Prey Surveys Research Articles

Harnessing Drones for Snow Leopard Conservation

Censusing snow leopard prey species like argali, ibex or blue sheep, is time-consuming, expensive, and challenging. We tested thermal-sensor-equipped drones to census ungulate populations in Mongolia’s Ikh Nart Nature Reserve. In 2019 and 2022 we used drones to detect wild ibex and argali. Here we report on 2022 findings: ~400 km along 5 fixed transects totaling forty-three missions, including several double count surveys. Drones detected 259 prey animals and 265 livestock; on average, 34% of all sightings were in areas obscured by topographic features from ground-based observers. Overall, tests reinforced the utility of drones for counting ungulates, along with highlighting important issues and future advances for supporting largely autonomous prey surveys. We recommend biologists build upon existing technology to attain an inexpensive, easy to use, and field ready set of equipment and procedures that can reliably improve or replace traditional walking or transect count methods for large prey species.

Gray whale habitat use and reproductive success during seismic surveys near their feeding grounds: comparing state-dependent life history models and field data

We used a stochastic dynamic programming (SDP) model to quantify the consequences of disturbance on pregnant western gray whales during one foraging season. The SDP model has a firm basis in bioenergetics, but detailed knowledge of minimum reproductive length of females (Lmin) and the relationship between length and reproductive success (Rfit) was lacking. We varied model assumptions to determine their effects on predictions of habitat use, proportion of animals disturbed, reproductive success, and the effects of disturbance. Smaller Lmin values led to higher predicted nearshore habitat use. Changes in Lmin and Rfit had little effect on predictions of the effect of disturbance. Reproductive success increased with increased Lmin and with higher probability of reproductive success by length. Multiple seismic surveys were conducted in 2015 off the northeast coast of Sakhalin Island, with concomitant benthic prey surveys, photo-identification studies, and whale distribution sampling, thus providing a unique opportunity to compare output from SDP models with empirical observations. SDP model predictions of reproductive success and habitat use were similar with and without acoustic disturbance, and SDP predictions of reproductive success and large-scale habitat use were generally similar to values and trends in the data. However, empirical estimates of the proportion of pregnant females nearshore were much higher than SDP model predictions (a large effect, measured by Cohen’s d) during the first week, and the SDP model overestimated whale density in the south and underestimated density around the mouth of Piltun Bay. Such differences in nearshore habitat use would not affect SDP predictions of reproductive success or survival under the current seismic air gun disturbance scenario.

Diet and prey selection of clouded leopards and tigers in Laos.

In Southeast Asia, conservation of ‘Vulnerable’ clouded leopards (Neofelis nebulosa) and ‘Endangered’ tigers (Panthera tigris) might depend on the management of their preferred prey because large felid populations are limited by the availability of suitable prey. However, the diet of clouded leopards has never been determined, so the preferred prey of this felid remains unknown. The diet of tigers in the region has been studied only from one protected‐area complex in western Thailand, but prey preferences were not determined. To better understand the primary and preferred prey of threatened felids, we used DNA‐confirmed scats and prey surveys to determine the diet and prey selection of clouded leopards and tigers in a hilly evergreen forest in northern Laos. For clouded leopards, the primary prey was wild pig (Sus scrofa; 33% biomass consumed), followed by greater hog badger (Arctonyx collaris; 28%), small rodents (15%), and mainland serow (Capricornis sumatraensis; 13%; hereafter, serow). For tigers, the primary prey was wild pig (44%), followed by serow (18%), sambar (Rusa unicolor; 12%), and Asiatic black bear (Ursus thibetanus; 10%). Compared to availability, serow was positively selected by both clouded leopards (D = 0.69) and tigers (0.61), whereas all other ungulate species were consumed in proportion to the availability or avoided. Our results indicate that clouded leopards are generalist predators with a wide prey spectrum. Nonetheless, mid‐sized ungulates (50–150 kg) comprised nearly half of their diet, and were the preferred prey, supporting a previous hypothesis that the enlarged gape and elongated canines of clouded leopards are adaptations for killing large prey. Because serow was the only ungulate preferred by both felids, we recommend that serow populations be monitored and managed to help conservation efforts for clouded leopards and tigers, at least in hilly evergreen forests of Southeast Asia.

