Scavenger Guild Research Articles

A call to further understand the role of carrion in food webs: a case study of the Australian Alps

ABSTRACT Carcasses are integral to the structure and function of ecosystems, providing a food source for a variety of scavenger species that recycle nutrients back into the biosphere. However, in many systems globally there is limited information on the extent of carcass use by scavengers and the length of carcass persistence. This prevents land managers from making well-informed decisions on whether carcasses should be removed if produced in excessive numbers following activities such as culling, or extreme weather and disease outbreaks, or when to undertake management operations that add to the overall carcass biomass in ecosystems. In this paper, we focus on the Australian Alps and highlight results from recent studies to show that carcasses persist in this bioregion for long periods in winter when insects are less active. We show that vertebrate scavenging rates are relatively low in the Australian Alps compared to other bioregions in Australia, and that carcasses in this system can become hotspots for introduced species like European wasps (Vespula germanica), red foxes (Vulpes vulpes), and feral pigs (Sus scrofa). We advocate that further carcass monitoring in the Australian Alps should focus on scavenger use and persistence rates for different carcasses species, including across different elevations, seasons, and following culling operations. This will ultimately help to guide understanding around when native scavenger guilds can effectively accelerate carcass biomass loss, which is a key indicator of a healthy, functioning ecosystem.

Urbanization alters sandy beach scavenging assemblages and dogs suppress ecosystem function

AbstractUrbanization is rapidly transforming coastal landscapes around the world, altering the structure and function of marine, intertidal, and terrestrial ecosystems. In tandem, coastal areas are hotspots for human recreation, leading to shifts in wildlife behavior and activity patterns. Together, urban development and recreational use of wildlife habitats can shape wildlife behavior, abundance, and ecosystem dynamics at different spatial and temporal scales. In this study, we explore the impact of urbanization and human and domestic dog activity on the structure of vertebrate scavenging assemblages and the ecosystem functions they provide in sandy beach ecosystems across 40 km of the central California coast, USA. We surveyed vertebrate scavenging assemblages using baited camera traps on 17 beaches spanning a gradient of coastal urbanization. We found that urbanization extent within small spatial scales (i.e., 1 or 3 km radii of each site) and the rate of beach visitation by domestic dogs or humans were the best additive predictors of assemblage structure. We identified pronounced urbanization‐associated shifts in the composition of vertebrate scavenger guilds but found that the rate of carrion processing was more strongly influenced by domestic dog habitat use and diel period. Scavenging activity was substantially lower on beaches with more domestic dogs, suggesting that dogs interfere with critical scavenging ecosystem functions on sandy beaches. Our results underscore the pervasive and nuanced effects of urbanization and recreation on the dynamics of land–sea connectivity and suggest a need for comprehensive consideration of cross‐ecosystem linkages in ongoing shoreline conservation and development efforts.

Brushing up on carcass consumption: Investigating spatiotemporal scavenging dynamics of brushtail possums in Australian ecosystems

AbstractBrushtail possums (Trichosurus vulpecula) are becoming increasingly recognized as key members of local scavenger guilds in Australia. Yet, our understanding of the spatiotemporal scavenging dynamics of this mainly herbivorous marsupial species remains limited. We investigated abiotic and biotic factors influencing possum carcass use across an alpine and temperate bioregion in Australia. Using camera traps set on experimentally placed kangaroo carcasses, we first examined the influence of both open and closed canopy habitats and warm and cool seasons on possum scavenging behaviour across both bioregions. While scavenging was minimal in open habitats across both bioregions—likely a reflection of possums being an arboreal species—seasonality did significantly influence possum activity. Possums scavenged on carcasses in temperate regions entirely during cooler months. Scavenging was recorded year‐round in the alpine region, but with total possum feeding time on carcasses 5.9 times higher in cooler months. A more detailed 12‐month study in the alpine region confirmed this strong seasonal influence on possum scavenging, with possums up to 5.4 times more likely to discover carcasses in winter and spend up to 6.7 times longer feeding on carcasses during this season. The variability in possum scavenging behaviour between bioregions and seasons highlights the spatiotemporal complexity of possum scavenging behaviour and the importance of considering abiotic and biotic factors to understand the behaviours of scavengers more broadly. Recognizing primarily herbivorous animals as important yet often overlooked members of local scavenger guilds can help advance our understanding of complex scavenging networks and the intricate pathways through which energy flows in ecosystems, both in Australia and in other systems. Improving our understanding of the spatiotemporal scavenging dynamics of typically herbivorous species may also help to inform more nuanced and effective wildlife management strategies, where supplementary foraging on atypical food resources poses conservation concerns.

