We studied the population dynamics of endangered mountain nyala Tragelaphus buxtoni between 2003-2005 in the Bale Mountains National Park. Line-transect sampling and total count methods were used to gather data on dem...We studied the population dynamics of endangered mountain nyala Tragelaphus buxtoni between 2003-2005 in the Bale Mountains National Park. Line-transect sampling and total count methods were used to gather data on demographics and movement patterns. The population＇s age-group composition was 58% adults, 25% sub-adults, 9% juveniles, 5% calves and 3% unidentified with a female-male sex ratio of 2：1. Population density was found to be significantly different between the two sub-populations （Dinsho Sanctuary and Gaysay/Adelay）. A significant difference was found for age-group composition across the two sub-populations except adult females, sub-adult males and calves. The Dinsho sub-population was an isolated group. Separation and containment of the mountain nyala population could have negatively affected their ability to search for habitat requirements and mates from distant areas. The population varied between 830-908 individuals （95% CI）, a reduction of 45% from earlier reports. However, the mean population density increased due to contraction of the species＇ habitat range. We observed a population decrease of 2%-5% per year over the course of our study. Many of the assessed demographic parameters did not significantly change over the three years. This suggests that the decrease in nyala population was not due to random variations in reproduction. Anthropogenic factors such as competition with livestock for forage, habitat encroachment and poaching by the local people might have been partly responsible for the depleted population in our study areas [Current Zoology 56 （6）： 660q569, 2010].展开更多
Here, we conducted a survey to examine the diversity, distribution and habitat association of small mammals from August 2011 to February 2012 incorporating both wet and dry seasons in Aridtsy forest, Awi Zone, Ethiopi...Here, we conducted a survey to examine the diversity, distribution and habitat association of small mammals from August 2011 to February 2012 incorporating both wet and dry seasons in Aridtsy forest, Awi Zone, Ethiopia. Using Sherman live traps and snap traps in four randomly selected trapping grids, namely, natural forest, bushland, grassland and farmland, a total of 468 individuals comprising eight species of small mammals（live traps） and 89 rodents of six species（snap traps） were trapped in 2352 and 1200 trap nights, respectively. The trapped small mammals included seven rodents and one insectivore： Lophuromys flavopuntatus（30.6%）, Arvicanthis dembeensis（25.8%）, Stenocephalemys albipes（20%）, Mastomys natalensis（11.6%）, Pelomys harringtoni（6.4%）, Acomys cahirinus（4.3%）, Lemniscomys zebra（0.2%） and the greater red musk shrew（Crocidura flavescens, 1.1%）. Analysis showed statistically significant variations in the abundance and habitat preferences of small mammals between habitats during wet and dry seasons.展开更多
A study of the population status of and threats to the Black-winged Lovebird(Agapornis taranta) was carried out from September 2008 to February 2009 in Entoto Natural Park(ENP) and in Bole SubCity,Addis Ababa,Ethiopia...A study of the population status of and threats to the Black-winged Lovebird(Agapornis taranta) was carried out from September 2008 to February 2009 in Entoto Natural Park(ENP) and in Bole SubCity,Addis Ababa,Ethiopia.A point transect count technique was employed to examine the status of the lovebirds.An average total of 58 birds was recorded of which 46 were counted in Bole Sub-City and 12 in Entoto Natural Park areas.The maximum number recorded during our census was 57 in the dry season and 15 in the wet season in Bole Sub-City and Entoto Natural Park,respectively.The ratio of adult males to adult females in Entoto Natural Park was 1:0.71 and 1:0.60,and 1:0.76 and 1:0.78 in Bole Sub-City during both wet and dry seasons,respectively.The seasonal variation and difference in sex ratios between males and females was not significant(p > 0.05) at either of the study sites.The threat for the Blackwinged Lovebird or other birds in Entoto Natural Park is due to the fragmentation of natural habitats,thus decreasing food sources,owing to the domination of eucalyptus(Eucalyptus globulus) trees in the area.Grazing by livestock,intensive farming practices and deforestation by the local community have contributed greatly to the degradation of the land resulting in erosion,thus devastating the habitat of the Natural Park.The vegetation cover of Entoto Natural Park and urban gardens should be managed effectively for the survival of the avian fauna of the area.展开更多