Food web perspectives and methods for riverine fish conservation

AbstractFood web analyses offer useful insights into understanding how species interactions, trophic relationships, and energy flow underpin important demographic parameters of fish populations such as survival, growth, and reproduction. However, the vast amount of food web literature and the diversity of approaches can be a deterrent to fisheries practitioners engaged in on‐the‐ground research, monitoring, or restoration. Incorporation of food web perspectives into contemporary fisheries management and conservation is especially rare in riverine systems, where approaches often focus more on the influence of physical habitat and water temperature on fish populations. In this review, we first discuss the importance of food webs in the context of several common fisheries management issues, including assessing carrying capacity, evaluating the effects of habitat change, examining species introductions or extinctions, considering bioaccumulation of toxins, and predicting the effects of climate change and other anthropogenic stressors on riverine fishes. We then examine several relevant perspectives: basic food web description, metabolic models, trophic basis of production, mass‐abundance network approaches, ecological stoichiometry, and mathematical modeling. Finally, we highlight several existing and emerging methodologies including diet and prey surveys, eDNA, stable isotopes, fatty acids, and community and network analysis. Although our emphasis and most examples are focused on salmonids in riverine environments, the concepts are easily generalizable to other freshwater fish taxa and ecosystems.This article is categorized under: Water and Life > Nature of Freshwater Ecosystems Water and Life > Conservation, Management, and Awareness Water and Life > Methods

The importance of species-specific survey designs: prey camera trap surveys significantly underestimate the detectability of endangered spotted-tailed quolls

The spotted-tailed quoll (Dasyurus maculatus) is an endangered marsupial carnivore that is often surveyed using camera traps. Camera trap surveys targeting quolls typically use meat-based lures and specific camera setups tailored to increase the probability of quoll detection. However, where quolls occur, they can also be incidentally detected as non-target species in camera surveys targeting small to medium-sized herbivorous or omnivorous mammals (‘prey’ surveys). We investigated whether quoll detectability using traditional ‘prey’ camera surveys could sufficiently approximate quoll detectability using targeted ‘quoll’ surveys, potentially enabling quoll data from prey surveys to be used in lieu of undertaking additional quoll-specific surveys. We used 50 Reconyx HC600 cameras to quantify and compare quoll detectability between prey and quoll surveys at each of two different sites. The number of quoll detections, number of individual quolls detected and the probability of quoll detection at both sites were significantly higher in quoll surveys than in prey surveys. Our findings suggest that prey surveys substantially underestimate quoll detectability, resulting in incomplete datasets. We therefore caution against using quoll detection data from prey camera trap surveys for anything other than incidental presence observations, to avoid misleading survey and management outcomes.

Diet, prey selection, and activity of Asian golden cats and leopard cats in northern Laos

AbstractThe Asian golden cat (Catopuma temminckii) occurs in small, declining, and highly fragmented populations throughout Southeast Asia, whereas the smaller leopard cat (Prionailurus bengalensis) is common and widespread. In contrast to leopard cats, little is known about the ecology of Asian golden cats, and resource partitioning between these species has not been studied. We used DNA-confirmed scats, camera-trap data, and prey surveys, to determine the diet, prey selection, and activity, of Asian golden cats and leopard cats in a protected area in northern Laos. The two felids had different diets: Asian golden cats consumed mostly ungulates (35% biomass consumed), murid rodents (23%), and carnivores (15%), whereas leopard cats consumed mostly murid rodents (79%). Asian golden cats were not random in their consumption of ungulates, because muntjac (Muntiacus spp.) were selectively consumed over larger ungulates, indicating muntjac were preyed upon rather than scavenged. Dietary overlap between the two felid species was moderate (R0 = 0.60), and the dietary niche breadth of Asian golden cats (B = 8.44) was nearly twice as high as that of leopard cats (4.54). The mean (± SD) scat diameter was greater for Asian golden cats (2.1 ± 0.3 cm) than leopard cats (1.8 ± 0.2 cm), although diameters of leopard cat scats were considerably larger than previously assumed for this species. The felid species differed in their activity patterns, because Asian golden cats were diurnal, whereas leopard cats were nocturnal, although they did not differ in their use of elevation, suggesting there was no habitat segregation. Overall, leopard cats appeared to coexist with Asian golden cats, a potential predator and competitor, by exhibiting dietary and temporal partitioning. Our results showed that muntjac were important prey of Asian golden cats, suggesting the management of muntjac might be important for conserving populations of Asian golden cats.

