2.4│ Methods of data collection
The standard field techniques including direct and indirect observations were employed from July to December 2019 in FCF to collect data.  The survey was carried in the first two consecutive days every month and twice a day (early in the morning during 06:00 to 08:00 hour and late in the afternoon during 17:00 to 19:00 hour) following Legese et al. (2019).
Direct and indirect observations for medium and large-sized mammals surveys were started 200 meters inside from forest edge and were recorded at the maximum of 100-meter distance from both the left and right side during walking along the fixed-width transect line (Krebs, 2006).
Direct observation was made through binocular and naked eyes to assess mammalian species and threats and indirect observation was made based on indirect evidence of mammals such as carcass, footprint, holes, sound, and fecal-pellet (Larsen, 2016; Laurindo et al., 2019).
During transect visits, a researcher and five trained field assistants traversed the track lines. While the observer was walking quietly and gently along each transects against the direction of the wind to minimize disturbances of mammals, the data on any mammalian direct and indirect observation such as species, size, and threats were trapped by the camera and recorded on the datasheet. Body size, coloration, presence, and absence of horn, horn shape, genitalia, and dominant behavior were used to identify observed mammals following the Kingdom Field Guide to African Mammals (Kingdom, 2003).
2.5│ Data analysis
All the observed (direct or indirect) mammals were identified to their respective orders, families and species level by using the taxonomic characters listed in Kingdom (2003), and Yalden and Largen (1992). The relative abundance of each species was computed using the percentage, from total number of each species observed per total individuals observed in the area.
Both qualitative and quantitative data were analyzed with descriptive statistics. SPSS Version 16.0 statistical program, PAST version 3.26b Statistical Package (Software) and appropriate statistical methods such as mean and percentage were used. Gini Simpson and Shannon-Wiener Diversity Index were computed by using PAST. A chi-square test was used to compare the seasonal variation in species abundance at 0.05 levels of significance. The threats were analyzed systematically by condensing and summarizing information.
3│RESULTS
3.1│ Mammalian taxonomic composition
A total of twenty-one mammalian species belong to six orders and thirteen families were identified by direct and indirect field evidence in FCF. The species richness varied across orders and families. Order Carnivora represented by the largest number of families (five) followed by Artiodactyla (three) and Rodentia (two). Tubulidentata, Primates, and Lagomorpha each represented by single-family. Order Artiodactyla composes 33% of total species followed by Order Carnivora composes 29% of total species (Figure 3). More mammalian species were recorded for the family Bovidae (four species), followed by Cercopithecidae (three species). The families Suidae, Felidae and Sciuridae were represented by two species each. The remaining seven families Hippopotamidae, Orycteropodidae,  Hystricidae, Hyeaniadae, Mustelidae, Viverridae, Canidae, Leporidae were represented by single species (Table 1).
Among identified mammals eleven (52.4%) species were large-sized and ten (47.6%) species were medium-sized (Table 1). Eight of the recorded mammal species observed using indirect evidence (Table 1) whereas the remaining thirteen records of observation for mammal species were through direct sighting (Table 1). Out of a total of 21 species recorded, 20 species occurred during wet and dry seasons. Panthera pardus recorded only in the wet season.
3.2│ Abundance of mammals
A total of 685 medium and large-sized mammalian individuals belong to six orders, thirteen families and twenty-one species were identified in FCF. The number of individuals varied among orders and families (Figure 3) and among species (Figure 4). The abundant order by the number of observations from the study area was recorded by order Primates which include 284 individuals followed by order Artiodactyla include 201 individuals. The least abundant order was Tubulidentata which composes only 8 individuals. The most abundant family was Cercopithecidae (284 individuals) whereas the least was Viverridae comprises only two individuals. Among mammals, Chlorocebus aethiops (19.27%) andPapio anubis (19.27%) were the most abundant mammalian species in the study area followed by Phacochoerus aethiopicus (7.74%).Panthera pardus and Civettictis civetta each contributed only 0.29% of the total recorded individuals.
