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Top carnivores have suffered widespread global declines, with well-documented effects on mesopredators and herbivores. We know less about how carnivores affect ecosystems through scavenging. Tasmania’s top carnivore, the Tasmanian devil (Sarcophilus harrisii), has suffered severe disease-induced population declines, providing a natural experiment on the role of scavenging in structuring communities. Using remote cameras and experimentally placed carcasses, we show that mesopredators consume more carrion in areas where devils have declined. Carcass consumption by the two native mesopredators was best predicted by competition for carrion, whereas consumption by the invasive mesopredator, the feral cat (Felis catus), was better predicted by the landscape-level abundance of devils, suggesting a relaxed landscape of fear where devils are suppressed. Reduced discovery of carcasses by devils was balanced by the increased discovery by mesopredators. Nonetheless, carcasses persisted approximately 2.6-fold longer where devils have declined, highlighting their importance for rapid carrion removal. The major beneficiary of increased carrion availability was the forest raven (Corvus tasmanicus). Population trends of ravens increased 2.2-fold from 1998 to 2017, the period of devil decline, but this increase occurred Tasmania-wide, making the cause unclear. This case study provides a little-studied potential mechanism for mesopredator release, with broad relevance to the vast areas of the world that have suffered carnivore declines.

Top predators cause avoidance behaviours in competitors and prey, which can lead to niche partitioning and facilitate coexistence. We investigate changes in partitioning of the temporal niche in a mammalian community in response to both the rapid decline in abundance of a top predator and its rapid increase, produced by two concurrent natural experiments: 1) the severe decline of the Tasmanian devil due to a transmissible cancer, and 2) the introduction of Tasmanian devils to an island, with subsequent population increase. We focus on devils, two mesopredators and three prey species, allowing us to examine niche partitioning in the context of intra‐ and inter‐specific competition, and predator–prey interactions. The most consistent shift in temporal activity occurred in devils themselves, which were active earlier in the night at high densities, presumably because of heightened intraspecific competition. When devils were rare, their closest competitor, the spotted‐tailed quoll, increased activity in the early part of the night, resulting in increased overlap with the devil's temporal niche and suggesting release from interference competition. The invasive feral cat, another mesopredator, did not shift its temporal activity in response to either decreasing or increasing devil densities. Shifts in temporal activity of the major prey species of devils were stronger in response to rising than to falling devil densities. We infer that the costs associated with not avoiding predators when their density is rising (i.e. death) are higher than the costs of continuing to adopt avoidance behaviours as predator densities fall (i.e. loss of foraging opportunity), so rising predator densities may trigger more rapid shifts. The rapid changes in devil abundance provide a unique framework to test how the non‐lethal effects of top predators affect community‐wide partitioning of temporal niches, revealing that this top predator has an important but varied influence on the diel activity of other species.

Dry lightning is a prevalent episodic natural ignition source for wildfires, particularly in remote regions where such fires can escalate into uncontrollable events, burning extensive areas. In this study, we aimed to understand the interplay of environmental, fuel, and geographical factors in evaluating the probability of fire initiation following dry lightning strikes in Tasmania, Australia. We integrated dry lightning, active fire records, and gridded data on fire weather, fuel, and topography into a binary classification framework for both fire‐initiating and non‐fire‐causing lightning strikes. Employing statistical and machine learning techniques, we quantified the likelihood of fire initiation due to dry lightning, with the resampled Random Forest model exhibiting notable performance with an ROC‐AUC value of 0.98. Our findings highlight how fuel characteristics and moisture content associated with particular vegetation types influence fire initiation and provide an objective approach for identifying susceptible regions of dry lightning ignitions, informing associated fire management responses. Plain Language Summary Lightning strikes occurring with minimal rainfall, known as dry lightning strikes, often ignite wildfires in dry vegetation, especially in remote areas. These fires can remain undetected for hours to days and quickly grow out of control under favorable conditions, causing extensive damage and burning large areas. Our study investigated how environmental factors such as weather, terrain, and fuel variables (fuel load, fuel type, and fuel moisture) affect the probability of a fire starting after a dry lightning strike in Tasmania, Australia. We analyzed data on lightning strikes, active fires, topography, fuel (via vegetation and fire history), and weather conditions, to build advanced machine learning models to predict the chances of a fire started following a dry lightning strike. Our findings indicate a high probability of ignition in scenarios characterized by high fuel loads and low fuel moisture content, particularly in treeless vegetation types such as buttongrass sedgelands. This information can help fire authorities identify areas or times most at risk of dry lightning‐ignited wildfires, allowing for better fire prevention and response strategies. Key Points Random Forest modeling accurately identified fires ignited by dry lightning strikes in Tasmania Western Tasmania exhibits heightened vulnerability to wildfires ignited by lightning strikes Treeless fuel types have higher risk than forests of dry lightning ignitions

