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The blenny Alticus monochrus Bleeker inhabits exposed rocky shores of Mauritius and other islands of the southwestern Indian Ocean. A. monochrus is an amphibious species and remains almost exclusively above the water line, migrating vertically with the tide while feeding on a thin algal layer scraped from the moist substratum. Spawning activity peaks were observed at Pointe aux Caves, Mauritius, during the full moon periods of October and November and two corresponding oocyte size cohorts were identified in excised ovaries collected over the breeding season. Larvae hatched in approximately four days and otolith ring counts showed that settlement occurred 28 days later. Initial post-settlement growth was rapid but growth rate in length declined linearly beyond 50 mm. Length frequency time series showed that the 1991 cohort reproduced at age one, but that none of this cohort survived into the 1993 breeding season, consistent with annual semelparity. By contrast, other expected correlates of semelparity were not observed: fecundity in A. monochrus was lower than in some iteroparous blennies, and there was no obvious physical deterioration of adults following the breeding season, despite their high mortality rate.
Ungulates can reduce the quantity of food available for other herbivores in general or reduce the available cover for small mammals in particular. On the other hand, browsing and grazing may facilitate foraging by other mammals if the quality and palatability of young re-sprouting tissue is high. An exclosure experiment was set up in Mokolodi Nature Reserve, Botswana, to study ecological effects of large herbivores on the small mammal community. Specifically, we attempted to answer the following questions: 1) are population sizes and community composition of small rodents affected by the exclusion of large herbivores?; 2) if so, what changes in the environment caused by the exclusion of large herbivores are related to changes in small mammal populations?; 3) in what way do such changes in the environment affect small mammals? The populations were significantly larger in the exclosures than in the control areas. A higher number of species was also found in the exclosures. It seems that the smaller populations of small mammals in areas with large herbivores are a result of a reduction in vegetation cover. In general, the exclosures had a higher grass cover than their paired controls. This same relation also held for percentage cover of litter and dead grass.
This paper examines the home ranges and seasonal movements of eight GPS-collared elephants (two females and six males) in the northwestern Kunene region of Namibia. Minimum convex polygon (MCP) and the fixed kernel density estimation (FKDE) methods were used to analyse home ranges. The collared elephants showed defined home and seasonal ranges. In the eastern section of the research area, the elephants generally had smaller home ranges that were at their least during the hot and cold dry seasons, expanding during the wet season. In the western areas, the elephants moved between the Hoanib and Hoarusib Rivers in response to available vegetation that did not necessarily correspond to rainfall. The length of movement of collared elephants varied from 54.5 to 473 km in the eastern section of the research area to between 251 to 625 km in the west, over periods of up to five months.
The ranging behaviour and habitat occupancy by three elephant groups (cow herd, bulls, and an orphan group) were studied over a two-year period in a small, fenced reserve. No summer dispersal was observed. Distinct seasonal home ranges were exhibited for all groups, with the summer (wet season) ranges being smaller than the winter (dry season) ranges. Home range size was much smaller than in other locations. The dam and surrounding high density of patches of vegetation of high nutritional quality are thought to be the reasons. Habitat selection was strongly evident with all of the elephant groups selecting River Line habitats in the dry season. In the wet season the cow herd and orphans selected the more open Acacia habitats and the bulls exhibited no significant habitat preference.
Graemontia viridiceps n.sp., is described from the southwestern part of South Africa. This is the seventh species of the genus and the second species for which male genitalia are described and illustrated. A key is given to all species of Graemontia. This genus is important for studying phylogenetic relationships within the family Triaenonychidae because, although traditionally placed in the tribe Triaenonychini, it shares some derived similarities with members of the tribe Triaenobunini, which is absent from Africa. If, as suggested, Graemontia is the sister group of the Triaenobunini, it provides corroboration for the biogeographical sequence (South Africa (southern South America, Australia, New Zealand)).
Our study examined the short-term response of grassland invertebrate communities to fire in the South African Drakensberg, in relation to distance from the edge of a burn. We aimed to establish which species survive fire and the dynamics of the post-fire recolonization process, and thereby contribute to establishing the ideal area of a prescribed burn for invertebrate conservation. Four transects were sampled two and 12 weeks after burning. Along each transect one unburnt control and four burnt sites were quantitatively sampled. Richness, abundance and diversity were calculated for each site and canonical correspondence analysis was applied to transect and morphospecies counts to determine the impact of distance from the edge of the burn on community structure. Distance from burn edge affected invertebrate richness and abundance, especially for flying insects. Burning appeared to minimally impact on wingless invertebrates, suggesting they tolerated fire by finding refuge. Invertebrate community structure changed with increasing distance from burn edge two weeks, but not 12 weeks post-burn. A distance of 280 m from burn edge appears to allow sufficient recolonization to maintain invertebrate diversity. Taxa found in the unburnt control and site closest to the edge in burnt grassland may be fire sensitive and require further study.
