Can camera traps monitor Komodo dragons a large ectothermic predator?

Camera trapping has greatly enhanced population monitoring of often cryptic and low abundance apex carnivores. Effectiveness of passive infrared camera trapping, and ultimately population monitoring, relies on temperature mediated differences between the animal and its ambient environment to ensure good camera detection. In ectothermic predators such as large varanid lizards, this criterion is presumed less certain. Here we evaluated the effectiveness of camera trapping to potentially monitor the population status of the Komodo dragon (Varanus komodoensis), an apex predator, using site occupancy approaches. We compared site-specific estimates of site occupancy and detection derived using camera traps and cage traps at 181 trapping locations established across six sites on four islands within Komodo National Park, Eastern Indonesia. Detection and site occupancy at each site were estimated using eight competing models that considered site-specific variation in occupancy (ψ)and varied detection probabilities (p) according to detection method, site and survey number using a single season site occupancy modelling approach. The most parsimonious model [ψ (site), p (site survey); ω = 0.74] suggested that site occupancy estimates differed among sites. Detection probability varied as an interaction between site and survey number. Our results indicate that overall camera traps produced similar estimates of detection and site occupancy to cage traps, irrespective of being paired, or unpaired, with cage traps. Whilst one site showed some evidence detection was affected by trapping method detection was too low to produce an accurate occupancy estimate. Overall, as camera trapping is logistically more feasible it may provide, with further validation, an alternative method for evaluating long-term site occupancy patterns in Komodo dragons, and potentially other large reptiles, aiding conservation of this species

Life-history and spatial determinants of somatic growth dynamics in Komodo dragon populations

Somatic growth patterns represent a major component of organismal fitness and may vary among sexes and populations due to genetic and environmental processes leading to profound differences in life-history and demography. This study considered the ontogenic, sex-specific and spatial dynamics of somatic growth patterns in ten populations of the world\u27s largest lizard the Komodo dragon (Varanus komodoensis). The growth of 400 individual Komodo dragons was measured in a capture-mark-recapture study at ten sites on four islands in eastern Indonesia, from 2002 to 2010. Generalized Additive Mixed Models (GAMMs) and information-theoretic methods were used to examine how growth rates varied with size, age and sex, and across and within islands in relation to site-specific prey availability, lizard population density and inbreeding coefficients. Growth trajectories differed significantly with size and between sexes, indicating different energy allocation tactics and overall costs associated with reproduction. This leads to disparities in maximum body sizes and longevity. Spatial variation in growth was strongly supported by a curvilinear density-dependent growth model with highest growth rates occurring at intermediate population densities. Sex-specific trade-offs in growth underpin key differences in Komodo dragon life-history including evidence for high costs of reproduction in females. Further, inverse density-dependent growth may have profound effects on individual and population level processes that influence the demography of this species

Population assessments of ungulate prey and Komodo dragons across protected areas in eastern Indonesia