The abundance of mammals varied between seasons (Table 2). 371 (54.16%) individuals were recorded in dry season while 314 (45.84%) individuals were recorded in wet seasons. The variation of mammals between seasons was statistically significant (𝜒2 = 40.783; df = 20; 𝑃 < 0.05). The relative abundance of the different mammalian species varied from 0.32 to 20.38% in the wet season and from 0.27 to 21.56 % in the dry season. Two speciesPapio anubis , and Chlorocebus aethiops were relatively the most abundant in both seasons (Table 2). These two species contributed 36.94% and 39.89% of the total sample of the wet and dry season survey, respectively. The remaining mammalian species of individuals contributed between 0.23 and 8.28% in the wet season and 0.27 and 7.28% during the dry season survey. Mammals of individuals ofPontamochoreus larvatus, Papio anubis and Chlorocebus aethiops showed significant variation between wet and dry seasons and the other species significant level did not reveal variation between seasons.
3.3│ Diversity indices of mammals
The overall species richness of FCF was 21 and Shannon–Wiener Index values (H) was 2.56 and Simpson’s index of diversity showed the highest species diversity (0.8968) in the study area (Table 3).
3.4│ Threats to mammals in the study area
Human and non-human activities have threatened mammals and their habitats in the study area. During the present study periods, the major threats observed in the area were hunting, logging, deforestation, predation, invasive alien plants, overgrazing, and mining.
Hunting : The high rate of incidence of hunting was recorded for Papio anubis because its extent of damage was high to the local community and agricultural crops.Chlorocebus aethiops was also a pest on crops resulting in hunting. Xerus rutilus was hunted by young men also recorded in the area. During the fieldwork, the researcher had counted 8 carcasses of mammals of Phacochoerus aethiopicus, Chlorocebus aethiops , Panthera pardus, and Papio anubis .
Predation : Papio anubis killed and eat the young ofRedunca redunca was recorded.  Predation by dogs of animals likeCivettictis civetta and Orycteropus afer were recorded.
Overgrazing : Locals regularly bring cattle to the forest mainly for drinking water in the Lake Abaya. Mammals Cattle overgrazing and competition for food resources were recorded. Even though cattle are prohibited, they cause severe overgrazing around the edge of the forest.
Deforestation : Deforestation for agricultural land expansion was observed at the edges of the forest. Clearing forest by humans from adjacent croplands to avoid large mammal pests was also recorded. Papio anubis damage to the natural forest through debarking and destroying the young and seedling plants was also recorded.
Logging : During the transect walk evidence of illegal logging such as the removal of trees for timber production, for fuelwood and construction materials and grass collection for cattle and thatching houses were observed.
Invasive alien species : The encountered invasive alien species during the transect survey were water hyacinth Parthenium weed (Parthenium hysterophorus ) and Lantana weed (Lantana camara ) at the edges of forests and roads. The invasive plant Parthenium weed (Parthenium hysterophorus ) dominated the place at some edges of the forest and homogenized the place (see Appendix 3). Also, they reduced the grass species abundance for herbivores mammals.
Mining : Mining of stone for cobblestone by different enterprises in different parts of the forest was another challenge observed during the survey, and severely affecting forest habitat of mammals.
4│ DISCUSSION
4.1│ Mammals composition and abundance
The present survey revealed different large and medium-sized mammals from FCF and a total of 21 species were identified from 685 total observational records. These mammal species were grouped into six orders and thirteen families. Some studies that have used similar transect line techniques and to areas of different protection levels across the country and elsewhere revealed that the medium and large-sized mammals recorded were lower than the result obtained from the present study. For example, Geleta and Bekele (2016) recorded 15 mammal species in Wacha Protected Forest, Western Ethiopia by direct and indirect evidence. Also, Woldegeorgis and Wube (2012) recorded 14 mammal species from Yayu forest in southwest Ethiopia; Atnafu and Yihune (2018) recorded even lower (12) mammal species in the Mengaza communal forest, East Gojjam, Ethiopia. This variation might account for variation in mammals’ group composition, variation in vegetation structure and human influence and livestock grazing.