Monthly collections of the African yellow bat, Scotophilus dinganii, were made in the Kruger National Park. Examination of serially sectioned reproductive tracts of females showed that the African yellow bat is a monoestrous species and that insemination, ovulation and fertilization took place during mid to late autumn (April to May). Early embryonic development of normally two embryos (one in each uterine horn) was retarded and implantation delayed until mid-winter (July), when the blastocysts implanted.
We examined the putative defence system of a king cricket, Onosandrus sp., in particular the efficacy of the noxious faeces against two types of predator: a lizard, the skink Mabuya striata (an active, diurnal forager), and the toad Bufo gutturalis (a nocturnal, ambush predator). Contrary to our predictions, the faeces did not act as a deterrent to either predator. Tongue-flick trials with cotton scent applicators indicated that the skinks showed a heightened predatory response to king cricket faeces over king cricket integument, field cricket integument and an odourless control. We suggest that ‘primary’ defence mechanisms, such as nocturnal behaviour, cryptic colouration and immobility, are more effective than ‘secondary’ defence mechanisms, such as stridulation, kicking and defecation. Given that the noxious faeces already have a demonstrated role in inter- and intrasexual communication, we suggest that the assumed defensive role of the faeces is minor or an epiphenomenon.
In this study we investigated intraspecific prey choice of illegal bushmeat hunters outside the Serengeti National Park, Tanzania. During the study 151 animals belonging to 12 species were reported killed. The majority, 76%, of prey species were migratory herbivores. Night hunting with dogs was the most common hunting method for medium-sized prey (biomass ≤40 kg), while the majority of the large herbivores were killed by snares. When actively stalking, hunters killed more males of most of the species recorded, as well as more immatures than adults. Passive hunting also generally had a male-bias. This suggests that the male-bias in kills probably is more a result of behavioural factors among the animals, combined with poor hunting technology, than deliberate choice of the hunters.
The Kariega Estuary channel was sampled using an otter trawl and the demersal fish catch analysed using the PRIMER statistical package. A biological-environmental (BIOENV) analysis was undertaken using the catch per unit effort ichthyofaunal data from the spring/summer period of 1996/97 and concurrent water temperature, salinity and turbidity data. No strong correlations between the ichthyofauna and recorded physicochemical parameters were documented, although temperature did show a weak correlation to demersal fish distributions. A second sampling programme undertaken in 2004 was specifically designed to test the influence of sedimentary characteristics on the distribution patterns of the dominant demersal species. Analyses showed that sediment size composition and organic content was strongly correlated (r = 0.70) to the distribution of the soles Solea bleekeri and Heteromycteris capensis, as well as the goby Glossogobius callidus. S. bleekeri and G. callidus showed a preference for the muddier middle and upper reaches of the Kariega Estuary channel, whereas H. capensis and Psammogobius knysnaensis were more abundant in the sandier lower reaches and mouth region of the estuary. The exact reasons for these preferences are unknown but are likely to be related to preferred prey availability, foraging success and predator avoidance in the different types of sediment. Other species caught in the otter trawl were not significantly correlated to sedimentary characteristics.
The aim of this study was to provide information on sexual size dimorphism (SSD) in Pseudocordylus nebulosus and to discuss the observed variation in SSD among montane cordylids. Data for P. nebulosus were recorded in the Landdroskop area in the Hottentots Holland Mountains, South Africa. The total sample of 87 lizards, consisted of 26 adult males, 49 adult females and 12 juveniles. Size at sexual maturity was determined as 60 mm snout–vent length (SVL) for both sexes. Generation glands were found to be present in males only and the number present was significantly correlated to body size. Both adult males and adult females possessed active femoral glands, but males had significantly more than females. Females were found to reach larger body sizes than males, but adult males had relatively larger heads than females. No significant difference in scar frequency was found between male and female samples. The female-biased SSD in P. nebulosus and its sister species, P. capensis, is tentatively ascribed to fecundity selection for offspring to be large at birth in order to survive in a predictable unfavourable environment at high altitudes. Variation in SSD among montane cordylids is discussed and the need for more comprehensive data is highlighted.
