Seasonal Variation, Habitat Protection, and Disturbance Influence Bird Assemblages in a Tropical Guinea Savannah

IntroductionSeasonality and anthropogenic disturbance are key drivers of avian community structure in tropical savannah ecosystems, yet their effects on taxonomic and functional diversity across protected and unprotected landscapes remain insufficiently understood, especially in Nigeria. We examined how seasonal variation and human disturbance shape bird assemblages at different site protection statuses in the Nigerian Guinea savannah.MethodsWe conducted point count surveys across four stratified habitats (forest, woodland, grassland, and riverside) at four sites in the Guinea savannah of Nigeria, covering dry and wet seasons, and protected and unprotected sites. Patterns in taxonomic richness, diversity, functional richness, and functional diversity were analyzed alongside quantified indices of anthropogenic disturbance.ResultsDuring the wet season, taxonomic richness and diversity were higher, whereas functional metrics, especially functional richness, were lower. Unprotected sites supported higher taxonomic richness and diversity, particularly in the dry season. In contrast, protected sites, despite lower species richness, retained broader functional trait representation. An increase in anthropogenic disturbance resulted in declines in both taxonomic and functional richness across all sites, with particularly steep losses in functional richness within protected areas.DiscussionWe provide evidence of a complex influence of seasonality, protection status, and anthropogenic disturbance on avian communities in the Nigerian Guinea savannah, revealing notable divergences between taxonomic and functional diversity metrics. Higher wet-season taxonomic diversity and richness, with contrasting functional richness and diversity, reflect increased resource availability and favourable breeding conditions and a decoupling between species richness and functional roles, respectively. Observable higher taxonomic metrics and yet a high functional redundancy at the unprotected sites may indicate dominance by disturbance-tolerant generalist species with overlapping ecological roles. Furthermore, the observable steeper decline in functional richness within protected sites highlights that these sites are more affected by disturbance than the more human-modified unprotected sites. Our findings demonstrate that reliance on taxonomic metrics alone may obscure functional erosion within bird communities and emphasize the need for landscape management and monitoring focused on functional and taxonomic dimensions of biodiversity coupled with the influence of seasonal dynamics and disturbance to ensure long−term ecosystem resilience.