Browsing by Department "Animal Demography Unit (ADU)"

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    Accuracy of ARGOS locations of pinnipeds at-sea estimated using Fastloc GPS
    (Public Library of Science, 2010) Costa, Daniel P; Robinson, Patrick W; Arnould, John P Y; Harrison, Autumn-Lynn; Simmons, Samantha E; Hassrick, Jason L; Hoskins, Andrew J; Kirkman, Stephen P; Oosthuizen, Herman; Villegas-Amtmann, Stella
    BACKGROUND: ARGOS satellite telemetry is one of the most widely used methods to track the movements of free-ranging marine and terrestrial animals and is fundamental to studies of foraging ecology, migratory behavior and habitat-use. ARGOS location estimates do not include complete error estimations, and for many marine organisms, the most commonly acquired locations (Location Class 0, A, B, or Z) are provided with no declared error estimate. METHODOLOGY/PRINCIPAL FINDINGS: We compared the accuracy of ARGOS locations to those obtained using Fastloc GPS from the same electronic tags on five species of pinnipeds: 9 California sea lions ( Zalophus californianus ), 4 Galapagos sea lions ( Zalophus wollebaeki ), 6 Cape fur seals ( Arctocephalus pusillus pusillus ), 3 Australian fur seals ( A. p. doriferus ) and 5 northern elephant seals ( Mirounga angustirostris ). These species encompass a range of marine habitats (highly pelagic vs coastal), diving behaviors (mean dive durations 2-21 min) and range of latitudes (equator to temperate). A total of 7,318 ARGOS positions and 27,046 GPS positions were collected. Of these, 1,105 ARGOS positions were obtained within five minutes of a GPS position and were used for comparison. The 68 th percentile ARGOS location errors as measured in this study were LC-3 0.49 km, LC-2 1.01 km, LC-1 1.20 km, LC-0 4.18 km, LC-A 6.19 km, LC-B 10.28 km. Conclusions/Significance The ARGOS errors measured here are greater than those provided by ARGOS, but within the range of other studies. The error was non-normally distributed with each LC highly right-skewed. Locations of species that make short duration dives and spend extended periods on the surface (sea lions and fur seals) had less error than species like elephant seals that spend more time underwater and have shorter surface intervals. Supplemental data ( S1 ) are provided allowing the creation of density distributions that can be used in a variety of filtering algorithms to improve the quality of ARGOS tracking data.
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    African penguins Spheniscus demersus recolonise a formerly abandoned nesting locality in Namibia
    (2003) Roux, J-P; Kemper, J; Bartlett, P A; Dyer, B M; Dundee, B L
    African Penguins Spheniscus demersus disappeared from Neglectus Islet probably between 1885 and 1952. Visiting birds were only noted rarely before the mid 1990s, but since 1995 penguin numbers on the islet have increased and breeding was first confirmed in 2001. Neglectus Islet is the only formerly abandoned nesting locality to be recolonised by African Penguins in Namibia. Although the population is still very small (estimated at around 11 breeding pairs), the re-establishment of this breeding locality is important for the conservation of the African Penguin, which is considered to be Critically Endangered in Namibia.
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    Big Science: SKA and the next phase of astronomy in Africa
    (2013) Horrell, Jasper
    In 2012 the country celebrated the news that South Africa had won a substantial part of the bid to build the most ambitious radio astronomy array in the world - the Square Kilometer Array. This audio lecture explains the purpose and function of this massive investment in international astronomy, and its implications for the future of astronomy in South Africa. This resource is useful for anyone interested in the Square Kilometer Array and astronomy in general.
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    Bird Ringing
    (2014-09-12) Oschadleus, Dieter; Neary, Tim
    In this radio broadcast, Dieter Oschadleus discusses bird ringing in South Africa, from its beginning in 1948, to the tools and techniques used (mist nets, aluminium or stainless steel rings), to the ethical considerations involved in ringing and tagging. The interview explains the purpose and value of bird ringing in the scientific process and the ways in which citizens can get involved in bird ringing in South Africa. Image provided coutesy of Kim and Forest Starr under a Creative Commons Attribution 3.0 Unported license.
