Diversity , distribution and habitat association of birds in Menze-Guassa Community Conservation Area , Central Ethiopia

A study was conducted in Menz-Guassa Community Conservation Area (MGCCA) from November 2016 to March 2017, to assess the diversity, distribution and habitat association of birds. Three habitat types including forest, grassland, and moorland habitats were identified based on their vegetation composition. Point count method in Eucalyptus and Juniperus forest, and line transect technique in grassland and moorland habitats were used to study avian diversity. Data were collected in the early morning (6:30 to 9:30 a.m.) and late afternoon (4:30 to 7:00 p.m.) when the activities of birds were prominent. Species diversity and evenness was given in terms of Shannon-Weaver diversity Index. A total of 86 avian species belonging to 14 orders and 35 families were identified. The identified areas are rich with seven (8.14%) endemic bird species namely; abyssinian catbird (Parophasma galinieri), abyssinian longclaw (Macronyx flavicollis), ankober serin (Crithagra ankoberensis), black-headed siskin (Serinus nigriceps), blue-winged goose (Cyanochen cyanoptera), moorland francolin (Scleroptlia psilolaema), spot-breasted plover (Vanellus melanocephalus), and five (5.81%) near-endemic bird species including rouget's rail (Rougetius rougetii), wattled ibis (Bostrychia carunculata), white-collared pigeon (Columba albitorques), thick-billed raven (Corvus crassirostris), and white-winged cliff chat (Myrmecocichla semirufa). Avian diversity was high in moorland (H’=4.57) and low in grassland (H’=3.42) habitats. The highest even distribution of birds was recorded in the forest habitats and the lowest in grassland habitats with E=0.75 and E= 0.59 values respectively. Families Accipitridae, Apodidae, Columbidae, Corvidae, Fringillidae, Motacillidae, Muscicapidae and Turdidae were commonly distributed in all habitats, however the highest number of avian family was encountered in Moorland (15 families) and lowest (9 families) in Forest habitats. The area supported variety of avian species with high endemics and habitat specifics. Conservation of the area is vital for habitat restricted and endemic birds. Further ecological investigation is suggested in the seasonal abundance of birds, and population dynamics of wildlife for biodiversity conservation and ecotourism.


INTRODUCTION
Ethiopia is one of the richest and incredible ornithological destinations in Africa with more than 926 bird species identified so far (Yalden, 1983).The astonishing avian richness can be attributed to its rich and diverse climatic zones, topography, and habitats.Thus, the various lush and green forests, woodlands, moist and arid savannah, lakes, rugged terrain and wetlands are home of Ethiopian birds (Urban and Brown, 1971).
Birds are considered as the most easily recognized categories of vertebrate animals.Among the key characteristical categories of such birds that allow their easy recognition include: (1) The presence of feathers which are unique to them, (2) The development of forelimbs as wings used mostly for flight; (3) Feathered tail for balancing, steering and lifting; (4) Toothless horny beak and skeleton exhibiting unique adaptations, mainly for flight and bipedal locomotion (Wallace, 1955;Padian and Chiappe, 1998).
Worldwide, there are about 10,000 known avian species and they are considered as part of the global ecosystem.They are known as good indicators of habitats quality and environmental degradation (Jarvis, 1993).Since they serve as good indicators to monitor environmental changes like the level of contamination and environmental impacts as a result the conservation of such bird species could contribute to ensure the survival of their environment and the conservation of a correspondingly large number of other taxa (Stattersfield et al., 1998).
Patterns of abundance and distribution of birds are strongly related to environmental factors.According to Pomeroy (1992), the areas with non-uniform topography and variable climatic conditions tend to support more species than uniform ones.On the contrary, small geographical range tends to be associated with habitat specialization (Reif et al., 2010).As a result, the diversity of avifauna represents one of the most important ecological indicators to evaluate the quality of habitats.Although avifaunal diversity has been decreasing due to the destruction of natural habitats and human disturbances (Bhadja and Vaghela, 2013) while area occupancy by bird species in disturbed or strongly seasonal habitat types tend to be larger.Factors affecting bird species distribution include bird body size and birds' abundance.According to Allen (1961), large species in size usually occur at lower densities than small bird species.The power of flight allows them to move easily allowing them to adapt perfectly to every environment, conditions for successful reproduction and birds survival (Estrella, 2007).
Protected areas, known as specific and unique natural habitats, are essential for biodiversity conservation because they often provide habitats protection and conservation from hunting, especially for threatened and endangered species.However, such conservation areas Aynalem and Afework 373 represent only a small proportion of the total land mass and only a few of the diverse ecosystems available in eastern Africa.This is the case of Afroalpine habitat in eastern Africa.Afroalpine areas are found at altitudes over 3,200 m above sea level in Africa and they consist of grasslands, shrub lands and moorlands.In Ethiopia for example, only 2% of the total land area belongs to Afroalpine habitat type but covers 80% of land above 3,000m sea level in the Afrotropical realm (Ashenafi et al., 2012).Menz-Guassa Community Conservation Area (MGCCA) is one of Ethiopian highlands' most pristine and sheltered natural (Ashenafi et al., 2012).The area is known as a home to important Afroalpine biodiversity including endemic and rare species (Biniyam and Tefera, 2011).The vegetation composition of the Guassa area is characterized by high altitude Afro-alpine vegetation with different habitat types which consist of three groups of bird species; namely, globally threatened species, biomerestricted assemblage and congregations of populations, as such the area is listed as important bird areas of Ethiopia (EWNHS, 1996).
The area is also part of the Conservation International's Ethiopian Highland Biodiversity Hotspot and an Endemic Bird Area (EWNHS, 1996).Thus, the present study was designed to investigate the diversity, distribution and habitat association of Birds in Menze-Guassa community conservation area.

