An autecological study of bushbuck and common duiker in relation to forest management.
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Date
1986
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Abstract
Frequent reports of damage caused by bushbuck and common
duiker browsing on commercially important timber seedlings,
and an interest in the potential and feasibility of hunting
these two species on State land were the primary factors
responsible for the Directorate of Forestry's motivation of
this study. The study area at Weza State Forest comprised
approximately 21 000 ha of plantations, grasslands and
indigenous forests which were considered representative of
timbered areas throughout the Natal midlands.
Several methods of age determination were investigated
and these findings permitted assessments of growth, fecundity
and population structure. The physiological condition of
both antelope species was examined in relation to age, sex,
reproduction and management strategies, and the results
discussed in conjunction with mortality patterns. Principal
foods of both bushbuck and duiker were determined from rumen
analyses while 112 marked animals were regularly monitored to
facilitate assessments of habitat selection and levels of
spatial and social organisation.
of these largely solitary and
Estimates of the abundance
nocturnal antelope were
influenced by local movements in response to the availability
of food and cover which varied seasonally and also fluctuated
dramatically with forest succession and timber management
activities.
Although bushbuck and duiker bred throughout the year
and had almost identical rates of reproductive performance,
different factors were responsible in limiting the sizes of
these two populations. All the available evidence gathered
in this study indicated that food resources during winter and
early spring were inadequate for bushbuck, particularly in
1983 when 33% of the marked population died from starvation
and/or exposure. Notable differences in forage utilization
and habitat selection inferred little interspecific
competition at this time of the year.
In contrast,
territorial duiker appeared to be susceptible to highly
localised habitat modifications (including the availability of food and cover) which occurred throughout the year and
resulted from silvicultural and timber harvesting practices.
Rumen analyses and quantitative damage assessment
surveys revealed that browsing on timber seedlings was
usually confined to localised areas during the winter months
and was much less severe than had been originally suggested.
Conifers were regarded as a starvati~n food and methods of
reducing damage to these young trees were recommended for
potential problem areas.
Both antelope species were considered overabundant at
Weza and recommendations for the future management of these
populations included the limited utilization of surplus
animals, by sport hunting on a sustained yield basis, and
methods of manipulating and improving forest habitats.
Description
Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1986.
Keywords
Bovidae., Bushbuck., Sylvicapra grimmia., Duikers., Theses--Zoology.