21 research outputs found
Food Habits of a Pelomedusid Turtle, Pelomedusa subrufa, in Tropical Africa (Nigeria): The Effects of Sex, Body Size, Season, and Site RID F-2663-2011
No full textPhotographic Identification Method (PIM) using natural body marks: a simple tool to make a long story short
No full textA simple tool to make a long story short: Photographic Identification Method (PIM) using natural body marks
No full textPhotographic identification method (PIM) using natural body marks: A simple tool to make a long story short
No full textIndividual marking allows researchers to collect important data using Mark-recapture method. Photographic Identification Method (PIM) has obtained favorable opinions, being effective and less intrusive with respect to traditional marking procedures. Here, we developed and tested the efficacy of a software-aided PIM based on different characteristics, which act as natural marks. Target species were the northern spectacled salamander (Salamandrina perspicillata, Amphibia: Urodela) and the stag beetle (Lucanus cervus, Coleoptera: Lucanidae). We considered as natural mark the ventral pattern of S. perspicillata and, for the first time in L. cervus, the presence/number of small denticles on male mandibles. We selected 4 independent characteristics, each one with several states, for each species. We asked participants, with different degree of familiarity with the species, to identify recaptured individuals through manual PIM. To assess the advantages of the software, we compared the time spent by experts of the species to identify an individual through manual PIM and software-aided PIM. We further compared our semi-automated method with a fully automated one. The software efficiency was calculated by increasing the number of characteristics used to filter individuals from the database (from 1 to 4). The chosen characteristics proved their reliability for individual identification and can be used as natural marks. The proposed software-aided PIM shorten the identification time, does not led to mismatching errors and proved its efficacy regardless of the taxa/characteristic used. Thus, this tool can be consider a more practical alternative to conventional marking techniques, in particular for sensitive and threatened species that need quick and effective monitoring programs carried out with non-invasive samplin
Research NoteEstimation of browse biomass of Ficus thonningii, an indigenous multipurpose fodder tree in northern Ethiopia
No full textFicus thonningii is a multipurpose browse tree in northern Ethiopia. Despite its importance, techniques for quantifying its browsable biomass have not been developed. To develop best-estimation equations, the dendrometric parameters total height (H), crown height (CH), crown diameter (CD), diameter at stump height (DSH), diameter at breast height (DBH), crown depth (CDp), crown area (CA) and crown volume (CV) were measured from 12 sampled trees comprising three age ranges. Leaves and edible twigs of the sampled trees were clipped, oven dried, weighed and recorded as dry weight (DW). Regression analysis and a multicollinearity test were employed to remove non-significant predictors of DW. Results showed that only CV, CA, CD, CDp and DSH showed a strong correlation with DW. There was high collinearity between CD and CA, CD and CV, and CA and CV. However, CV and DSH had a higher correlation with DW than their counterparts, which suggested their use in the model. Therefore, the best allometric equation was: DW = 0.8470*CV − 0.2202*DSH − 1.5315 (R2 = 0.99). This equation estimated that F. thonningii produces a very high amount of browsable biomass at all ages compared to common fodder species. The model can be used to plan the browsing rate and understand the ecological role of the species.Keywords: allometry, indigenous fodder trees, TigrayAfrican Journal of Range & Forage Science 2012, 29(1): 25–3
Living With Hyraxes: Biogeography and Comparative Ecology of West African Fornasinius Beetles
No full textAmong the flower beetles (Scarabaeidae, Cetoniinae), the Goliathini comprise several genera of medium- and large-sized beetles widely distributed in sub-Saharan Africa. In this tribe, the genus Fornasinius Bertoloni, 1853, includes two species found in West Africa: F. higginsi (Westwood) and F. klingbeili Zöller, Fiebig,and Schulze. In this study, we present new data on the comparative ecology and biogeography of these two species, including sex ratio, population structure by size, monthly activity patterns and habitat features at two different spatial scales. These observations were conducted, mostly opportunistically, over a 20-year period in Cote d'Ivoire, Ghana and Togo. Both species exhibited similar overall population structure and morphometrics. They were characterised by a male-skewed adult sex ratio (with possible bias), male-larger sexual size dimorphism and consistent population structure by size; the two species are seemingly parapatric (with the potential contact zone being separated in eastern Ghana by the Volta River and Volta Lake). Both are primarily found in the vicinity of trees that contained middens of hyraxes, such as Dendrohyrax dorsalis (F. higginsi), Dendrohyrax interfluvialis (F. klingbeili) and Procavia capensis (F. klingbeili). F. higginsi has been primarily observed in forest habitat, while F. klingbeili was found in both forests and Guinea savannahs. Occurrence sites of F. higginsi were predominantly characterised by higher tree cover, less bare areas and built-up zones. Although these beetles may be locally abundant within hyrax middens, they typically occur in only a relatively small number of sites within their preferred habitat. Monthly activity patterns differed between the two species. Although adults of both species were observed throughout the year, sightings of F. higginsi were more common during the wet season, whereas F. klingbeili sightings were more frequent in the dry season. The observed differences in monthly activity patterns between these ecologically and morphologically similar species may help to minimise interspecific competition in potential—yet unknown—sites of syntopy. Although some Fornasinius populations might be locally threatened by deforestation or overhunting of hyraxes, the careful management of hyrax populations should adequately ensure the conservation of these two beetle species
Generalist, selective or ‘mixed’ foragers? Feeding strategies of two tropical toads across suburban habitats