Taphonomic impact of vertebrate scavengers on degradation and dispersal of remains, southeastern British Columbia.

Vertebrate scavengers represent important taphonomic agents that can act on a body, particularly when in an outdoor environment. Understanding the effects of these agents will direct how and where to search for human remains and influence the likelihood of discovery in a particular region. The current study aimed to identify the taphonomic impact of scavenger guilds in the peri-urban and rural regions of southeastern British Columbia. Vertebrate scavenger activity on pig carcasses was recorded remotely using trail cameras and analyzed to determine temporal scavenging profiles. Both the peri-urban and rural environments produced comparable scavenger guilds, namely: turkey vultures, American crows/northern ravens (classified as "corvids"), American black bears, and coyotes. Although the two locations had different study lengths due to variable degrees of scavenging, for the period that was common to both locations (summer to early fall), the black bear was the most frequent scavenger followed by coyote. However, the dispersal of remains by the mammalian scavengers was distinctly different between sites. Only 12%-33% of skeletal elements were recovered at the rural sites compared to 80%-90% recovered at the peri-urban sites, even though the latter sites had a longer study timeframe. The extended timeframe of the peri-urban sites confirmed that certain scavengers (e.g., turkey vultures and black bears) are only seasonally active in this region. These findings demonstrate the variability of scavenger behavior and the need to assign caution and local ecological knowledge when predicting scavenger trends. Such taphonomic information is relevant for human remains searches in regions with comparable scavenger guilds.

The influence of vertebrate scavengers on leakage of nutrients from carcasses

The decomposition of carcasses by scavengers and microbial decomposers is an important component of the biochemical cycle that can strongly alter the chemical composition of soils locally. Different scavenger guilds are assumed to have a different influence on the chemical elements that leak into the soil, although this assumption has not been empirically tested. Here, we experimentally determine how different guilds of vertebrate scavengers influence local nutrient dynamics. We performed a field experiment in which we systematically excluded different subsets of vertebrate scavengers from decomposing carcasses of fallow deer (Dama dama), and compared elemental concentrations in the soil beneath and in the vegetation next to the carcasses over time throughout the decomposition process. We used four exclusion treatments: excluding (1) no scavengers, thus allowing them all; (2) wild boar (Sus scrofa); (3) all mammals; and (4) all mammals and birds. We found that fluxes of several elements into the soil showed distinct peaks when all vertebrates were excluded. Especially, trace elements (Cu and Zn) seemed to be influenced by carcass decomposition. However, we found no differences in fluxes between partial exclusion treatments. Thus, vertebrate scavengers indeed reduce leakage of elements from carcasses into the soil, hence influencing local biochemical cycles, but did so independent of which vertebrate scavenger guild had access. Our results suggest that carcass-derived elements are dispersed over larger areas rather than locally leak into the soil when vertebrate scavengers dominate the decomposition process.

Scavengers in the human-dominated landscape: an experimental study.

Rapid urbanization is a major cause of habitat and biodiversity loss and human-animal conflict. While urbanization is inevitable, we need to develop a good understanding of the urban ecosystem and the urban-adapted species, in order to ensure sustainable cities for our future. Scavengers play a major role in urban ecosystems, and often, urban adaptation involves a shift towards scavenging behaviour in wild animals. We experimented at different sites in the state of West Bengal, India, to identify the scavenging guild within urban habitats, in response to human-provided food. Our study found a total of 17 different vertebrate species across 15 sites, over 498 sessions of observations. We carried out network analysis to understand the dynamics of the system and found that the free-ranging dog and common myna were key species within the scavenging networks. This study revealed the complexity of scavenging networks within human-dominated habitats. This article is part of the theme issue 'Connected interactions: enriching food web research by spatial and social interactions'.

Validating the concept of top scavenger: the Andean Condor as a model species.

