Diversity, Species Composition, and Relative Abundance of Avifauna at Debre Libanos Monastery, Ethiopia

. Data on avifaunal diversity and distribution are vital to enhance and inform conservation eforts. Terefore, this study was conducted to explore the diversity, distribution, and relative abundance of bird species in the Derbe Libanos Monastery Forest. Te data were collected from December 2019 to September 2020, covering both the wet and dry seasons. Natural forest, plantation, clif forest, and settlement were identifed as an important habitat for the birds using a stratifed random sampling design based on vegetation composition and characteristics. Point counts were employed to identify and record birds in the four habitat types. During the study, 61 avian species belonging to 13 orders and 31 families were identifed. Te highest diversity ( H ′ � 3.43) and evenness ( E � 0.96) were observed in the summer season in natural forests. Te diference in abundance of bird species was statistically signifcant between observed and expected counts of each species in diferent habitats ( χ 2 � 629.97, df � 60, and p < 0 . 001). Recognizing that the monastery forest has a large number of bird species, enhanced avian monitoring and forest reintegration opportunities should be prioritized for conservation.


Introduction
Ethiopia is a tropical country with a wide altitudinal range, great geographical diversity with high and rugged mountains, fat-topped plateaus and deep gorges, incised river valleys and rolling plains, and macro-and micro-climate variability [1]. As a result, the country is endowed with great biological diversity of plant, animal, and microbial genetic resources [2].
Birds are the best-known group of vertebrates in Ethiopia [3]. Most birds are useful for humans, for example, pollination [4] and control of insect populations [5] in diferent ecosystems. Bird abundance as a bioindicator species shows a strong and signifcant positive correlation with both tree abundance and cover [6].
To date Ethiopia has 873 species of birds, of which 19 are Ethiopia's endemic 39 are globally threatened, one exotic species and 13 species are near endemic shared the highlands of Ethiopia and Eritrea [7]. However, according to diferent studies, the number, distribution, and abundance of bird species vary as a result of habitat variabilities.
As shown in the above, Ethiopia has a diverse number of species as a result of its diverse habitat types and agroecological variability [8]. However, the diversity and abundance of the species are decreasing at an alarming rate [9][10][11][12]. Forest reduction, fragmentation, and loss are greatly afecting the population dynamics and dispersal potential of birds, as well as the ecological functions of birds [13,14].
By considering the rapid decrement of bird population and range, Ethiopia has established 69 Important Bird Areas (IBAs) to protect the country's biodiversity and boost economic growth through tourism and related activities [15]. Debre Libanos monastery forest is found in Oromia Regional State and is one of the bird areas designated for biodiversity protection [16]. However, diferent protected areas have been established, but the organized baseline data needed to help the conservation and management of the area are lacking with regard to birds. Some studies have been conducted on the diversity and distribution of birds in diferent areas in Ethiopia, but no research has been conducted on the diversity and distribution of birds in the Debre Libanos monastery forest. Due to habitat variability and anthropogenic extent in this area, a specifc study is required for the management and conservation plans. Terefore, the goal of this study was to investigate the bird diversity, distribution, and avian diversity in the Debre Libanos Monastery forest.

Description of the Study Area.
Te study area is located in the Oromia Regional state, North Shoa Zone, Ethiopia, 104 km to the north of Addis Ababa, the capital city of Ethiopia. It lies between 09°43′ 30″N latitude and 38°51′0″E longitude ( Figure 1). Te study area lies along the eastern part of Fiche Selale town with altitude ranging from 2400 m whilst the rim of the valley rises to over 2560 m [17,18]. Te area is characterized by bimodal rainfall season (June to September) and shorter rainy season (March to April). Te mean annual rainfall is about 1037 mm, while the minimum temperature is 5.7°C and the maximum temperature is 22.9°C.

Data Collection and Sampling
Design. Field binoculars, Geospatial Positioning System (GPS72hz), sound recorder, Sony digital camera, and bird guidebook were used during the study period [19]. Binocular used to determine the clear vision of bird species at a distance; GPS used for determine the position of sampling area and area demarcation; Bird Guidebook for identifcation of on bird species to the other; Sound recorder helps to record calls and sounds of birds, to analyze efectively; Sony digital camera is used to take photos of birds.
A pilot survey was carried out in December, 2019 to collect basic information about the study site. Te real study was carried out from January 2020 to September 2020 by considering both the wet and dry seasons. Te wet season data covers from June to September, and the dry season is from January to May. In this study, stratifed random sampling design was employed since the study area was not uniform in terms of habitat types. Te area was stratifed into four habitat types (natural forest, plantation, clif/riverine forest, and settlement). Natural forest is a forest which has reproduced naturally, consisting of naturally immigrant or indigenous tree species and strains; plantation area includes the area where human planted tree is found, i.e., Eucalyptus plant species in the monastery area; settlement is the place where peoples live; clif/riverine forest is an area, which is located or dwelling near a river and contain rocks.
In total, this survey established 19 sampling plots to cover the area, 4 plots on natural forest, 3 plots at clif/ riverine forest, 7 plots on plantation, and 5 plots on settlement contingent on the proportion of area coverage of the habitat. In each plot, there were 9-point count stations designed within 30 m radius to the observer. Birds did not easily observe if the distance is greater than 30 m radius. In each point station, 2-5 minutes were stayed for the birds to settle in case of any disturbance. To avoid double counting of avian species, the distance between each sampling plot was 250 m. Bird observation was carried out twice per day from 6:30 to 10:00 in the morning and 4:00 to 6:00 in the afternoon when birds were active [20]. Te survey was carried out for two days per week, depending on the air quality. Troughout this survey, two counting techniques such as direct observation and indirect observation (alarm call, song, and feather) were functional.

