查看文章

The diet of four sympatric anurans species was studied, from October 1998 to November 1999, in a temperate Neotropical environment (Espinas Stream, Maldonado, Uruguay). A total of 387 individuals were collected and their stomach prey content, examined (186 Physalaemus gracilis, 88 Leptodactylus ocellatus, 96 Hyla p. pulchella and 17 Bufo gr. granulosus). The main prey items were: coleopterans, spiders and acari for L. ocellatus; dipterans, spiders, coleopterans, hemipterans, and acari for H. p. pulchella; formicids for B. gr. granulosus; and collembolans, acari and formicids for P. gracilis. Leptodactylus ocellatus and H. p. pulchella showed the highest diet amplitude, P. gracilis occupied a middle position, and B. gr. granulosus presented the lowest diet amplitude value. According to prey items attributes, a sit-and-wait foraging strategy is proposed for L. ocellatus and H. p. pulchella, and an active capture strategy for B. gr. granulosus. Seasonal analysis indicated that, except for P. gracilis, all the other predator species increased their diet richness during the cold season, mainly because each predator included new preys. This result, probably related to seasonal changes in prey availability, may indicate that species trophic behavior change along the year, and so, do not allow to locate a species in fixed place between generalist and specialist extremes.