Motion-activated Cameras Research Articles

Fruit resources shape sexual selection processes in a lek mating system.

The degree to which within-population variation in sexual trait expression relates to resource heterogeneity remains poorly explored. This is particularly true in lek-mating species, where genetic explanations for male phenotypic variance and mating success are dominant. Here, we demonstrate a link between fine-scale fruit resource availability and indices of male mating success in the white-bearded manakin (Manacus manacus), a lek-mating frugivorous bird that produces energetically costly courtship displays. We used motion-activated camera traps to monitor male display behaviour and female visitation at male courts while concurrently conducting twice-monthly fruit surveys around courts. We observed significant variability in ripe fruit biomass among display courts and leks, and mean fruit biomass at courts significantly predicted male display rates. In turn, male display rate was the strongest predictor of female visitation to courts. Causal modelling supported the hypothesis that hyper-local fruit availability indirectly affects female visitation via its direct effects on male display rate. The demonstration that resource availability at fine spatial scales predicts display rate in a lekking organism-for which resource-related variables are typically not considered to play important roles in shaping male reproductive variance-has implications for the expression, honesty and maintenance of sexually selected traits under fluctuating ecological conditions.

Anthropogenic features are the most important drivers of striped skunk (Mephitis mephitis) space use in a human-dominated Midwestern landscape

Striped skunks (Mephitis mephitis) are widespread generalist mesocarnivores that occur in a variety of habitats and are often associated with anthropogenic environments. They are also highly persecuted by humans, however, due to their noxious smell and propensity to carry disease. Consequently, the species is relatively understudied and there is still much unknown about the factors that affect their occurrences. To determine the probability of use patterns of striped skunks at the local (within 100 m) and landscape (within 1 km) scales, we deployed 46 and 54 motion-activated cameras between Dec 2021–Jun 2022 and Nov 2022–May 2023, respectively, across sites throughout the state of Illinois. We used an a priori, hypothesis-based approach to model striped skunk occupancy. The best local-scale probability of use model included road density and urban edge (w = 0.79), suggesting an avoidance of roads and selection for the interfaces of urban environments by skunks. The best model at the landscape scale included the interaction of housing density and coyote (Canis latrans) relative abundance (w = 0.31), describing a spatial niche differentiation among coyotes and skunks in urban settings compared to rural environments. Overall, our results suggest the primary drivers of striped skunk use in Illinois are anthropogenic features, but there exists a nuanced relationship, confirming the species’ designation as synanthropic misanthrope. Meanwhile, humans may mediate shifts in space-use patterns among sympatric mesocarnivores due to an expansion and divergence of ecological niches, resulting in reduced spatial overlap and competitive pressures among species.

Portion size matters: Carrion ecology lessons for medicolegal death investigations-A study in Cape Town, South Africa.

Forensic taphonomic studies are regionally specific and improve time since death estimates for medico-legal casework. Within forensic taphonomy and carrion ecology, vertebrate scavengers are under-researched with many studies conducted using multiple, unclothed carcasses. This is a forensically unrealistic experimental design choice with unknown impact. The effect of variation in carrion biomass on the decomposition ecosystem, particularly where vertebrate scavengers are concerned, requires clarification. To assess the effect of carrion biomass load on vertebrate scavenging and decomposition rate, seasonal baseline data for single, clothed ~60 kg porcine carcasses were compared to clothed multiple-carcass deployments, in a forensically relevant habitat of Cape Town, South Africa. Decomposition was tracked via weight loss and bloat progression and scavenging activity via motion-activated cameras. The single carcasses decayed more quickly, particularly during the cooler, wetter winter, strongly correlated with concentrated Cape gray mongoose (Galerella pulverulenta) scavenging activity. On average and across seasons, the single carcasses lost 68% of their mass by day 32 (567 accumulated degree days [ADD]), compared to 80 days (1477 ADD) for multi-carcass deployments. The single carcasses experienced substantially more scavenging activity, with longer visits by single and multiple mongooses, totaling 53 h on average compared to 20 h for the multi-carcass deployments. These differences in scavenging activity and decay rate demonstrate the impact of carrion biomass load on decomposition for forensic taphonomy research. These findings need corroboration. However, forensic realism requires consideration in taphonomic study design. Longitudinally examining many single carcasses may produce more forensically accurate, locally appropriate, and usable results.

