Diet Specialization in Small Vertebrates: Mite-Eating in Frogs

• Published in: Oikos 1991-06, Vol.61 (2), p.263-278
• Main Authors: Simon, Martin P., Toft, Catherine A.
• Format: Article
• Language: English
• Subjects: Acari; Amphibians; Animal and plant ecology; Animal, plant and microbial ecology; Animals; Ants; Anura; Autoecology; Biological and medical sciences; Diet; Food; Forest litter; Freshwater; Frogs; Fundamental and applied biological sciences. Psychology; Mini-Review; Mites; Plant litter; Reptilia. Amphibia; Stomach; Taxa; Vertebrata
• ISSN: 0030-1299; 1600-0706
• DOI: 10.2307/3545344

This study examines the morphological, taxonomic, ecological, and ontogenetic correlates of mite-eating (acariphagy) in anurans to increase our understanding of diet specialization in vertebrate "insectivores." In a review of the literature (Part I), mites were abundant in terrestrial habitats at many locations worldwide, yet mites are not commonly reported as prey in anuran diets. In a detailed study of tropical ground-dwelling anurans (Part II), the diets of all species included mites. In both the literature review and detailed study, mites constituted up to 45% of the diet (by number) of some species. In the paleotropics, at one montane cloud forest site in New Guinea, frogs ate mites in the same high proportions (45%) as they occurred in the substrate. In the neotropics, certain small anurans specialized on mites, in that they ate mites in higher proportions than occurred in the leaf litter (proportion of mites in the diet and in the environment was lower at these locations than at the New Guinea site). Neotropical mite specialists included juveniles of several species and adults of small dendrobatids in the genus Minyobates. Mites in the neotropics apparently constitute prey equivalent to ants and are included on the small end of the size continuum by species in the "ant-specialist" guild. We hypothesize that mites, like ants, present low costs of search and pursuit because they are abundant and slow-moving relative to anuran predators. The trade-off, however, is that these prey contain a higher proportion of chitin and are therefore costly to digest (e.g., require special enzymes, slow rate of passage) as primary prey. Nothing is known of the digestive physiology of anurans that specialize on mites and ants.