Thesis (M.Sc. (Zoology)) -- University of Limpopo, 2012 / Sparrow-larks form a relatively small genus in the family Alaudidae and comprise only seven species distributed widely throughout Africa and parts of the Eurasian landmass. Sparrow-larks are unique amongst larks in that they are sexually dichromatic and exhibit biparental care. The chestnut-backed sparrow-lark Eremopterix leucotis is endemic to Africa with five subspecies recognized based on differences in plumage colouration. The five subspecies are distributed throughout the arid to semi-arid savannas of Africa with two subspecies (E. l. hoeschi and E. l. smithi) occurring in southern Africa. Despite their widespread occurrence and its interest for research on the evolution of characteristics in the family (e.g. being sexually dichromatic and exhibiting biparental care), very little is known of the biology and ecology of the Eremopterix larks. The chestnut-backed sparrow-lark is no exception and most of what we know of the species is based on incidental observations from a few nests. In an attempt to improve our knowledge of this interesting group of species, it was decided to study various aspects of the breeding biology and ecology, moult, vocalizations and geographical variation in the chestnutbacked sparrow-lark. The breeding biology of the chestnut-backed sparrow-lark was studied at Al3 farm (De Loskop) near Mogwadi in the Limpopo Province of South Africa from January 2008 to December 2010. Data collected during the study included: breeding seasonality, egg and clutch characteristics, duration of the incubation and nestling periods, nest-site characteristics, the roles and relative contribution of the sexes in the breeding cycle, nestling development, diet and nestling provisioning rate, and breeding success. Chestnut-backed sparrow-larks bred mostly during the dry season, which is from April to September in the study area. Nevertheless, the results revealed that breeding is bimodal with a main peak in breeding activity in late summer and autumn (March to April) and a second smaller peak in spring (September to October). The species showed geographical variation in clutch size with a mean of 1.88 eggs recorded in the study area as opposed to 1.00 recorded in the northern parts of its range. Egg dimensions compared well with measurements obtained from the Nest Record Card Scheme of the Animal Demography Unit, University of Cape Town, South Africa. The mean incubation period of 10.33 days recorded in this study compares favourably with that of other Eremopterix species viii (8–10 days), a genus with some of the shortest incubation periods amongst larks. The mean nestling period of 9.2 days (range: 8–10) in the study area was significantly less than the 10–12 days reported for populations in the northern range of the species, but it compares well with those of other sparrow-larks. Nest site characteristics, which were quantified within a 1 m2 quadrant with the nest as the centre, including nest dimensions, were consistent with those reported in the literature. Chestnut-backed sparrow-larks in the study area preferred to nest in areas with a high percentage of bare ground (median = 67.5%) and very little vegetation cover (median = 25%). Most nests faced in a southerly direction compared to nests in the north of the species’ range, which face in a north-easterly or easterly direction. The species’ preference to face the nests away from the midday sun most probably serves a thermoregulatory function to avoid excessive heat during the warmest parts of the day. Most nests (78.2%) had an apron varying in size from small and insignificant to large and well-developed. The functional significance of the apron remains a matter of conjecture and there was no association between breeding success and presence or absence of the apron. In addition, one pair constructed one nest with and another without an apron, suggesting that individual preference or characteristic is not a determinant factor in the construction of an apron. Both sexes took part in nest construction, incubation and feeding and brooding of nestlings. However, the relative contributions were not entirely symmetrical as males incubated a greater proportion (50.1%) of the time compared to females (43.1%), and the mean and median of male incubation shift lengths were longer than that of females, albeit not statistically significant. However, females made statistically significantly (P < 0.05) more nest visits to deliver food compared to males (54.6% vs. 45.5%). The average breeding success, estimated using Mayfield’s method, was 16.1% but there were inter-annual differences with the overall breeding success in 2010 being only 8.1% compared to 20.6% of 2008. Known causes of failure included nest depredation, flooding, starvation, nest abandonment and hatching failure. Statistical analysis of morphometric data of live specimens and museum study skins suggest that, in addition to being sexually dichromatic, chestnut-backed sparrowlarks also exhibit mild sexual size dimorphism. However, there was considerable overlap in these measurements between the sexes and as a result the biological significance of this sexual size dimorphism may be negligible. Nevertheless, the ix results