The Use of Large-Scale Remote Sensing and Map Data to Determine Steppe Land Bird Distributions in Baixo Alentejo, Portugal


The cereal pseudo-steppes of Iberia, resulting from a rotating low intensity farming system, maintain significant numbers of several threatened steppe landbird species, such as the Great Bustard (Otis tarda), Little Bustard (Tetrax tetrax) and Calandra Lark (Melanocorypha calandra). Loss and degradation of habitat related to recent land use practises, such as agricultural intensification, have resulted in a general decline in the populations of these species and a contraction in their distribution. GIS-based Habitat Suitability Index models were used to determine the potential distribution of five critical species in the Baixo Alentejo region: Great Bustard, Little Bustard, Calandra Lark, Montagu’s Harrier (Circus pygargus) and Stone Curlew (Burhinus oedicnemus). For this purpose, presence and absence data was collected for all five species and combined with AVHRR satellite imagery data, a Digital Elevation Model, and road, river and town map data in a GIS matrix. As a result, habitat-based distribution modeling techniques can now be used for monitoring changes in the distribution of these species and their habitats.

Journal of Ornithology