© 2011 Achmad Ariefiandy HusenPrey species can influence the population dynamics of their predators. Therefore, to conserve and manage endangered or threatened species, it is crucial to understand predator-prey relationships and to monitor the abundance of predators and their prey. The Komodo dragon (Varanus komodoensis) is an apex predator endemic to Indonesia. It is considered a vulnerable species due to demographic decline and a limited distribution. However to date, little monitoring has been conducted to estimate the spatial and temporal variation in the abundances of the Komodo dragon and its ungulate prey species. This study evaluated the usefulness of faecal counts and distance sampling for monitoring the abundance of the three major prey species of Komodo dragons. This study also investigated site occupancy of Komodo dragons, and examined the influence of site-specific covariates (prey abundance, habitat type and level of protection) on site occupancy across 11 sites on five islands in and around Komodo National Park, eastern Indonesia. Faecal densities of three ungulate prey species: Timor deer (Cervus timorensis), feral pig (Sus scrofa) and water buffalo (Bubalus bubalis), were positively correlated with their population densities estimated from distance sampling. The abundance of Timor deer was negatively influenced by the abundance of water buffalo, possibly through competition for space and food. Whilst for feral pig and water buffalo all models give weak support (wi ≤ 0.37) to explain the variation in their abundances. Several competing models were evaluated to estimate their effects on the site occupancy of Komodo dragons. The two most parsimonious models indicated that ungulate prey, representing a deer density model (∆= 0.00; w= 0.68) and an additive model incorporating deer and buffalo density ((∆= 1.61; w= 0.30) were both positively correlated with site occupancy estimates for Komodo dragons and presumably the abundance of Komodo dragons. The site occupancy of Komodo dragons and the abundance of their prey on small islands and Wae Wuul Nature Reserve on Flores Island were lower than on the larger islands within Komodo National Park. This study concluded that faecal counts are more useful than distance sampling for population monitoring of the ungulate prey of komodo dragons, and recommends annual monitoring of ungulates in and around Komodo National Park to be undertaken using faecal counts. This study also recommends that continuous monitoring of Komodo dragon site occupancy and estimation of trends in prey densities should be implemented for detecting spatial and temporal changes across time. The implementation of long term population monitoring would ensure that robust data is available for managers to address population trends. I also propose conservation efforts essential to ensure the persistence of Komodo dragon populations: (i) increasing the level of protection to reduce the risk of deer hunting, (ii) translocating Timor deer to low abundance areas to recover their populations, (iii) excluding domesticated buffalo from Wae Wuul Nature Reserve, and (iv) investing in sustained annual monitoring program for the Komodo dragon and its ungulate prey populations, to be implemented across Komodo dragon distributions, and especially in small islands and the Wae Wuul Nature Reserve

Invasive toads are close to but absent from Komodo National Park

The islands of Komodo National Park in the Wallacea region are the habitats of Komodo dragon (Varanus komodoensis). Although the Wallacea islands have lower species richness compared to the other large islands in Indonesia, they are rich in endemics, and the occurrence of invasive species would therefore threatened the ecological, economic and social balance of the regions. Several papers have hinted at the possibility of the invasion of Komodo National Parks by Asian toads, a situation which would potentially affect the survival of the Komodo dragon. To detect the presence of the invansive toad Duttaphrynus melanostictus in Komodo National Park and its surroundings areas we carried out an amphibian survey using a Visual Encounter Survey method during February to April 2018. The surveyed location consisted of two main islands within Komodo National Park (Rinca island and Komodo island), Flores island (Labuan Bajo and Cumbi village) and Sumbawa island (Sape). Two species of amphibians were found in Komodo National Park (Rinca island and Komodo island), while seven species of amphibians were found across all four locations. No D. melanostictus toads were found in Flores (including in Komodo National Park), however the toad was found to be abundant in Sape (Sumbawa island)

The THE AMPHIBIANS AND REPTILES IN KOMODO NATIONAL PARK AND THE SURROUNDING AREA

The Komodo National Park in the Wallacea region is the komodo dragon’s primary habitats. Published report on the herpetofauna of this national park is mostly concentrated in Komodo island. To increase our knowledge of amphibian and reptile communities in Komodo National Park, we conducted a herpetofauna survey in Komodo and Rinca Island and the nearby coastal area to assess diversity and community similarity and developed a complete checklist of the herpetofauna of Komodo National Park. We conducted a Visual Encounter Survey and put glue traps from February-April 2018 at six locations on Komodo Island (Loh Liang, Loh Wau dan Komodo Village) and Rinca Island (Loh Buaya, Loh Baru, and Rinca Village); and three locations on coastal areas of Flores (Labuan Bajo and Cumbi Village) and coastal area of Sumbawa (Sape) adjacent to Komodo National Park. We found seven species of amphibians and 22 species of reptiles and, however, only two species of amphibians and 18 species of reptiles were found in Komodo and Rinca Island. The highest diversity (H’ = 2.14) is in Loh Buaya (Rinca Island), and the highest evenness (E=0.58) is in Loh Baru (Rinca Island). The highest similarity occurs between Komodo Island and Rinca Island (IS = 0.8). Using data from other research, we have compiled a list of four species of amphibians and 39 species of reptiles occurring at three main islands of Komodo National Park: Komodo island, Rinca Island and Padar Island.   Keywords: Herpetofauna diversity, Komodo National Park, Lesser Sunda Island