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    Birds along a transect across KwaZulu-Natal: altitudinal preference and altitudinal migration
    (2018) Scott, Tanya; Underhill, Leslie G
    The special ornithological advantage of KwaZulu-Natal is the massive altitudinal gradient between the coastline and the Drakensberg Mountains, an altitudinal range in excess of 3000 m. It is one of the best places in the world to study altitudinal bird migration. This dissertation uses the bird data from the Second Southern African Bird Atlas Project (SABAP2), and altitudinal data from a Digital Elevation Model to try to understand altitudinal migration in a band of KwaZulu-Natal between 29°S and 30°S. The bird atlas provides data on a five minute grid, grid cells with sides of c. 9km, known as pentads. The Digital Elevation Model gives spot heights at 0.5 minute intervals. It therefore provides 100 altitudes in each pentad. There is a description of the data analysis approach used to relate bird species abundance to altitude and selected examples to show how the method works, illustrating the strengths and weakness of the approach. The developed method is then applied to the study area to investigate altitudinal migration. For each of the 304 species which occur with some regularity in the study area, the altitudinal height preferences in summer and winter are plotted and compared. Some species, such as African Dusky Flycatcher, are definite altitudinal migrants, and some species are definite residents having essentially identical altitudinal distributions in summer and winter, such as Black-bellied Starling. There are also many intermediate strategies. Numerous species have been proposed as altitudinal migrants in KwaZulu-Natal. These claims are evaluated against the results obtains in this dissertation. For some species, the suggestion that they are altitudinal migrants is clearly incorrect, and for other species the hypotheses are confirmed by the bird atlas data. The project attempted to determine if there were common factors that helped explain which species engaged in altitudinal migration. A set of life history characteristics for each species, including aspects such as diet, mass, habitat, etc, was used to evaluate if there was a relationship between the extent of altitudinal migration and these explanatory variables. No meaningful relationships were found. Explanations of altitudinal migrations therefore remain an enigma.
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    Butterfly Photography
    (2014-09-12) Bode, Justin; Neary, Tim
    In this radio broadcast, Justin Bode discusses butterfly photography, including the differences between forest and bushveld butterflies and a rare sighting of the Golden Flash butterfly. Citizen scientists have been instrumental in developing knowledge of not only the adult life phase of butterflies, but also through recording the larval and pupal stages of both moths and butterflies in South Africa and discovering new localities for endangered species. Justin also discusses synergies with other research projects, such as ant researchers, that can be exploited by involving citizen scientists in the research process. Eyed Pansy Ilanda image provided courtesy of M Purves under a Creative Commons Attribution-Share Alike 3.0 Unported license.
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    Changes in some biophysical characteristics of African horsesickness virus (no. 3922) during attenuation
    (1967) Russell, B.W; Kipps, A; Polson, A.
    African horsesickness virus (No.3922, Type 7), attenuated for the horse by serial passage in suckling mouse brain, was studied at various passage levels to determine whether any change in the biophysical characters of the infectious particles had occurred. during the process of attenuation. Such changes were indeed observed. Propagation of the virus in tissue culture was accomplished only after the modification of standard culture media by the addition of egg white, a complex substance containing a number of proteins including the enzyme lysozyme. Some evidence is presented to show that the presence of egg white materially assisted in the successful cultivation of horsesickness virus; as well as in the formation of plaques in monolayers ·of cultured cells. Electron micrographs of horsesickness virus obtained from these cultured cells, and the results of a study of the fine structure of infected mouse nervous tissue, are presented. A remarkable change in the buoyant density of the infectious particles of this horsesickness virus was found to occur during attenuation. The 'wild' or virulent strain was found to consist mainly of particles of density 1.26 gm/ml. The attenuated strain however proved to be composed of particles with deneities quite different from that of the wild strain, predominantly 1.21 and 1.34 gm/ml. This alteration of the buoyant appeared to be directly related to the degree of attenuation. Studies in electrophoresis using a newly designed apparatus showed that the wild strain of horsesickness virus is homogeneous in its migration in an electric field. The attenuated strain showed a changed electrophoretic pattern· indicating the presence of particles of different mobilities. As in density gradient analysis, electrophoresis showed a fundamental difference between the wild and attenuated strains of this virus. It was possible also to show a correlation between the slowly migrating component of the attenuated strain and the fraction of higher density. The sedimentation coefficient of the infectious particles of the No.3922 strain of horsesickness virus was studied at various stages of attenuation ·and the particle size at three passage levels were calculated. The particle size and other characteristics determined in this way were compared with the results of measurements obtained from ultrafiltration of the virus through collodion membranes. It was found that the diameter of the infectious particles of the attenuated strain is greater than that of the wild strain. This study shows that physical measurements may be used to give
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    Citizen Science - Mammal Map
    (2014-09-12) Hoffman, Tali; Neary, Tim
    In this radio broadcast, Tali Hoffman explains the purpose and scope of MammalMAP - an online platform which aims to update the distribution records of all African mammal species - and how citizens all over Africa can contribute by sending in photos of animals in conjunction with their location. Tali discusses capacity and services offered by the platform, the ways in which this information is being used, and the ethical considerations required and the measures taken to prevent abuse of such a resource, such as poaching. Image provided courtesy of Johan Taljaard under a Creative Commons Attribution Non-Commercial Share-Alike 3.0 Unported license.
