• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 4
  • Tagged with
  • 4
  • 4
  • 4
  • 4
  • 3
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Biology of the greyheaded parrot Poicephalus fuscicollis suahelicus Reichnow.

Symes, Craig Thomas. 30 October 2013 (has links)
This study was conducted to investigate the biology of the Greyheaded Parrot Poicephalus fuscicollis suahelicus in the wild. Field work was conducted in north-east South Africa in the southern limit of the range of the Greyheaded Parrot during two field seasons. Observations from August to December 1999 in the Levubu region, south of the Soutpansberg mountain range, included months of the non-breeding season when Greyheaded Parrots occur seasonally in the area. Observations in the Luvhuvhu-Mutale river confluence area from March to August 2000 included months of the breeding season. No field work was conducted from January to March 2000 due to exceptionally high rains in the southern African sub-region, that prevented access to sites. The Greyheaded Parrot has a widespread distribution, through southern, south Central and East Africa, that has possible changed little in recent years. However, local populations are likely to have suffered extinctions due to habitat destruction and capture for the illegal trade. Populations in protected areas (Makuya Park and Kruger National Park) are less vulnerable to capture than unprotected areas. The conservation of the Greyheaded Parrot outside of protected areas is highlighted. In various parts of the range of the Greyheaded Parrot seasonal movements occur in response to food and nest site availability. Nest sites are possibly limiting in certain parts of its range due to habitat destruction. During post-breeding flocking, the occurrence of larger flocks, possibly family units (mean ± S.E = 4.7 ± 0.2), is common, when birds wander in search for seasonally available food sources. During this period density of Greyheaded Parrots is 0.28 birds/100 ha. Monogamous pairs are more conspicuous during the breeding season (mean ± S.E = 2.1 ± 0.1) and density estimates are 0.14 birds/100 ha. Egg laying is synchronous between pairs with the timed appearance and flocking of juvenile flocks in spring (August/September). Breeding during the dry season reduces competition with other large cavity nesting bird species. Observations suggest that a skewed sex ratio exists in the population (males:females = 2:1). Daily movements are characterised by a bimodal activity pattern. Early morning movements involve flights to activity centres where the accumulation of numerous smaller flocks occur. Here preening, allo-preening and socializing occur with drinking and/or feeding occurring if food and/or water are available. Thereafter, birds move to regular feeding sites, to feed. Activity is decreased during the heat of the day with birds sleeping, resting and/or preening in the canopies of trees. Late afternoon activities involve increased levels of activity and late afternoon return flights to roosts. Greyheaded Parrots are specialist feeders, accessing the kernel of predominantly unripe fruit. This feeding strategy reduces competition with other frugivore competitors. During any one time few tree species are fed on by the Greyheaded Parrot. Greyheaded Parrots were also observed feeding on bark in the breeding season. Two, almost fully fledged, chicks were found dead in a nest and the causes of death undetermined. Their crops contained numerous pieces of masticated bark and insect parts. Behaviours and vocalizations of the Greyheaded Parrot were similar to that recorded in the Cape Parrot. Recognition of the Greyheaded Parrot as a separate species based on species specific calls and DNA warrants further investigation. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.
2

The ecology and conservation biology of the Black-cheeked Lovebird Agapornis nigrigenis in Zambia.