Vultures provide the key ecosystem service of quickly removing carrion, so they have recently been assumed to be top scavengers. To challenge the concept of top scavenger (i.e. the most influential in the scavenging community and process), between 2012 and 2019, we recorded the consumption of 45 equine carcasses available for two different avian scavenger guilds in the Tropical Andes; each guild included the Andean Condor, the alleged top scavenger. The carcasses eaten by Andean Condors were consumed, on average, 1.75 times faster than those they did not eat. Furthermore, the greater abundance of feeding condors shortened carcass consumption time more than a greater abundance of any other species by 1.65 to 5.96 times, on average. These findings support the hypothesis that the Andean Condor significantly drives scavenging dynamics and is, therefore, an unrestricted top scavenger. Additionally, we established a gradient of tolerance of avian scavengers to domestic dog disturbance at carcasses, from highest to lowest: vultures > caracaras > condors. Our study framework holds great potential for advancing in food webs' comprehension through quantifying the relative functional role of scavenging communities' members and for guiding efforts to weigh up the ecological contributions of top scavengers and foster their conservation.

A dog-eat-dog world: predation and resource acquisition by free-ranging dogs around Ranthambhore Tiger Reserve, Rajasthan, India

Free ranging-dogs are being recognized as a potential threat for native wildlife around the globe. They interact with native wildlife at multiple levels, ranging from predation, competition, acting as a reservoir for diseases and hybridization with the native carnivores. We have recorded cases that focus on interactions of dogs with wildlife in and around Ranthambhore Tiger Reserve (RTR). Between 2017–2020, we collected data on free-ranging dogs interacting with native wildlife of RTR. We classified the interactions into two categories: resource acquisition and predation. Based on our results we propose that dogs in rural settings around wildlife reserves can cause more resource competition for the existing carnivore scavenging guild resulting in reduced biomass consumption for the native scavengers. When present in large numbers, they can have a negative interaction with native wildlife through predation and harassment. To understand how dogs can pose threats to the native wildlife, there is a need for an extensive study on the ecology of dogs around wildlife reserves, pertaining to their feeding ecology and their raging behaviour.

Behavioral interactions are modulated by facilitation along a heterotrophic succession.

Competition and facilitation drive ecological succession but are often hard to quantify. In this sense, behavioral data may be a key tool to analyze interaction networks, providing insights into temporal trends in facilitation and competition processes within animal heterotrophic succession. Here, we perform the first in-depth analysis of the factors driving temporal dynamics of carcass consumption by analyzing behavioral patterns (i.e., interactions) and community dynamics metrics (i.e., species richness, abundance, turnover, and diversity) in a Neotropical scavenger guild. For this purpose, we monitored goat carcasses using automatic cameras. From 573 reviewed videos, we registered 1784 intraspecific and 624 interspecific interactions, using intraspecific and interspecific aggressions (n = 2048) as a behavioral proxy of competition intensity. Our results show that resource availability shapes behavioral interactions between vultures, with a specific effect of the different species on behavioral and competition dynamics, showing the existence of a hierarchy between species. Furthermore, behavioral processes linked to carcass opening tended to be facilitative, related to moments of higher tolerance (i.e., lower aggressiveness), thus reducing competition intensity and also affecting community structure and dynamics. This novel framework demonstrates complex ephemeral successional processes characterized by a fluctuation in facilitation and competition intensity during the consumption of an unpredictable resource linked to key ecosystem processes.

The taphonomic impact of scavenger guilds in peri-urban and rural regions of central and southern Alberta. Part I - Identification of forensically relevant vertebrate scavengers.

As a body decomposes in an outdoor environment, numerous taphonomic agents can act on the process of human decomposition. It is important to understand the impact of these agents as they can vary the rate of soft and hard tissue loss which may alter postmortem interval estimations. One taphonomic factor which has not been extensively investigated in many regions of the world, including Canada, are vertebrate scavengers. The current study aimed to identify scavenger guilds in the peri-urban and rural regions of two major cities in Alberta (Calgary and Edmonton) where human remains are frequently located. Vertebrate scavenger activity was recorded continuously using cellular and noncellular trail cameras. Images were analyzed to determine how the scavenging profiles (i.e., scavenger species, arrival time, and feeding behavior) impacted the loss of soft and hard tissue. We identified a range of mammalian and avian scavengers and found that coyote and black-billed magpie were the predominant scavengers recorded at the Edmonton peri-urban and rural sites, and the Calgary peri-urban sites. In contrast, when a site was within bear territory such as the Calgary rural sites, black and grizzly bears were the predominant scavengers. At all sites, the large mammalian scavengers were responsible for most soft tissue loss and subsequent hard tissue dispersal. None of the scavengers demonstrated a clear preference for open versus closed sites. This taphonomic information is important to consider when searching for human remains at these locations or in other North American regions with comparable scavenger guilds.

