Spatio-Temporal Dynamics and Species Richness of Vertebrate Road Mortality on Four Major Highways in Jigawa State, Nigeria

Abstract

Vertebrate roadkill is a growing conservation concern in Nigeria, yet baseline data from Sahelian regions such as Jigawa State remain scarce. This study examined the spatio-temporal dynamics of vertebrate road mortality and species richness on four major highways in Jigawa State: Dutse–Jahun–Gujungu, Dutse–Ringim, Dutse–Balagu–Kafin Hausa, and Dutse–Birnin Kudu. Weekly surveys were conducted from a slow-moving vehicle (≤40 km/h) over six months with some randomly additional trips within the months (1 April to 30 September 2025), spanning the dry and wet seasons and covering 4,800 km. Carcasses were identified to the lowest possible taxonomic level and geo-referenced using GPS. A total of 246 vertebrate roadkills were recorded: mammals (58.9%), amphibians (19.9%), reptiles (17.1%), and birds (4.1%). Roadkill frequency differed significantly among taxa between seasons (χ² = 62.71, df = 9, p < 0.001), and mortality was significantly higher in the wet season (178 individuals, 72.4%) than in the dry season (68, 27.6%) (χ² = 49.19, df = 1, p < 0.001). The Dutse–Ringim highway was the deadliest, accounting for 42.3% of records. Mammals showed the highest species richness and abundance, with the four-toed hedgehog (Atelerix albiventris) and Egyptian toad (Sclerophrys regularis) contributing the largest wet-season increases. Although the affected species are not currently classified as globally threatened, sustained, localised road mortality poses long-term ecological risks. These baseline data can guide conservation policy, road planning, and mitigation measures such as speed regulation, wildlife crossings, and season-specific interventions.