show chestnut-backed sparrow-lark males tend to have longer wings and tails compared to females. This may be adaptive with respect to the extended display flights that males perform during the breeding season. Interestingly, the mean mass of breeding females in the study area was significantly more compared to males, whereas the SAFRING database, representing data recorded throughout the year, showed no significant differences in the mean mass between the sexes. The greater mass of breeding females may relate to physiological changes associated with the acquisition of resources and the development of structures and tissues associated with egg-laying and egg-production. Larks rely heavily on vocalizations to attract mates and advertise territories. Not surprisingly, the study revealed a rich vocal repertoire for the chestnut-backed sparrow-lark. The analysis of the vocalizations shows that chestnut-backed sparrowlarks have a display song performed by males, a sub-song sung by both sexes and various different calls used in different contexts, e.g. flight and alarm calls. The study also presents the first analysis and description of the vocalizations of nestlings. An interesting feature of the vocalizations of the chestnut-backed sparrow-larks was that they performed hetero-specific vocal mimicry, which was incorporated in the subsong. Moult is a relatively unknown aspect in the annual cycle of the majority of larks. Chestnut-backed sparrow-larks undergo post-breeding moult, which is an adaptation to reduce the conflict between moult and breeding as both activities have high energy demands. The moult study also showed that they undergo a partial moult in mid-winter, involving the inner-most secondaries and some of the contour feathers. The results of this study shed valuable light on the natural history of this species and contributed significantly to ornithology and our growing understanding of the biology and ecology of the family. The results can also form a basis for future inter- and intraspecific comparative studies. The study illustrates the importance of undertaking long term studies of species to account for inter-annual differences in various ecological parameters.

PhD (Zoology) / Department of Zoology / Ecosystem services and disservices are important features in agro-ecosystems and both can have relevant economic impacts on farmers. While there has been much research on the value of ecosystem services, especially that of pest control by bats and birds, ecosystem disservices are often overlooked or estimated separately. Both, services and disservices, however, change with landscape and may be supported by natural vegetation. It is hence inevitable to assess them together to uncover their relative value and importance. Habitat loss and fragmentation are major threats to biodiversity and ecosystem services. Agricultural intensification can cause habitat loss and can negatively affect natural ecosystems and their services. However, the removal of natural vegetation can also reduce ecosystem disservices that origin from natural areas. This study focused on the economic trade-off between biocontrol by bats and birds and crop raiding by vervet monkeys in South African macadamia orchards, using vertebrate exclusion experiments. Crop quality and yield were assessed and extrapolated to income values. The study furthermore focused in more detail on the impact of orchard edge habitat and farm management on bats as ecosystem service providers as well as the arthropod community, which can provide both services (pollination, biocontrol) as well as disservices (crop damage). The macadamia industry is highly profitable and plantings are expanding worldwide. South Africa is currently the largest macadamia producer in the world and the study area, Levubu, holds some of the oldest macadamia plantings in the country. The subtropical climate and high annual rainfall make this area an intensively farmed landscape. Levubu lies at the foothills of the Soutpansberg, a centre of biodiversity and patches of natural vegetation wind through orchards of macadamia, avocado, banana and timber. Insect pest pressure is high in the macadamia industry, with several stink bug species (Hemiptera) and two moth species (Lepidoptera) accounting for most of the damage to the crop. Chapter One provides a detailed overlook over the South African macadamia industry, describes the major pest insect species and their impact on the crop and highlights the role of ecosystem services and disservices and the potential importance of remaining natural areas. Over three consecutive seasons, between September 2015 and May 2018, bats, birds and monkeys were excluded, using cages with nets, from a total of 96 macadamia trees. Four treatments were applied (Full, Day, Night, Control) to distinguish between effects of the different functional groups. Exclusions took place at orchard edges with natural or human-modified edge habitat to assess the impact of vicinity to natural vegetation on pest control and crop raiding. Results presented in Chapter Two showed that biocontrol by bats and birds was stronger near natural vegetation and significantly impacted crop quality as well as yield. Effects of bats and birds were still