Warburton, Louise Sarah. January 2003 (has links)
This study was undertaken to investigate the ecology of the Black-cheeked Lovebird Agapornis nigrigenis in the wild. Prior to this study little was known about the ecology of this parrot or other members of the genus Agapornis. The Black-cheeked Lovebird is classified as Vulnerable and has suffered a severe population decline and reduced distribution, from which, for largely speculative reasons, it has never recovered. The overall aim of this project was to elucidate the basic biology of the Black-cheeked Lovebird and determine the conservation actions which are necessary to conserve the species in the wild. Fieldwork was conducted across the species' range in south-west Zambia over twenty-two months between May to December 1998; March to December 1999; and February to May 2000. An education project focussing on Black-cheeked Lovebird conservation was conducted with local schools, villagers and Zambia Wildlife Authority scouts during September 2001. Historical records pertaining to distribution of the Black-checked Lovebird, both within and beyond Zambia are few, anecdotal and often discredited, and it is suggested that the species should be considered as endemic to Zambia. Within its core range the species has a clumped and localised distribution, associated with Mopane woodland and permanent water sources. Two sub-populations occur and appear to be distinct. Black-cheeked Lovebirds were most active, in the early morning and late afternoon, forming the largest daily flocks sizes during these times, which correlated with drinking and feeding activities. The smallest flock sizes occurred when roosting. Overall flock sizes were significantly larger during the dry (non-breeding) season. Black-cheeked Lovebirds were observed feeding on 39 species. Food items included seeds, leaves, flowers (especially nectar), fruit pulp, invertebrates, bark, lichen, resin, and soil. Various foraging techniques were used. Terrestrial foraging was dominant, with little temporal or spatial variability. Arboreal foraging in plants varied seasonally and by availability. Feeding preferences were not specialised and there was no dependence on a limited food resource. Black-cheeked Lovebirds fed on two agricultural crops. There was no evidence to suggest an extended foraging range during the crop-ripening season, or the reliance on crops for survival. The crop-ripening season coincided with the lovebird breeding season. The species is widely perceived as a crop pest, with 18% of seed heads of millet crops suffering more than 20% damage during the ripening season. Local farmers attempted to protect their crops in a variety of ways, however, these were largely ineffective and rarely lethal to lovebirds. The importance of elevating local tolerance for the species through education programmes is highlighted. This study presents the first collection of breeding data on the species. Breeding occurred from midlate January to early May. A single clutch was raised by most pairs per breeding cycle. Seventy-eight nests were found and characteristics measured. Fidelity to nest-sites is suspected. Although breeding behaviour was non-cooperative most nests were found in a loosely clumped distribution. No nesting requirement appeared to be in limited supply, or had reason to affect the population's reproductive output. Behavioural data on nest location, building, defence and predation are presented. In addition courtship, copulation, parental care and juvenile behaviours are reported. Data on clutch size, laying intervals and hatching success with captive birds are included. One nestling tested positive for Psittacine Beak and Feather Disease Virus (PBFDV). Other observations suggest PBFDV is present in the wild population. Implications for research and conservation are discussed. Black-cheeked Lovebirds roosted inside naturally formed cavities in live Mopane trees. Roost cavities were found in a loosely clumped distribution. No roosting requirement appeared to be in limited supply. Black-cheeked Lovebirds are highly dependent on surface water supplies and need to drink at least twice daily. The lovebirds are highly cautious drinkers that will not drink if the water resource was actively disturbed by humans or livestock. Water availability is a limiting factor to the Black-cheeked Lovebird. The gradual desiccation of its habitat appears to be the major cause behind the reduction of occupancy within its small range. Over the last 45 years (1950 - 1997) the annual rainfall in the Black-cheeked Lovebird's habitat has decreased resulting in further reduction of its already highly localised distribution increasing the species dependence on artificial water supplies. The conservation management of the species should be prioritised towards maintaining and creating water resources with minimal external disturbance; upholding the wild-caught trade ban in the species, continuing environmental education with local schools promoting lovebird conservation, and monitoring populations through dry season water source counts. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 2003.
3

Comparative aspects of the thermal biology of African and Australian parrots.

Burton, Stephen Leslie. January 2006 (has links)
Deserticolous birds inhabit an environment characterised by high ambient temperatures and low rainfall that has low primary productivity. The combination of these factors may lead to the evolution of adaptations that minimise food and water requirements. One physiological adaptation that has been found in many deserticolous birds is the reduction of basal metabolic rate (BMR). I measured metabolic rate in the laboratory using four species of African lovebirds (Agapornis) , and four species of Australian grass parakeets (one Neopsephotus and three Neophema), all similar in body mass. Tests for differences between groups were carried out using both conventional and phylogenetically independent methods. The BMRs of the lovebird and grass parakeet species were not statistically correlated with habitat type. These results confirm the findings of previous studies on the effect of desert conditions on the BMR of parrots. I also found no significant differences in BMR between the species assemblages from different continents. The lack of significant differences in BMR between deserticolous and nondeserticolous parrots supports the idea that birds are "ex-adapted" to living in desert environments. I suggest that the results may have been affected by phenotypic plasticity in BMR, as recent evidence has shown that the scaling exponent of BMR differs between captive-raised and wild-caught birds. To elucidate the effect of origin (captive-raised vs. wild-caught) on the BMR of birds used in this study a large scale analysis of bird BMR data was undertaken. BMR and body mass data for 242 species of birds were obtained from the literature, this study, and unpublished data from various sources. A phylogeny was constructed using molecular and morphological phylogenies from the literature, and analysed using conventional and phylogenetically independent methods. The conventional analysis found significant differences in the scaling exponents of BMR of captive-raised and wild-caught birds. However the phylogenetically independent method showed non-significant differences between these two groups. Conventional analysis of differences between parrots and all other birds yielded significant differences between these two groups, with parrots having significantly higher BMRs than other birds. Again the phylogenetically independent analysis found non-significant differences between these VII two groups. A test of homogeneity of variance between these two groups found significant differences between the variances ofthe two groups, probably due to disparity in sample size and range of body sizes. The conventional and phylogenetically independent tests for differences between captive-raised and wild-caught parrots yielded non-significant results, suggesting that the parrots are not subject to the phenotypic adjustments postulated for all other birds. The lack of significant differences between captive-raised and wild-caught parrots suggests that the analyses of differing habitat type for African and Australian parrots is indeed valid. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.
4

The ecology of Meyer's parrot (Poicephalus meyeri) in the Okavango Delta, Botswana.

