The use of visual and automatized behavioral markers to assess methodologies: a study case on PIT-tagging in the Alpine newt

peer reviewedBiomarkers are now widely used as tools in various research fields to assess individual integrity. The recent advances in quantification methods of behavioral patterns, such as computerized video-tracking procedures, make them valuable biomarkers. However, the corollary of these novelties is that they remain relatively unknown and unused. In this study, we show that such tools can assess the validity of research methods, such as individual recognition. To demonstrate this we employed as a model a marking method (Passive Integrate Transponders: PIT-tagging) widely used in amphibians. Both detailed visual observations and video-tracking methods were complementary in highlighting components at different behavioral scales: locomotion, feeding, and breeding. We illustrate the scientific and ethical adequacy of the targeted marking method but also suggest that more studies should integrate behavioral analyses. Such biomarkers are a powerful tool to assess conservation concerns when other techniques cannot detect detrimental effects

Survival and Breeding Frequency in Marbled Salamanders (Ambystoma opacum): Implications for Spatio-temporal Population Dynamics

Despite known population-level sensitivity to adult vital rates, there is a shortage of robust estimates of adult survival and breeding frequency for pond-breeding amphibians. Evaluating the applicability of metapopulation principles to amphibians has also been constrained by the lack of demographic studies scaled beyond individual breeding populations. We investigate spatial and temporal demographic variability among six proximate breeding populations of Marbled Salamanders (Ambystoma opacum) in western Massachusetts, USA, focusing on the terrestrial adult life stage. Between 1999 and 2004, we captured and photographed approximately 1700 breeding adults, each between one and 12 times, at drift fences encircling breeding sites. After constructing individual capture histories from field data, we applied maximum likelihood approaches to estimate parameters for survival in the pond basins during breeding periods, survival in upland habitat during breeding and non-breeding periods, and both breeding and capture probabilities. Models selected using Akaike’s Information Criteria suggested that there was moderate variability in pond survival across years, but that generally, pond and upland survival varied little among populations within years. This suggests that asynchronous variability indicative of metapopulation dynamics is unlikely to be significant in the adult stage, at least among nearby populations in similar upland forests. An integrated measure of annual survival was 0.66 (SE = 0.02) for males and 0.62 (SE = 0.01) for females. Average breeding probabilities were very high (0.96; SE = 0.01) for males and high (0.67; SE = 0.02) for females, resulting in estimates of 2.5 and 2.0 lifetime breeding attempts, respectively. These parameter estimates will be used to develop spatially explicit population models to guide conservation and forest management strategies for A. opacum and other pond-breeding amphibians with similar life histories. Additional empirical work that estimates the effects of alternative management strategies on these vital rates will greatly improve the utility of these models

Impact of Beaver Dams on Abundance and Distribution of Anadromous Salmonids in Two Lowland Streams in Lithuania

European beaver dams impeded movements of anadromous salmonids as it was established by fishing survey, fish tagging and redd counts in two lowland streams in Lithuania. Significant differences in abundancies of other litophilic fish species and evenness of representation by species in the community were detected upstream and downstream of the beaver dams. Sea trout parr marked with RFID tags passed through several successive beaver dams in upstream direction, but no tagged fish were detected above the uppermost dam. Increase in abundances of salmonid parr in the stream between the beaver dams and decrease below the dams were recorded in November, at the time of spawning of Atlantic salmon and sea trout, but no significant changes were detected in the sections upstream of the dams. After construction of several additional beaver dams in the downstream sections of the studied streams, abundance of Atlantic salmon parr downstream of the dams decreased considerably in comparison with that estimated before construction