Predictive models for lesser kestrel Falco naumanni distribution, abundance and extinction in southern Spain

Environmental variables measured on 1:10,000 to 1:3,000,000-scale maps of southern Spain were used to build generalized linear models for presence/absence of lesser kestrel Falco naumanni colonies, extinction of colonies, and number of breeding pairs, in 6x6 km squares. Presence of breeding colonies in a square was positively associated with presence of urban areas, extent of non-irrigated cereal and sunflower crops, and mean annual rainfall, and negatively associated with extent of scrubland and forests. The model was statistically robust and had good predictive ability, correctly classifying 84% of the squares. Two alternative models were obtained for extinction of lesser kestrel colonies in a square. The first indicated extinctions where there were large areas of scrubland and low annual rainfall, and the second where there were very large or very small areas of non-irrigated cereal and sunflower crops. Although both were statistically significant, neither was very robust or had a good predictive ability. The number of lesser kestrel pairs breeding in a square showed a negative relationship with altitude, area of forest, and irrigated cultures, and a positive association with total length of rivers and streams. This model was not very robust and explained only 30.3% of the variance in kestrel numbers. The models indicate that some climatic and land-use variables, as measured on the available maps, are good predictors of the presence of lesser kestrel colonies in southern Spain, but less good at predicting the probability of extinction of colonies or the number of breeding pairs. (C) 1997 Published by Elsevier Science Ltd.