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    Citizen Science - Special Days
    (2014-09-12) Loftie-Eaton, Megan; Neary, Tim
    In this radio broadcast, Tim Neary interviews Megan Loftie-Eaton about the Animal Demography Unit's citizen science programme 'Special Days' - Mad Mammal Monday, Tree Tuesday, Weaver Wednesday, Threat Thursday, Frog Friday, Scorpion Saturday and Snake Sunday. Megan discusses strategies to engage citizens in science, including the use of social media and potential strategies for more productive strategies for mainstream media, and the valuable contributions citizens can make to scientific knowledge and wildlife conservation in South Africa. This resource introduces some of the basic citizen science initiatives undertaken by UCT and offers guidance for members of the public interested in getting involved. Image supplied courtesy of the Animal Demography Unit under a Creative Commons Attribution Non-Commerical Share-Alike 3.0 Unported license.
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    Effects of smart position only (SPOT) tag deployment on white sharks Carcharodon carcharias in South Africa
    (Public Library of Science, 2011) Jewell, Oliver J D; Wcisel, Michelle A; Gennari, Enrico; Towner, Alison V; Bester, Marthán N; Johnson, Ryan L; Singh, Sarika
    We present 15 individual cases of sub-adult white sharks that were SPOT tagged in South Africa from 2003-2004 and have been re-sighted as recently as 2011. Our observations suggest SPOT tags can cause permanent cosmetic and structural damage to white shark dorsal fins depending on the duration of tag attachment. SPOT tags that detached within 12-24 months did not cause long term damage to the dorsal fin other than pigmentation scarring. Within 12 months of deployment, tag fouling can occur. After 24 months of deployment permanent damage to the dorsal fin occurred. A shark survived this prolonged attachment and there seems little compromise on the animal's long term survival and resultant body growth. This is the first investigation detailing the long term effects of SPOT deployment on the dorsal fin of white sharks.
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    Environmental influences on the abundance and sexual composition of white sharks Carcharodon carcharias in Gansbaai, South Africa
    (Public Library of Science, 2013) Towner, Alison V; Underhill, Les G; Jewell, Oliver J D; Smale, Malcolm J
    The seasonal occurrence of white sharks visiting Gansbaai, South Africa was investigated from 2007 to 2011 using sightings from white shark cage diving boats. Generalized linear models were used to investigate the number of great white sharks sighted per trip in relation to sex, month, sea surface temperature and Multivariate El Niño/Southern Oscillation (ENSO) Indices (MEI). Water conditions are more variable in summer than winter due to wind-driven cold water upwelling and thermocline displacement, culminating in colder water temperatures, and shark sightings of both sexes were higher during the autumn and winter months (March-August). MEI, an index to quantify the strength of Southern Oscillation, differed in its effect on the recorded numbers of male and female white sharks, with highly significant interannual trends. This data suggests that water temperature and climatic phenomena influence the abundance of white sharks at this coastal site. In this study, more females were seen in Gansbaai overall in warmer water/positive MEI years. Conversely, the opposite trend was observed for males. In cool water years (2010 to 2011) sightings of male sharks were significantly higher than in previous years. The influence of environmental factors on the physiology of sharks in terms of their size and sex is discussed. The findings of this study could contribute to bather safety programmes because the incorporation of environmental parameters into predictive models may help identify times and localities of higher risk to bathers and help mitigate human-white shark interactions.
