Some Important Observations on the Populations of Hooded Vultures Necrosyrtes monachus

Despite major declines in the population of vultures around the world, noticeable increases were reported in the populations of Hooded Vultures Necrosyrtes monachus over the past decade in Accra—an important vulture habitat in Ghana. In recent times, however, there is a growing concern that the vulture numbers are decreasing even though scientific data to support this is nonexisting. As a vital zoogeographical and conservation tool, it is important to keep an up-to-date knowledge about urban bird populations amidst rapid urbanization and associated changes. Using a combination of field data, literature review, and stakeholder consultations, it was indicative that severe decline might have indeed occurred in the populations of Hooded Vultures in Accra. Evidence suggests the killing of vultures for consumption, traditional medicine, and black magic in an undercover trade with possible transboundary connections as important underlying factor. Additional factors suspected to underlie the declines include changes in management of urban facilities and destruction of roosting and nesting trees. The implications of interspecific competition with Pied Crows Corvus albus on Hooded Vultures however remain unclear. There is an urgent need for conservation campaign and education to save the Hooded Vulture in Ghana

Seasonal variation in species richness and abundance of waterbirds in Mole National Park, Ghana: Implication for conservation and ecotourism

Mole National Park is the largest and the oldest national park in Ghana and an important bird area, yet its waterbird fauna is poorly documented because it is situated in the northern ecological zone far away from the coast of Ghana. Information on the seasonal variation in the park’s bird abundance and diversity is generally patchy but necessary for effective birdwatching planning and management of the park’s birds. Therefore, as a guide to potential ecotourists interested in waterbirds, this study described the seasonal variation in waterbird species diversity and abundance at Mole National Park. As waterbirds mostly congregate around open wetlands and their abundance is more appropriately determined by counting all individuals in the congregant, data were collected using the total area count of waterbirds from August 2015 to October 2015 (the wet season) and from December 2015 to February 2016 (the dry season). Secondary data on arrival of tourists in the park were also analysed. The park’s waterbird species richness was 29 in the dry season compared to 18 in the wet season. There was significant difference (p < 0.05) in the abundance of waterbirds in the dry season in which 4014 waterbirds were encountered compared to 646 in the wet season. The yearly tourist arrival data at Mole National Park shows an increasing trend with peak visitation period occurring during the wet season. The chances of tourists encountering more species and numbers of waterbirds in the park are higher in the dry season compared to the wet season. Conservation implications: Species richness and abundance of waterbirds in Mole National Park varied according to the wet and dry seasons with both the number of species and abundance higher in the dry season than the wet season. It is therefore indicative that most birdwatchers who visit the park in the wet season miss out on a number of species and numbers of waterbirds. To achieve effective birdwatching, management should schedule birdwatching activities to coincide with the dry season as the chances of encountering more species and numbers of waterbirds are higher

Impact of commercial salt production on wetland quality and waterbirds on coastal lagoons in Ghana

A comparative study conducted on two saline coastal wetlands that have been developed into saltpans and two others (referred to as ‘non-saltpans'), that are also saline but have no saltpans, describes the quality of lagoon water, benthic macroinvertebrates and waterbird communities characterising these wetlands. The wetlands were sampled monthly from September 2005–April 2006. Except for turbidity, which was significantly higher in the non-saltpans, (p 0.05). The waterbird communities of the saltpans and non-saltpans, characterised by 48 and 50 species respectively, scored a Sorenson Index value of 0.88, indicating a high similarity. The population density of benthic macroinvertebrates in the saltpans and the non-saltpans was statistically similar (p > 0.05) but the population densities of waterbirds feeding exclusively on benthic macroinvertebrates were significantly higher in the non-saltpans (p 0.05) in the two wetland types.Ostrich 2007, 78(1): 81–8

Habitat use pattern of three species of egrets in a small coastal lagoon in Ghana

The foraging and pattern of habitat use of Western Reef Heron Egretta gularis, Little Egret Egretta garzetta and Great Egret Egretta alba were studied in Sakumo II Lagoon in Ghana to determine the extent of utilisation of non-fish resources by these species, which compete with humans for fisheries resources. The species were counted in grassland and marginal water areas of the lagoon on the assumption that individuals found in the grassland area feed on non-fish resources, whereas those in marginal water forage on fish and possibly aquatic invertebrates. Average numbers of E. gularis and E. garzetta making use of the grassland were higher than those utilising the water, indicating preference for the grassland area. Egretta alba did not show a preference for either habitat. Catch per unit effort and swallow rates of each species were similar in grassland and water habitats, with the exception of E. alba, which recorded a higher swallow rate in grassland. It was concluded that the grassland habitats of Sakumo II Lagoon are important for ardeids, and that non-fish resources constitute an important food for ardeids in coastal Ghana, contrary to previous observations.Keywords: arthropods, Egretta, fish, human-wildlife conflict, niche segregation, waterbirdsOSTRICH 2013, 84(3): 213–21

Abundance and prey capture success of Common Terns (Sterna hirundo) and Pied Kingfishers (Ceryle rudis) in relation to water clarity in south-east coastal Ghana

