Thesis (Ph.D.) - University of Queensland, 2003. / Includes bibliography.

The body and central nervous system of the Nile crocodile (Crocodylus niloticus) is known to grow continuously, even past sexual maturity. Previous studies on crocodilians show a gradual decrease in the rate of growth of the brain as individuals mature; however, the data on brain growth are limited and there are no data on growth rates of the spinal cord and retina. The current thesis provides a description of the growth rates of the brain, spinal cord and eye (ocular volume) of 70 juvenile and sub-adult Nile crocodiles ranging between 92 g and 90 kg in mass. Body growth in the crocodiles is accompanied by growth of all central nervous system structures (brain, spinal cord and eye), although growth occurs at different rates, with the spinal cord being the fastest growing structure, followed by the eye and the brain. The neurogenic regions (areas to which new neurons are continuously added) of the brain were revealed using doublecortin immunohistochemistry. Labelled cells were observed in all the regions of the telencephalon (including the cortical mantle, dorsal ventricular ridge, striatum, septal nuclei and the olfactory bulbs) as well as the molecular and granular layers of the cerebellar cortex, but not in the diencephalon or brainstem.

Diss. : Völkerkunde : München : 1980-81. - Bibliogr. p. 429-472. Index. -

A dissertation submitted to the Faculty of Science, School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. 30 October 2014. / My study investigated the significance of spatiotemporal heterogeneity on the Nile crocodile (Crocodylus niloticus), a long-lived, apex predator, occupying many African and some South African riverine ecosystems. The scales of study included a long-term investigation of the (indirect) impacts of anthropogenic, landscape scale (100 km2) disturbances on the population demographics of C. niloticus, over 35 years. At the intermediate scale (15 km2), indirect and direct impacts of flooding and seasonality on the health of the C. niloticus population were investigated over a three-year period. This was performed by investigating preferred habitat availability and river quality assessments, including physiochemical variables and rapid bioassessment measures, which served as the ‘smallest’ scale (with samples taken every 500 m). All scales were compared with long-term and short-term investigations into crocodile population demographics. Total crocodile population size within the study river increased over time (from 18 in 1981 to 35 in 2013), but the number of adults decreased (from 9 to 3). Human population size increased at a rate of 3300 individuals per year and anthropogenically altered habitat increased over time from 24% total coverage attributable to farmland on the banks of the Mutale River in 1977, to 66% land coverage in 2013. Increases in humaninduced habitat alterations also created shifts in preferred crocodilian habitat availability. Investigations into the effects of natural disturbances revealed that physiochemistry was seasonally variable, and changed drastically with changes in climate and runoff. The macroinvertebrate communities in the Mutale River differed in time and space for a multitude of reasons, including climate change and changes in habitat. The results of my study showed that Nile crocodiles were affected by alterations to the environment on multiple scales. The study concludes that the long-term population viability of C. niloticus is limited by a combination of these factors.

Thesis (Ph.D.)--Drexel University, 2010. / Includes abstract and vita. Includes bibliographical references (leaves 134-147).

Thesis (M.Sc.) - University of Queensland, 2002. / Includes bibliography.

The Greater St Lucia Wetland Park (GSLWP) World Heritage Site, is one of the most important remaining protected areas for the conservation of Crocodylus niloticus (Nile crocodile) in the Republic of South Africa Although crocodiles are present at low densities in some of the wetlands throughout the GSLWP, at Kosi Bay and Lake Sibaya, the majority is found at Lake St Lucia Concern about the status of the crocodile population at Lake Sibaya prompted a quantitative assessment of the present situation to direct appropriate management action to secure the future viability of this population Due to the complex nature of crocodile surveys, and the paucity of available scientific literature in South Africa, a literature review of global crocodilian survey techniques provided the basis for a survey strategy to determine an index of relative abundance of the crocodile population at Lake Sibaya The population was estimated in 2003 through aerial and spotlight surveys and nest surveys were conducted in 2003 and 2004. The highest count dwing the 2003 aerial surveys was 36 crocodiles, suggesting a decline of 66% during the past 13 years in the population index based on earlier surveys. Sixty five crocodiles were cowlted during the spotlight surveys, 72% more than the highest aerial count (excluding hatchlings), which indicates the importance of using a combined survey approach. A correction factor of 1.72 was calculated for future aerial surveys and the population is estimated at 112 crocodiles, \\-ith a variance of22.49 and standard error of 4.47. Three nests were found during the 2003 nest survey, but none during 2004. Crocodiles rarely produce every year in the wild, and the Lake Sibaya population might display a low reproductive frequency, similar to the nearby Lake St Lucia population Sixty three potential nesting areas were identified and evaluated in terms of their relative suitability for nesting. These sites could play an important role in increasing the population to support a sustainable use progralllffie at Lake Sibaya. Despite legal protection, the population is clearly under threat as a result of direct and secondary pressures. To secure the future viability of this population, I recommend that Ezemvelo KZN Wildlife develop an integrated crocodile management plan through collaboration with The Greater St Lucia Wetland Park Authority and the local communities adjacent to Lake Sibaya, where the conservation and increase of crocodiles will benefit the communities that are dependent on the lake for their daily livelihoods. The likely alternative might be extinction of this important predator from the largest freshwater ecosystem in South Africa's first World Heritage Site. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.

Thesis (M.S.)--Florida State University, 2004. / Advisor: Dr. Gregory M. Erickson, Florida State University, College of Arts and Sciences, Dept. of Biological Science. Title and description from dissertation home page (viewed June 17, 2004). Includes bibliographical references.