Capturing red squirrels (Sciurus vulgaris) on camera: A cost-effective approach for monitoring relative abundance and habitat preference.

Effective methods for monitoring animal populations are crucial for species conservation and habitat management. Motion-activated cameras provide an affordable method for passively surveying animal presence across the landscape but have mainly been used for studying large-bodied mammals. This paper explores the relative abundance and habitat preferences of red squirrels (Sciurus vulgaris) in coniferous forests using cameras and live trapping. The study was conducted in two forests (Newborough and Pentraeth) on Anglesey, North Wales, with a total of 50 sampling locations across four habitat categories. Detailed woodland structure and composition data were gathered around each sampling location. We found a strong positive correlation between the number of individual red squirrels live trapped over 10 days with the number of camera images of squirrels recorded during a previous 5-day period. The time interval between camera deployment and the first recorded image of a red squirrel showed a significant negative correlation with the number of individuals live trapped. Red squirrel relative abundance was negatively related to forest canopy openness, while the presence of Scots pine and increased tree species diversity were positively associated with the relative abundance of squirrels. There was also a strong site difference with lower relative abundance at Newborough compared with Pentraeth, which likely reflects the heavy thinning of mature forest at Newborough reducing tree crown connectivity. The results show that remotely activated cameras are an effective method for monitoring red squirrel populations across varying animal densities. The cameras also provided crucial information on red squirrel habitat preferences that can aid in woodland management and conservation efforts. Cameras have great potential to collect data on the population status of other small mammals, but it is essential that these methods are validated on a species-by-species basis.

Operational Considerations for Using Deer-Targeted 4-Poster Tick Control Devices in a Tick-borne Disease Endemic Community.

In the northeastern United States, recommendations to prevent diseases spread by black-legged ticks ( Ixodes scapularis ) and lone star ticks ( Amblyomma americanum ) often rely on individuals to use personal protection or yard-based strategies. The 4-Poster deer treatment stations (4-Posters) suppress tick populations by treating deer hosts with acaricide, potentially offering a community-wide approach for reducing tick-borne diseases in endemic areas. The 4-Poster deployment logistics in mainland community settings are not well documented but are needed for future public health tick control efforts. As part of a public health research effort to design a population-based 4-Poster effectiveness study aimed at reducing tick-borne disease incidence, TickNET researchers partnered with the Town of Ridgefield (Connecticut) to understand the feasibility and operational logistics of deploying 4-Posters on public land within a residential community to inform future public health interventions by municipalities or vector control agencies. We deployed three 4-Posters on a municipal property from July to December 2020 and used motion-activated cameras to record wildlife activity nearby. We documented per-device operational details, costs, materials consumed, and animal activity. Operation of 4-Posters was feasible, and device challenges were easily remedied. Deer visitation and heavy nontarget animal use were documented at all devices. Unexpectedly, monthly corn consumption was not correlated with monthly deer-view days. The monthly cost per device was US $1279 or US $305 per hectare with an average 21 minutes of weekly service time. Use of 4-Posters by communities, public health agencies, or vector control programs may be a practicable addition to tick management programs in tick-borne disease endemic areas in the Northeast. Such programs should carefully consider local and state regulations, follow manufacturer and pesticide label guidelines, and include wildlife monitoring. High labor costs incurred in this project could be mitigated by training vector control agency or municipality staff to service 4-Posters.

