Species diversity, The Ecology of WATTLED IBIS (BOSTRYCHIA CARUNCULATA) and land use/cover change of Chelekleka Lake, BISHOFTU

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Addis Ababa University


Chelekleka Lake supports different bird species including endemic birds like Wattled ibis (Bostrychia carunculata). The present study aimed to examine species diversity, ecology of Wattled ibis and land use/ cover change of Chelekleka Lake. In order to assess the population of Wattled ibis and other bird species, total count method was used. The census was done by classifying the study area into four habitats as forest, farmland, grassland and settlement area. The foraging behavior of Wattled ibis was sampled using 2 minutes focal observations of foraging individuals during wet and dry seasons. The activity pattern of Wattled ibis was recorded using scan sampling method. Observation was made on nest location, their construction, clutch size and hatching success of Wattled ibis. The length, breadth and weight of the egg found in the nest were measured using vernier caliper and a Pesola spring balance, respectively. Intensive nest searching in the study area was carried out using a spotting scope and binoculars. Nests found in different macro-habitats were measured. A total of 54 species of birds categorized under 17 families, were observed during wet and dry seasons. The total individuals of Wattled ibis was 170 and 191 during dry and wet seasons, respectively. Worms accounted (74.3 ± SD 12.9%, range=54-90%) of the annual diet of Wattled ibis. Insects were the second most dominant food items, which contributed to (18.3 ± SD 11.6 %, range = 3.5-36.5%) of the overall diet. Wattled ibis also consumed other food items, such as frogs, (2.4 ± SD 2.2 %, range =0-5 %) and small mammals (rodents 0.6 ± SD 1.0 %, range=0-3 %), which made a very small contribution to the annual diet. Wattled ibises were actively engaged in foraging during early morning (81%) and late afternoon to early evening (19%). 340 breeding pairs were observed in eight nesting site of the study area. The nest comprised of mainly sticks, a mixture of weed stems, their roots and grass clumps. In some nests, artificial items such as nylon ropes and cable wires were found. Fledgling and entirely feathered chicks were able to fly approximately at 20 days old. In the forest, egg laying started at the beginning of October. Mean clutch size at the forest and farmland were 2= 1.82; p > 0.05). In the forest, the mean number of hatchlings per nest with eggs was 1.7 and the average number of hatchlings per nest with was 2.3 2 = 3.30; p >0.05); hatching success was 66 %. There were usually a single egg of the Wattled ibis and 2-3 eggs of the cattle egret in those mixed clutches. Nestlings were weighted to the nearest 0.1 gm. After hatching, the chicks weighed 40 g with culmen (16 mm in length), skull (38 mm), forearm (20 mm) and tarsometatarsus (18 mm). During the first three weeks of life, the chick’s weight increased exponentially, although marked differences among the chicks were recorded. The extent of the land use/cover change and its effects seen on Chelekleka Lake and its swamp areas were very dramatic. The majority of the forest use/cover during the (1973-2010) in Chelekleka Lake water shades and its surroundings were converted to crop land, settlement, degraded bare lands and grasslands. Deforestation and soil degradation in the Chelekleka Lake watersheds and its surroundings were very severe. Horticulture expansion, poorly planned infrastructure developments, lack of awareness, poor attention from governments and climate change/variability exacerbate the drying of the lake. Undertaking appropriate resource conservation and management approaches, creating awareness among the local communities and sustainable agricultural activities should be practiced. The surrounding degraded land should be rehabilitated by afforestation. The socio-economic status of the local community should be improved. The stakeholders shoul give special attention to maintain the lake. Key Words: Chelekleka Lake, Ecology, Land use/cover change, Wattled ibis



Chelekleka Lake, Ecology, Land Use/Cover Change, Wattled Ibis