The Ecology of Black Crowned Crane (Pavonina Pavonina Ceciliae) in Relation to Changes of Land Use at Lake Tana, Ethiopia
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Date
2017-06
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Addis Ababa University
Abstract
Black Crowned Crane is a resident species in Ethiopia. However, the available information
on the breeding, feeding ecology and its status is in adequate. This study was carried out
in Lake Tana area, from 2014-2016. The study aims to investigate the breeding and feeding
ecology, distribution, abundance and habitat change of cranes. Different statistical tools
were used to evaluate the different parameters. ANOVA and Shannon diversity index, a
fixed GLM procedure and MANOVA were applied. A total of 74 and 56 transects in 2015
and 2016 was carried out to estimate the abundance and density of cranes. Multiple
Covariate Distance sampling model was employed for distance analysis. Wetland habitat
shrinkage was evaluated from the land use land cover change from 1986 to 2016. The
result showed that all crane nests were located only in wetlands where water depth ranged
135-220 cm. The active nesting time was September to October. The inter-distance between
nests did not vary from site to site. Cranes utilized nest materials collected from the nesting
place. The mean vegetation height at which the nest constructed was variable. The nest
morphology parameters were not different statistically. The nesting density was 6-7 /100
ha. The average clutch size of Black Crowned Crane was two (n=92). The mean length of
eggs was 76.94±.22 mm, and width measured 54.05±.07 mm. The mean weight of eggs
(n=92) were 111.99±.65g. There was a positive correlation between egg length and width,
and were statistically significant. Hatchability was 91.3%, but the pre-fledged percentage
was about 50%. Oryza longistaminata and Leersia hexandra were the dominant
macrophytes. The distribution and biomass of macro-invertebrates were significantly
different across study sites (P<.05). The most abundant and frequently occurring taxa were
Libellulidae, Coenagrionidae, Hydrophilidae, and Culicidae. Grass seeds and crop seeds
were major food sources of cranes. Fecal analysis of cranes revealed that the diet
contained parts of plants, fragments of animal origin and small quantities of inorganic
materials and shells at different proportion. There was spatial and seasonal variation in
the distribution of cranes. Crane population was more abundant during the dry season.
Chimba and Yiganda wetlands are identified as the main breeding and feeding sites;
however, the habitats shrunk by 47% in Chimba and by 25% in Yiganda. Agricultural
encroachment, livestock pressure and population growth are the main threats.
Keywords/phrases: Breeding, crane density, diet, egg and nest morphometry, land use
land cover, nest
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Keywords
Breeding, Crane Density, Diet, Egg and Nest Morphometry, Land Use Land Cover, Nest