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International audience; River floodplains are disturbance-dominated landscapes where floods are major regulators of both aquatic and nearby terrestrial communities. Amphibians are common inhabitants of floodplains and their life cycle depends on both aquatic and terrestrial habitats. We focused on how different syntopic species of amphibians reacted to the environmental conditions of a large river floodplain. We examined life-history traits such as population age structure and growth in small- and large-bodied species of anurans and urodeles in the lower Danube River floodplain in Romania. Two newt species, Triturus vulgaris (small-bodied) and Triturus dobrogicus (large-bodied), and two anuran taxa, Bombina bombina (small-bodied) and the Rana esculenta complex (large-bodied), were included in the study. The ages of individuals estimated by skeletochronology varied from 3 to 5-6 years for T. vulgaris and from 2-3 to 4-5 years for T. dobrogicus. In the anurans, ages varied from 2 to 5 years in B. bombina and from 4 to 10 years in the R. esculenta complex. The numbers of breeding opportunities (i.e., the number of years the adults reproduce) are similar in both newt species (3), while growth rates and age at maturity differ between the large- and small-bodied species. In anurans, the number of breeding opportunities for the smallest species, B. bombina (4), is associated with a high growth rate and earlier maturation. In the larger R. esculenta complex, the higher number of breeding opportunities (7) is associated with a low growth rate and delayed maturation. The study of age distribution and associated parameters provides useful information on population life history. We discuss how age structure and growth of amphibian populations in large river floodplains can be used as indicators of environmental conditions.

International audience; Compared to other vertebrate groups, movement patterns and microhabitat use in amphibians has been little studied. The two goals of this study were (1) to compare two different methods of tracking amphibians (implantable transmitters and fluorescent pigments); and (2) to characterize movement patterns and habitat use in the nocturnal, fossorial spadefoot toad (Pelobates fuscus) A fluorescent pigment method was useful for microhabitat studies, as trails could be detected in all kinds of terrestrial habitats, even under wet conditions Using this method it was possible to trace complete nocturnal movement patterns (maximum distance moved 73 m). Implantable transmitters were particularly appropriate for fossorial species, such as Pelobatesfuscus. Diel home range and microhabitat preferences were more precisely defined using a combination of telemetry and pigments. In addition, the vertical component of habitat use could be assessed. The spadefoot toad was more likely to use areas of bare soil or short vegetation and seemed to avoid shrub-covered areas. Mean distance moved between two successive burrows was higher in females (22.9 m) than in males (12.9 m).