Sabretooths, giant hyenas, and hominins: Shifts in the niche of Early Pleistocene scavengers in Iberia at the Epivillafranchian-Galerian transition

The Epivillafranchian and the transition to the Galerian (1.2–0.9 Ma) was a period marked by environmental fluctuations and faunal turnover. Homo arrived into Europe around 1.4 Ma. ago, and was established in Iberia during the Epivillafranchian, as evidenced by the oldest sites with hominin fossils located in the Iberian Peninsula. The Iberian ecosystems offered a variety of trophic resources to hominins, including the opportunity to scavenge carcasses of large ungulates killed by a diverse predatory guild, especially due to the presence of two sabre-toothed cats. It has been claimed that the presence of Pachycrocuta brevirostris, a strong competitor for carrion, prevented hominins from exploiting abandoned carcasses as a reliable meat and fat resource. However, computer simulation experiments suggest that the coexistence of P. brevirostris and hominins competing for carrion was ecologically viable in the Epivillafranchian. Nevertheless, the faunal turnover of the Epivillafranchian-Galerian transition drastically changed the composition of the large carnivore fauna. The changes include the extinction of the sabre-toothed felid Megantereon, frequently considered a key provider of partially consumed carcasses, and the demise of the hyperscavenger P. brevirostris. All these changes modified the ecological scenario and the opportunities for hominins and other facultative scavengers. Computer simulation experiments using the agent-based model SCAVCOMP-ABM are used here to evaluate the viability of the coexistence of hominins and giant hyenas in the Epivillafranchian-Galerian transition. Different ecological scenarios defined by the composition of the predatory guild, ecosystem productivity, and competition pressure from other scavengers are evaluated. Results suggest that hominins and giant hyenas could coexist during the Epivillafranchian with different carnivore guilds, but a disruption of the scavenging niche likely occurred in the transition to the Galerian, coinciding with the extinction of P. brevirostris. A low ecosystem productivity during the cold intervals, maintenance of a high competition for carrion with other facultative scavengers, and a hypothetical social behaviour of the sabre-toothed cat Homotherium latidens appear as key factors to explain the changes in the scavenger guild at the Epivillafranchian-Galerian transition.

Scavenger Activity and Anti-Predator Behaviour in an Apennine Wolf Area

Scavenging guilds often have several trophic levels with varying dominance and intra-guild predation, competition, and interaction. Apex predators can control subordinate predators by limiting their numbers and affecting behaviour but also supply a continuous food source by abandoning carcasses. Camera traps monitored the scavenger guild in Alpe di Catenaia, Tuscan Apennine, for three years to determine intraguild interactions and the behaviour response. Wild boar visited most feeding sites but only scavenged in 1.4% of their visits. Red fox was the most frequent scavenger, traded vigilance and feeding equally, and selected low vegetation density, while marten invested more in feeding than vigilance. Marten was the prime follower, appearing within the shortest time after another scavenger had left the site. Red fox occasionally looked upwards, possibly to detect birds of prey. Badger showed scarcely any vigilance, did not feed much on carcasses but scent-marked abundantly. Wolves showed the highest vigilance in proportion to feeding at carcasses among the scavengers. Sites with good visibility were selected by all scavengers except martens who selected poor visibility and new moon illumination. Scavengers were mostly nocturnal, showed weak responses to twilight hours or lunar illumination, and all but red fox avoided human disturbance areas.

