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During the flooding of primary lowland rain forest by the filling of a hydroelectric reservoir in French Guiana, live-trapping was conducted on 175 subsequently formed islands. Different factors affecting the mammal trap efficiency were analysed. The main results show the real complexity of the sampling problem and the influence of the habitat disturbance due to the flooding. The location and/or the type of traps influenced captures of Dasypus novemcinctus, Proechimys spp., Metachirus nudicaudatus and Philander opossum in relation to their foraging and/or locomotion behaviour, and to to their size. The conformation of the islands (height and size) had no influence on the number of captures, nor on the species richness. The number of captures increased with the number of trapnights during the first water inflow and the level stretch. The best trapping success was observed during the wet season, when the strong habitat modification and the forest fragmentation became more significant. It resulted from the reduction of available land area and trophic resources. One year after the beginning of the water inflow, the decrease of the number of captures with the increasing number of trapnights reflected a real decrease of the number of mammals on the islands. The species richness increased with the number of trapnights in all periods, and was also the highest during the wet season.

Wetland ecosystems are highly biodiverse, essential to human health and well-being, and in decline, yet knowledge of the natural dynamics and distributions of wetland systems is lacking globally, hindering conservation efforts. We integrated data generated from novel remote-sensing techniques and Bayesian hierarchical modeling to estimate the daily surface area of 149 wetlands (vernal pools) over a 20-year period. We used these data to quantify the proportion of pools found suitable for local threatened and endangered species, and we discuss how to apply these methods to help answer fundamental ecological questions. Our modeling approaches, which can be applied to many kinds of wetlands and other freshwater systems, expand our ability to understand hydrologic dynamics across scales relevant to species, populations, and ecosystems, as well as to human needs, concerns, and decision making.

The Giant Gartersnake (Thamnophis gigas) is a low density visually evasive species with a low detection probability based on standard field survey methods (e.g., traps, visual census). Habitat loss has resulted in extirpations or serious declines for T. gigas populations throughout the southern two thirds of its historic range. Uncertainty regarding its current distribution and occupancy present management challenges for the species. Enhancing survey sensitivity through development of environmental DNA sampling (eDNA) methods would improve compliance monitoring under the Endangered Species Act, recovery planning for T. gigas, and evaluation of California’s Central Valley tule marsh habitat on which this species depends. To address these needs, we designed and validated diagnostic quantitative Polymerase Chain Reaction (qPCR) assays for identifying portions of the Cytochrome B (CytB) and the Nicotinamide adenine dinucleotide (NADH) dehydrogenase subunit 4 (ND4) genes of the T. gigas mitochondrial genome. The designed ND4 qPCR assay was not specific to T. gigas DNA and amplified DNA from a closely related and spatially co-occurring Thamnophis species (T.s. fitchi). The CytB T. gigas qPCR assay proved specific to a species level with a sensitivity that reliably detected T. gigas DNA at a concentration of 2.0x10-5 ng μL-1. To assess detection range, coordinated field sampling was conducted at aquatic sites with an observed and documented population of T. gigas. The T. gigas qPCR assay reliably detected DNA from samples taken 300m downstream from the known source. We then used environmental eDNA sampling and qPCR analysis to augment unsuccessful trap surveys in the southern range of T. gigas and detected DNA in 28 of the 52 locations sampled, confirming that T. gigas was still present at some sites where physical trapping failed to identify presence. QPCR-based DNA detection coupled with eDNA sampling methods provides an effective means to obtain critical population metrics from this otherwise cryptic, federally protected and hard to study organism, offering great promise for elucidating patterns of occupancy with greater efficiency and at far less cost than trapping methods, particularly where detection probabilities are low.

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