Living on the edge: forest edge effects on microclimate and terrestrial mammal activity in disturbed lowland forest in Sumatra, Indonesia

AbstractSpecies–environment relationships are often studied at large spatial scales, but effective conservation requires an understanding of local-scale environmental drivers and pressures. Widespread degradation and fragmentation of forests have increased the proportion of tropical mammal habitat that is affected by edge effects. Edge effects include greater exposure to anthropogenic disturbance and abiotic changes that synergistically influence how well populations can cope with climate change. We investigated relationships between distance to the forest edge, forest structure, microclimate and terrestrial mammal detections in a selectively logged forest at the boundary of Gunung Leuser National Park in Sumatra, Indonesia. We collected mammal detection data from motion-activated camera traps, microclimate data from automated climate data loggers and forest structure data from vegetation plots. Daily mean and maximum temperatures significantly decreased with distance from the forest edge, whereas tree height and minimum temperature increased. Mammal diversity was lower at the forest edge compared to the interior. Mammals were detected less frequently at the forest edge, although this relationship varied between mammal orders. Mammal detections were best explained by temperature, tree height and tree diameter at breast height. These results demonstrate that abiotic changes in forests brought on by edge effects have negative impacts on mammals, but these effects vary between mammal taxa because of differing sensitivities to human disturbance. Our findings highlight the importance of considering local-scale environmental drivers in determining species–environment relationships to identify key habitat features such as microclimate refuges that should be prioritized in ecosystem management.

Streamflow and flood prediction in Rwanda using machine learning and remote sensing in support of rural first-mile transport connectivity

Flooding, an increasing risk in Rwanda, tends to isolate and restrict the mobility of rural communities. In this work, we developed a streamflow model to determine whether floods and rainfall anomalies explain variations in rural trail bridge use, as directly measured by in-situ motion-activated digital cameras. Flooding data and river flows upon which our investigation relies are not readily available because most of the rivers that are the focus of this study are ungauged. We developed a streamflow model for these rivers by exploring the performance of process-based and machine learning models. We then selected the best model to estimate streamflow at each bridge site to enable an investigation of the associations between weather events and pedestrian volumes collected from motion-activated cameras. The Gradient Boosting Machine model (GBM) had the highest skill with a Kling-Gupta Efficiency (KGE) score of 0.79 followed by the Random Forest model (RFM) and the Generalized Linear Model (GLM) with KGE scores of 0.73 and 0.66, respectively. The physically-based Variable Infiltration Capacity model (VIC) had a KGE score of 0.07. At the 50% flow exceedance threshold, the GBM model predicted 90% of flood events reported between 2013 and 2022. We found moderate to strong positive correlations between total monthly crossings and the total number of flood events at four of the seven bridge sites (r = 0.36–0.84), and moderate negative correlations at the remaining bridge sites (r = -0.33– -0.53). Correlation with monthly rainfall was generally moderate to high with one bridge site showing no correlation and the rest having correlations ranging between 0.15–0.76. These results reveal an association between weather events and mobility and support the scaling up of the trail bridge program to mitigate flood risks. The paper concludes with recommendations for the improvement of streamflow and flood prediction in Rwanda in support of community-based flood early warning systems connected to trail bridges.

Human effects on brown bear diel activity may facilitate subadults foraging on Pacific salmon

Humans can markedly alter the temporal activity of wildlife. The ecological consequences of such temporal shifts are poorly understood but can lead to reduced fitness, increased competition, and induce trophic cascades under certain conditions. Furthermore, if individuals or species vary in their tolerance to human disturbance, then they may be able to exploit resources left vacant by more human-sensitive animals. Here, we explored the potential of a “temporal-shield” offered by human disturbance, using brown bears (Ursus arctos) foraging on sockeye salmon (O. nerka) in southwestern Alaska as a model system. We deployed motion-activated cameras on six salmon spawning streams over five summers (2013-2018), capturing footage of 1,935 independent bear encounters including single adult bears (n=1,612), females with cubs (n=197) and subadults (n=126). Using a von Mises circular kernel density estimation procedure, we estimated the overlap of activity for each bear group type relative to humans observed on our cameras (n=932 encounters; all researchers). All bears avoided peak times of human activity, but socially-subordinate subadults exhibited significantly higher overlap with humans (23%) as compared to females with cubs and single adults (11% and 12%, respectively). Furthermore, subadult bears increased their overlap with human activity over the course of each sampling year, while females with cubs and single adults generally decreased their overlap. These results highlight that the effects of human-disturbance on large carnivores can be complex and may allow for increased foraging opportunities for socially subordinate, but more human-tolerant, individuals.

