BIRD POPULATIONS - Birdpop.org

WETLAND BIRDS OF GHANAAvicennia africana interspersed with Cyperusarticulatus, Paspalum vaginatum and Azadirachtaindica (Attuquayefio and Gbogbo 2001). LaiwiLagoon (5º42’N, 0º04’E) is 7.5 km 2 in extent andhas Avicennia africana, Sesuvium portulacastrumand Philoxerus vermicularis as the maincomponents of its vegetation. Mukwe and Laiwilagoons are two of the many small non-Ramsarsites on the Ghana coast that are publiclyowned. The only management at Mukwe andLaiwi lagoons is a customary regulation thatforbids people from fishing on Fridays andTuesdays, respectively.SURVEY METHODSThe total area of each wetland was divided intosectors with the aid of natural and artificialfeatures that serve as land marks. By walkingalong designated routes through each sector, thenumber of individuals of each waterbird specieswas recorded monthly between September 2008to April 2009 and September 2009 to April 2010,which are non-breeding seasons. Counting wasdone in the third quarter of each month duringlow tide using the naked eye, binoculars (8 x42mm) and a telescopes (zoom 20-60) mountedon tripods. To minimize the incidence of doublecounting, birds seen flying were not counted(Bibby et al. 2000). Data from the various sectorsfor each species were compiled after everycounting session to obtain the total number ofindividuals on the various wetlands.DATA ANALYSISData were separated between Ramsar and non-Ramsar sites. The number of each waterbirdspecies on the Ramsar and non-Ramsar siteswas divided by the species total number andmultiplied by 100 to obtain an estimate ofRelative Abundance (RA).Thus,RA R = N_________R x 100, andN R +N NRRA RN = ___________ N NR x 100,N R +N NRwhere RA R = relative abundance of species i onthe Ramsar sites, N R = total number of species ion the Ramsar sites, N NR = total number ofspecies i on the non-Ramsar sites and RA NR =relative abundance of species i on the non-Ramsar sites. On the basis that the Ghana coasthas ~100 wetlands of which five are managed asRamsar sites, the number of waterbirds of eachspecies that the five Ramsar sites might supportwas extrapolated from the number counted onthe two Ramsar sites, given thatE R = _____ 5 N R,2where E R = the extrapolated number ofwaterbirds of species i that the 5 Ramsar sites incoastal Ghana might support.Similarly, the number of waterbirds of eachspecies that the 95 non-Ramsar sites mightsupport was extrapolated from the number ofwaterbirds on the two non-Ramsar sitessurveyed, such thatE NR= 95 N NR ,______2where E NR = the extrapolated number of waterbirdsof species i of the 95 non-Ramsar sites. Thenumber of non-Ramsar sites needed to supportthe equivalence of E R (W NR) was calculated foreach species of waterbird given thatW NR = E R / (N NR ÷ 2).The percentage bird representation on theRamsar sites (E BR), signifying the number ofbirds on the Ramsar sites as a fraction of thetotal number of birds on Ghana’s coastalwetlands, was calculated for each species. Thus,E BR = E R x 100._________E R + E NROn the basis of W NR and E BR, the waterbirdswere put into 6 categories as follows:Category 1. Species found solely on the Ramsarsites whose E BR was 100% and W NR wasundetermined.Category 2. Species for which the total number ofnon-Ramsar wetlands needed to support thebird equivalence E R is greater than the numbersthat exist on the coast. Thus calculated W NR is>95.Category 3. Species for which the total number ofnon-Ramsar wetlands needed to support thebird equivalence E R was lying between 51% and100% of the total number of non-Ramsarwetlands on the coast. Thus W NR lies between 48and 95.Category 4. Species for which the total number ofnon-Ramsar wetlands needed to support thebird equivalence E R lies between 21% and 50% of[58]