No full textSuitable habitats for anurans can be found in the ever-growing tropical urban environments but anurans' adaptations to urban conditions, including their trophic ecology remain largely unknown. We studied the food habits of two generalist, widespread West African Sclerophrys adult toads: African common (Sclerophrys regularis) and Hallowell's toad (Sclerophrys maculata). The first was studied in Lomé (Togo), Cotonou (Benin) and Ikeja (Nigeria), and the second in Port Harcourt and Ikeja (both Nigeria); the latter city represents the only studied sympatric occurrence. Mean dietary overlap between population pairs was relatively high, and diet composition of the two species when sympatric did not differ significantly. Food niche width was significantly positively correlated with local rainfall in both species, and diet composition changed significantly between the dry and wet seasons. Diversity metrics revealed that females had a more diversified diet, with higher evenness and lower dominance index values than males. The diet of both species was not correlated to prey type availability, in both the wet and dry season. Both toad species targeted specific food items rather than opportunistically consume prey as observed in most anurans which may be a response to high anuran diversity typically found in the tropics or an adjustment to urban habitats
Tortoise ecology in the West African savannah: multi-scale habitat selection and activity patterns of a threatened giant species, and its ecological relationships with a smaller-sized species
No full textThe status of most vertebrates in the African Sahel is not well known. Among these, the African spurred tortoise (Centrochelys sulcata), a charismatic but also one of most threatened vertebrates in the Sahel, is still poorly studied. We investigated the status of this species, its potential distribution, habitat selection (at multiple spatial scales) and activity patterns in Mali and Burkina Faso, two countries within the tortoise’ known range. We employed field surveys and villager interviews in 23 sites to determine the presence of the species. In these surveys and interviews, we also included the Western hinge-back tortoise (Kinixys nogueyi), a sympatric chelonian also suspected of being in decline. Age-stratified interviews revealed that C. sulcata is widespread in Mali, but since there was a statistically higher frequency of older respondents that remembered C. sulcata present around their village, compared to younger respondents, it is likely that the species has been declining throughout the study area. We encountered a total 77 C. sulcata and 20 K. nogueyi individuals during our field surveys. Most C. sulcata were found along areas of intermittent streams and stabilised dunes, known locally as koris. Centrochelys sulcata individuals were more likely to occur in sandy dry savannah areas that were further away from human settlements, and which contained inland waters or were closer to these. Kinixys nogueyi exhibited instead an allopatric distribution, with no ascertained sympatry with C. sulcata at the microhabitat scale. Cattle incidence was negatively correlated with the presence by C. sulcata. Our results also indicate that aboveground activity of C. sulcata is limited to the wet season and has a clearly bimodal diel activity cycle, with most sightings in the early morning hours. We provide suggestions on how best to survey this species in the wild while advancing new information on its distribution and biology. These data are invaluable to assess the status of this species as part of future conservation planning efforts
The density and diversity of birds on farmland in West Africa
No full textThe area of land farmed in Africa is predicted to double by the year 2050 yet very few African studies have investigated the impact of different farming intensities and regimes on bird communities. This study examined avian species richness and diversity along with the densities of some common bird species on the Jos Plateau, Nigeria, in relation to habitat features on farmland over a gradient of differing farming intensities. The study area exhibited a variety of different levels of farming which differed in the habitat available for birds. Birds normally associated with savanna woodland were more associated with less intensive farming, and open-country birds were more associated with more intensive sites, with more species of birds observed where farming was less intensive. Common species of birds using cultivated land associated with different crops, with acha and millet being the most commonly used. Tree density was the most important variable predicting avian species richness and diversity, with medium tree density predicting the highest species richness and diversity. The densities of two common farmland birds were predicted best by tree density, but varied in their responses to the habitat variables, with common bulbul, a savanna generalist, associating more with less intensive, wooded areas and red-cheeked cordon-bleu, an open savanna granivore, associating with medium intensity, more open farmland. Whinchats were common in open, intensively farmed areas with few trees and good herbaceous vegetation cover. The data presented indicates the importance of retaining natural features of savanna habitat in farmland in order to maintain high avian diversity on farmland. More detailed studies are needed in order to determine the mechanisms involved in the associations observed and collaborations between ecologists and social scientists will be necessary to develop effective policies to limit the impact of the intensification of agriculture in Africa on avian biodiversity
Ecology of the bushmeat trade in west and central Africa
No full textThe bushmeat trade in West and Central Africa embraces a broad range of ecological, economic, and conservation issues. To date, most studies have focused on the economic and conservation aspects of the bushmeat trade, with less emphasis on the ecological implications of wildlife extraction. Here, we analysed available literature on the bushmeat trade in 5 countries in west and central Africa exploring ecological traits such as niche width breadth and trophic position of the species involved, and habitats impacted. We also examine temporal changes over a 40-year period. Our results confirm that mammals dominated the trade in all studied areas and time periods, in terms of (i) number of species, (ii) number of traded individuals, and (iii) overall biomass. Herbivores were the most common trophic animal guild traded. Forest-specialists were the most abundant in the trade, and in riverine habitats reptile biomass almost as important as mammals. Overall, the most traded species and individuals were non-threatened according to the IUCN Red List. Our temporal analyses indicated that more habitat generalist and water-linked species were traded during 1971 - 2000, but forest dependent taxa predominated during the following decade (2001 - 2010). Additionally, the number of individuals of large-bodied herbivores rose relative to small and medium-sized ones, whereas traded biomass over time increased: (a) in the consumption of super-predators; (b) of large-bodied herbivores, but (c) a significant decrease in consumed biomass of medium and small-bodied herbivores. We suggest that the observed trends may suggest an imminent reduction of large-bodied herbivores and, as a cascade effect, also of super-predators in African moist forests