文摘We studied the population dynamics of endangered mountain nyala Tragelaphus buxtoni between 2003-2005 in the Bale Mountains National Park. Line-transect sampling and total count methods were used to gather data on demographics and movement patterns. The population＇s age-group composition was 58% adults, 25% sub-adults, 9% juveniles, 5% calves and 3% unidentified with a female-male sex ratio of 2：1. Population density was found to be significantly different between the two sub-populations （Dinsho Sanctuary and Gaysay/Adelay）. A significant difference was found for age-group composition across the two sub-populations except adult females, sub-adult males and calves. The Dinsho sub-population was an isolated group. Separation and containment of the mountain nyala population could have negatively affected their ability to search for habitat requirements and mates from distant areas. The population varied between 830-908 individuals （95% CI）, a reduction of 45% from earlier reports. However, the mean population density increased due to contraction of the species＇ habitat range. We observed a population decrease of 2%-5% per year over the course of our study. Many of the assessed demographic parameters did not significantly change over the three years. This suggests that the decrease in nyala population was not due to random variations in reproduction. Anthropogenic factors such as competition with livestock for forage, habitat encroachment and poaching by the local people might have been partly responsible for the depleted population in our study areas [Current Zoology 56 （6）： 660q569, 2010].
基金supported by Addis Ababa University,Ministry of Education and Zoological Natural History Museum of Addis Ababa University
文摘Here, we conducted a survey to examine the diversity, distribution and habitat association of small mammals from August 2011 to February 2012 incorporating both wet and dry seasons in Aridtsy forest, Awi Zone, Ethiopia. Using Sherman live traps and snap traps in four randomly selected trapping grids, namely, natural forest, bushland, grassland and farmland, a total of 468 individuals comprising eight species of small mammals（live traps） and 89 rodents of six species（snap traps） were trapped in 2352 and 1200 trap nights, respectively. The trapped small mammals included seven rodents and one insectivore： Lophuromys flavopuntatus（30.6%）, Arvicanthis dembeensis（25.8%）, Stenocephalemys albipes（20%）, Mastomys natalensis（11.6%）, Pelomys harringtoni（6.4%）, Acomys cahirinus（4.3%）, Lemniscomys zebra（0.2%） and the greater red musk shrew（Crocidura flavescens, 1.1%）. Analysis showed statistically significant variations in the abundance and habitat preferences of small mammals between habitats during wet and dry seasons.
文摘A study of the population status of and threats to the Black-winged Lovebird(Agapornis taranta) was carried out from September 2008 to February 2009 in Entoto Natural Park(ENP) and in Bole SubCity,Addis Ababa,Ethiopia.A point transect count technique was employed to examine the status of the lovebirds.An average total of 58 birds was recorded of which 46 were counted in Bole Sub-City and 12 in Entoto Natural Park areas.The maximum number recorded during our census was 57 in the dry season and 15 in the wet season in Bole Sub-City and Entoto Natural Park,respectively.The ratio of adult males to adult females in Entoto Natural Park was 1:0.71 and 1:0.60,and 1:0.76 and 1:0.78 in Bole Sub-City during both wet and dry seasons,respectively.The seasonal variation and difference in sex ratios between males and females was not significant(p > 0.05) at either of the study sites.The threat for the Blackwinged Lovebird or other birds in Entoto Natural Park is due to the fragmentation of natural habitats,thus decreasing food sources,owing to the domination of eucalyptus(Eucalyptus globulus) trees in the area.Grazing by livestock,intensive farming practices and deforestation by the local community have contributed greatly to the degradation of the land resulting in erosion,thus devastating the habitat of the Natural Park.The vegetation cover of Entoto Natural Park and urban gardens should be managed effectively for the survival of the avian fauna of the area.