Statistical Analysis.
Te data were analyzed using SPSS version 23.0 software [21]. Shannon-Weiner index, t-test, and chi-square test were used. One sample t-test was used to analyze the efect of season and habitat type on the abundance of avian species. Chi-square test was used to compare seasonal variations in diversity and evenness of birds at a 95% level of signifcance. Shannon-Weiner index was used to evaluate the diversity and evenness of bird species in diferent habitats within the study area [22].
Shannon Diversity Index (H′) � (pilnpi), where H′ is the Shannon-Wiener Index of Diversity; Pi is the proportion of the species relative to the total number of species; and ln indicates the natural logarithm.
Evenness or equitability index (E) � H′/H max, where H′max � ln (S) � natural logarithm of the total number of species (S) in each habitat [23]. E values range from 0 to 1, in which 1 indicates complete evenness.
Sørensen similarity index (S) is used to measure species similarity among diferent habitat types. It is equal to 1 in the case of complete species similarity between four habitats and 0 if species of two habitat types are dissimilar [24]: where C is the number of bird species common in all four habitats, A is the number of bird species observed in site A, B is the number of bird species observed in site B, C is the number of bird species observed in site C, and D is the number of bird species observed in site D.
Te relative abundance of each species was estimated from encounter rates. Tis value is used to give each species an ordinal rank of abundance using the ranking scale [25]: encounter rate � number of individual of a species number of observation hours * 100. (2) Te value of encounter rate was used to categorize each species into the following categories: <0.1 (rare), 0.1-2.0 (uncommon), 2.1-10.0 (frequent), 10.1-40.0 (common), and >40 (abundant) [26].

Species Composition.
A total of 61 avian species belonging to 13 orders and 31 families were recorded in the study area (Table 1). Among the thirteen identifed orders, Passeriformes (60.7%) was the dominance order, containing a high number of species followed by order Accipitriformes (9.8%), whereas the least number of bird species was recorded in Apodiformes, Coliiformes, Psittaciformes, and Strigiformes that accounts (1.6%) of the other order ( Figure 2).
Among the 61 bird species, 30 were common for both wet and dry seasons, while 18 and 13 bird species were exclusively recorded during the wet and the dry seasons, respectively. Abyssinian Woodpecker (Dendropicos abyssinicus; Stanley, 1814) is one of the endemic species of in Ethiopia, and fve semiendemic avian species were recorded in the study area (Table 1). Hooded Vulture and Ethiopian Boubou are the threatened species observed in the study area.

Species Diversity and Distribution.
Te species diversity was higher (H′ � 3.43) in the natural forest during the dry season. While the least species diversity (H′ � 2.07) was recorded in the plantation habitat during the wet season ( Table 2). Te highest evenness (E � 0.96) was observed in the natural forest during the dry season, and the lowest evenness (E � 0.78) was observed at settlement habitat in the wet season (Table 2). Te distribution of bird species was varied between the study sites across seasons during the study period. During the wet season, 48 bird species were observed in wet season and 43 species of birds were observed during the dry season throughout the study period. Te highest species richness (41 species) was noted in natural forest during the wet season, and (37 species) were observed in the dry season. While the lowest species richness was recorded at plantation habitat during the wet season (Table 2). Te chi-square test analysis of bird species was statistically signifcantly diferent, in wet and in dry seasons (χ 2 � 629.97, df � 60, p < 0.001) in four habitat types throughout the study period.

Similarity of Bird Species between the Wet and Dry
Seasons. Tere was 80% of avian species similarity between natural forest and clif/riverine forest during the dry season and 68.6% of species similarity recorded in wet season (Table 3). However, the lowest 15.4% avian species similarity was observed between natural forest and plantation habitat  Figure 1: Map of the study area.
International Journal of Zoology

