Line-transect data may not produce reliable estimates of interannual sex-ratio and age structure variation in West African savannah ungulates

Adult sex ratios and age structures are important wildlife populationparameters, but they have been poorly investigated in ungulate species in West Africansavannahs. We used line transects to investigate these parameters in 11 ungulates froma protected area in south-western Burkina Faso during the period 2010-2018. Wecreated an empirical model of "detectability" for each species based on its mainecological characteristics (habitat and group size) and body size, and then comparedthe observed interannual inconsistency in sex ratios and age structures with the a prioridetectability score. Six out of 11 species showed low interannual inconsistency in sexratio and age structure. In 82% of the study species, however, the predicteddetectability score matched the observed score, with two exceptions being Tragelaphusscriptus and Sincerus caffer