significant at human-modified edges, whereas crop raiding by monkeys is limited to the natural orchard edges. The economic impact analysis shows that the benefits of biocontrol through bats and birds outweighed the income losses due to crop-raiding monkeys. The value of bats and birds was as high as USD 5000 per hectare per year through prevented insect damage and a 60% crop increase. Crop-raiding affected the yield, which dropped by about 26% and resulted in losses of about USD 1500 per hectare. These results highlight the importance of integrating natural areas into agricultural landscapes, even if they incur the risk of being disadvantageous. Farmers need to be made aware of the enormous economic benefits. Effective crop raiding mitigation strategies still need to be researched to avoid negative association with natural areas. These can, however, possibly also limit access for biocntrol agents, like bats and birds and thereby reduce their economic impact. Especially the removal of natural areas or establishment of buffer zones of unpalatable crops between agricultural land and forests is not advisable. Integrative research in agro-ecosystems on trade-offs between a variety of ecosystem services and disservices is necessary in future, rather than assessing them separately. The bat community on macadamia farms was monitored monthly and compared between orchard edges. Stationary bat detectors were placed at each set of exclosures for two consecutive nights a month, automatically recording from sunset to sunrise. Recorded bat calls were identified manually to species level and activity converted to Miller’s activity index, which counts the number of active minutes per species per night. We analysed the activity per feeding guild over season and landscape setting, estimated species richness and diversity (Hill’s numbers) and species turnover between farms, season and landscape setting, using diversity partitioning. The bat community was mostly influenced by seasonality with season turn-over accounting for 21% of total bat diversity (21.25 species). Edge habitat on the other hand only accounted for 5%. We found higher species richness and activity in the high season compared to the low. While there was no difference in diversity in the high season between the two orchard edge types, species diversity at the human-modified edge was lower than in the natural during the low season. Natural habitat might therefore be more important in the low season, while its effect is overwritten by high food availability during the high season. Clutter-edge species furthermore were more active at the natural orchard edges than open-air feeders, which were in turn more active at human-modified edges. Both activities dropped significantly during the low season. Chapter Three concludes that the macadamia landscape is able to support a high bat species diversity, which is affected by seasonal differences, probably due to food availability. Natural areas are important to be maintained to support sensitive species, relying on clutter habitat and natural roosts. Habitat features as well as farm management can also influence arthropod communities. Visual observations took place each month for 20 minutes per tree. Observations were counted and identified to at least order level. Chapter Four concentrates on the impact of orchard edge habitat and insecticide treatment on honey bees (83% of Hymenoptera observations) abundance. Honey bees were the only taxon significantly responding to both variables, with higher abundance close to natural areas and increasing abundance with increasing time since pesticide application. Honey bees furthermore seemed to recover slightly quicker from population crashes after insecticide treatments at natural edges than they did at human-modified edges. Hymenoptera can be highly beneficial to macadamia farmers, as farmers are heavily relying on pollination by honey bees and parasitoids are known to feed on major macadamia pest insect species. These ecosystem service providers were mostly affected by habitat and management practices, which may compromise their ecosystem service provision. Although commercial bee hives are exposed throughout macadamia orchards, they do not appear to fully replace the pollination and biocontrol services provided by feral species, which can be enhanced through resource supplementation by patches of nearby natural vegetation. Chapter Five concludes with emphasizing the general importance of natural vegetation in landscape planning of agricultural areas. This study proved confidently that benefits through ecosystem services largely outweigh negative impacts of ecosystem disservices, both stemming from these natural areas. Through the inclusion, maintenance and restoration of such patches of natural vegetation, farmers can potentially increase the value and effectiveness of biocontrol by bats and birds or other services. Seasonality largely determined bat species diversity, and a general high species diversity was observed in the macadamia landscape, possibly due to a certain degree of landscape heterogeneity and high food availability. Activity patterns of clutter-edge and open-air feeding bats varied with edge habitat, while clutter-dependent bat species / NRF