Space use patterns of a large mammalian herbivore distinguished by activity state: fear versus food?

Space use patterns have generally been interpreted using home‐range concepts without distinguishing the particular activities performed in different regions. The relative influences of food resources, security from predation and shelter from thermal extremes on space occupation are likely to vary with time of day and changing conditions over the seasonal cycle. We used hourly movement rates obtained from GPS telemetry to infer the predominant activity states of blue wildebeest in the Kruger National Park, South Africa, at different times of day. Food procurement was assumed to be the primary consideration during the morning and late afternoon, shade seeking to become important over midday, and security from predation to be the overriding factor at night when stalking predators are most active. Travelling excursions were expected to occur mostly during daylight when lurking predators are most readily detected. Movements beyond the preferred range should occur more frequently in the late dry season when food has been depleted and surface water sources become restricted. As anticipated, we observed shifts in space occupation by the collared wildebeest herds with time of day and activity state. During the night, wildebeest herds remained within the ranges they occupied during prime foraging times in the early morning and late afternoon. However, they contracted their space occupation away from habitat edges where concealment for stalking lions increased, both while resting and while foraging. Herds inconsistently expanded their space use into surrounding areas with more shade but taller grass over midday. Risky excursions beyond the prime foraging ranges became more frequent late in the dry season. Security from predation seemed to be the overriding influence and restricted access to food resources. By taking into account temporal variation in prevailing activity states and other influences, space occupation patterns can be related to particular vital needs and their interactions

Mapping and modelling the population and habitat of the roan antelope (Hippotragus equinus langheldi) in Ruma National Park, Kenya

PhD ThesisWildlife-based tourism, which is Kenya’s second largest economic sector, is threatened by the risk of extinction of many wildlife species in the country. The endemic roan antelope (Hippotragus equinus langheldi) now only survives in Ruma National Park (RNP) where its population has been declining continuously since 1976. This thesis investigates the roan’s habitat use and selection, causes of population decline and population viability in RNP with the aim of recommending scientifically-based management interventions for population recovery and sustainable conservation. Roan movement patterns and habitat use were investigated using 4 home range estimation techniques. Habitat selection was studied at multi-spatial scales using compositional analysis, logistic regression, and information-theoretic (IT) and multi-model inference (MMI) techniques. Data for this study consisted of population estimates for roans and other grazers, Landsat images, soil maps, digital terrain data, rainfall records, snare distribution records, and roan ground tracking data. Identification of causes of population decline was carried out using both multivariate and univariate techniques. A generic population viability analysis (PVA) package was used to (i) estimate the likelihood of roan extinction under various management options; and (2) rank the management alternatives for roan population recovery. All 4 home range estimators are useful in characterizing different aspects of the roan home range, but overall the local convex hull method produced the most realistic home ranges. The three habitat selection methods yielded similar results but the IT techniques demonstrated superior qualities as they identified important habitat variables and produced the most accurate model predictions. MMI averaged models coupled with GIS data developed very informative habitat suitability and poaching risk maps. Analysis of habitat selection indicated different usage in seasons and spatial scales depending on water availability, habitat composition and burned status, and distribution of eco-geographical features. High adult mortality due to poaching with snares was identified as the main cause of roan population decline. Other important factors included habitat change and rainfall variability with its associated droughts and floods. PVA showed that under the current conditions, the roan population cannot persist more than 3 decades. Several anti-poaching and prioritized management interventions to curb poaching and promote population recovery are described.Commonwealth Scholarship Commission

Home range and resource use of sable antelope in the Okavango Delta

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Masters in Science Centre for African Ecology, School of Plant Animal and Environmental Sciences, 2011.Habitat selection occurs across a range of different spatial scales and is influenced by a variety of factors, ultimately determining how animals distribute themselves across the landscape. Studying the decisions that an individual animal makes across different levels of selection, from its choice in dietary item to predator avoidance strategies, is a fundamental link in understanding the response of groups of animals and ultimately entire populations that may provide insight into population performance. The study formed part of a broader study focused on the decline of rare antelope species. Specifically this study was aimed at establishing the home range and resource use of sable antelope in a region where they were initially expected to be thriving. The levels of selection covered in this study are: the location of home ranges of an individual or social group within the landscape; the use of various habitat components within the home range; and the procurement of food items within those habitats. At the highest level, the broad objectives were (1) to determine where sable occupied home ranges within the landscape, indicating the suitability of various landscape units to sustain sable populations and (2) to determine the relative use of habitat types within those home ranges that may enable sable to avoid predation and acquire resources required to survive and reproduce. At the lowest level of selection the characteristics of forage selection and how the grass quality in the different vegetation types during different seasons affects the success of sable herds was explored. The broad objectives were (1) to determine the effect of seasonal flooding and rainfall on grass greenness in the floodplains and upland vegetation types and the consequent use of those vegetation types by sable antelope and (2) to determine how exploitation of resources in the floodplains and in the uplands contributed to the nutritional status of sable. I additionally quantified the time spent browsing and determined the composition of the browse component of the diet of sable. Adult female sable from each of three adjacent sable herds were fitted with GPS collars providing hourly GPS co-ordinates. Adaptive LoCoH was used to determine home range location and annual, seasonal and core home range extents. A vegetation map was created and the number of GPS locations within each vegetation type was counted to determine their relative use in relation to availability within the home ranges. GPS collars were used to locate herds daily so that foraging observations of browsing and characteristics of the grasses grazed could be attained. Acceptability and dietary contributions of grass species and browse were determined for each sable herd during different seasons. The availability of grass species on the floodplain grasslands and in the upland grasslands and woodlands was estimated. Water and the availability of key resources posed a constraint on where sable home ranges were established. Sable simply did not occupy the region in the north of the study area further than 7 km from permanent water and floodplain grasslands. Herds generally avoided open savanna, mopane woodlands and Kalahari apple-leaf woodlands characterised by sparse grass cover, particularly during the dry season. Home ranges were relatively small compared 4 to the range estimates from herds in Kruger National Park. There was no obvious seasonal difference in home range extent nor were there large areas of overlap between home ranges of adjacent herds. Observations during the study indicated that competitor species, including zebra and wildebeest, concentrated on the floodplain grasslands. Throughout the year H. dissoluta was the most strongly favoured grass species and contributed most to the diet of the sable herds in both the wet and dry season. During the dry season sable herds expanded their diet to include Aristida stipitata and Aristida meridionalis which are generally considered poor forage value species for cattle but that retained some greenness. Additionally, the contribution of browse, especially the leaves of Croton megalobotrys, Philenoptera nelsii and Combretum mossambicense and the flowers of Kigelia africana, constituted an important bridging resource during the extended dry season. Crude faecal protein levels remained above the suggested maintenance levels throughout the annual cycle. Crude faecal protein levels were elevated prior to calving when sable spent more time foraging on the floodplain grasslands where high value forage species such as Paspalum scrobiculatum, Panicum repens and Urochloa mossambicense and sedges were eaten. Indications are that the constraint posed by the distribution of water within the landscape, rather than resource limitations within occupied home ranges, are the primary limitation to population performance in the Kwedi concession.Wilderness Safari, the Wilderness Wildlife Trust, the Conservation Foundation, Classic Africa and National Research Foundation (NRF) of South Africa