Description of the study area
The study was conducted in the Menz-Guassa Community Conservation Area (MGCCA) of Menz-Gera Midir Woreda, North Shewa Zone, Amhara National Regional State.It is located in the central highlands of Ethiopia at about 20km from Mehal Meda, the capital of Menz Gera-Midir district (Biniyam Admassu and Ashenafi et al., 2012).The area lies between 10˚ 15' to 10˚ 27'N latitudes and 39˚45' to 39˚ 49′E longitudes.The total area is estimated to be 100Km 2 .Its altitude ranges from 3,200 to 3,700 masl (Admassu and Tefera, 2011).The area forms part of the high-altitude plateau of the central Ethiopian highlands at the edge of the Rift Valley escarpment, and comprises hills and valleys interspersed with swamps and open areas of Afro-montane and Alpine grassland (Ashenafi et al., 2012) (Figures 1 and 2).

Materials
The materials used during the study period includes binoculars, Global Positioning System (GARMIN, tRex-30), digital camera, field guide books, data sheets and notebooks.*Corresponding author.E-mail: yihenew.aynalem@aau.edu.et.

Preliminary survey
Ecological survey, focusing on avian species, was carried out during the month of December 2016 to assess parameters such as: habitat types and distribution, topographic features and vegetation area cover.

Sampling design
Ecological investigation based on ornithological survey and habitat assessment were all undertaken to study the avian diversity, especially the avian species coupled with their activities, and habitats distribution.Random sample sites were selected based on the bird type of habitats mostly.A stratified random sampling was used to select sample units represented by each habitat type.In order for the ecological survey to be represented, at least 20 to 25% of the study area was covered in each sample site or location (Bibby et al., 1992).The identified sample site consists of blocks that were laid down randomly around selected habitats in the study area, and on a basis of random numbers (Sutherland, 1996).

Data collection
Three habitat types; forest, moorland and grassland areas were identified and avian species observed in each of the selected habitats were recorded.For each of the selected habitat, line transects were used for open grassland habitats only while points count techniques were used for collecting data in both dense forest and moorland habitats.Data were collected from 6:30 to 9:30 a.m. and 4:30 to 7:00 p.m when the activities of birds were prominent.During such range time, birds observed in each observation point were recorded on 500 meters on either sides of the transect.To minimize disturbance, a waiting period of 3 to 5 minutes were applied prior to counting (Bibby et al., 1992).For identification of species in the field, plumage pattern, size, shape, color, songs and calls were used as key parameters (Bekele and Aynalem, 2009).However, in case of poor identification of species in the field, samples of birds' plumage pattern, size, shape, color, songs and calls were taken into the laboratory for future identification.Thus, the avian species were identified and their taxonomic groups were categorized based on field guide books (Pol, 2001;Redman et al., 2011).

Data analysis
Avian species diversity and evenness of the area were analyzed in terms of Shannon-Weaver diversity Index and Evenness (Shannon and Wiener, 1949).Shannon-Weaver diversity Index is calculated as follows: H' = -∑ (Pi*lnPi) where: H' = Shannon-Weaver Diversity Index Pi = Fraction of the entire population madeup of species i ln = Natural logarithm ∑ = Sum from species 1 to species S The species evenness was evaluated using Shannon-Wiener evenness Index (E) as: E = H'/ H max where: E = Shannon-Wiener Evenness Index H' = Shannon-Wiener Diversity Index Hmax=lnS=natural logarithm of the total number of species(S) in each habitat.