Abstract Background Water clarity may negatively influence rate of plunge diving and prey capture success of piscivorous plunge-diving birds, and therefore has implications for their conservation in polluted urban wetlands. We studied the relationship between water clarity and the abundance and prey capture success of Pied Kingfishers (Ceryle rudis) and Common Terns (Sterna hirundo) in two polluted coastal waters of south-east Ghana—the Weija Lake and Densu Delta Ramsar Site. Methods On each wetland, data on abundance and prey capture success of plunge-divers were collected in four spatio-temporal quadrats of 100 m × 100 m and analysed with concurrent measurements of water quality parameters using GLM regression with Pearson’s correlation coefficients. Results Mean prey capture success of Pied Kingfishers (34.7 ± 13.1%) and Common Terns (35.3 ± 11.0%) were similar but the two species responded differently to water clarity. The abundance of Common Terns was significantly higher in less transparent/more turbid water while that of Pied Kingfishers showed no significant relationship with turbidity and transparency. In contrast, the prey capture success of Common Terns was neither related to transparency nor turbidity, as opposed to that of Pied Kingfishers which was significantly higher in more turbid/less transparent waters. Correlations between capture success and bird abundance, as well as capture attempts were insignificant, suggesting that increased fish abundance associated with cloudy water may not necessarily promote higher abundance and capture success of foraging birds. Thus, when foraging in less transparent water, capture success may depend more on predator avoidance by fish prey than lower prey detectability of foraging birds. Conclusion Within a gradient of 15–51 cm transparency studied, lower water clarity did not constrain prey capture success of Common Terns and Pied Kingfishers. Further studies on the foraging ecology of plunge-divers in coastal Ghana are however required to make firm conclusions on the relationship between water clarity and foraging birds and fish prey abundances, as well as capture success

The effect of heavy metals and physicochemical variables on benthic macroinvertebrate community structure in a tropical urban coastal lagoon

Benthic macroinvertebrates are key bioindicators of pollution and an important component of food chains on wetlands. Here, we investigated the effect of heavy metals and physicochemical variables on the benthic macroinvertebrates community struc- ture in a tropical urban coastal lagoon in Ghana which is known for its importance in the support of migratory waterbirds. Sediment samples were collected from seven different sites in the lagoon and analyzed for heavy metals. The physicochemi- cal characteristics of the overlying water, sediment organic matter and silt/clay content were determined at these sites. The benthic macroinvertebrates abundance, species richness and diversity at each of the sites were further determined. The results indicated low levels of Zn, Cr, Pb, Cu and Cd in the lagoon with chironomids being the dominant benthic macroinvertebrates. Overall, the benthic macroinvertebrates community structure was not affected by the levels of heavy metals as toxic units were less than one. The benthic macroinvertebrates community structure was generally influenced by the dissolved oxygen, temperature levels of the overlying water, silt/clay and organic matter in the sediment. Increased benthic macroinvertebrates abundance was associated with lower water temperatures and elevated levels of silt/clay and organic matter in the sediment

Risk of heavy metal ingestion from the consumption of two commercially valuable species of fish from the fresh and coastal waters of Ghana.

The need to evaluate the human health safety of fishery resources remain urgent in the mist of the ever-increasing fear of heavy metal toxicity from the consumption of Ghana's fisheries resource, as a consequence of pollution from several anthropogenic activities including artisanal gold mining. Nevertheless, the bigeye grunt (Brachydeuterus auritus) and Bagrid catfish (Chrysichthys nigrodigitatus) remain commercially valuable fish species in West Africa and continue to attract high patronage.Forty-five specimens each of C. nigrodigitatus and B. auritus collected from the Weija Dam and the Tema Fishing Habour in Ghana, between June and September 2016, were analysed for seven heavy metals using Atomic Absorption Spectrometry.Lead and Cadmium were below detection in all samples while Cu was not detected in B. auritus. Levels of the remaining metals (mg kg-1) were below FAO/WHO maximum permissible limits in fish and occurred in the rank order Se (3.5) > Zn (2.34) > Cu (0.59) > As (0.37) > Hg (0.19) in C. nigrodigitatus and Se (2.97) > Zn (2.28) > Hg (0.31) > As (0.21) in B. auritus. Only As in C. nigrodigitatus recorded Estimated Weekly Intake (EWI) greater than FAO/WHO Provisional Tolerable Weekly Intake (PTWI). Also, As in C. nigrodigitatus and Hg in B. auritus had Targeted Hazard Quotient (THQ) greater than 1 for individuals consuming the fishes on daily basis and therefore, raising concerns. However, for both species of fish, cancer risk of As was 1 in 10,000,000,000 and modified Health Benefits values of Se (HBVSe) were positive indicating the health risks that might accompany Hg exposure would be negated. Since toxicity depends on the concentration and quantity of a pollutant consumed, safe maximum consumption rate of C. nigrodigitatus based on As concentrations was 0.21 mg per day and that of B. auritus was 0.058 mg per day for Hg. With an average of 0.227 kg fish per meal of an adult human, these translated into not more than 24 C. nigrodigitatus and nine (9) B. auritus meals in a month but because fish is consumed at 0.0685 kg per person per day in Ghana, these values respectively translates to 93 and 30 safe days of consumption per month.At the rate of 0.0685 kg fish per person per day that fish is consumed in Ghana, the consumption of the two species of fish in Ghana would essentially be of little or no consequence to consumers

Human health risk assessment parameters of heavy metals from the consumption of <i>Chrysichthys nigrodigitatus</i> and <i>Brachydeuterus auritus</i> respectively from the fresh and coastal waters of Ghana.

<p>Human health risk assessment parameters of heavy metals from the consumption of <i>Chrysichthys nigrodigitatus</i> and <i>Brachydeuterus auritus</i> respectively from the fresh and coastal waters of Ghana.</p

Frequency distribution of metal concentrations in the muscle tissues of <i>Chrysichthys nigrodigitatus</i> and <i>Brachydeuterus auritus</i> from the waters of Ghana.

<p>Note: Pb, Cd and Cu were excluded from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0194682#pone.0194682.g001" target="_blank">Fig 1</a> because Pb and Cd were below detection in all samples while 96% of the C. nigrodigitatus and 100% of the B. auritus samples had Cu levels below detections.</p