Oukaïmeden Plateau is a herpetologically rich locality in the High Atlas (Morocco) where four lizard species coexist in strict sympatry: three lacertids (Lacerta perspicillata chabanaudi, L. andreanszkyi and Podarcis vaucheri – formerly P. hispanica vaucheri) and one gekkonid (Quedenfeldtia trachyblepharus). The diet composition of this lizard community during the early spring was analysed based on 132 faecal pellets which could be individually assigned to a species and a size and sex class. Quedenfeldtia trachyblepharus had the highest prey number and the most specialized prey composition based mainly on small Coleoptera (62.5%) which were consumed in aggregates. All three lacertids displayed higher but similar levels of populational prey diversity. Lacerta p. chabanaudi mainly fed on flying insects, whereas L. andreanszkyi and P. vaucheri had diets based on terrestrial prey. Larger lizards ate larger prey at both inter- and intraspecific levels. Species overlap was medium-high (48–84%). Within species, P. vaucheri showed moderate segregation between males and females (74% overlap) whereas the other species did not (>94%). Pseudocommunity analyses revealed community structure based on segregation due to prey not consumed (species) and to the restriction of niche breadth (classes). The influences of species interactions on habitat use, restrictions in trophic availability and evolutionary history as determinant factors are discussed.
Macrofauna communities colonizing intertidal mussel beds were sampled at seven sites between Swakopmund (Namibia) and Salt Rock (KwaZulu-Natal). Mean mussel cover, length, biomass and bed depth were all low in the southeast (former Transkei). Faunal abundance and biomass were minimal along the south coast, increasing up both west and east coasts. Species diversity and richness showed the reverse trends, peaking at south coast sites and dropping off to the west and east. Multivariate analysis grouped the faunal communities into four distinct clusters, corresponding to the recognized Namib, Namaqua, Agulhas and Natal biogeographical provinces. The low mussel biomass and cover in the Eastern Cape can be attributed to intense human exploitation, but the low faunal abundance and biomass along the south coast was unexpected, as was the negative correlation between faunal abundance and diversity. Over recent decades intense exploitation has resulted in marked declines in mussel cover along the east coast, while the M. galloprovincialis invasion has resulted in dramatic increases in mussel cover to the west. The results given here indicate how these changes might have affected the wider intertidal communities in these regions.
Commerson's Dolphins Cephalorhynchus commersonii are distributed in two disjunct populations, one around southern South America and the other around the sub-Antarctic Kerguelen Islands. These populations have been shown to be morphologically and genetically distinct and movement between the two populations is unlikely. We report on the sighting of a single specimen over the South African continental shelf on 13 November 2004. To our knowledge this is the first record of this species in South African waters and such a vast distance (over 4000 km) from the known distribution limits.
Optimal foraging in caracals has never been substantiated. However, several authors have found that these predators select foraging paths to minimize distances between areas of high prey availability. The foraging pattern used by a predator relative to a common prey animal can give an insight into the optimality of hunting behaviour. Foraging behaviour in caracals relative to the dispersion of Brants's whistling rat colonies was investigated in the southern Kalahari. We show that foraging paths used by caracal during the hot season increase the likelihood of encountering colonies, suggesting that optimal foraging occurs, but that in the cold season foraging appears to be random.
In estimates of population genetic diversity based on allozyme heterozygosity, some enzymes are regularly more variable than others. Evolutionary theory suggests that functionally less important molecules, or parts of molecules, evolve more rapidly than more important ones; the latter enzymes should then theoretically be less polymorphic. In this paper I review most of the published papers on allozyme variability in southern African mammals, and correlate heterozygosity values with enzyme quaternary structure and the perceived importance of enzymes. Results provide support for the hypothesis of a linkage between enzyme quaternary structure and diversity. No association between enzyme function and heterogeneity was, however, observed.
We successfully artificially cultured and bred Bulinus nyassanus, endemic to Lake Malawi and an intermediate host of Schistosoma haematobium. The laboratory culture of this snail species is essential in relation to further experiments on the feasibility of using facultative snail-eating fishes as biological control agents for intermediate hosts of Schistosoma haematobium in the open waters of Lake Malawi. The artificial culture of B. nyassanus will also enable us to collect important life history information including fecundity, egg development, hatchability, survival at varying temperatures and growth rates.
Three vagrant Subantarctic fur seals, Arctocephalus tropicalis, were seen amongst a colony of Antarctic fur seals, A. gazella, at the isolated subantarctic island, Bouvetøya. Possible sources of the vagrants are populations at either Gough Island or the Prince Edward Islands Archipelago.
The reproductive cycle of the Namaqua sand lizard, Pedioplanis namaquensis, from southern Africa is described from histological examination of gonadal material from museum specimens. Males followed a seasonal testicular cycle in which sperm was produced in January–March and September–December. Testes in regression were present in March and May. Females with enlarged ovarian follicles (>4 mm length) or oviductal eggs were collected between November and February. Clutch size for 14 females was 3.8 ± 0.97 S.D. eggs, range 3–5. Histological evidence is presented that two clutches may be produced in the same reproductive season.
Preliminary results based on two satellite-tracked adult leopards in the arid, open savanna of the southern Kalahari indicated that most movement occurred at night, with some movement in the daytime to seek shade.
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