Diet and Prey Selection of Dholes in Evergreen and Deciduous Forests of Southeast Asia

ABSTRACTEndangered dholes (Cuon alpinus) are restricted to small and declining populations in Southeast Asia, and little is known about how their ecology differs within the region. We used DNA‐confirmed scats and prey surveys to determine the seasonal diet and prey selection of dholes in 2 different landscapes that dominate Southeast Asia: closed evergreen forests in hilly terrain in northern Laos, and open deciduous forests in relatively flat terrain in eastern Cambodia. On both sites, muntjac (Muntiacus spp.; 20–28 kg) was the dominant prey item and was selectively consumed over other ungulates in all seasons. Our findings differ from previous conclusions, based largely on studies from India, that the preferred prey weight range of dholes was either 40–60 kg or 130–190 kg. Other important prey were sambar (Rusa unicolor) in Laos, and wild pig (Sus scrofa) and banteng (Bos javanicus) in Cambodia. Seasonal differences in overall diet occurred in Laos, but not Cambodia, primarily because of an increase in livestock consumption. The mean number of dhole scats in group defecation sites was higher in Cambodia (5.9 ± 0.5 [SE]) than Laos (2.4 ± 0.2), suggesting pack sizes were larger in Cambodia. Our results suggest that regardless of land cover type, prey diversity, or pack size, the management of muntjac will be important for conserving dhole populations in Southeast Asia. In Laos, we recommend that local villagers remove livestock from the protected area during the hot‐dry season to reduce livestock predation by dholes. © 2020 The Authors. The Journal of Wildlife Management published by Wiley Periodicals LLC on behalf of The Wildlife Society.

Species recovery and recolonization of past habitats: lessons for science and conservation from sea otters in estuaries.

Recovering species are often limited to much smaller areas than they historically occupied. Conservation planning for the recovering species is often based on this limited range, which may simply be an artifact of where the surviving population persisted. Southern sea otters (Enhydra lutris nereis) were hunted nearly to extinction but recovered from a small remnant population on a remote stretch of the California outer coast, where most of their recovery has occurred. However, studies of recently-recolonized estuaries have revealed that estuaries can provide southern sea otters with high quality habitats featuring shallow waters, high production and ample food, limited predators, and protected haul-out opportunities. Moreover, sea otters can have strong effects on estuarine ecosystems, fostering seagrass resilience through their consumption of invertebrate prey. Using a combination of literature reviews, population modeling, and prey surveys we explored the former estuarine habitats outside the current southern sea otter range to determine if these estuarine habitats can support healthy sea otter populations. We found the majority of studies and conservation efforts have focused on populations in exposed, rocky coastal habitats. Yet historical evidence indicates that sea otters were also formerly ubiquitous in estuaries. Our habitat-specific population growth model for California’s largest estuary—San Francisco Bay—determined that it alone can support about 6,600 sea otters, more than double the 2018 California population. Prey surveys in estuaries currently with (Elkhorn Slough and Morro Bay) and without (San Francisco Bay and Drakes Estero) sea otters indicated that the availability of prey, especially crabs, is sufficient to support healthy sea otter populations. Combining historical evidence with our results, we show that conservation practitioners could consider former estuarine habitats as targets for sea otter and ecosystem restoration. This study reveals the importance of understanding how recovering species interact with all the ecosystems they historically occupied, both for improved conservation of the recovering species and for successful restoration of ecosystem functions and processes.

