, but is less suited for studying the universal resource preference of a certain grazer. For wildlife and range management this method provides detailed information on the food selection of grazers within a certain area. The method simultaneously gives insight into grazer food preference and the spatial distribution of the preferred food resources in the area.
Bird & Mammal Release Site
The Greater Makalali Private Game Reserve (GMPGR) acts as a release site for rehabilitated birds of prey. After rehabilitation, the birds are relocated and released on the Conservancy. To date, over 40 barn owls and a green pigeon have been released.
Similarly, a number of small rehabilitated mammals have been released onto the Conservancy including small spotted genets, caracal, serval and duiker. In order to give these mammals a second chance, they undergo an extensive period of rehabilitation. Thereafter, the process of integrating them back into the wild begins. In some cases, this takes months.
WE NEED YOUR HELP!
Once released, the small cats are monitored and all sightings are recorded religiously. To further aid in monitoring and to assess the success of reintroduction, some of the cats are fitted with telemetry collars. This allows us to follow the cats for long periods post release and to determine the animal’s ranging and feeding patterns.
Another female caracal will be relocated to GMPGR by end May 2009. We require a telemetry collar to assist us with her monitoring post release. As the Trust is a non-profit organisation, it is dependent on donations to continue its work. If you would like to make a donation for a telemetry collar please contact Audrey Delsink for further details.
Over the years, a substantial database has been compiled which illustrates the bird diversity that exists within the GMPGR. This is invaluable in the managing of endangered species e.g. Ground hornbills and Lappet-faced vultures. The monitoring has revealed that a resident group of Ground hornbills continue to forage on GMPGR, and have successfully nested and fledged two chicks in the last 3 years. Sadly, the last chick to be fledged is not present with the group in early 2009 and is presumed to have died. However, the birds have produced a healthy chick in the 2008/2009 season. The birds have used the same nest for a number of years.
One of the greatest threats these birds face in the wild is a lack of suitable nesting sites. Together with the help of Scott Ronaldson of the Endangered Wildlife Trust, a number of artificial nests have been erected within the birds ranging area to facilitate nesting. Birds are recognised as good indicator species for biodiversity monitoring and thus monitoring is essential in the long-term preservation of a healthy ecosystem.
The effects of savanna trees on grass
The effects of savanna trees on grass: possible consequences for grazing herbivores in the Greater Makalali Conservancy, South Africa
Frank A. Looringh van Beeck
Wageningen University, the Netherlands
The savanna biome is characterized by a dynamic balance between trees and grasses. This study was performed to give an insight into the effects of savanna trees on grass quality and quantity, and what the possible consequences are for grazing herbivores. Also a small study was performed to analyze the impact of elephants on trees. To determine the role of trees on quality and quantity of grass in subtropical savannas, grass and soil samples were taken inside and outside the canopy area of Acacia nigrescens (nitrogen-fixing) and Sclerocarya birrea (non-nitrogen-fixing) trees in three different tree densities in the Greater Makalali Conservancy, Limpopo Province, South Africa. Grass selection of blue wildebeest (Connochaetes taurinus), Burchell’s zebra (Equus burchelli), warthog (Phacochoerus africanus) and impala (Aepyceros melampus) was recorded to determine whether the grass resource selection was related to the difference in grass quality. Finally, the impact of elephants (Loxodonta africana) on trees was observed to determine the indirect effects that elephants may have on the grass resource.
Soil nutrient contents, for both nitrogen and phosphorous, were higher in soil under the canopy compared to soil outside the canopy. Tree density did not significantly alter soil nutrient concentrations. The canopy seemed to increase soil nutrients in open, moderate and dense tree density areas. Trees with nitrogen fixing capabilities did not significantly change the concentration of soil nutrients. The above ground biomass was not significantly different inside the canopy compared to outside. In areas with high tree density the above ground dry grass biomass was about three times lower (103±9 g m -2 ) than in the open areas (304±35 g m -2) or in areas with moderate tree density (282±38 g m -2 ). Both the stem-to-leaf ratio and green-to-dead ratio were reduced with increasing tree density. The percentage alive grass was significant higher inside the canopy compared to outside. The tree canopy increased nitrogen and therefore the crude protein (CP) oncentrations in grass. Grass in areas with high tree density had a lower CP-content. CP-content in grass was higher around N-fixating trees. The phosphorous content in grass was reduced by increasing tree density. On the other hand, fibre content (%NDF) increased with tree density and was also lower under N-fixing trees. High nutritional grass species had a CP- and P-content of respectively 2.5 and 3.3 times higher than low nutritional grass species (range CP-content in grass species: 6.46-16.50%; P-content: 0.07-0.23%), and a lower %NDF (range: 62.9-73.9%).
The relative number of zebra observations was significantly higher in open woodland than expected. The relative grazing activity of both zebra and wildebeest seems to be higher in the open woodlands than in closed woodlands. This study showed that grass quality was higher in the areas with low tree density. This might indicate that resource selection of large grazing herbivores is influenced by grass quality, in particular by phosphorous content in grass. The impact of elephants on trees seems to be very low, 65 of the 347 recorded trees were utilized by elephants, and only 14 trees were utilized and dead. Tree utilization by elephants was mainly characterised by the breaking of main branches.
This study clearly shows that savanna trees have an effect on grass, and are therefore able to affect the resource of grazing herbivores. The most important factor is tree density, grass quality and quantity reduces with increasing tree density. This is possibly due to resource (nutrient, light and water) competition between trees and grasses which reduces the nutrient uptake and grass biomass production. The tree crown also plays a role by increasing the nitrogen availability in the soil which results in higher crude protein content in grass, and therefore a higher grass quality.