Abyssinian Blue-winged Goose <i>Cyanochen cyanoptera</i> Rüppell, 1845 population size, distribution, and habitat association in the central-south highlands of Ethiopia

Abstract

The endemic and threatened Abyssinian Blue-winged Goose Cyanochen cyanoptera is restricted to the Ethiopian highlands, yet its population ecology and habitat use remain limited. This study assessed population size, spatial and temporal distribution, and habitat utilization across wetlands in the central-south highlands of Ethiopia over three consecutive years (2015–2018). Population counts were conducted using the total count method, and data were analysed in Jamovi (v2.5.6) and R (v4.5.1). Mean population counts varied significantly across months, with peak abundance in August (3,136 ± 105 individuals) and the lowest in May (420 ± 24 individuals). Generalized linear mixed models indicated that habitat type and season significantly influenced abundance, while random effects of sites (ICC = 0.682) and month (ICC = 0.141) accounted for substantial unexplained variation. Model-adjusted estimates showed significantly lower abundance in farmland habitats (39.9 geese, 95% CI: 19.3, 82.1) compared with shoreline (63.4 geese, 95% CI: 30.7, 131, ratio = 0.63, z = -5.37, p < 0.001) and grassland (69.8 geese, 95% CI: 33.9, 143.7, ratio = 0.57, z = -6.95, p < 0.001), with no significant difference between the latter two (ratio = 0.91, z = -1.09, p = 0.52). Habitat use showed strong seasonal variation (p < 0.001), with increased reliance on farmland during the dry season and preference for shoreline and grassland habitats during the wet season, reflecting seasonal plasticity. Although the overall population appears to be stable, its distribution is highly dynamic and driven by resource availability and specific habitat preferences. Increasing conversion of wetlands and communal grazing lands into agricultural fields has reduced core habitats, altering traditional land-use systems and intensifying human–geese interactions. These findings underscore the importance of wetland size, habitat quality, and socio-ecological drivers in shaping the distribution of C. cyanoptera. The long-term persistence of this range-restricted species will depend on protecting key wetlands and promoting sustainable land-use practices that balance conservation with local livelihoods.