Bird Species Abundance.
Highest abundance (n � 1825) of bird was detected during the wet season and (n � 1005) individuals were observed in dry season. Te maximum number of individual (n � 1326) bird species account in the forest habitat followed by (n � 784) riverine habitat, (n � 463) settlement habitat, and the least abundance of bird species recorded in plantation habitat (Table 4). Te t-test analysis indicated that abundance of bird was statistically and signifcantly diferent in wet and dry seasons (t � 39.5, df � 2829, p < 0.001) and statistically signifcantly diferent in four habitat types (t � 87.9, df � 2829, p < 0.001) throughout the study period.
Most avian species, 31 and 20, were found within the ordinal rank of "uncommon" during the wet and dry seasons, respectively, in the natural forest (Table 5). Least number of avian species was recorded in settlement and plantation. Te plantation habitat hold one species within the ordinal rank as "uncommon" in wet season but in settlement habitat one species recorded within the ordinal rank as "common" and "uncommon" in wet and dry seasons, respectively. Abundant and rare bird species did not record in this study area in both wet and dry seasons.
Among the total of 61 species of birds recorded in the study area, the relative abundance of nine bird species accounts for 64.28%. Out of these nine top avian species, Ethiopian Boubou accounted for the highest relative abundance (13.64%), followed by Abyssinian Woodpecker (13.43%), but Dusky Turtle Dove had the least relative abundance (Figure 3).    [20,[29][30][31]. Most bird species are recorded in the order Passeriformes due to the rapid   International Journal of Zoology evolution of Passerine species and their adaptation to all terrestrial environments and the presence of a large number of species [32]. Alemu et al. [33] studied that most of the avian composition was recorded in the order of Musophagiformes in the Bahr Dar City report. In our study, among the 61 species of birds recorded during the study period, the maximum abundance of 48 species was recorded in the wet season and 43 species of birds were recorded in the dry season. Bibby et al. [25] suggested that bird richness was higher during the wet season than during the dry season because of the increased availability of insects during the wet season. However, the present study contradicts the fndings of [34] that bird species richness was the highest in all habitats during the dry season. Moreover, Genet and Ejigu [35] recorded 90 bird species in the wet and 96 in the dry season. In the present study, a high diversity and evenness of bird species was observed in the natural forest in both wet and dry seasons, probably due to the good availability of food, nesting sites, vegetation composition, and diving sites. A study supported by Tsegaye et al. [26], indicated that diferences in species diversity, species abundance, and number of individuals among diferent species were associated with diferences in habitat characteristics and feeding habits. In addition, Mola et al. [36] reported that the distribution and abundance of many bird species is determined by the vegetation structure.  [30,37] say that the lowest species richness and abundance were observed in forest habitats than in farms and settlements. According to their reasons, in natural forest in their study area, the vegetation composition is low; as a result, only specialist bird species live there. We found the second highest number of bird species recorded in the riverine forest. Tis is possible because there are diferent types of fora and fauna in the river basin forest, which are used as a habitat for diferent species of birds. On the contrary, in our study, the lowest bird species richness was recorded in settlement habitat. Similarly, according to the fndings of [38], the lowest bird species diversity was recorded in settlements. Te reason is that humans destroy forests and the habitats of wild animals in order to meet their needs and for housing. Moreover, Mengesha et al. [13] pointed out that land use and land cover infuence the diversity and abundance of bird species in their study.
In this study, 80% species similarity between natural forest and riverine forest was observed in the dry season and 68.6% was observed in the wet season. Tis is possible because they are interspersed with similar plants, and may contain similar species of birds that share the same plants for habitat. Tis result is consistent with [26,29], reported that animals in the same ecological condition were more similar to each other in terms of species richness and geographic structure than animals in diferent ecological conditions. In contrast, the least avian species were observed to be similar between natural forest and plantation. Tis is possible because they may not have shared species between the two habitats and may not have had the same type of fora as they occurred in diferent areas.
Most of the bird species in this study were found within the ordinal rank of uncommon. Tis is because the species may have a large home range and a high demand for the species due to the complexity of the fora [36,39]. Similarly, Genet and Ejigu [35] reported the presence of more uncommon bird species in the Apin forest during the wet and dry seasons. Te presence of a large number of rank "uncommon bird species" may be due to the breading nature and large home range of bird species [40]. On the other hand, the Ethiopian bubu, Abyssinian Woodpecker, redwinged starling, Abyssinian oriole, and moorland chat are relatively abundant compared to other bird species. Tis is due to the fact that the abundance of those species correlated with the availability of feeding, watering, and breeding grounds [41].

Conclusion
Te result of this research has informed us the presence of a considerable number of species of birds in the area. Among them, the Abyssinian Woodpecker, an endemic species is 13  International Journal of Zoology 7 found only in Ethiopia. Due to habitat variation, bird species found in the four habitats are diferent. Te Hooded Vulture is classifed as one of the critically endangered species listed by the IUCN. Both bird species diversity and richness are high in natural forests; this may be due to the availability of sufcient food, living conditions, and nesting grounds. Sixty one species of birds have been found, and it has been realized from the study that Debre Libanos monastery is important for the protection of species. However, it draws researchers' attention and tourists to establish eco-tourism activities that beneft the local community and assure it is protected sustainably; the efort made to protect the area and its wildlife is low. Terefore, better management strategies and conservation plans need to be in place. In addition, further ecological studies need to be conducted to understand which threats are afecting the ecology of birds and management strategies.

Data Availability
Te data used for this study are available from the corresponding author upon reasonable request.

Conflicts of Interest
Te authors declare that they have no conficts of interest.