Wildlife-vehicle collisions imperil humans, wildlife, and property. Collisions with moose (Alces alces ) are especially consequential and there are indications they may increase during severe winters. We tested hypotheses regarding the influence of moose movements and vehicular traffic patterns on collision risk. We first modeled daily snow depth and accumulation across 5.6 million km 2 of the North American Arctic-Boreal region. Next, we analyzed the movements and road use of 113 GPS-collared moose in response to snow depth. Finally, we examined the influence of these snow properties on vehicular traffic and 7680 moose-vehicle collisions. As winter progressed and the snowpack deepened in each study area, GPS-collared moose migrated to lower elevations, leading them into areas with shallower snow but higher road densities. This elevational migration corresponded with a higher probability of road-use by moose (by up to ten-fold) in winter than in summer. Corresponding to these patterns, moose-vehicle collisions were 2.4–5.7 times more frequent from December through February (compared to early summer). Collision risk was highest when and where snow depth was less than 120 cm, indicating that migration into areas with shallower snow increased collision risk in those areas. Most (82%) moose-vehicle collisions occurred after dark. This pattern was strongest during winter, when nighttime traffic volumes were eight times higher than summer due to longer nights. Overall, our findings suggest that concurrent seasonal changes in human and wildlife behavior increase the frequency of moose-vehicle collisions during winter. Snow depth influences collisions primarily through its impacts on moose movement, while strong seasonal changes in daylight hours cause an increase in nighttime traffic that further contributes to risk. This information may help predict times and places where risk of moose-vehicle collisions are highest and to develop seasonally dynamic mitigation strategies.

Dangerous fire weather is increasing under climate change, but there is limited knowledge of how this will affect fire intensity, a critical determinant of the socioecological effects of wildfire. Here, we model relationships between satellite observations of fire radiative power (FRP) and contemporaneous fire weather index, and then we project how FRP is likely to change under near-term warming scenarios. The models project widespread growth in FRP, with increases expected across 88% of fire-prone areas worldwide under 1.5 °C warming. Projected increases in FRP were highest in the Mediterranean biome and Temperate Conifer Forest biome, and increases were twice as large under 2 °C warming compared to 1.5 °C. Disaster-prone areas of the wildland-urban interface saw an average of 3.6 times greater projected increases than non-disaster-prone areas, suggesting wildfire impacts will intensify most in regions already vulnerable to dangerous wildfires. These findings emphasise the urgent need to anticipate changes to fire behaviour and proactively manage wildland-urban ecosystems to reduce future fire intensity. The intensity of wildfires is projected to rise across 88% of global fire-prone areas under 1.5°C warming, with the largest increases expected in wildland-urban interfaces already prone to disasters, based on modelled fire radiative power in response to projected fire weather.

Climate change is exacerbating wildfire conditions, but evidence is lacking for global trends in extreme fire activity itself. Here we identify energetically extreme wildfire events by calculating daily clusters of summed fire radiative power using 21 years of satellite data, revealing that the frequency of extreme events (≥99.99th percentile) increased by 2.2-fold from 2003 to 2023, with the last 7 years including the 6 most extreme. Although the total area burned on Earth may be declining, our study highlights that fire behaviour is worsening in several regions—particularly the boreal and temperate conifer biomes—with substantial implications for carbon storage and human exposure to wildfire disasters. Analysis of fire radiative power derived from satellite data finds that the frequency of extreme fire events increased 2.2-fold from 2003 to 2023 and that these increases were mostly driven by extreme fires in temperate conifer and boreal forest biomes.

Devil facial tumor disease (DFTD) is a transmissible cancer affecting Tasmanian devils Sarcophilus harrisii. The disease has caused severe population declines and is associated with demographic and behavioral changes, including earlier breeding, younger age structures, and reduced dispersal and social interactions. Devils are generally solitary, but social encounters are commonplace when feeding upon large carcasses. DFTD tumors can disfigure the jaw and mouth and so diseased individuals might alter their diets to enable ingestion of alternative foods, to avoid conspecific interactions, or to reduce competition. Using stable isotope analysis (δ13C and δ15N) of whiskers, we tested whether DFTD progression, measured as tumor volume, affected the isotope ratios and isotopic niches of 94 infected Tasmanian devils from six sites in Tasmania, comprising four eucalypt plantations, an area of smallholdings and a national park. Then, using tissue from 10 devils sampled before and after detection of tumors and 8 devils where no tumors were detected, we examined whether mean and standard deviation of δ13C and δ15N of the same individuals changed between healthy and diseased states. δ13C and δ15N values were generally not related to tumor volume in infected devils, though at one site, Freycinet National Park, δ15N values increased significantly as tumor volume increased. Infection with DFTD was not associated with significant changes in the mean or standard deviation of δ13C and δ15N values in individual devils sampled before and after detection of tumors. Our analysis suggests that devils tend to maintain their isotopic niche in the face of DFTD infection and progression, except where ecological conditions facilitate a shift in diets and feeding behaviors, demonstrating that ecological context, alongside disease severity, can modulate the behavioral responses of Tasmanian devils to DFTD. Tasmanian devils generally maintain their isotopic niche in the face of infection and progression of devil facial tumor disease. The exception was where ecological conditions facilitated a shift in diets and feeding behaviors, such as at Freycinet National Park. Ecological context, alongside disease severity, can modulate the behavioral responses of Tasmanian devils to DFTD. ​