Prey colour biases in jumping spiders (Habronattus brunneus) differ across populations

AbstractPredators often avoid aposematic prey as a result of aversions to particular prey signals (e.g., bright colours and noxious odours). These aversions may be flexible, that is, they can be reinforced or extinguished with experience. As such, we might expect populations to differ in their biases against certain prey characteristics (e.g., colour or pattern) depending on the prey available in the community. Here, we tested whether the jumping spider, Habronattus brunneus(Salticidae), exhibits colour biases against red prey using choice tests with novel (artificially coloured) prey, and then went on to examine how these biases differ across four geographically distinct focal populations. We then conducted preliminary field surveys at each of these four sites to explore differences in habitat type and prey availability. Overall, we found that field‐caught H. brunneusexhibited a bias against the colour red (compared with black) when tested with artificially coloured prey in the laboratory. However, the degree of colour bias varied among our four focal populations (with two populations exhibiting strong biases against red and two showing no colour biases). Preliminary habitat and prey surveys suggest that these populations also differed in both habitat structure (percentage of grass, leaf litter and bare ground) and prey availability across many taxa, suggesting that the spiders from each population may have been exposed to, and had experiences with, different potential prey. We discuss how prey availability may influence colour biases in predators, as well as how predator experience may shape the evolution of prey colour signals.

Diving Behavior and Fine-Scale Kinematics of Free-Ranging Risso's Dolphins Foraging in Shallow and Deep-Water Habitats

Air-breathing marine predators must balance the conflicting demands of oxygen conservation during breath-hold and the cost of diving and locomotion to capture prey. However, it remains poorly understood how predators modulate foraging performance when feeding at different depths and in response to changes in prey distribution and type. Here, we used high-resolution multi-sensor tags attached to Risso’s dolphins (Grampus griseus) and concurrent prey surveys to quantify their foraging performance over a range of depths and prey types. Dolphins (N=33) foraged in shallow and deep habitats [seabed depths less or more than 560m, respectively] and within the deep habitat, in vertically stratified prey features occurring at several aggregation levels. Generalized linear mixed-effects models indicated that dive kinematics were driven by foraging depth rather than habitat. Bottom-phase duration and number of buzzes (attempts to capture prey) per dive increased with depth. In deep dives, dolphins were gliding for >50% of descent and adopted higher pitch angles both during descent and ascents, which was likely to reduce energetic cost of longer transits. This lower cost of transit was counteracted by the record of highest vertical swim speeds, rolling maneuvers and stroke rates at depth, together with a 4-fold increase in the inter-buzz interval, suggesting higher costs of pursuing and handling prey compared to shallow-water feeding. In spite of the increased capture effort at depth, dolphins managed to keep their estimated overall metabolic rate comparable across dive types. This indicates that adjustments in swimming modes may enable energy balance in deeper dives. If we think of the surface as a central place where divers return to breathe, our data match predictions that central place foragers should increase the number and likely quality of prey items at greater distances. These dolphins forage efficiently from near-shore benthic communities to depth-stratified scattering layers, enabling them to maximize their fitness.

Dietary niche differentiation facilitates coexistence of two large carnivores

AbstractAn animal's diet is an important attribute of its niche, and affects the role that it plays in the ecosystem. Comparing the diets of sympatric species reveals the level of dietary niche overlap between them, which can be used to gauge the potential for competition, as well as each species’ vulnerability to competitive exclusion. Because of a morphology adapted to predation, sympatric carnivores can have particularly aggressive and dangerous competitive interactions; the intensity of which may be directly related to the amount of overlap in prey species consumed. Using predator scat analysis and prey survey techniques, we analyze and compare the underlying mechanisms of prey selection – prey body size and group size – between sympatric populations of leopard Panthera pardus and lion Panthera leo, to test for possible means of competitive avoidance between them. Because leopard and lion differ in both size and social structure, we controlled for the differing prey handling ability of each species, and found that there was still a significant difference in mean prey body size preference between the two carnivores (P = 0.050), despite a relatively high level of dietary niche overlap (0.717). Both species avoid prey in larger groups, but the tendency is more pronounced for leopards. Where intraguild competitors overlap spatiotemporally, dietary niche segregation such as this may be a mechanism through which competition is avoided and, in the case of carnivores, could reduce the frequency of potentially costly interactions.

