Arabian and Nubian bustards are among the largest flying birds, yet their ecology across Sahelo-Saharan regions is virtually unknown. Both species are experiencing moderately rapid population declines as a result of habitat destruction and poaching. Understanding their spatial and geographic distribution, as well as their habitat requirements, is critical for their conservation. We combined field surveys conducted over a 15-year period (2001-2016) in Chad and Niger with remotely sensed variables of vegetation greenness (NDVI) and surface roughness (derived from SRTM elevation data) to predict the spatial and temporal distribution of bustard locations (Arabian and Nubian). Data were formulated in a generalized linear model framework to: (a) identify the influence of environmental factors on species habitat requirements; (b) investigate niche differentiation; and (c) identify suitable habitat throughout the study area. We included temporal variables, year and season of the survey, to identify potential changes in bustard presence.
Results/Conclusions
Arabian and Nubian bustards were observed to have strong shifts in their distributional ranges. Data also provide evidence of significant declines in the occurrence of both species. In particular, Arabian bustards appear to prefer areas with intermediate levels of greenness and prefer areas of low terrain roughness, valley bottoms. Prevalence did not change across seasons. In contrast, Nubian bustards appear to be more prevalent during the dry season, compared to cold and wet seasons. Nubian bustards also preferred lower levels of greenness (hyper-arid conditions) than Arabian bustards, and areas of low to mid terrain roughness. These results highlight differences in habitat requirements of each species, which may help in improved conservation management plans. Our study provides a first step in fulfilling a critical knowledge gap of the ecology of these species, as well as the first spatial assessment of Nubian and Arabian bustards’ habitat and distribution.