Distribution, seasonal use, and predation of incubation mounds of Orange-footed Scrubfowl on Komodo Island, Indonesia

Megapodes are unique in using only heat from the environment, rather than body heat, to incubate their eggs as well as the precocious independence of their chicks on hatching. Of 22 recognized species of megapodes, 9 are listed as threatened due to factors including habitat loss and fragmentation, and predation on eggs and chicks. Orange-footed Scrubfowl (Megapodius reinwardt) are conspicuous components of the Oriental/Austral avifauna that inhabit the monsoon forests of the Lesser Sunda chain of islands in Indonesia. We examined the abundance, patterns of distribution, physical characteristics, seasonal activity, and predation risk of incubation mounds of Orange-footed Scrubfowl on Komodo Island in eastern Indonesia. We surveyed 13 valleys on Komodo Island from April 2002 to January 2005 and located 113 tended and 107 untended incubation mounds. Densities of scrubfowl mounds in our study were similar to that reported by investigators during the 1970s, suggesting little change in the scrubfowl population since then. Most scrubfowl mounds were on sandy or loamy soils in open monsoon forest with little overhead shade, and placement of mounds in such areas may ensure adequate temperatures for egg incubation. Although some mounds were tended during all months, mound use peaked during the late wet season in March. During the dry season (April-November), only a few mounds were tended. Komodo dragons (Varanus komodoensis) and wild pigs (Sus scrofa) were the primary predators of scrubfowl eggs, with no indication of egg predation by humans. The valley with the largest number of untended mounds in our study also had the largest number of active Komodo dragon nests. This suggests an effect of Komodo dragons on scrubfowl numbers, but additional study is needed

First record of komodo dragon nesting activity and hatchling emergence from North Flores, Eastern Indonesia

For wild varanid populations, basic measures of reproductive ecology, such as distribution and selection of nest sites, are difficult to obtain. To date, nest distributions and nesting behavior for Komodo dragons (Varanus komodoensis) have only been reported from Komodo National Park. Here we report the first record of V. komodoensis nesting activity and hatchling emergence on Ontoloe Island, off the north coast of Flores. This is a significant finding for it suggests that this relatively small but well protected island supports a viable population of V. komodoensi

Monitoring the ungulate prey of the Komodo dragon Varanus komodoensis: distance sampling or faecal counts?

Monitoring the abundances of prey is important for informing the management of threatened and endangered predators. We evaluated the usefulness of faecal counts and distance sampling for monitoring the abundances of rusa deer Rusa timorensis, feral pig Sus scrofa and water buffalo Bubalus bubalis, the three key prey of the Komodo dragon Varanus komodoensis, at 11 sites on five islands in and around Komodo National Park, eastern Indonesia. We used species-specific global detection functions and cluster sizes (i.e. multiple covariates distance sampling) to estimate densities of rusa deer and feral pig, but there were too few observations to estimate densities of water buffalo. Rusa deer densities varied from from 2.5 to 165.5 deer/km2 with coefficients of variation (CVs) of 15-105%. Feral pig densities varied from 0.0 to 25.2 pigs/km 2 with CVs of 25-106%. There was a positive relationship between estimated faecal densities and estimated population densities for both rusa deer and feral pig: the form of the relationship was non-linear for rusa deer, but there was similar support for linear and non-linear relationships for feral pig. We found that faecal counts were more useful when ungulate densities were too low to estimate densities with distance sampling. Faecal count methods were also easier for field staff to conduct than distance sampling. Because spatial and temporal variation in ungulate density is likely to influence the population dynamics of the Komodo dragon, we recommend that annual monitoring of ungulates in and around Komodo National Park be undertaken using distance sampling and faecal counts. The relationships reported here will also be useful for managers establishing monitoring programmes for feral pig, rusa deer and water buffalo elsewhere in their native and exotic ranges.<br /