Home Ranges and Diving Behavior of New Zealand Sea Lions along the Catlins Coast, South Island, New Zealand

New Zealand sea lions (Phocarctos hookeri) were extirpated from the North and South Islands of New Zealand during pre-European native hunting, and their numbers were greatly reduced on the Auckland and Campbell Islands during European commercial sealing. However, they began reoccupying South Island in 1994, and pup production remains low but steady. The home range, at-sea movements, and diving behavior of females at the breeding colony along the Catlins Coast of South Island have not been studied since its inception in 2006. The goal of the study was to: 1) evaluate the performance of home range models to identify the most accurate model(s) for a semi-aquatic distribution, 2) track movements to identify home ranges, and 3) record diving behavior of females to characterize foraging behavior and estimate energy expenditure. To accomplish this study, we attached satellite telemeters and video and data recorders to females along the Catlins Coast during austral winter of 2019. Home ranges were most accurately modeled by separating inshore and offshore habitats and applying adaptive local convex hulls (LOCOH) and fixed kernel density with plug-in bandwidth selection (PKDE), respectively. This method minimized the ranges outside of used habitat, handled boundaries to movement, and performed accurately in cross-validation evaluation. The results showed the importance of home range model selection. Total home ranges were small and restricted to coastal areas. Foraging cycles were frequent, with short times at sea and onshore. Dives were shallow, short in duration, and divided into three types based on variables derived from three-dimensional dive analysis. Dive characteristics indicated a benthic foraging strategy with transit periods between foraging patches. At-sea estimated metabolic rate varied by activity, with an estimated field metabolic rate lower than that of females at the Auckland Islands, possibly indicating differences in energetic expenditure among populations. It appears that females along the Catlins Coast consume nearshore, abundant prey and require less time and smaller home ranges for foraging compared to that for females in the Auckland Islands. Although reoccupation of their historic range on South Island will take decades, suitable habitat for breeding and prey availability along the southeast coast are encouraging

Spatio-Temporal Recruitment Dynamics Of Mountain-Dwelling Caribou In The Yukon Territory, Canada

Thesis (Ph.D.) University of Alaska Fairbanks, 2010Understanding processes and mechanisms resulting in observed ecological patterns is critical information for biologists charged with effectively managing and conserving wildlife populations. In many areas across North America woodland caribou (Rangifer tarandus caribou Gmelin) populations are declining, as are caribou and reindeer populations globally. Why these declines are occurring is a key research question of biologists and managers. I investigated factors influencing recruitment of mountain-dwelling woodland caribou using long-term time series from ten herds (populations) in the Yukon Territory, Canada (Yukon). Recruitment was indexed by the calf:cow ratio observed during the fall breeding season using data collected during aerial monitoring surveys. I first examined the seasonal effects of the Pacific Decadal Oscillation (PDO), on observed recruitment in these herds. The PDO was positively related to recruitment and had its strongest effect during the winter preceding birth and immediately before calving. These results indicate that female body condition, and hence conception rates, were not affecting observed recruitment patterns. Rather, parturition and/or early calf survival were the most likely vital rates affecting the number of calves being recruited into the breeding population. I next examined the interacting effect of large-scale climate (PDO) and predation [wolf (Canis lupus L.) density] on recruitment in the Finlayson herd of east-central Yukon. A large-scale wolf control program in the 1980s allowed me to assess recruitment over a range of wolf densities and climatic conditions. The effect of the PDO immediately before calving was negligible when wolf numbers were significantly reduced indicating the climatic effect was modified by wolf density. Additionally, as springtime climate improved (i.e. increasing PDO) the difference in recruitment between years with and without wolf removals was reduced