Assessment of species composition, morphological characteristics and conservation threats of bats within Lokoja metropolis in Kogi state

Abstract

This study assessed bat species composition, morphological characteristics and conservation threats within Lokoja Metropolis, Kogi State, Nigeria. Field surveys were conducted across eight urban sites between June and October 2025. Data were collected through mist netting, using nets of 12 m by 2.7 m with 36 mm mesh, at three rooftop survey sites during nocturnal sampling sessions from 18:00 to 23:00 and 04:00 to 06:30 hours, and through camera based dislodgement counting at five treetop survey sites. Morphological measurements were recorded for captured individuals, while threats were assessed through direct observation, community interviews and review of land use change evidence. A total of 255 bats representing two taxa were detected: Eidolon helvum (Pteropodidae), with 180 individuals representing 70.59 percent of the catch, and Scotophilus nigrita (Vespertilionidae), with 75 individuals representing 29.41 percent. Eidolon helvum was detected only at the sampled treetop sites and Scotophilus nigrita only at the sampled rooftop sites. Because mist netting was applied at rooftop sites and camera counting at treetop sites, this complete separation is confounded with survey method and is reported as a feature of the sampling design rather than as evidence of ecological partitioning. Species diversity was low, with a Shannon-Wiener index of 0.606, a Pielou evenness of 0.874 and a Simpson dominance of 0.585, placing the assemblage well below the range reported for forest and savannah habitats in the region. Sex composition differed significantly between the two taxa, χ 2 (1) = 11.12, p < 0.001 with continuity correction. Eidolon helvum was male biased at a ratio of 1.57 to 1 and Scotophilus nigrita female biased at 1 to 1.68, and each departed significantly from parity. Seven threat categories were documented under the IUCN Unified Threat Classification System, of which habitat loss and urban expansion, roost disturbance and vegetation clearance were assessed as of high overall severity. The study concludes that the recorded richness of two species is a minimum estimate constrained by method, that the urban assemblage of Lokoja is impoverished and dominated by two ecologically flexible generalists, and that roost protection in both built structures and mature trees is the intervention most likely to retain what remains.