Feeding, agonistic and cooperative behavioural responses of shallow-water benthic marine scavengers

ABSTRACT Baited remote underwater video station (BRUVS) investigations of benthic scavenging by fish and invertebrates were conducted in an Irish sea lough. Mackerel (Scomber scombrus) baits were deployed under natural light during the day and under dim red light at night. Ethograms for feeding mechanisms and agonistic behaviours were established for four abundant scavengers (two crabs: the harbour crab Liocarcinus depurator, and the European green crab Carcinus maenas; two fish: the shanny Lipophrys pholis, and the small-spotted catshark Scyliorhinus canicula). Crabs’ feeding mechanisms were similar, with differences reflecting their morphologies. Feeding bouts lasted minutes/tens of minutes. Intraspecific agonistic responses were mild and did not result in mutilation or mortality. Feeding mechanisms on macerated baits focussed on ‘chewing’ (combined use of chelipeds and mouthparts to feed continuously); agonistic behaviour was reduced, especially at night when balls of crabs showed ‘cooperative feeding’. Fish feeding bouts lasted for a few seconds in all cases. Shannies showed anticipatory agonistic behaviour (bait ‘guarding’ and ‘patrolling’ by large shannies) before bait maceration. Catsharks exhibited no intraspecific agonistic behaviour but removed large bait morsels by ‘biting’, ‘chewing’ and ‘spinning’. The common prawns Palaemon serratus only scavenged at night and were invisible to other scavengers; they showed no agonistic behaviours. Kleptoparasitism amongst the scavenger guild was common but intra-community predation was extremely rare. Phoretic feeding on bait scraps by red-speckled anemones (Anthopleura ballii) attached to the carapaces of the edible crab Cancer pagurus was observed.

Behavior of Wild Pigs toward Conspecific Carcasses: Implications for Disease Transmission in a Hot, Semiarid Climate

Wild pigs (Sus scrofa) are a prolific, invasive species in the United States of America and act as vectors for many pathogens. An emerging pathogen of concern to the USA is African swine fever (ASF), a deadly viral disease affecting swine that is endemic to Africa and has spread to parts of Europe, Asia, and the Caribbean. ASF affects both wild and domesticated pigs and can be transmitted via several avenues, including interactions between and consumption of dead pigs by their live conspecifics. As wild pigs are considered a serious threat in the transmission of ASF, understanding the behavior of wild pigs towards their dead conspecifics is imperative when considering the transmission of ASF and other diseases in the USA. We placed camera traps at a sample of wild pig carcasses dispatched during four aerial shooting events between November, 2020, and June, 2022, at East Foundation’s San Antonio Viejo Ranch, South Texas. We recorded visitation events to carcasses by live wild pigs and recorded their behavior. Furthermore, we assessed daily carcass decomposition rates by visiting carcass sites without cameras. We found no evidence of cannibalism and recorded live wild pig visitations to only 33% of carcasses before advanced stages of decomposition were reached. Carcass decomposition was rapid (2.5 to 3 days), regardless of season, and the time to the first visitation and investigation of carcasses by live conspecifics was quicker than has been recorded in Europe. We posit that active scavenger guilds at our study site, coupled with high temperatures, result in the rapid decomposition of wild pig carcasses, which reduces opportunities for live wild pigs to interact with them when compared to milder climates. We suggest additional research investigating the persistence of ASF in hot, arid climates and the interactions between live pigs and the skeletonized remains of conspecifics.

Climate-driven animal mass mortality events: is there a role for scavengers?

SummaryAnimal mass mortality events (MMEs) will increase with weather and climate extremes. MMEs can add significant stress to ecosystems through extraordinary nutrient pulses or contribute to potential disease transmission risks. Given their efficient removal of carrion biomass from landscapes, we argue here for the potential of scavenger guilds to be a key nature-based solution to mitigating MME effects. However, we caution that scavenger guilds alone will not be a silver bullet. It is critical for further research to identify how the composition of scavenger guilds and the magnitude of MMEs will determine when scavengers will buffer the impacts of such events on ecosystems and when intervention might be required. Some MMEs are too large for scavengers to remove efficiently, and there is a risk of MMEs subsidizing pest species, altering nutrient cycling or leading to disease spread. Prioritizing native scavenger taxa in conservation management policies may help to boost ecosystem resilience through preserving their key ecological services. This should be part of a multi-pronged approach to MME mitigation that combines scavenger conservation with practices such as carcass dispersal or removal when exceeding a threshold quantity. Policymakers are urged to identify such thresholds and to recognize both the insects and the vertebrate scavengers that could act as allies for mitigating the emerging problem of climate-driven MMEs.