The number of medium and large-sized mammals recorded during the present study was comparable to several other studies conducted in Ethiopia and elsewhere. For instance, Njoroge et al. (2009) recorded 23 species in Arawale National Reserve, Kenya; Bene et al. (2013) recorded 23 species in Sime Darby, Liberia; Girma et al. (2012b) recorded 19 species in Wendo Genet, Ethiopia; and Ofori et al. (2012) recorded 23 species in the moist semi-deciduous forest of Ghana. The relative abundance of food sources, dense green vegetation cover, and high survey period, good management practice of local people and availability of water (Lake Abaya) were might be the major factors governing their abundance and species richness in the present study area.
Some studies conducted in different countries revealed that the medium and large-sized mammals recorded were higher than the result obtained from the present study. Some of the studies among others include Cortes‐Marcial et al. (2014) recorded 35 mammals in Oaxaca, Mexico and Melo et al. (2015) recorded 33 mammals in northern Amazon, Brazil. This might account for variation in sample sites, season considered, and variation in vegetation cover.
Most mammals were recorded by direct observations during the present survey. This result disagreed with the result obtained by Alves et al. (2014) in which out of a total of 239 individuals 75% were obtained from indirect evidence, footprints but agrees with most studies in different localities (e.g. Legese et al., 2019;  Gonfa et al., 2015)
The orders and families of mammals recorded in the present study were higher than with the study conducted on medium and large-sized mammal’s indifferent localities. For instance, Legese et al. (2019) identified five orders and seven families in Wabe forest, Ethiopia. Also Qufa and Bekele (2019) identified seven orders and 11 families from Lebu Natural Protected Forest, Southwest Showa, Ethiopia; Laurindo et al. (2019) found out six orders and 12 families, Cerrado remnants in south eastern Brazil; herein FCF 6 orders and 13 families were recorded.
The Primates were the most abundant orders recorded and all belongs to a family Cercopithecidae. Pabio anubis and Chlorocebus aethiops were the most abundant mammal species in the study area. Similarly, several studies have also reported a higher relative abundance of Primates than other orders from different parts of Ethiopia (e.g. Geleta and Bekele, 2016; Gonfa et al., 2015; Girma et al., 2012b). This is could be due to the high reproductive successes, their more adaptive nature to different habitats, diversified foraging behavior and high tolerance level of Primates to human disturbances (Negeri et al., 2015).
The abundance of carnivores was minimal; however, it contained the highest number of family (4) among other orders. Among the recorded carnivores, Civettictis civetta, Panthera leo and Panthera pardus were least abundant. This might be associated with a minimal number of herbivores and their nocturnal behavior. As described by Hunter and Yonzon (1993), most carnivore species are solitary, nocturnal and crepuscular so that their presence could not be easily documented.
Order Artiodactyla has the highest species richness and the second abundant order recorded. Phacochoerus aethiopicus was abundant and Ourebia ourebi was the least abundant species recorded in this order. The destruction of habitat is especially harmful to large mammals that require large home ranges to fulfill their nutritional requirement (Ripple et al., 2016).
Orders such as Rodentia, Tubulidentata, and Lagomorpha were recorded as less in the number of individuals. This inline with other studies in different localities in Ethiopia (e.g. Atnafu and Yihune, 2018; Geleta and Bekele, 2016; Gonfa et al., 2015).
The number of individuals of mammals recorded during the dry season (371) surpassed the number of recorded during the wet season (314). This inline with the work of Kasso and Bekele (2017) in Assela fragmented forest, Ethiopia.  The possible explanation for this could be the high number of people and livestock were encroaching more during the wet season than the dry season. Growth of herbaceous and ground vegetation might have provided thick cover for the mammals, which makes the sighting of them difficult (Gundogdu, 2011).
The species index of the diversity of the study area showed higher species richness (H = 2.56; 1-D = 0.8968) than to study conducted by Qufa and Bekele, (2019) in Lebu natural protected forest, Ethiopia (H = 2.119; 1-D = 0.8167). Different possible factors contributed might be due to higher survey period and availability of food sources, dense forest cover, and water.