Avian species composition and diversity
A total of 86 species of birds were identified.The identified bird species were grouped into 14 orders and they belong to 35 families.Family Accipitridae (13.09%) had the highest number of species followed by Fringillidae (9.52) and Motacillidae families (8.33%  1).
Besides, the endemic and the near endemic species of the bird species, 26 (30.23%) recorded birds belong to restricted highland biome while only 6 (6.97%) of them belong to both the endemic and restricted highland biome.

Overall and specific diversity and evenness of bird species in Menz-Guassa community conservation area
The highest and lowest diversity of birds were recorded in the moorland (H'= 4.57) and grassland habitats (H'=3.42).On the contrary, the relatively even distribution of birds was high in forest (E=0.75) and low in grassland habitats (E= 0.59) (Table 2).

Overall and specific distribution of avian species in the Menz-Guassa community conservation area
The distribution of avian family showed variation among habitats.Highest number of bird families were recorded in moorland (15 families) and lowest number of families were recorded in forest habitats (9 families) (Table 3).In all habitats, the families of the following bird species Accipitridae, Apodidae, Columbidae, Corvidae, Fringillidae, Motacillidae, Muscicapidae and Turdidae were the most abundant and they were commonly distributed.

Avian species composition and diversity in the Guassa-Menze community conservation area
Guassa-Menze Community Conservation Area supports a variety of avian species and it consists of high diversity and abundance of endemics and highland biome restricted bird species.The diversity in habitat characteristics of the Afro-montane area coupled with less human disturbance are certainly among the key reasons explaining the richness of bird species (including restricted-range bird species) in the conservation area.
According to MacArthur (1961), habitat disturbance and poor environmental quality tend to drive avian fauna decline or loss.On the contrary, the richness of the environment in adequate food supply can increase the abundance of avian species at a given area.However, in the case of this study, the diversity of avian species was distributed differently among habitats.The highest number of bird species was observed in the moorland and grassland habitats and the lowest was encountered in forest habitat.This is probably due to the diversity of vegetation that provides heterogeneous habitats and the availability of food resources from which birds can feed into.In avian ecology, the relationship between habitat heterogeneity and bird species diversity is a welldocumented patterns (Tews et al., 2004).Available literature tends to show that changes driving habitat disturbances (that is, forest stratification) influence the richness and avian diversity.In that regards, Asmare (2009) has reported that birds tend to be more diverse and abundant in lower stratum shrub communities (small plants and trees) than in complex forests (taller trees).
Similarly, a study by Mamo et al. (2016) carried out in Bale mountains National Park revealed that bird diversity

Avian species habitat preferences in Guassa-Menze community conservation area
Similarly, among habitats, the number of avian species was the highest in moorland and grassland habitats than in forest habitat.The results of field observations tend to showed the highest number of different seeds producing shrubs and grasses in moorland and grassland habitats than in forest habitat.It can be pointed out that the presence of seeds producing shrubs might drive the abundance of avian species in moorland and grassland habitats than in forests.Habitat heterogeneity is a measure of the diversity and evenness of variation in land cover.However, habitat diversity is dependent, in part, on the scale of observation and the corresponding landscape scale.

Avian species distribution in Guassa-Menze community conservation area
The distribution of avian families showed variation among habitats.The highest numbers of bird families was observed in moorland and grassland habitats while the least number of families was in the forest habitat due certainty in the richness, the complexity of the vegetation and the floristic composition of its habitats in those habitats.Tellaria (1992) pointed out that habitat structure tend to affect the distribution of individual avian species.Similarly, habitat size, foraging modes and floristic composition are also among the other driving factors that tend also to influence the distribution of birds species (Manley et al., 2006).Menz-Guassa Conservation Area is known as a conservation area of high Endemism and restricted-range bird species that are commonly associated with Afro-Alpine ecosystems while serving as a wintering ground for many palearctic migrant birds.Therefore, there is need to reinforce measure for protection of the area that will likely contribute to safeguard bird specific habitats while acting as an ideal place for avian species watching in the highlands of Ethiopia since it supported variety of avian species with high endemics and habitat specific bird species.

Table 1 .
Avian species composition and diversity in Menz-Guassa community conservation area.

Table 2 .
Species diversity of birds by habitat types in Menze -Guassa community Conservation area.

Table 3 .
Overall distribution of birds by habitat types in the Menze-Guassa community conservation area.