Second-generation anticoagulant rodenticides in the blood of obligate and facultative European avian scavengers

The widespread use of second-generation anticoagulant rodenticides (SGARs) and their high persistence in animal tissues has led to these compounds becoming ubiquitous in rodent-predator-scavenger food webs. Exposure to SGARs has usually been investigated in wildlife species found dead, and despite growing evidence of the potential risk of secondary poisoning of predators and scavengers, the current worldwide exposure of free-living scavenging birds to SGARs remains scarcely investigated. We present the first active monitoring of blood SGAR concentrations and prevalence in the four European obligate (i.e., vultures) and facultative (red and black kites) avian scavengers in NE Spain. We analysed 261 free-living birds and detected SGARs in 39.1% (n = 102) of individuals. Both SGAR prevalence and concentrations (ΣSGARs) were related to the age and foraging behaviour of the species studied. Black kites showed the highest prevalence (100%), followed by red kites (66.7%), Egyptian (64.2%), bearded (20.9%), griffon (16.9%) and cinereous (6.3%) vultures. Overall, both the prevalence and average ΣSGARs were higher in non-nestlings than nestlings, and in species such as kites and Egyptian vultures foraging in anthropic landscapes (e.g., landfill sites and livestock farms) and exploiting small/medium-sized carrions. Brodifacoum was most prevalent (28.8%), followed by difenacoum (16.1%), flocoumafen (12.3%) and bromadiolone (7.3%). In SGAR-positive birds, the ΣSGAR (mean ± SE) was 7.52 ± 0.95 ng mL−1; the highest level detected being 53.50 ng mL−1. The most abundant diastereomer forms were trans-bromadiolone and flocoumafen, and cis-brodifacoum and difenacoum, showing that lower impact formulations could reduce secondary exposures of non-target species. Our findings suggest that SGARs can bioaccumulate in scavenging birds, showing the potential risk to avian scavenging guilds in Europe and elsewhere. We highlight the need for further studies on the potential adverse effects associated with concentrations of SGARSs in the blood to better interpret active monitoring studies of free-living birds.

Scavenger assemblages are structured by complex competition and facilitation processes among vultures

AbstractUnderstanding the factors that allow multiple species to coexist and share resources is an outstanding question in community ecology. Animals that share resources tend to use different strategies to decrease potential competition, through morphological adaptations, establishment of hierarchies, behavioral adaptations or spatial or temporal segregation. The main objective of this study was to infer interspecific processes of competition and facilitation through the study of species co‐occurrence patterns in a vertebrate scavenger guild in de Brazilian cerrado. We analyzed patterns of spatial and temporal co‐occurrence between species pairs, both qualitatively and quantitatively, and determined the activity patterns of the different scavenger species. For this purpose, we placed and monitored 11 large (i.e. goat) and 45 small (i.e. chicken) carcasses by camera‐trapping, obtaining a total of 27 448 images. Our results show complex competitive and facilitative relationships among scavenging species in the Brazilian cerrado that are influenced by carcass size and change depending on the spatial and temporal scale at which they are analyzed. The scavenger assemblages that consumed large and small carcasses were different, evidencing resource partitioning between obligate and facultative scavengers. Furthermore, as an alternative to reduce competition levels, most species showed differences in their scavenging patterns, in addition to a strong temporal segregation during carcass consumption. Regarding New World vultures, our results suggest a strong interference competition between species with clear differences in their ecological traits (e.g. size, social behavior). However, we also found evidence of facilitation processes between vulture species in the location and access to the interior of the carcasses. Our findings highlight the role of obligate scavengers both in competition and facilitation processes in this vertebrate scavenger community. Future research should focus on investigating which species play the most important role in the structure and dynamics of this community, also considering intraspecific and behavioral patterns.