Landscape determinants of European roller foraging habitat: implications for the definition of agri-environmental measures for species conservation

Across much of Europe, farmland birds are declining more than those in other habitats. From a conservation perspective, identifying the primary preferred habitats could help improve the foraging conditions of target species and, consequently, enhance their breeding success and survival. Here, we investigated the ranging behaviour and foraging habitat selection of the European roller (Coracias garrulus) during the breeding season in an agricultural landscape of South Iberia. The occurrence of foraging rollers was predicted to gradually increase with decreasing distance from the nest and increasing availability of perches, such as fences and electric wires. Traditional olive groves and stubble fields were positively and negatively associated with the occurrence of rollers, respectively. Additionally, analysis of hunting strikes showed that rollers highly prefer foraging in fallows rather than cereal or stubble fields. Prey surveys revealed that fallows had the highest abundance of grasshoppers, rollers’ preferred prey during chick-rearing. Pair home-ranges, obtained from 95% fixed Kernel estimators averaged 70.9 ha (range = 34–118 ha) and most foraging trips (80%) occurred in the close vicinity of the nest (<500 m). Number of chicks fledged was not affected by mean foraging distances travelled during the chick-rearing period. Overall, our results suggest that traditional extensive practices of cereal cultivation, with large areas of low-intensity grazed fallows, represent a high-quality foraging habitat for rollers and should be promoted through agri-environmental schemes within at least 1-km radius from the nest. These recommendations are targeted at the roller, but have been shown to apply broadly to several other steppe-bird species.

Spatial Ecology of Armenian Vipers, Montivipera raddei , in Two Different Landscapes: Human-Modified vs. Recovered-Natural

Armenian Vipers, Montivipera raddei , have a range that includes Armenia and portions of eastern Turkey, western Azerbaijan, and northwestern Iran. They have a fragmented and restricted distribution that has been severely impacted by human activities, namely habitat alteration/degradation and over-collection for the pet trade, over the past 40 years. We used radiotelemetry to study and compare the spatial ecology of Armenian Vipers inhabiting a human-modified landscape near Abovian in Koytak Province and a recovered-natural landscape in Shikahogh State Reserve in Syunik Province. Radio-tracking at Abovian took place during 2008 – 2009 (8 males, 6 females) and during 2010 – 2012 at Shikahogh State Reserve (7 males, 4 females). Prey surveys were conducted at both sites to evaluate the abundance of small mammals. We found significant differences between the two populations in terms of home range size and mean movements. Home range and movements were significantly larger in the human-modified landscape. We found no difference in body condition between the two landscapes or a correlation between body condition and home range size. Prey abundance was significantly higher in the recovered-natural landscape. While the conservation of intact natural habitat should be given the highest priority, management strategies in agricultural landscapes should include both the inclusion of corridors to allow for movement between parcels of habitat and the maintenance of high quality habitat within these landscapes to provide cover and food for both small mammals and vipers.

Linking northern fur seal behavior with prey distributions: the impact of temporal mismatch between predator studies and prey surveys

