Impact of Seasonal Variation on Avian Species Diversity in Dagona Waterfowl Sanctuary, Yobe State, Nigeria

A study was conducted at Dagona Waterfowl Sanctuary to examine the impact of seasonal variation on bird diversity. The research spanned six months and covered both the dry season (April to June) and the wet season (July to September). The objective was to evaluate seasonal fluctuations in bird diversity and species richness within the sanctuary. An initial reconnaissance survey was carried out to select suitable study locations and sampling points. Five distinct locations Zemo, Oxbow, Incheduwa, Maram, and Gustu Lakeswere identified for sampling, and the point count method was used for bird census. Bird observations were conducted at each point twice a day: in the morning (6:00 AM to 10:00 AM) and in the evening (4:00 PM to 6:00 PM). Data were compiled using Microsoft Excel and analyzed with PAST version 3.26b software. Bird diversity was assessed using the Shannon-Wiener Diversity Index. The results revealed that the majority of birds observed were categorized as Resident (12,225 individuals), Migratory (8,186), and Palearctic Migrant species (10,876). Some of the resident birds recorded included the African Jacana, Long-tailed/Reed Cormorant, African Mourning Dove, Vinaceous Dove, Pied Kingfisher, and Common Moorhen. Migratory species observed included the Yellow Wagtail, African Marsh Harrier, Intermediate Egret, Red-billed Hornbill, and Garganey. Palearctic migrants such as the White-faced Whistling Duck, Squacco Heron, Fulvous Whistling Duck, Yellow-billed Kite, and Green Sandpiper were also recorded. The Shannon Diversity Index value was found to be 1.94 during the dry season and 3.63 in the wet season, indicating significantly greater bird diversity during the wet season. However, human activities such as overgrazing, fishing, and animal rearing pose serious threats to the avifaunal population and the ecological balance of the wetland ecosystem. Based on these findings, the study recommends continuous monitoring and the implementation of effective conservation strategies. Public awareness campaigns and better management practices are necessary to preserve Dagona Waterfowl Sanctuary as a vital habitat for both resident and migratory bird species.