Boyes, Rutledge Stephen. January 2008 (has links)
Meyer’s Parrot Poicephalus meyeri is the smallest of the nine Poicephalus parrots, forming the P. meyeri superspecies complex with five congeners. Their distributional range far exceeds any other African parrot, extending throughout subtropical Africa. Meyer’s Parrots had previously not been studied in the wild, and therefore, gathering high-quality empirical data on their behavioural ecology became a research and conservation priority. The primary aim of the study was to correlate environmental (e.g. rainfall, habitat availability, resource characteristics, food resource abundance and temperature) and social (e.g. inter- and intra-specific competition, predation, and human disturbance) variables with aspects of their ecology (e.g. flight activity, food item preferences, breeding activity, and group dynamics) to evaluate the degree of specialization in resource use (e.g. trophic, nesting and habitat niche metrics). African deforestation rates are the highest in the world, resulting in twelve out of the eighteen Meyer’s Parrot range states undergoing drastic loss of forest cover over the last 25 years. Most commentary on the population status of Meyer’s Parrots and other Poicephalus parrots pre-dates this period of rapid deforestation In addition, over 75 000 wild-caught Meyer’s Parrots and almost 1 million wild-caught Poicephalus parrots have been recorded in international trade since 1975. Empirical data from this study was used to identify ecological weaknesses (e.g. niche specialization or low breeding turnover) for evaluation within the context of deforestation in the African subtropics. Baseline data on the breeding biology and nest cavity requirements of Meyer’s Parrots was also necessary to assess the viability of applying the conservative sustained-harvest model to African parrots. A unifying goal of this study was to advance our knowledge of the ecology of African parrots and other Psittaciformes by assessing the validity of current hypotheses put forward in the literature. The Meyer’s Parrot Project was initiated in January 2004 on Vundumtiki Island in the north-eastern part of the Okavango Delta, Botswana. Due to high flood waters between March and July 2004, road transects were postponed till August 2004. Transects were conducted at Vundumtiki from August 2004 to July 2005 and February 2007 to August 2007, and at Mombo from August 2005 to January 2006. During 480 road transects over 24 months, food item preferences closely tracked fruiting and flowering phenology, resulting in significant positive correlations between Levins’ niche breadth, rainfall and food resource availability. Meyer’s Parrot can, therefore, be considered opportunistic generalists predispersal seed predator that tracks resource availability across a wide suite of potential food items, including 71 different food items from 37 tree species in 16 families. Meyer’s Parrots were, however, found to be habitat specialists preferring established galleries of riverine forest and associated Acacia-Combretum marginal woodland. These strong habitat associations facilitate their wide distribution throughout the Kavango Basin, Linyanti Swamps, down the Zambezi valley, up along the Rift Valley system in associations with the great lakes, through the Upper Nile and the Sudd, and west as far as Lake Chad through the Sahel. Seventy-five nest cavities were measured during this study, including 28 nest cavities utilized by Meyer’s Parrots within the 430ha sample area at Vundumtiki. Over 1700 hours of intensive nest observations at six nest cavities was undertaken. Meyer’s Parrots formed socially monogamous pair-bonds maintained over at least four breeding seasons. Breeding pairs established breeding territories up to an estimated 160ha within which there were 1–6 nest cavities. Eggs hatched asynchronously, yet nestlings fledged synchronously with similar body size and condition. There was evidence to support the incidence of extra-pair copulations, however, mitochondrial DNA sequence data are required to confirm the incidence of extra-pair fertilizations. Meyer’s Parrots had no preferences in regard to nest tree species beyond the incidence of suitable nest cavities, which are selected and further excavated to accommodate their non-random nest cavity preferences. There was a significant non-nesting Meyer’s Parrot population during the breeding season, likely due to this longlived cavity-nester delaying nesting until a suitable breeding territory becomes available. Meyer’s Parrots utilize communal roosts during summer and disperse from them according to the Foraging Dispersal Hypothesis. Due to the requirement to roost during the middle of the day to avoid heat stress, Meyer’s Parrots have bimodal flight and feeding activity patterns. The highest probability of locating Meyer’s Parrots is between 08h30 and 11h00 during summer when both adults are feeding on the seeds of fleshy-fruits in riverine forest communities. Due to the paucity of data on the current distribution and population status of Meyer’s Parrots and other African parrots, a continent-wide survey of all African parrots represents a conservation priority. Current deforestation rates in several Meyer’s Parrot range, their specialist habitat associations, and lack of evidence to support adaptability to a changing landscape mosaic necessitate the re-classification of Meyer’s Parrots as data deficient or nearthreatened. Based on low breeding population due to limited breeding opportunities, the CITES Appendix II wild-caught bird trade should also be halted until the sustainability of this trade has been evaluated and the relevant information made available. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

Page generated in 0.0375 seconds