An essential part of foraging ecology research is identifying how the distribution and abundance of prey influence predator behavior. However, in marine systems, temporal or spatial mismatches often exist between prey surveys and predator tracking periods, especially for species with large foraging ranges. Using northern fur seals (Callorhinus ursinus) as a model, we investigated how conclusions about predator–prey relationships change with increasing temporal disparity between predator tracking periods and prey surveys. To measure foraging behavior, northern fur seals (n = 20) from St. Paul Island (Alaska, USA) were equipped with satellite tracking transmitters and time-depth recorders from July to October 2006. Fur seal dive and movement metrics were examined in relation to the relative abundance of the fur seals’ primary prey, walleye pollock (Gadus chalcogrammus), reported from the annual eastern Bering Sea groundfish survey. Relationships between foraging behavior metrics and prey abundance were examined within the Bering shelf survey grid cells at three timescales: within 2 weeks of the prey survey, within 1 month, and over the northern fur seal reproductive season (>4 months). We found significant relationships between northern fur seal behavior and prey abundance, even with the limited sample size at the shortest temporal resolution (2 weeks). Changes in dive behavior that were associated with areas of abundant pollock (for example, increased vertical distance traveled and longer periods of diving) were consistent with previously reported metrics of pinniped foraging success. When behavioral metrics, such as vertical distance traveled and time spent diving, remained significantly related to prey abundance at multiple temporal scales, the relationship strength was reduced as temporal mismatch increased. Our results suggest that relationships between behavioral metrics and prey abundance vary as temporal mismatch increases between prey surveys and predator tracking periods. For northern fur seals, pollock surveys conducted early in the reproductive season may still provide information useful to examine predator–prey relationships as the reproductive season progresses, albeit with diminished predictive power. Understanding predator–prey relationships, including the impact of varying temporal scales, is particularly valuable for guiding research and conservation strategies for northern fur seals as the population continues to decline.

Linking northern fur seal behavior with prey distributions: the impact of temporal mismatch between predator studies and prey surveys

Linking northern fur seal behavior with prey distributions: the impact of temporal mismatch between predator studies and prey surveys

Evaluating environmental, demographic and genetic effects on population‐level survival in an island endemic

The population dynamics of island species are considered particularly sensitive to variation in environmental, demographic and/or genetic processes. However, few studies have attempted to evaluate the relative importance of these processes for key vital rates in island endemics. We integrated the results of long‐term capture–mark–recapture analysis, prey surveys, habitat quality assessments and molecular analysis to determine the causes of variation in the survival rates of Komodo dragons Varanus komodoensis at 10 sites on four islands in Komodo National Park, Indonesia. Using open population capture–mark–recapture methods, we ranked competing models that considered environmental, ecological, genetic and demographic effects on site‐specific Komodo dragon survival rates. Site‐specific survival rates ranged from 0.49 (95% CI: 0.33–0.68) to 0.92 (0.79–0.97) in the 10 study sites. The three highest‐ranked models (i.e. ΔQAICc &lt; 2) explained ∼70% of variation in Komodo dragon survival rates and identified interactions between inbreeding coefficients, prey biomass density and habitat quality as important explanatory variables. There was evidence of additive effects from ecological and genetic (e.g. inbreeding) processes affecting Komodo dragon survival rates. Our results indicate that maintaining high ungulate prey biomass and habitat quality would enhance the persistence of Komodo dragon populations. Assisted gene flow may also increase the genetic and demographic viability of the smaller Komodo dragon populations.

How to catch more prey with less effective traps: explaining the evolution of temporarily inactive traps in carnivorous pitcher plants.

Carnivorous Nepenthes pitcher plants capture arthropods with specialized slippery surfaces. The key trapping surface, the pitcher rim (peristome), is highly slippery when wetted by rain, nectar or condensation, but not when dry. As natural selection should favour adaptations that maximize prey intake, the evolution of temporarily inactive traps seems paradoxical. Here, we show that intermittent trap deactivation promotes ‘batch captures' of ants. Prey surveys revealed that N. rafflesiana pitchers sporadically capture large numbers of ants from the same species. Continuous experimental wetting of the peristome increased the number of non-recruiting prey, but decreased the number of captured ants and shifted their trapping mode from batch to individual capture events. Ant recruitment was also lower to continuously wetted pitchers. Our experimental data fit a simple model that predicts that intermittent, wetness-based trap activation should allow safe access for ‘scout’ ants under dry conditions, thereby promoting recruitment and ultimately higher prey numbers. The peristome trapping mechanism may therefore represent an adaptation for capturing ants. The relatively rare batch capture events may particularly benefit larger plants with many pitchers. This explains why young plants of many Nepenthes species additionally employ wetness-independent, waxy trapping surfaces.

