Zoology and Entomology
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Browsing Zoology and Entomology by Subject "Activity pattern"
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Item Open Access Activity patterns of birds in the central Free State, South Africa(University of the Free State, 2009-11) Van Niekerk, Daniël Johan; Kok, O. B.Activity patterns of bird species were studied at Glen Agricultural College within the grassland area of the central Free State, South Africa, during a period of 11 years (July 1997 - July 2008). The study focused on a specific grassland locality where 5-minute checklists were compiled continuously from dawn to dusk at least once a week for a total of 656 days. Data were also collected each minute for selected species. Additional observations in an adjacent tree and shrub dominated drainage line included I-minute checklists compiled during transects over a two-year period (late autumn 2000/1 to mid-autumn 2002/3) as well as surveys from a fixed position from dawn to approximately 70 minutes after sunrise during 2007/8. The central aim of the study was to quantify and explain annual, seasonal and daily activity patterns of all bird species recorded in the study area. This data is summarised in separate species accounts where aspects of the annual cycle, particularly breeding and moulting, were also considered. In addition, the potential influence of rainfall was investigated. The study reveals, for the first time, how the activity patterns of a southern African bird community change through time, and how the amount and timing of rainfall can influence these patterns. In spite of similarities amongst species when daily, seasonal and annual patterns are considered separately, the study also shows that each species is unique when all its data is considered simultaneously. Because activity patterns can have a substantial influence on the detectability of a species, the accuracy and usefulness of surveys aimed at estimating bird numbers is consequently questioned. The study at Glen also shows how activity patterns can be used to help unravel the annual cycle of species in a time and cost effective way.Item Open Access Social organisation and reproductive behaviour of sable antelope (Hippotragus niger Harris, 1838): implications for captive management(University of the Free State, 2015-07) Jacobs, Nadine; Butler, H. J. B.English: Sable antelope (Hippotragus niger) are considered to be one of the most profitable wildlife species in southern Africa favoured by photographers and trophy hunters. Intensive wildlife production of sable antelope is practiced to improve reproductive rate which would normally be retarded by deficiencies and mortalities in extensive management systems. Intensive wildlife production refers to the management of wildlife in a fenced area where management practices such as the provision of dietary supplementation and water (throughout the year), the control of parasites and the provision of health care are implemented in order to increase productivity. Up to now studies investigating the effects of captivity on social and reproductive behaviour of sable antelope, have been focused on populations in zoos and conservancies where management practices are centred on conservation. Additionally, no published scientific data is available concerning the effects of intensive management practices used in the wildlife ranching industry of South Africa. The main objective of this study was therefore to determine the effects of management strategies practiced specifically in intensive wildlife production in South Africa, on aspects of social and reproductive behaviour of sable antelope. To determine the effects of different management strategies, the social and reproduction behaviour of three sable antelope populations under different management regimes were investigated. Interactions pertaining to reproductive behaviour, territorial displays, and agonistic behaviour were evaluated and compared between populations. The success of management strategies practiced was evaluated by determining the reproductive rate of each population. To determine why these behavioural patterns were affected, differences in the activity pattern and range use of breeding herds and territorial males of populations were also assessed. Populations in intensively managed systems showed 100% calving and survival rates compared to a 75% survival rate observed for the extensively managed population. Though the implementation of intensive management strategies resulted in increased production, it also resulted in increased rates of agonistic interactions. However, the occurrence of aggressive displays that could result in injury was not abnormally high in the intensively managed populations compared to that observed in the extensively managed population. However, in the two intensive populations agonistic interactions directed at immature individuals were not only more numerous but also contained a larger percentage of aggressive displays. Increased rates of agonistic behaviour were primarily as a result of the provision of dry feed. Other factors that could have influenced the rate of agonistic interactions in both the extensively and intensively managed populations included, the artificial provision of water, activities that result in decreased personal space, the rate of territorial displays and limited resources. Therefore it can be concluded that though intensive management strategies definitely succeed in increasing productivity, in practice these strategies could adversely affect aspects of social behaviour of sable antelope in intensively managed systems.