Mammals in the Chornobyl Exclusion Zone's Red Forest: a motion-activated camera trap study

Abstract. Since the accident at the Chornobyl Nuclear Power Plant in 1986, there have been few studies published on medium and large mammals inhabiting the area from which the human population was removed (now referred to as the Chornobyl Exclusion Zone, CEZ). The dataset presented in this paper describes a motion-activated camera trap study (n=21 cameras) conducted from September 2016 to September 2017 in the Red Forest located within the Chornobyl Exclusion Zone. The Red Forest, which is likely the most anthropogenically contaminated radioactive terrestrial ecosystem on earth, suffered a severe wildfire in July 2016. The motion-activated trap cameras were therefore in place as the Red Forest recovered from the wildfire. A total of 45 859 images were captured, and of these 19 391 contained identifiable species or organism types (e.g. insects). A total of 14 mammal species were positively identified together with 23 species of birds (though birds were not a focus of the study). Weighted absorbed radiation dose rates were estimated for mammals across the different camera trap locations; the number of species observed did not vary with estimated dose rate. We also observed no relationship between estimated weighted absorbed radiation dose rates and the number of triggering events for the four main species observed during the study (brown hare, Eurasian elk, red deer, roe deer). The data presented will be of value to those studying wildlife within the CEZ from the perspectives of the potential effects of radiation on wildlife and also rewilding in this large, abandoned area. They may also have value in any future studies investigating the impacts of the recent Russian military action in the CEZ. The data and supporting documentation are freely available from the Environmental Information Data Centre (EIDC) under the terms and conditions of a Creative Commons Attribution (CC BY) license: https://doi.org/10.5285/bf82cec2-5f8a-407c-bf74-f8689ca35e83 (Barnett et al., 2022a).

Habitat structure facilitates coexistence of native and invasive mesopredators in an Australian tropical savanna

Context The introduction of the cat (Felis catus) to Australia has been a key driver of the decline and extinction of the continent’s endemic mammals. Currently, there is no clear long-term solution to controlling feral populations of cats at a landscape scale. As such, understanding how environmental conditions and habitat attributes can mediate the coexistence between introduced predators and native mammals can improve management outcomes for threatened species. Aim We sought to compare the differences in habitat use by feral cats and a remnant population of the endangered northern quoll (Dasyurus hallucatus) to understand what environmental variables allow these two mesopredators to coexist in tropical savanna of Cape York Peninsula, Queensland. Methods We deployed grids of motion-activated cameras three times per year over a 3-year period, across Eucalyptus tetrodonta-dominated plateaux known to be inhabited by feral cats and northern quolls. We modelled the spatial variation in the frequencies of detection of feral cats and northern quolls (referred to as ‘habitat use’), as a function of biotic and abiotic environmental variables by using a generalised linear model for consistent variables and a generalised linear mixed-effect model for fluctuating variables. Key results Habitat use by feral cats was most frequent in areas with high fire frequencies and low tree basal area, whereas habitat use by northern quolls was most frequent in areas of high basal area of E. tetrodonta (a commonly used den tree species), topographic ruggedness, and long-unburnt savanna. Conclusions Frequent fires in tropical savanna promote habitat use by feral cats and can result in a reduction of critical habitat for northern quolls. Implications We postulate that remnant populations of northern quolls on Cape York Peninsula occur in less frequently burnt refugia, primarily on top of plateaux that support high-biomass tropical savanna dominated by E. tetrodonta. Our findings highlighted that threatened mammals can persist alongside introduced predators in tropical savanna but are dependent on the maintenance of structurally complex habitat.

Effects of a modern exhibit design on captive tiger welfare.