Foraging ecology and choice of feeding habitat in the New Zealand Fairy TernSternula nereis davisae

SummaryNo published information is available on the foraging ecology and choice of feeding habitat of New Zealand’s rarest breeding bird: the New Zealand Fairy Tern (NZFT)Sternula nereis davisae. To address this gap, we conducted an assessment of the largest remaining breeding population at Mangawhai Harbour, Northland, New Zealand, during the chick-rearing period of the 2010/2011 breeding season. We combined visual tracking of birds with prey surveys and stable isotope analyses, and we present the first quantitative assessment of NZFT foraging. We recorded 405 foraging dives that show NZFT foraging habitat includes the water edges, shallow channels, and pools on the tidal flats of mangrove-lined (Avicennia marinavar.resinifera) parts of the estuary; tidal pools on mud- and sandflats in the mid-estuary and lower harbour; the shallow margins of the dredged main channel in the lower harbour; the oxbow lagoons on the sand spit; and coastal shallows. Our study identifies the mangrove-lined highly tidal and shallow mid-estuary and the lagoon on the sand spit as foraging hotspots for the Mangawhai breeding population of the NZFT. The prey survey employed a seine-net sampling method at identified NZFT foraging sites and yielded 4,367 prey-sized fish of 11 species, two of which had not previously been reported in Mangawhai Harbour, as well as numerous shrimps. The most abundant fish were gobies of the genusFavonigobius. Our stable isotope results highlight gobies as the most important prey for NZFT chick rearing, also indicating that flounderRhombosoleasp. contribute to NZFT diet. We raise the possibility that shrimps may also constitute a substantial diet component for NZFT, potentially providing up to 21% of diet mass for adult birds. While our results provide a first basis to understanding the feeding ecology of NZFT during their breeding season in order to facilitate conservation planning, further research is required to address inter-annual variation and to identify key foraging grounds for this Critically Endangered bird at other breeding sites.

Road use by the Iriomote Cat (Prionailurus bengalensis iriomotensis) on Iriomote-Jima Island in Relation to its Herpetile Prey

The Iriomote cat is an endangered subspecies (CR on the Japanese Red List) found only on Iriomote-jima Island in the Ryukyu Archipelago, Japan. One of the main factors threatening the Iriomote cat is the main paved road that contributes to traffic mortality of this wildcat and also alters its preferred lowland habitats with abundant prey. One of the reasons why the Iriomote cat appears on the road may be due to the presence of prey; therefore, we investigated road use by this wildcat in relation to its prey. In 2009, scat surveys were conducted to assess road use by the Iriomote cat, and prey surveys were undertaken in the morning and at night, mainly targeting terrestrial frogs and reptiles. To analyse the importance of factors related to road use by the Iriomote cat, the influences of prey density along road types, habitat types, presence or absence of road construction activities, and survey regions on number of scats were examined using nested generalised linear models (GLM), assuming Poisson error and a log-link function. Diurnal lizard density was strongly correlated with scat along roads, and the density of road-killed Fejervarya sakishimensis was positively correlated with scat presence along roads.

Dietary Partitioning in Sympatric Large Carnivores in a Tropical Forest of Western Ghats, India

Abstract. We investigated dietary partitioning among tiger Panthera tigris, leopard Panthera pardus and dhole Cuon alpinus in Mudumalai Tiger Reserve, India between January 2008 and April 2010 based on scat analyses and prey surveys. Scat analysis revealed that though the diet of the three predators consisted of 15 to 21 prey species, wild ungulates formed a major portion of their diet (88.4 to 96.7%). The three predators exhibited high diet overlap (> 61%). Prey availability, estimated from an effort of 473 km of line transects (n = 33) revealed high density of chital Axis axis (43.8 ± 10.7 (mean ± SE) individuals/km2), followed by langur Semnopithecus entellus (31.0 ± 3.8), gaur Bos gaurus (6.7 ± 1.5), giant squirrel Ratufa indica (6.4 ± 1.3), sambar Rusa unicolor (4.9 ± 0.96) and elephant Elephas maximus (4.9 ± 0.75). Mean biomass (kg/km2) of chital, gaur and sambar was 2058.6, 3015 and 656.6 respectively. In terms of biomass, tiger consumed mostly large sized prey (> 50 kg). Although leopard and dhole...