Since the ceding of the Panamá Canal from the United States to the Republic of Panamá in 1999, human development has accelerated, resulting in the loss of tropical rainforest habitat and declines in wildlife populations. In 2007 this area of vast plant and wildlife diversity experience further loss of habitat as land clearing and excavation commenced for the Panamá Canal Third Locks Expansion Project. As one of the largest construction projects in the world, the potential impacts of the expansion prompted the Panama Canal Authority to work with a local non-governmental conservation organization to initiate a wildlife rescue and relocation operation to conserve wildlife in the affected areas. From 2007 to 2010, 896 wildlife rescue events occurred in 11 areas along the Canal; 806 of these individuals (90%) were successfully relocated to protected areas (n=749) or captivity (n=57). These wildlife rescue efforts were summarized, including human labor required, wildlife species composition, and conservation statuses according to the IUCN and CITES. Also quantified were wildlife dominance and biodiversity using the Simpson, Shannon, Berger-Parker, and Brillouin diversity indices, relative abundance of >100 Neotropical species, and habitat-abundance relationships for four focal species: Hoffman's two-toed sloth, Choloepus hoffmanni; brown-throated three-toed sloth, Bradypus variegatus; American crocodile, Crocodylus acutus; and common caiman, Caiman crocodilus. Relationships between diversity indices and habitat for the wildlife rescued during the wildlife rescue project were also analyzed. Results indicate the Panamá Canal Watershed to ii possess a diverse representation of Neotropical wildlife. Habitat-abundance relationships of focal species suggest two-toed sloth numbers increased as the edge of secondary forest decreased and number of three-toed sloths increased as total landscape area of agriculture decreased. Crocodile populations increased as number of patches on the landscape and mean patch size of secondary forest decreased, and caiman numbers increased as the edge density of secondary forests decreased and mean patch size of agriculture increased. Diversity-habitat relationships revealed wildlife diversity increased with heterogeneous secondary forest landscape consisting of less edge. This project provides rare insights into wildlife rescue operations and wildlife-habitat relationships for Neotropical wildlife species that will be useful for a range of conservation efforts. Additionally, this research provides updated population assessments for many of the species included in the research, especially the focal species, in which a need for them has been stressed in the conservation literature.

A pilot study was launched in 1993 to determine the movements of crocodiles in the Olifants River in Kruger National Park (KNP). This turned into a research project in 1994 and lasted for five years until 1998. The objectives of the study were to determine movement, study nesting preferences and to investigate the possible effects of metal pollution in crocodiles. The movements of the total population were studied by doing regular foot counts, four times per annum. The basis for movement was found on the principle that a change in numbers signified movement. Foot counts were supported by spot counts at three different locations in the study area at 14 day intervals. The foot counts were done along a pre-determined route, followed with every count, and this resulted in data indicating a definite change in numbers at certain times of the year. A comparison was made between the movements of crocodiles in large bodies of open water (lakes & estuaries), a so called "closed" system and the Olifants River or "open" system. There was a movement of the population during August of every year, followed by another one in December/Jan and yet another in May. The largest movement, in August, co-coincided with the prelude to mating and ultimately nesting. The spot counts indicated that there was a smaller and probably localized movement during May and December of each year. This corresponds to nesting behaviour and the flood status of the river. All indications are that major movements took place during periods of high flow and thus during the rain season (Sept - Feb). A major flood was experienced during February 1996 which changed the geomorphology of the river. In addition to the foot and spot counts, eleven large adult crocodiles were fitted with radio transmitters to monitor their movements for a period of one year (1997 -1998). The results indicated that movements over large distances occurred. The longest distance covered was in access of 36 km. Some individuals returned to the location of origin, thus completing a round trip from their point of departure. The majority of crocodiles fitted with transmitters left the protection of KNP, spent time in neighbouring Mozambique and some returned to Kruger after an average period of three months. Indications are that there is a lack of territorial dominance amongst large individuals at certain times of the year, allowing for less restricted movement up and down the river. A difference was found between the movements of crocodiles in the Olifants River as opposed to a large body of water eg. a lake or estuary. The second objective was to collect data on nesting preference, nest content and egg dimensions. A total of seven parameters were measured including slope, distance to water, height above water, soil type, vegetation, exposure to direct sunlight and the size of the female. Besides these parameters, a comparison was made between egg size, mass and length and the correlation with female size. The results indicated that egg mass and length increased with an increase in female size. The average clutch size was 34 eggs. A difference was found between two nesting years (1997 and 1998) with the larger females nesting in 1998 (egg mass 122.7g). A higher rainfall was measured for 1998, leading to the conclusion that smaller females nested during dryer years. The larger females, because of physical abilities, dug deeper nests ,36 cm in 1998 as opposed to 25 cm in 1997. No difference was found between nesting habits elsewhere in Africa and that in the Olifants River. Twelve individuals of varying sizes ranging from 1.4 m to 4.1 m, were collected from three locations and various tissue samples were analysed for metal content. Tissue from muscle, liver, kidney and fat were analysed for Al, Cu, Cr, Fe, Mn, Ni, Pb, Section ranger and Zn. As this was the first data of its kind to be collected, no meaningful conclusions could be reached, except to offer the data as base line data and for future comparisons. There was however a correlation between Fe concentration in muscle tissue and body size, total length (TL). An increase in TL resulted in an increase in Fe concentration. The opposite were found with Fe in fat tissue. Smaller crocodiles (TL) had higher concentrations of Fe in their fat tissues. Besides the large amount of base line data that resulted from this study, it also highlighted the shortage of knowledge on this species, particularly in Kruger, to enable us to manage and protect them successfully. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1999.