Significant decline of an endemic bustard in the Canary Islands

Abstract

Abstract The declines of species are caused by a combination of factors that affect survival or breeding success. We studied the effects of a set of environmental and anthropogenic variables on the disappearance of African houbara bustards Chlamydotis undulata fuertaventurae on Fuerteventura (Canary Islands), once the main stronghold of this endangered bird. Of 83 male display sites detected in 1997-1998, only 29 remained occupied in 2020-2021 (65% decrease in only 23 years). We compared habitat quality, density of conspecifics, other steppe birds and crows, presence of human infrastructure, and degree of environmental protection between these 29 extant sites and the 54 extinct sites using univariate analyses and generalised linear models. The most influential variable in the abandonment of display sites was the Normalised Difference Vegetation Index (NDVI), used as an indicator of food resources available to the species, which suggests a strong effect of aridification due to climate change on the species’ extinction process. Power line density was the second most important factor. This suggests that hubaras have survived where higher vegetation productivity has enabled a higher breeding success, and powerline fatalities have caused lower mortality. Higher densities of houbaras, other steppe birds and crows at extant display sites confirmed the better habitat quality in these areas. Extant display sites, located generally in protected areas, had also lower densities of human infrastructure (buildings, roads). We discuss the conservation implications of these results and provide management recommendations for this endangered subspecies.