Erasmus H. Owusu

Distribution and abundance of forest birds in Ghana

Ntiamoa-Baidu, Y., Owusu, E.H., Asamoah, S. & Owusu-Boateng, K. 2000. Distribution and abundance of forest birds in Ghana. Ostrich 71 (1 & 2): 262–268. Forest reserves within the Ghanaian rain forest have been classified into categories (Condition I-VI) on the basis of their botanical importance and status of the vegetation. We present data on the distribution and abundance of avifauna of 28 Condition II and III forest reserves in southern Ghana based on line transect counts and mist-net captures. A total of 227 species were recorded for all the sites; species records for individual sites ranged from 78–119. The dominant groups in the overall survey were Muscicapidae (represented by 40 species), Pcynonotidae (21) and Cuculidae (12). The most abundant bird species in the Ghanaian forests were Yellow-whiskered Greenbul, Green Hylia, Green Pigeon and Olive Sunbird. Species encounter rates ranged from 16.7 to 50.7 species per km with individual bird encounter rates of 27.9 to 172.0 birds per km. Capture rates in mist-nets ranged from 1.2 to 3.9 birds per 100 metre net-hr (mnh). A total of 183 species were recorded in Condition II forest as compared with 167 in Condition III forests. The effects of forest condition and vegetation types on the total number of species recorded were, however, not statistically significant. The Similarity Index for bird communities within Condition II and III forests was 0.72. Bird species composition in the two forest types also differed: e.g., seven primary forest species, as well as 40% of the species associated with primary and matured secondary forest which were recorded in Condition II forests, were absent from Condition III forests. Bird communities of Moist Evergreen, Upland Evergreen and Moist semi-Deciduous were more similar than communities in the Wet Evergreen forest type. The implication of the results for conservation of the Ghanas forests is discussed.

Insect Diversity of the Muni-Pomadze Ramsar Site: An Important Site for Biodiversity Conservation in Ghana

An inventory of species diversity of insects of the Muni-Pomadze Ramsar site, with special reference to species of conservation concern, was carried out as part of an evaluation of changes in the ecological character of the site, twenty years after designation. Samples were taken from two protected areas within the Ramsar site, in the wet (July), dry (January), and intermediate (June) seasons. Community diversity was characterized in terms of number of species accumulated, species richness, Shannon-Weiner indices of diversity, Pielou’s evenness, and Bray-Curtis similarity. A total of 134 families from 19 insect orders were recorded during the entire study period. Yenku Block A recorded the highest species richness (98) and the highest diversity index (14.97), corroborated by the highest Margalef index of 3.82 with a relatively even distribution of species (0.834) during the intermediate season, and recorded the lowest diversity (6.957) and species richness (41) during the dry season. On the whole, the Muni-Pomadzi Ramsar site showed a high diversity of insect species. The presence of species such as Junonia oenone and Papilio demodocus which are specialized in degraded habitats at Yenku Block A in large numbers is a clear indication of degradation of the forest, but the presence of forest species such as Salamis anacardii and Euphaedra crokeri is an indication that some parts of this reserve are still in good shape. A comparison of the butterfly species recorded with findings in a 1997 survey showed a marked increase in numbers from 75 to 130; this may be attributed to the habitat changes that have taken place at the site offering more diverse habitat types.

Natural resource and biodiversity conservation in Ghana: the use of livelihoods support activities to achieve conservation objectives

Threats to biodiversity from increasing populations and poverty has resulted in the use of investments in livelihoods support activities as economic incentives for natural resource and biodiversity conservation in Ghana. Examples of such activities include woodlots, beekeeping, snail breeding, and mushroom farming. In order to assess and evaluate the effectiveness of these activities as tools for conservation planning and resource allocation, it is essential to document their use for environmental conservation. This study presents a consolidated documentation of the use of livelihoods support activities for natural resource and biodiversity conservation in Ghana. This documentation includes the specific activities, the number of such interventions since they were first used until 2010, their geographical distribution in the country, and implementation strategies. The methods used in this study include thematic and chronological analysis of conservation project reports, interviews with project managers, collection of primary data on the specific activities, and focus group discussions with participants of livelihoods support activities in rural Ghana. Seventy-one different types of livelihoods support activities belonging to eight categories have been employed for conservation in Ghana since 1993. The majority of these activities were based on non-timber forest products. A chronological trend analysis indicated an increasing tendency to make livelihoods support activities part of conservation projects in Ghana. These activities have become very relevant to Ghana’s current collaborative policy because they are used to buy-in local support for natural resource and biodiversity conservation.

