| dc.description.abstract | Globally, biodiversity resources have been in decline since mankind began to keep records of their surrounding environments. With the combination of different natural catastrophes over centuries and human-induced activities, the decline in biodiversity continues to accelerate. With the high rate of human population increase, demand for resources for both survival and development has increased, causing the rapid declines in biodiversity that are so vividly observed. As mankind realized this decline, areas were set aside to help protect and conserve the precious gifts of biodiversity for the benefit of future generations. Conservation efforts began over 3,000 years ago; however, the first legal Protected Area (PA), Yellowstone National Park, was not established until 1872. Protected Areas (PAs) are the first line of defence in the global effort to protect biodiversity, particularly rare, endangered species and fragile ecosystems, and different categories of these areas with different levels of protection have been expanding worldwide in number and size since they were first established. In developing countries, many extremely negative challenges, including widespread conditions of poverty, rapid human population growth, biofuel projects, agriculture and political instability, are faced by those charged with the management of protected areas. The primary challenges facing biodiversity/wildlife conservation include human populations, land use and land cover change (LULC), diseases, alien and invasive species and illegal off-take.
The focus of this thesis is on the behaviour, ecology and conservation of Masai giraffe (Giraffa camelopardalis tippelskirchi) in Tanzania. Giraffes are the most elegant, conspicuous and tallest animals of the African savannah. Giraffes prefer savannah and are responsible for the architectural beauty of trees through browsing. Giraffes are social but are non territorial because individuals within a group are in constant change. Females are more often in mixed herds with calves, whereas males maintain a primarily solitary life. Giraffes are widespread; however, in a recent preliminary population estimate, an unnoticed decline in the total population as occurred because of habitat degradation and illegal hunting.
The aim of this thesis was to investigate and assess the ecology, behaviour and conservation status of the Masai giraffe in the two largest PAs in Tanzania, which have different management objectives. In these two areas, the effect of illegal off-take on the sex ratio, the factors affecting group size and vigilance behaviour, and the effect of management objectives were assessed, and a hormonal investigation was conducted to determine the response towards threats.
The major result of this study was that the sex ratio at birth was skewed in favour of female offspring because of illegal hunting and other disturbances, primarily in areas with a high risk of illegal activities. The skew in sex ratio was significantly more pronounced towards females of all age classes in areas with a high risk of illegal hunting than in low risk areas. Furthermore, our results support the hypothesis that distorted sex ratios, particularly those with a female bias, are likely to appear within populations subjected to high levels of environmental disturbance. Additionally, individuals in areas with a high risk of illegal activities were more vigilant and had a longer flight distance than those found in low risk areas. We also found that the proportion of vigilant individuals within a group decreased as the number of individuals within the group increased. Vigilance was also higher when females were with calves.
In general, the maximum group size of giraffes was 30 individuals, with an average group size of 2.2 individuals. The most common groups contained1-10 individuals. We found that males preferred to be solitary compared with females and that male numbers decreased with increasing group size. Males also preferred more wooded habitats than females. Season of the year and habitat had no significant effects on group size.
Furthermore, in this study, the type of PA and the risk of poaching significantly affected a pattern of differences for group size, behaviour, and Flight Initiation Distance (FID). Selous Game Reserve (SGR) had fewer singleton groups and more larger groups than those in Serengeti National Park (SNP), and males formed slightly larger groups in SGR than those in SNP in which male singleton groups were common (Paper_II).Vigilance behaviour was also higher in males in SGR than those in SNP. Additionally, FID was longer in SGR than that in SNP. Although both study areas were highly threatened by illegal hunting from the surrounding human populations, human influence in SGR remained much higher. Habitat strongly affected group size of giraffes in both study areas, with giraffes primarily found in wooded habitats. No relationships between sex and habitat preferences were observed in these two PAs.
Based on analysis of hormonal effects, no significant differences in FGM concentrations in giraffes were detected between SNP and SGR. However, in both areas, the mean stress levels were high. These results were consistent with our hypothesis concerning stress response in giraffes, and a significantly higher level of FGM was found in groups with<10 individuals, whereas a decrease was observed in extremely large groups of > 11 individuals. Moreover, calves and other young had higher FGM levels than those in adults. High levels of stress in young individuals may lead to higher mortality (Hatchwell 1989; Müllner et al. 2004). The level of FGM was also higher in females than males, which did not support our hypothesis.
In this research, reproduction, movement patterns, genetics and threats (including predation) to the Masai giraffe were thoroughly investigated. More studies are required to determine how giraffes are targeted by illegal activities. Moreover, sex ratios of adults are not necessarily correlated with sex ratios at birth or conception, and therefore, conclusions are difficult to reach on the potential cause of the skew in the sex ratio. Additionally, a detailed investigation on calf survival and a determination of the effects of female biased sex ratios on giraffe populations are recommended. | nb_NO |