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    Evaluating the impact of handling and logger attachment on foraging parameters and physiology in southern rockhopper penguins
    (Public Library of Science, 2012) Ludynia, Katrin; Dehnhard, Nina; Poisbleau, Maud; Demongin, Laurent; Masello, Juan F; Quillfeldt, Petra
    Logger technology has revolutionised our knowledge of the behaviour and physiology of free-living animals but handling and logger attachments may have negative effects on the behaviour of the animals and their welfare. We studied southern rockhopper penguin ( Eudyptes chrysocome ) females during the guard stage in three consecutive breeding seasons (2008/09−2010/11) to evaluate the effects of handling and logger attachment on foraging trip duration, dive behaviour and physiological parameters. Smaller dive loggers (TDRs) were used in 2010/11 for comparison to larger GPS data loggers used in all three seasons and we included two categories of control birds: handled controls and PIT control birds that were previously marked with passive integrative transponders (PITs), but which had not been handled during this study. Increased foraging trip duration was only observed in GPS birds during 2010/11, the breeding season in which we also found GPS birds foraging further away from the colony and travelling longer distances. Compared to previous breeding seasons, 2010/11 may have been a period with less favourable environmental conditions, which would enhance the impact of logger attachments. A comparison between GPS and TDR birds showed a significant difference in dive depth frequencies with birds carrying larger GPS data loggers diving shallower. Mean and maximum dive depths were similar between GPS and TDR birds. We measured little impact of logger attachments on physiological parameters (corticosterone, protein, triglyceride levels and leucocyte counts). Overall, handling and short-term logger attachments (1-3 days) showed limited impact on the behaviour and physiology of the birds but care must be taken with the size of data loggers on diving seabirds. Increased drag may alter their diving behaviour substantially, thus constraining them in their ability to catch prey. Results obtained in this study indicate that data recorded may also not represent their normal dive behaviour.
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    Good days, bad days: wind as a driver of foraging success in a flightless seabird, the southern Rockhopper Penguin
    (Public Library of Science, 2013) Dehnhard, Nina; Ludynia, Katrin; Poisbleau, Maud; Demongin, Laurent; Quillfeldt, Petra
    Due to their restricted foraging range, flightless seabirds are ideal models to study the short-term variability in foraging success in response to environmentally driven food availability. Wind can be a driver of upwelling and food abundance in marine ecosystems such as the Southern Ocean, where wind regime changes due to global warming may have important ecological consequences. Southern rockhopper penguins ( Eudyptes chrysocome ) have undergone a dramatic population decline in the past decades, potentially due to changing environmental conditions. We used a weighbridge system to record daily foraging mass gain (the difference in mean mass of adults leaving the colony in the morning and returning to the colony in the evening) of adult penguins during the chick rearing in two breeding seasons. We related the day-to-day variability in foraging mass gain to ocean wind conditions (wind direction and wind speed) and tested for a relationship between wind speed and sea surface temperature anomaly (SSTA). Foraging mass gain was highly variable among days, but did not differ between breeding seasons, chick rearing stages (guard and crèche) and sexes. It was strongly correlated between males and females, indicating synchronous changes among days. There was a significant interaction of wind direction and wind speed on daily foraging mass gain. Foraging mass gain was highest under moderate to strong winds from westerly directions and under weak winds from easterly directions, while decreasing under stronger easterly winds and storm conditions. Ocean wind speed showed a negative correlation with daily SSTA, suggesting that winds particularly from westerly directions might enhance upwelling and consequently the prey availability in the penguins' foraging areas. Our data emphasize the importance of small-scale, wind-induced patterns in prey availability on foraging success, a widely neglected aspect in seabird foraging studies, which might become more important with increasing changes in climatic variability.
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    Hand-rearing, release and survival of african penguin chicks abandoned before independence by moulting parents
    (Public Library of Science, 2014) Sherley, Richard B; Waller, Lauren J; Strauss, Venessa; Geldenhuys, Deon; Underhill, Les G; Parsons, Nola J
    The African penguin Spheniscus demersus has an ‘Endangered’ conservation status and a decreasing population. Following abandonment, 841 African penguin chicks in 2006 and 481 in 2007 were admitted to SANCCOB (Southern African Foundation for the Conservation of Coastal Birds) for hand-rearing from colonies in the Western Cape, South Africa, after large numbers of breeding adults commenced moult with chicks still in the nest. Of those admitted, 91% and 73% respectively were released into the wild. There were veterinary concerns about avian malaria, airsacculitis and pneumonia, feather-loss and pododermatitis (bumblefoot). Post-release juvenile (0.32, s.e. = 0.08) and adult (0.76, s.e. = 0.10) survival rates were similar to African penguin chicks reared after oil spills and to recent survival rates recorded for naturally-reared birds. By December 2012, 12 birds had bred, six at their colony of origin, and the apparent recruitment rate was 0.11 (s.e. = 0.03). Hand-rearing of abandoned penguin chicks is recommended as a conservation tool to limit mortality and to bolster the population at specific colonies. The feasibility of conservation translocations for the creation of new colonies for this species using hand-reared chicks warrants investigation. Any such programme would be predicated on adequate disease surveillance programmes established to minimise the risk of disease introduction to wild birds.
