Wetland characteristics such as wetland size, water level fluctuation, vegetation cover, and microclimate serve as a waiting, foraging, and breeding site for a number of bird species. In the flood plain, the highest abundance was observed during the wet seasons. The increased water volume during the wet season may have reduced the likelihood of human disturbance and provided a variety of food sources, contributing to the habitat of wetlands, which is home to a significant diversity of bird species.
Wetland vegetation composition provide a variety of food resources, used as a shelter, protect from the predators and create a good breeding ground for birds (Aynalem and Bekele, 2008). This condition determined the extent of richness and quantity of bird species in the region. The wetland characteristics may also vary among seasons (Rajpar and Zakaria, 2014). It has been reported that fluctuations in the water level and food availability influenced the distribution and quantity of waterfowl (Tavernia et al., 2021).
There were more different species of birds during the rainy season. This result was contradicted with (Atnafu et al., 2011) who stated that “in Shesher wetland the greatest quantity of birds were observed in dry season. In rainy season, birds were not much observed”. Our findings indicated that Shesher wetland had a bigger area than the others, which could account for the higher bird population during the wet season. As the dry season advanced Shesher shrunk more rapidly than other wetlands. The site has been cultivated for more than four months on a yearly basis. Due to the expansion of agricultural practices, there are no more waterfowl in the dry season. The birds moved to other locations when Shesher contracted and dried up.
Birds like the Vanellus spinosus, Ardea melanocephala and Corvus capensis were observed in all seasons and use the wetland for getting certain basic needs. African Paradise-flycatcher (Terpsiphone viridis), Black-winged Lovebird (Agapornis taranta), and Greater Blue-eared Glossy-Starling (Lamprotornis chalbeus) were common in both Dilimo and Bebeks wetland. Dilimo wetland is under Orthodox Church administration. The community and the institution abide by laws to protect the wetland resources. The wetland serves to the community as a holy water, used for irrigation and sources of harvested goods during dry season. A similar administration strategy is launched in the Bebeks wetland, but the expansion of agricultural practices reduces its area from time to time. In the target areas species numbers vary due to accessibility of food, human and livestock disturbance levels, and suitable area selection nature of birds. Similarly, Gibru and Biru, (2022) reported that avian species diversity may be persuaded by various factors such as floristic composition, size and quality of the habitat, and bird foraging techniques.
Eastern Lake Tana wetlands are suitable for nesting and rearing grounds for different macro- and macro-invertebrates, including fish (Anteneh et al., 2012). The area has a vast array of bird species, including those that are threatened and internationally endangered. For instance, Shesher wetlands are shallow with a maximum depth of 1.75 m in 2012, but now its depth decreased to 0.5 to 1 meter. Shesher wetland dries during February-March (Anteneh et al., 2012). Due to climate change and the irregular rainfall, the dry season extended from February to mid-June.
Availability of food resources comprising seeds, leaves, tubers, rhizomes, invertebrates, vertebrates such as fish and amphibians at shallow depths of the wetland which enables birds find their food without spending too much energy for capturing their food (Evans & Gawlik, 2020).
Seasonal wetlands are changed to grazing and cultivation practices in the study area. Irrigation activity takes an ample amount of water to cultivate vegetables and cash crops. Consequently, fish and other food resources for birds are seriously affected during the pick dry seasons which in turn affected the diversity of species. Similarly (Desta et al., 2021; Gaona et al., 2021; Malekian et al., 2022; Awash and Tekalign, 2023b) reported that Seasonal variations in the quantity of food resources and the unique seasonality of rainfall led to seasonal shifts in the quantity of birds.
In the study area, the residual crops after harvesting attracts so many birds including migratory birds like Crane species. Rice and other cereal crop development has a great potential in the Fogera floodplain area, which is one of the areas that produces excess crops. Locals say that each year, common cranes arrive in the Lake Tana flood plain on mid-October and depart on mid- March. For the purpose of conserving biodiversity and bird populations, it is crucial to restore water flow, manage invasive species, and restore native vegetation. These actions will ultimately revitalize wetland habitats and protect their fundamental biological services.