The distinctions between a predator's diet, its prey-choice behaviour and its preferences are illustrated in a study of Aelurillus muganicus, a salticid spider from the Apsheron Peninsula in Azerbaijan. Laboratory experiments showed that A. muganicus has an innate predisposition to choose ants as prey. The natural diet of this species was determined by sampling individuals seen feeding in the field (n= 64). Ten arthropod orders were represented. Seven were from the class Insecta (Coleoptera, Collembola, Diptera, Heteroptera, Homoptera, Hymenoptera, Lepidoptera) and three from the class Arachnida (Acari, Araneae, Pseudoscorpiones). Collectively, four orders accounted for >70% of the prey records: Hymenoptera (20%), Lepidoptera (19%), Acari (19%) and Homoptera (14%). No other order accounted for >10% of the prey records. Of the 45 insects among the prey, 13 (29%) were Hymenoptera, with ants (family Formicidae) alone accounting for 24% of the prey records. Although ants were the preferred prey of A. muganicus, as revealed by laboratory testing, and also the most common single category of prey from the field prey records, records of A. muganicus feeding on prey other than ants were actually more common than records of it feeding on ants, suggesting that, besides prey choice, other factors have a strong influence on the diet of this species.