Seasonal changes in small mammal assemblage in Kogyae Strict Nature Reserve, Ghana

The small mammal community at Kogyae Strict Nature Reserve (KSNR) in the Ashanti Region of Ghana were studied in two habitats during the wet and dry seasons to investigate seasonal changes in species richness, abundance, composition and diversity. Ninety-six individuals belonging to nine species were recorded in 720 trap-nights, giving overall trap-success of 13.33%. Species richness (Sr), trap-success (Ts) and relative abundance (Ra) were higher (Sr = 6 species; Ts = 23.1%; Ra = 86.5%) in wooded grassland than forest (Ra = 4 species; Ts = 3.6%; Ra = 13.5%). However, species diversity was higher (Shannon-Wiener index Hʹ = 1.157) in forest than in wooded grassland (Hʹ = 1.089). Mastomys erythroleucus dominated in wooded grassland (68%) and Hylomyscus alleni in forest (53.8%). The species composition was unique for both habitats, with Mus musculoides being the only species common to both habitats. Seasonal changes in community assemblages were evident in both habitats, with species richness, diversity and abundance of the dominant species being highest in the wet seasons. Sex-ratio was unity in both habitats, and remained fairly constant throughout the rainy and dry seasons. Breeding activity was evident all-year-round for most species, but peaked in the rainy season. Our findings are consistent with that of other studies in Ghana and elsewhere in the African subregion, highlighting the importance of rainfall to the ecology of tropical small mammals.

Urban green area provides refuge for native small mammal biodiversity in a rapidly expanding city in Ghana

Urbanization is a key driver of global biodiversity loss. Although sub-Saharan African countries are experiencing unprecedented urbanization and urban expansion, very little is known about how this impacts tropical biodiversity. Here, we assessed the effects of urban expansion and urban green space on local small mammal species diversity in Accra, Ghana. We surveyed small mammals in the University of Ghana botanical garden, an urban green area (UGA) and adjoining built-up environment (BE) and compared the results with baseline data (BLD) collected when large areas of the current city still remained mostly undeveloped. The methodology involved live-trapping using Sherman collapsible live-traps. Our data showed higher small mammal abundance and diversity in the UGA than BE. Similarity of species composition was higher between UGA and BLD than between BE and BLD. The small mammal species captured in BE (the rodents Mastomys erythroleucus, Rattus rattus, and Arvicanthis rufinus, and the shrew Crocidura olivieri) are known to easily adapt to human-modified landscapes. Our results suggest that urbanization negatively influenced the abundance, diversity, and community composition of small mammals. Efforts should be directed towards the integration of urban green areas into urban land development planning in developing countries in order to conserve local wildlife and ecological services that enhance the quality of urban life.

Species distribution of kobs ( Kobus kob ) in the Shai Hills Resource Reserve: an exploratory analysis

The well-being of a species fundamentally rests on understanding its biology, home range, and distribution. The highly seasonal distribution of kobs poses conservation and management difficulties, particularly because of the capricious nature of the ever-changing ecological and vegetation dynamics of the ecosystem. Assessing the distribution of kobs and their associated vegetation provides insight into the vulnerability and conservation status of the species. Species distribution and habitat suitability maps were developed and created respectively for the management of kobs in the Shai Hills Resource Reserve. Kob presence data collected was analyzed using the spatial analyst and Hawth’s tool in the ArcGIS software where the gradients of kob distribution within the protected area landscape were plotted and mapped. Seven environmental variables including location, land cover/use, slope/elevation, nearness to dams and rivers, temperature, and rainfall were considered to have effect on kob distribution pattern and as such used in the development of species distribution and habitat suitability maps. The results indicated that kobs in the Shai Hills Resource Reserve (SHRR) assume a clumped or contagious distribution pattern where individual kobs are aggregated in patches. Rainfall, temperature, nearness to dams and rivers, slope/elevation, and land cover/use had influence in kob distribution. Of all the cataloged habitats, 86, 13, and 1% were moderately suitable, suitable, and unsuitable, respectively. Long-term survival of species depends on adequately large areas of suitable habitats and opportunities for home range activities between such areas. As such, it is recommended that suitable habitats for kobs be dedicated and designated as conservation areas, especially areas along the western boundary.

A rapid assessment of species-specific bird strike risk at the Kotoka International Airport in Accra, Ghana

The Kotoka International Airport in Accra, the capital city of Ghana, has in recent years been confronted with increased presence of birds posing great challenges to aviation safety due to a high risk of bird strikes. As part of measures to mitigate the negative impacts of increasing numbers of birds, a species-specific bird strike risk index (SSBR) was modelled and calculated for a total of 86 species recorded within and near the airport. Based on the SSBR index, four species were classified as ‘critical risk’ and another four species as ‘high risk’. All six species, namely Corvus albus, Necrosyrtes monachus, Milvus migrans parasitus, Bubulcus ibis, Falco biarmicus and Falco tinnunculus, constituting 7% of the total species assemblage, were considered ‘problem species’. During the intensive, albeit short, study period, we also recorded bird strikes of N. monachus, F. biarmicus and notably M. m. parasitus. We conclude that wildlife management to avert the risk of bird strikes could be successfully achieved by adopting both proactive and reactive measures to reduce the presence of problem species at the aerodrome.