Habitat degradation due to hydropower development within protected areas has a marked negative effect on resident wildlife species. However, efforts to develop appropriate conservation and management plans are hampered by a general lack of quantitative information and a poor understanding of relevant ecological constraints. Great Argus Argusianus argus, a large galliform species sensitive to habitat degradation, can reflect the impacts of the Chiew Larn reservoir in southern Thailand on local wildlife. Great Argus abundance in the remaining lowland areas of Khlong Saeng Wildlife Sanctuary (KSWS) was estimated using line transects along the Chiew Larn reservoir edges and in the forest interior between February and April 2017. The population estimate for KSWS was 108 individuals (95% CI: 41–272) based on the sampled area of 18.06 km2, with a density estimate of 5.9 calling males/km2. The abundance increased with increased distance from the reservoir shoreline, which might be related to the high level of direct and indirect human disturbance close to the hydropower reservoir.

The clouded leopard Neofelis nebulosa is a potent ambassador species for conservation, occurring from the Himalayan foothills eastwards to Indochina, between which Myanmar is a biogeographical land bridge. In Myanmar's Northern Forest Complex, the species co-occurs with the tiger Panthera tigris, leopard Panthera pardus, marbled cat Pardofelis marmorata, golden cat Catopuma temminckii and leopard cat Prionailurus bengalensis. We deployed cameras within the Htamanthi Wildlife Sanctuary over 2 consecutive years. In 2014–2015 we deployed 82 camera stations around the Nam Pa Gon stream (Catchment 1) for 7,365 trap days. In 2015–2016 we deployed 80 camera stations around the Nam E Zu stream (Catchment 2) for 7,192 trap days. In Catchment 1 we identified five tigers from 26 detections, five clouded leopards from 41 detections (68 photographs) and 11 marbled cats from 13 detections. Using Bayesian-based spatial capture–recapture we estimated the densities of tigers and clouded leopards to be 0.81 ± SD 0.40 and 0.60 ± SD 0.24 individuals per 100 km2, respectively. In Catchment 2 we identified two tigers from three detections, nine clouded leopards from 55 detections and 12 marbled cats from 37 detections. Densities of clouded leopards and marbled cats were 3.05 ± SD 1.03 and 8.80 ± SD 2.06 individuals per 100 km2, respectively. These differences suggest that human activities, in particular gold mining, are affecting felid populations, and these are a paramount concern in Htamanthi. We demonstrate the importance of Htamanthi within the Northern Forest Complex and highlight the Yawbawmee corridor as a candidate for protection.

The Green Corridor of Argentina and Brazil is the largest forest remnant of the Upper Paraná Atlantic Forest. The jaguar population of this region is highly fragmented and reduced. To assess the status of the subpopulation of jaguars of the Green Corridor we conducted four camera-trap surveys in three sites with different levels of protection. At Urugua-í (34 stations, 1,495 trap-days) we recorded one individual (minimum density = 0.12–0.33 per 100 km2). At Yabotí Biosphere Reserve (42 stations, 1,871 trap-days) we recorded two individuals (minimum density = 0.11–0.25 per 100 km2). At Iguazú National Park we conducted two surveys. In 2004 (39 stations, 1,839 trap-days) we recorded four adult individuals, estimating a density of between 0.49 ± 0.16 and 1.07 ± 0.33 per 100 km2. In 2006, we increased the area sampled (47 stations, 2,059 trap-days) and recorded 11 adult individuals, estimating a density of 0.93 ± 0.2 to 1.74 ± 0.34 per 100 km2. These density estimates are the lowest recorded for the species. Estimates for Iguazú are between 2–7.5 times lower than those reported in the early 1990s. This population decline probably results from the interaction of several factors, including lack of prey as a result of poaching and persecution. We estimate that there is currently a population of 25–53 adult jaguars in the Green Corridor. In spite of having sufficient potential habitat available this population is threatened and urgent conservation action is required.

Abundance of floor-dwelling frogs was studied in the humid subtropical lowland forest of Iriomote Island, the Ryukyu Archipelago, southern Japan. Field survey was conducted monthly for 1 y, and the seasonal pattern of abundance was examined for each species. We observed 251 frogs belonging to four species of three families in a total sampling of 600 m2. Of these species, Microhyla ornata (66.5% of total frogs) and Fejervarya limnocharis (30.3%) were dominant in number. Total abundance of the frogs was strongly seasonal and peaked in the hottest month, August, while the number of frog species was one to three throughout the year. The seasonal pattern of abundance showed considerable variation among species, most likely due to their differences in reproductive season, and in physiological characteristics under the influence of varying temperature and rainfall. These patterns are more similar to those of temperate species than those of tropical species. The estimated density of all frogs ranged from 0.08 to 1.60 individuals m−1, and their average annual density and biomass were 4180 individuals ha−1 and 11460 g ha−1, respectively. These values, among the highest so far reported for floor-dwelling anurans, may be a feature of amphibian fauna in the humid subtropical forests on a small island.

Despite its wide use in terrestrial ecology, distance sampling is as yet rarely used in underwater visual censuses. The present study attempts to compare density estimators based on distance sampling and on strip transects. Three stations with increasing densities of Chaetodontidae and Pomacanthidae were sampled twice by two divers of unequal experience, using two different transect types. A total of 96 transects and 2970 records of Chaetodontidae and Pomacanthidae were analysed. Nine estimators based on distance sampling were calculated and only the best fit (DT estimator) was kept for comparison with other estimators. These were either based on the average distance of the fish to the transect (AD estimator), or a 3-m- or 5-m-wide strip transect estimator (FW3 and FW5, respectively). There were no significant differences between the means found by DT, AD and FW3. Lower density estimates were given by FW5 in all cases. FW3 and FW5 did not detect several significant differences between stations which were otherwise detected by DT or AD. The number of transects needed to detect a significant difference between stations was four to ten times higher with FW3 or FW5 than with DT or AD. Diver experience was found to be a significant factor in density estimates. However, this factor was less important than the choice of the density estimator. Transect type or the day of sampling had no consequence for the estimates. The distance distributions of fish were divided into three different patterns which may be explained by a combination of detectability function and a behavioural component.