Dogs suppress a pivotal function in the food webs of sandy beaches

Domestic dogs are the most abundant carnivore globally and have demonstrable negative impacts to wildlife; yet, little evidence regarding their functional roles in natural food webs exists. Adding dogs to food webs may result in a net loss (via suppression of naturally occurring species), net gain (via mesopredator release), or no change (via functional replacement) to ecosystem function. Scavenging is a pivotal function in ecosystems, particularly those that are energetically supported by carrion. Dogs also scavenge on animal carcasses, but whether scavenging by dogs influences the structural and functional properties of food webs remains unclear. Here we used camera traps baited with carrion to test the effect of dogs on the composition and diversity of the vertebrate scavenger guild, as well as carrion detection and consumption rates. We conducted this work in sandy beach ecosystems, which rely on the import of marine organic matter (i.e. stranding of dead marine animals). Diversity of the scavenger community was similar on beaches without dogs. Dogs increased the time it took for carcasses to be detected and decreased the proportion of carrion consumed. This ‘dog suppression effect’ on scavenging was stronger for nocturnal mammalian scavengers, presumably being driven by indirect trait-mediated effects, which raises further questions about the broader ecological consequences of domestic dogs in natural systems.

Seasonal impact of scavenger guilds as taphonomic agents in central and northern Ontario, Canada.

The process of human decomposition is driven by biological decomposers, mainly bacteria, vertebrates, and invertebrate scavengers. When vertebrate scavengers have access to a body, they can considerably accelerate decomposition through consumption of soft tissue and dispersal of skeletal elements. Presently, there are limited data available on vertebrate scavenging activity in Canada, particularly in densely populated provinces such as Ontario. This study aimed to determine which vertebrate species belong to the scavenger guilds in central and northern Ontario, and the impact of season and habitat on these taphonomic agents. Seasonal trials were conducted in summer, fall, and spring of 2020/2021 with pig carcasses placed in open (grassland) and closed (forest) sites. Vertebrate scavenger activity was recorded continuously using cellular and non-cellular trail cameras. Photographs were analyzed to identify species, quantify feeding intensity, and document scavenging behavior. We identified four mammalian scavengers, namely coyote, red fox, fisher, and pine marten, and three avian scavengers, namely bald eagle, turkey vulture, and American crows/northern ravens (grouped as corvids) across the trials. Season impacted scavenger presence with feeding and loss of soft tissue occurring more quickly in the summer, followed by spring and fall. None of the scavengers demonstrated a clear preference for the open versus closed sites. Our findings have identified the most prevalent vertebrate scavengers in central and northern Ontario and their taphonomic impact on soft and hard tissues. It is important to consider these agents and their ability to degrade and disperse remains during the search and recovery of human remains.

Scavenger guild and consumption patterns of an invasive alien fish species in a Mediterranean wetland.

Invasive Alien Species (IAS) alter ecosystems, disrupting ecological processes and driving the loss of ecosystem services. The common carp Cyprinus carpio is a hazardous and widespread IAS, becoming the most abundant species in many aquatic ecosystems. This species transforms ecosystems by accumulating biomass to the detriment of other species, thus altering food webs. However, some terrestrial species, such as vertebrate scavengers, may benefit from dead carps, by incorporating part of the carp biomass into the terrestrial environment. This study describes the terrestrial vertebrate scavenger assemblage that benefits from carp carcasses in a Mediterranean wetland. We also evaluate the seasonal differences in the scavenger assemblage composition and carrion consumption patterns. Eighty carp carcasses (20 per season) were placed in El Hondo Natural Park, a seminatural mesohaline wetland in south‐eastern Spain, and we monitored their consumption using camera traps. We recorded 14 scavenger species (10 birds and four mammals) consuming carp carcasses, including globally threatened species. Vertebrates consumed 73% of the carrion biomass and appeared consuming at 82% of the carcasses. Of these carcasses consumed, 75% were completely consumed and the mean consumption time of carcasses completely consumed by vertebrates was 44.4 h (SD = 42.1 h). We recorded differences in species richness, abundance, and assemblage composition among seasons, but we did not find seasonal differences in consumption patterns throughout the year. Our study recorded a rich and efficient terrestrial vertebrate scavenger assemblage benefitting from carp carcasses. We detected a seasonal replacement on the scavenger species, but a maintenance of the ecological function of carrion removal, as the most efficient carrion consumers were present throughout the year. The results highlight the importance of vertebrate scavengers in wetlands, removing possible infectious focus, and moving nutrients between aquatic and terrestrial environments.