Abstract:
This study aimed to connect habitat and landscape scale variation, through
time and space, to wildlife population dynamics. I studied African buffalo (Syncerus
caffer) group size according to habitat structure, landscape heterogeneity, forage
quality, and water availability in Hluhluwe-iMfolozi Game Reserve, South Africa. I
used two approaches to study grouping behavior of buffalo-daily field observations
and digital vegetation classification and mapping home range areas to quantify
seasonal and geographic changes.
Daily buffalo observations included a record of tree and shrub density within
habitat patches and buffalo group counts. I concluded that buffalo occurred in smaller
groups during the dry season. During both seasons, buffalo maintained larger groups
in more open habitat and in the dry season, group size also depended on grass quality.
To examine landscape heterogeneity, a Landsat Enhanced Thematic Mapper
(ETM) satellite image was classified into structural vegetation types and radio tracking
data from ten herds were used to calculate and delineate home range area. Vegetation structure and water availability were summarized in each home range area and an
average buffalo group size was calculated for each herd in each season. During the
dry season, average vegetation density was the only significant influence on group
size. Again, buffalo maintained larger groups in more open areas. During the wet
season, vegetation density did not affect group size, but the heterogeneity of
vegetation types within the home range did. Buffalo were found in larger groups in
more heterogeneous home range areas. The total size of the herd was also a
significant influence in the wet season. Larger herds maintained larger average
groups.
I also determined the influence of vegetation structure and landscape
heterogeneity on group size variability within herds. During the dry season,
variability was affected by home range heterogeneity, total herd size, and, marginally,
by water availability. In the dry season, more variability was observed in
heterogeneous areas and areas with more permanent water. Larger herds also had
more group size variability than small herds. In the wet season variability was
determined by total herd size only. Larger herds had more variability than small
herds.
This study has important implications in terms of wildlife management. I have
shown that habitat structure, forage availability, and landscape heterogeneity
significantly affect buffalo population dynamics. I have also presented a method to
quantify vegetation factors on a landscape scale and determine how those factors can
influence wildlife populations. The map of structural vegetation can also be used to examine the effects of landscape change, yearly burning regimes, and large herbivores
on the reserve's ecosystem.
