The use of sighting data to analyse Iberian lynx habitat and distribution

1. Over a large part of its very restricted and fragmented range, Iberian l ynx Lynx pardinus occur in remote mountainous country at low density, where the only information about the species comprises records of incidental sig htings obtained by inquiry. In this study we developed an approach for quan tifying lynx-habitat relationships and distribution patterns from sighting data, using records from western Algarve (Portugal) in 1990-95. 2. Habitat was described in terms of land cover, topography, human disturba nce and rabbit abundance, in 25-km(2) cells surrounding lynx sightings and at random locations within the study area. 3. Lynx sightings were consistently associated with predictable habitat fea tures. Sighting probabilities estimated from a logistic regression model in creased with the abundance of rabbits and the proportion of land covered by tall Mediterranean maquis, and declined with road density and the amount o f developed land. This model identified correctly 85.7% of lynx sightings; at the same time only 20.7% of the random locations were misclassified. 4. Indices of human presence were never associated positively with lynx sig htings, suggesting that observation patterns were not influenced by the spa tial distribution of potential observers. 5. Kriging was used to interpolate spatially between sighting probabilities derived from the logistic model in order to produce a map of sighting pote ntial for the Iberian lynx in western Algarve. Jack-knife resampling assess ed the accuracy of this map. Three well-defined areas of high sighting pote ntial were identified, probably representing the lynx core areas in this re gion. 6. Our analysis of lynx sighting records suggests that these data may provi de a first approximation to lynx habitat and distribution when further info rmation is lacking. The application of this approach to other ran and reclu sive species is discussed.