Evaluation of Weaver Birds (Ploceus cucullantus) as Bio-indicator of Contaminants in Benue State, North East and North West Agricultural Belts, Nigeria

Abstract

Contamination of heavy metals (Hg, Pb, As, Cr, Cd and Cu) in agricultural landscapes is a major threat locally, regionally and globally because it affects the structural and functional properties of the farm environment. In this study, heavy metals were assessed in diverse organs, liver, kidney, feather, skin and bone of weaver birds (Ploceus cucullatus) trapped from six sites in Benue State, Northeast and Northwest agricultural belts using a mist net. The organs were digested and subjected to Flame Atomic Absorption Spectrophotometer (AAS) to determine the level of heavy metals bioaccumulation. The heavy metal concentrations differ with locations and among the organ and out of five organs (liver, kidney, bone, skin, and feathers), bone, skin and feather contained the highest concentration of heavy metals. In Gboko, bone stored Hg (5.240±0.012ppm), As, (2.458±0.005ppm), skin stored Hg (1.273±0.010ppm), As (0.445±0.005ppm), feather stored Hg (3.683±0.0019ppm), As(1.828±0.005ppm). In Makurdi, bone stored Hg (3.333±0.006ppm), As, (1.545±0.009ppm), skin stored Hg (1.158±0.006ppm), As (0.318±0.005ppm), feather stored Hg (2.713±0.006ppm), As, (1.515±0.009ppm) In Gwer, bone stored Hg(2.313±0.008), As(1.330±0.007ppm), skin stored Hg (1.768±0.010ppm), As(0.240±0.004ppm), father stored Hg (2.313±0.008ppm), As (1.318±0.005ppm). Some of the contamination pathways can be demonstrated based on correlation analyses due to antagonistic relationships (Pb, Cu), while as co-accumulation clusters (Cu, Hg, As). Random Forest classification of the organ-metal profiles provided 100% accuracy in site identification, indicating that each location had its own distinctive pollution fingerprints. The research shows that P. cucullatus species is a good bio-indicator of heavy-metal pollution and offers spatially relevant baseline information in assessing the impacts on environmental planning, pollution reduction, wildlife conservation, and conservation research in the agricultural belts of Benue State.