Offering captive animals larger, more complex spaces are thought to benefit their welfare. To this end, some zoos use trail systems linked to several enclosures. Since little is known about the effects of such designs on the welfare of captive carnivores specifically, we timed the behaviors exhibited by four tigers (Panthera tigris [Linnaeus]) given access to three exhibit configurations: one exhibit only (E, baseline); one exhibit and approximately 19 m2 of trail (ET); and two exhibits connected by approximately 46 m2 of trail (E2T). Behaviors were recorded during 1-h AM, Noon, and PM periods in Phase I (2017), and 2-h AM and PM periods in Phase II (2018). Percentages of behavior occurrence were analyzed using generalized linear mixed models (GLMM), with treatment and time of day as fixed effects. Tigers were least active at noon (Phase I), while active behaviors were prevalent during mornings and afternoons in both Phases. In Phase II (E2T vs. E), active and exploratory behaviors such as sniffing increased, while pacing and inactivity decreased (all p ≤ .001). We also examined nocturnal tiger movement using infrared motion-activated cameras. In parallel with diurnal observations, tiger activity in E2T greatly exceeded that in E. Nocturnal movement was most pronounced from 1800 to 2200 and least frequent from 0100 to 0400, closely matching patterns observed in the wild. Results indicate that offering tigers voluntary access to larger and more complex spaces stimulates natural behaviors and decreases stereotypical behaviors.

Long-term monitoring reveals the value of continuous trapping to curtail the effects of free-roaming cats in protected island habitats

Free-roaming domestic cats (Felis catus) pose numerous risks to biodiversity conservation, especially in island ecosystems. However, the removal of cats is costly, labor-intensive, and often demands more resources than land managers have at their disposal. These costs might be reduced, however, if trapping effort is regularly scaled to match the prevalence of cats on the landscape rather than consistently exhausting trapping resources even when cats are scarce. Here we analyze the efficacy of a long-term (2014 – 2021) cat removal program which uses motion-activated camera traps to determine monthly trapping effort in the Florida Keys. Furthermore, we compare the trapping effort required for this program against that of a hypothetical removal program with the same resources which does not use surveillance-informed trapping. We hypothesized that cat detections would decline over the study period as a result of the removal program, and that the surveillance-informed approach would require less trapping effort than uninformed trapping would. Our analyses reveal that the sustained, year-round trapping program has reduced the volume and geographic extent of cat detections within the study area. Furthermore, the use of camera traps to inform removal efforts has reduced the number of trap nights required to achieve these goals compared to the hypothetical removal program that did not use surveillance-informed trapping. While climatic and landscape variables also contribute to monthly cat detections, our study reveals that long-term surveillance-informed trapping reduces cat detections without exhausting resources. Such an approach may aid other land managers in their efforts to conserve biodiversity by removing invasive predators.

Confluence and Implications of Cats, Coyotes, and Other Mesopredators at a Feral Cat Feeding Station

Abstract Trap-neuter-return (TNR) is promoted as a “humane” alternative to lethal methods for population control of feral domestic cats (Felis catus). This paper explores feedbacks between feral domestic cats, coyotes (Canis latrans), raccoons (Procyon lotor), and skunks (Mephitis mephitis) at a TNR feral cat colony in Rhode Island, USA. A total of 12,272 photographs from a motion-activated camera were analyzed. Cat population size and visitation frequency of wildlife were estimated during three different feeding regimes. Abundant food on the ground was associated with increased wildlife visits, while elevated or limited food was associated with decreased wildlife visits. During the two-year study period, the population of cats dropped from 17 to 12 individuals and the cats appeared to have short life spans, which could have been due to predation by coyotes. Our results suggest that wildlife confluence and predation risks can be influenced by feeding regime.

Count me in: Leopard population density in an area of mixed land‐use, Eastern Cape, South Africa

Count me in: Leopard population density in an area of mixed land‐use, Eastern Cape, South Africa

End of the road: Short-term responses of a large mammal community to forest road decommissioning