Extreme weather events are becoming more frequent, with poorly known consequences for wildlife. In December 2021, an atmospheric river brought record-shattering amounts of rain and snow to interior Alaska, creating conditions expected to cause mass mortality in grazing ungulate populations that need to access ground forage. We characterized snowpack conditions following the storm and used a 36-year monitoring dataset to quantify impacts on caribou ( Rangifer tarandus ) and their primary predator, wolves ( Canis lupus ). December precipitation was 7.3 SD above the 99-year mean and 2.5-fold higher than the prior record, with a return period of 333 years. However, ice thickness within the snowpack was highly variable across vegetation types, and caribou shifted to use higher elevations that can blow free of snow. Caribou and wolf mortality rates were 1.3–1.8 SD above normal and caribou population growth rates were low but similar to recent years, indicating a surprisingly weak demographic response. These findings indicate that landscape diversity may bolster resistance of wildlife populations to short-term, potentially devastating effects of extreme weather. Using weather data combined with multi-decadal caribou and wolf demographic data, heterogeneous habitat and topography are shown to mitigate the impact of an extreme precipitation event on wildlife populations in Alaska.

Global declines of large carnivores have reduced the ‘landscape of fear’ that constrains the behaviour of other species. In recent years, active and passive trophic rewilding have potentially begun restoring these lost top–down controls. The Tasmanian devil Sarcophilus harrisii has declined severely due to a novel transmissible cancer. In response to extinction fears, devils were introduced to the devil‐free Maria Island, where their abundance rapidly increased. We tested how this introduction influenced risk‐sensitive foraging in the common brushtail possum Trichosurus vulpecula, a major prey species for devils, using giving‐up densities (GUDs). Before the introduction of devils, possum GUDs on Maria Island were indistinguishable from the long‐diseased region of Tasmania, where devils have been rare since ~2000. Three years after devil introduction, GUDs were 64% higher on Maria Island than the control region, demonstrating that after an initial period of high mortality, possums quickly adopted risk‐sensitive foraging behaviours. Devil activity across Maria Island was variable, leading to a heterogeneous landscape of fear and highlighting that top predators must be at functional densities to elicit behavioural responses from prey. Our study provides strong evidence that top predators modify the behaviour of prey by instilling fear, causing rapid ecological change following recoveries.

Non-native deer are becoming increasingly common in peri-urban landscapes, where they pose a risk to the health and wellbeing of people. Professional vehicle-based shooting is commonly used to control deer populations in these complex landscapes, but the effectiveness and cost of this method have seldom been evaluated. We analyzed the effectiveness and cost of using professional vehicle-based shooting to reduce the abundance and impacts of non-native rusa deer ( Cervus timorensis ) in a peri-urban landscape in Wollongong, eastern Australia, during 2011–2021. We incorporated the results from an independent monitoring program into a Bayesian joint-likelihood framework to model spatio-temporal changes in rusa deer abundance. Finally, we used our findings to assess the effect of the management program on the number of complaints from the residents. After eleven years and the removal of 4701 rusa deer from Wollongong LGA (712 km 2 ), deer abundance did not change in 74.7% of the area, decreased in 19.4% of the area (mostly in and around the sites where the professional shooting occurred), and increased in 5.9% of the area. Shooting was most cost-effective during winter when the longer hours of darkness meant that shooters could visit more sites. In contrast to deer abundance, the probability of residents complaining about deer increased in space and time. Our study shows that professional vehicle-based shooting can locally reduce the abundance of invasive deer in a peri-urban landscape, providing that sufficient control effort is expended. We suggest that shooting effort is currently too thinly spread across this peri-urban landscape, and that concentrating shooting effort on the areas of greatest deer abundance and resident complaints might be a more cost-effective strategy for managing invasive deer in peri-urban landscapes.