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    How to create a species distribution map in the Virtual Museum
    (2014-07-02) Loftie-Eaton, Megan
    A slide show explaining how to use the data held in the Animal Demography Unit's Virtual Museum to create a distribution map for any of the species for which there are data in the museum. These slides walk students, academics and citizen scientists engaged in animal demography through the process of using the software tool LepiMAP to improve animal demography information in South Africa.
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    How to create a species list from the Virtual Museum projects
    (2014-07-02) Loftie-Eaton, Megan
    A this resource is a PowerPoint slide presentation showing how to create a species list for any area, as defined by the user, based on data held in the Animal Demography Unit's Virtual Museum. This resource covers the practical stepes needed to create a species list, and includes tutorials on the software and data tools used in this process. This resource is useful for citizen scientists interested in contributing to animal demography in South Africa.
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    Large Terrestrial Birds
    (2014-09-12) Hofmeyr, Sally; Neary, Tim
    In this radio broadcast, Sally Hofmeyr discusses the Coordinated Aviafaunal Roadcount programme, which maps populations of large terrestrial birds in agricultural areas. This programme supplies demographic data that can be used to inform conservation efforts and stimulate further research into declining or endangered populations. Sally discusses are methodological considerations required in order to make the information gathered from the approximately 800 citizen scientists are involved in the projects most useful, as well as the effect of farming on large terrestrial bird demography. Image provided courtesy of Brian Snelson under a Creative Commons Attribution 2.0 Generic license.
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    Overlap in utilization of juvenile Cape Horse Mackerel by Cape Fur Seals and the purse-seine fishery in Namibia
    (Southern African Wildlife Management Association, 2007) Mecenero, Silvia; Underhill, Les G; Krakstad, Jens-Otto; Kirkman, Stephen P; Roux, Jean-Paul
    The Cape horse mackerel Trachurus trachurus capensisis one of Namibia's most valuable fish stocks, and an important component to the diet of Cape fur seals, Arctocephalus pusillus pusillus, off northern Namibia. The level of overlap in the utilization of this resource between seals and the purse-seine fishery was investigated using two overlap indices. For high overlap measures, seals and the purse-seine fishery utilized age-2 horse mackerel. For low overlap measures, seals mainly consumed age-0 fish whereas the fishery caught age-2 fish. Both indices were adjusted by the proportion of horse mackerel in the seal diet, with the assumption that the proportion consumed by the seals reflects the abundance of horse mackerel in the coastal waters of Cape Cross, Namibia. Both unadjusted and adjusted overlap indices showed that overlap between seals and the fishery in their utilization of juvenile horse mackerel was high only at times when horse mackerel abundance was high, and low when abundance was small. Confidence intervals and significance testing were included. Overall, there was little overlap between seals and the purse-seine fishery. This study provides important information that should be taken into account in the management of the horse mackerel resource.
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    Penguin Watch
    (2011) Department of Zoology
    This website is designed to contain up-to-date news and information about the issues facing penguins in their natural habitat, specifically the African Penguin. Penguin Watch is designed to disseminate up to date information about the issues facing penguins in the wild, especially the African penguin. It is a resource aimed firstly at the global African Penguin community from individuals working to conserve the species within its native range of South Africa and Namibia to everyone worldwide who is concerned about the welfare of penguins in the wild.
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    Penguins
    (2014-09-12) Sherley, Richard; Neary, Tim
    In this radio broadcast, Richard Sherley discusses penguin tracking in South Africa, and how tracking mechanisms support research on feeding, breeding and migration patterns. Also discussed are how the miniturisation of tracking devices has dramatically improved information gathering, especially for tracking young birds and breeding populations. This information feeds into the Departmental of Environmental Affairs and the Department of Agriculture, Forestry and Fisheries for national planning purposes. Image provided courtesy of Namastesa under a Creative Commons Attribution 1.0 Generic license.