Anthropogenic disturbances are increasing worldwide, causing wildlife habitat loss, alteration, and fragmentation. In Canada, the decommissioning of linear anthropogenic structures is identified as a promising tool to restore the habitat of threatened populations of boreal caribou (Rangifer tarandus caribou) by reducing food availability for alternate prey and decreasing encounter probabilities with predators. In this study, we monitored the use of 40 km of decommissioned forest roads by caribou, gray wolves (Canis lupus), black bears (Ursus americanus), and moose (Alces americanus) 1–3 years after reclamation, using 232 motion-activated camera traps. We compared four additive treatments (meaning that each successive treatment included the treatment prior): closing the road to human access, decompacting its soil, planting black spruce (Picea mariana) trees, and adding enriched soil. We assessed the influence of treatments, use by other large mammals, and characteristics of the surrounding environment on road use by the four species. Caribou used the planted treatment (which also included closing and decompacting) more than the closed-only (reference) treatment, but treatments did not influence the use of decommissioned roads by bears and moose. We could not assess the use of treated roads by wolves because of low sample size. Road use by caribou declined with local moose density, but increased with local bear density. Caribou were observed more frequently on roads surrounded by regenerating and mature coniferous stands; caribou also preferentially used roads surrounded by wetlands. Our results suggest that the treatment combining road closure, soil decompaction, and tree planting could be beneficial to caribou, highlighting the relevance of including active restoration efforts in caribou conservation programs. We recommend that such a treatment be added to road decommissioning protocols for the conservation of caribou, alongside broad-scale habitat protection.

Den-Associated Behavior of Octopus rubescens Revealed by a Motion-Activated Camera Trap System.

Dens are a crucial component of the life history of most shallow water octopuses. However, den usage dynamics have only been explored in a few species over relatively short durations, and Octopus rubescens denning behavior has never been explored in situ. We built four underwater camera traps to observe the behavior of O. rubescens in and around their dens. To distinguish individuals, octopuses were captured and given a unique identifiable visible implant elastomer tag on the dorsal side of their mantle. After being tagged and photographed, each octopus was released back to its original capture site within its original den bottle. The site is unique in that octopuses reside almost exclusively in discarded bottles, therefore aiding in locating and monitoring dens. Motion-activated cameras were suspended in a metal field-of-view above bottle dens of released octopuses to observe den-associated behaviors. Cameras were regularly retrieved and replaced to allow continuous monitoring of den locations in 71 h intervals for over a month. We found that O. rubescenswas primarily active during the day and had frequent interactions with conspecifics (other members within the species). We also found that rockfish and red rock crabs tended to frequent den locations more often when octopuses were not present, while kelp greenling both visited dens more frequently and stayed longer when octopuses were present. Our results, demonstrate the utility of motion-activated camera traps for behavioral and ecological studies of nearshore mobile organisms.

Mixed methods study design, pre-analysis plan, process evaluation and baseline results of trailbridges in rural Rwanda

We present a study design, pre-analysis plan, process evaluation and baseline results designed to establish the impact of trailbridges on health, education, agricultural and economic outcomes of households in rural Rwanda. This intervention and study is being implemented in communities that face barriers to socioeconomic development through periodic isolation caused by flooding. We describe a mixed methods approach to measure the impacts of these trailbridges on outcomes at the village level. The study is anchored on a stepped-wedge randomized controlled trial (RCT) implemented in 147 sites: 97 phased-in intervention sites and 50 long-term control sites. These sites are being monitored in four annual waves comprising of a baseline period and three subsequent follow-up waves. We will supplement the RCT with three sub-studies. First, we are investigating the role of weather events and streamflow variability on temporal and spatial bridge use patterns among intervention sites. We will then find the relationship between the weather events, streamflow and bridge use from motion-activated cameras installed in intervention sites. Secondly, we are following 42 markets serving study sites to investigate the impact of the trailbridges on the market prices of key goods including crops, livestock and agricultural inputs. Lastly, we are following 30 villages that are more distant from the river crossings to determine the spatial extent of the trailbridge impacts. Our study will advance knowledge by generating new data on the impact of rural infrastructure and providing the opportunity to explore a range of outcomes for future evaluation of infrastructure in low- and middle-income countries. We will enable an outcomes-based funding model that ties implementer payments to demonstrated positive impacts of these trailbridges. Furthermore, we will identify cost-effective, easily assessed measures that are highly correlated to the economic and health benefits of the intervention. These measures may then be used by a portfolio of interventions across multiple geographies without always requiring complex trials.

Camera traps are an effective tool for monitoring insect-plant interactions.

Insect and pollinator populations are vitally important to the health of ecosystems, food production, and economic stability, but are declining worldwide. New, cheap, and simple monitoring methods are necessary to inform management actions and should be available to researchers around the world. Here, we evaluate the efficacy of a commercially available, close‐focus automated camera trap to monitor insect–plant interactions and insect behavior. We compared two video settings—scheduled and motion‐activated—to a traditional human observation method. Our results show that camera traps with scheduled video settings detected more insects overall than humans, but relative performance varied by insect order. Scheduled cameras significantly outperformed motion‐activated cameras, detecting more insects of all orders and size classes. We conclude that scheduled camera traps are an effective and relatively inexpensive tool for monitoring interactions between plants and insects of all size classes, and their ease of accessibility and set‐up allows for the potential of widespread use. The digital format of video also offers the benefits of recording, sharing, and verifying observations.

Identifying forensically relevant urban scavengers in Johannesburg, South Africa

Unidentified human remains are frequently recovered in urban environments in South Africa, which undergo forensic (medico-legal) investigations. These remains often exhibit animal scavenging modifications and are frequently scattered by animals. This impacts the collection and forensic analysis of the remains. This study aimed to identify scavenging animals present in two urban environments in Johannesburg, South Africa, and describe their scavenging and scattering behaviours. Six pig carcasses (Sus scrofa domesticus) (30–80 kg) were placed in a veldt in Johannesburg and in an abandoned building complex. Motion-activated cameras recorded the scavenging activities. Scavenger species were identified and their behaviours, scattering pattern, and scavenging bone modifications were described. Slender mongooses (Galerella sanguinea) were the most prolific veldt scavengers. They scattered remains to a maximum distance of 10.5 m in two directions: north and southeast. These mongooses scavenged during the advanced and dry decomposition stages. Gnawing on the angle of the mandible - with multiple parallel scores on the flat surfaces and the angle margin having a stepped appearance - may be a distinguishing scavenging modification feature of the slender mongoose. Hadeda ibis (Bostrychia hagedash) were the only scavengers recorded scavenging on the intestines of a pig carcass in the abandoned building complex. They favoured colonizing insects and created multiple, large holes in the skin and removed the lips to access the insects. The described scavenging behaviours will assist in the reconstruction of postmortem events in forensic cases and the location and collection of scattered remains in Southern Africa.

Targeted Mop up and Robust Response Tools Can Achieve and Maintain Possum Freedom on the Mainland.

Simple SummaryTo achieve the goal of Predator Free 2050, new pest control methods must be found and existing ones refined. We achieved the first >11,000-hectare possum elimination (all possums removed, and re-invaders subsequently mopped up) on mainland New Zealand at an unfenced site, largely protected from possum reinvasion by mountains and rivers. This was within a project to eliminate rats, possums and stoats. We spread a biodegradable poison called sodium fluoroacetate twice by helicopter and used existing ground-based methods (leghold traps, cage traps and a dog) paired with new technology (trail cameras and remote reporting of traps instead of manual checking) to maximise response efficiency. Possums were eliminated in 11 months from 11,642 hectares at a cost of NZD 1.6 million (1080 costs for all 3 species combined and ground-based costs for possums only). New possums entered the site at a rate of four per year and were detected and caught before a breeding population could establish. This proof of concept can now be repeated to confirm its success elsewhere, refine methods, and reduce costs. In the future, if possums are the sole target, we will likely spread 1080 once only and use effective mop-up tools to finish the job.Unfenced sites on mainland New Zealand have long been considered impossible to defend from reinvasion by possums, and are thus unsuitable for eradication. In July 2019, we began eliminating possums from 11,642 ha (including approximately 8700 ha of suitable possum habitat) in South Westland, using alpine rivers and high alpine ranges to minimise reinvasion. Two aerial 1080 (sodium fluoroacetate) applications, each with two pre-feeds, were used. Here, we detail the effort to mop up existing possums and subsequent invaders in the 13 months following the aerial operation. Possums were detected and caught using a motion-activated camera network, traps equipped with automated reporting and a possum search dog. The last probable survivor was eliminated on 29 June 2020, 11 months after the initial removal operation. Subsequently, possums entered the site at a rate of 4 per year. These were detected and removed using the same methods. The initial elimination cost NZD 163.75/ha and ongoing detection and response NZD 15.70/ha annually. We compare costs with possum eradications on islands and ongoing suppression on the mainland.