Austral Ecology最新文献

Although the incorporation of mammalian hair in nest construction for thermal insulation has been extensively documented among birds, the kleptotrichy—where birds pluck hair directly from living mammals—remains a relatively underreported behaviour in the scientific literature. Our camera trap monitoring effort in Pumalín Douglas Tompkins National Park, Chile, captured a chucao tapaculo (Scelorchilus rubecula) plucking hair from a southern pudu (Pudu puda). The observed behaviour suggests an adaptation for obtaining nest material, particularly in high-latitude regions like our study area. The pudu's minimal reaction suggests that the hair removal was not perceived as uncomfortable, potentially because the hair was already being shed. This could also be interpreted as a case of ectoparasite removal or other mutualistic interactions. Further research is needed to determine the use of pudu hair as nest construction material and to explain the ecological implications of this behaviour. Our findings highlight the value of camera trap monitoring in expanding the knowledge of species interactions and providing insights about wildlife behaviours.

Amphibians are increasingly threatened, leading to growing concern about their key role in natural ecosystems globally as predators and essential consumers in food webs. Effective conservation plans are linked to up-to-date distributional and ecological information, but dietary knowledge is often underrepresented. This information is essential for understanding ecological requirements, changes in the species and populations, impacts of habitat modification, and developing conservation strategies. Here, we present the current knowledge on amphibian diets in Colombia, to determine (a) the number of species studied and their distribution across families and genera; (b) the temporal and regional patterns in number of articles on amphibian diets; and (c) the trends in topics studied associated with amphibian diets; and to offer (d) a qualitative description of amphibian diets and the methods used for stomach contents collection. We found 70 published studies on the diet of Colombian amphibians between the years 1914 and 2022, including 100 species (11.6% of Colombian species). The Andean region is the best represented, and the Amazon and Orinoco the least. The topics most frequently studied were prey items consumed and ontogeny, followed by systematics and taxonomy, and land-use change impacts. Forty-one prey items were consumed, where Coleoptera and Hymenoptera were the most common prey items. While the development of information on amphibian diets has recently increased, knowledge remains limited, with a significant information gap for many Colombian species in different regions. Conducting studies in little-explored areas of the country, especially the Amazon, Orinoco, and Pacific regions, should have high priority. Investigations should be focused on Caudata and Gymnophiona, plus the anurans of the Hemiphractidae and Pipidae families that do not have diet records in Colombia. Indeed, we evidence the necessity to perform trophic network analysis to understand better the energy flow between species and the associated spatial, temporal, or functional trait changes.

We evaluated the most relevant natural and anthropogenic factors for the occurrence and co-occurrence of jaguars (Panthera onca) and pumas (Puma concolor) in the eastern Amazon, the most degraded portion of this tropical rainforest in Brazil. We found that in a context of high human pressure, a more significant amount of primary forest and more significant annual rainfall most positively influence the occurrence of jaguars. In contrast, pumas are negatively influenced by proximity to roads and positively by slope. Additionally, the presence of primary forest areas and high annual rainfall also favour the co-occurrence of jaguars and pumas in the same areas. In contrast, open areas more related to anthropogenic zones disfavour the co-occurrence of these two species in this degraded portion of the Amazon. Our results support landscape management for conserving big cat species in the Amazon and reinforce the importance of forest conservation for maintaining big cats in altered landscapes. Although these animals occur in open habitats, in the Amazon, these species are dependent on primary forests, as they are better-structured habitats that maintain the capacity to support prey and shelter.

Apex predators are vulnerable to environmental changes which can cascade through trophic levels of an ecosystem. Investigating prey-predator relationships is important for directing conservation efforts and understanding how species may respond to ecosystem changes. This case study examined the diet and breeding success of the threatened powerful owl Ninox strenua in central Victoria where the box-ironbark forests have undergone widespread clearing, fragmentation, and degradation. The powerful owl preys predominantly on arboreal mammals, however, some birds are also consumed. By analysing the contents of regurgitated owl pellets of two owl pairs, we found that birds comprised 29.3% of all prey items and contributed the largest proportion of prey biomass for one pair (34.4%). All mammalian prey species identified in the pellet remains are dependent on tree hollows, which are now a scarce and competitive resource in box-ironbark forests. Despite consuming a diet lower in mammalian prey than found in other studies, breeding success over five consecutive years was 1.4 chicks fledged per pair per year, which is notably higher than historical observations in the region and similar to powerful owls in other parts of their distribution. Our observations suggest that flexibility in prey selection enables powerful owls to occupy ranges that have undergone significant ecosystem change.

Freshwater fish are facing an extinction crisis on a global scale, with increasing demand for human water consumption driving the regulation and degradation of freshwater ecosystems. Flow regulation especially poses a threat to small-bodied floodplain and creek specialist species through increasing population fragmentation and isolation, loss and degradation of habitats, and interactions with predators and competitors, resulting in reductions in species' range and abundance. Conserving and recovering many small-bodied fish species will likely require translocation from wild habitats to refuge habitats to reduce extinction risk and provide buffers against catastrophic natural events (e.g., drought, bushfires). We assessed the value of semi-artificial farm dams, an abundant feature in the Australian landscape, as interim refugia for the threatened southern pygmy perch Nannoperca australis (Percicthyidae). We compared the relative abundance, population size–structure and body condition of fish introduced (3–4 years prior) into three farm dams with those of three nearby creeks to assess the feasibility of farm dams as a resource to assist small-bodied native fish conservation and recovery. Farm dams had higher abundance of fish, and equivalent size structure and body condition compared with creek populations, highlighting that suitable farm dams are a valuable and underutilized asset for threatened species' conservation globally.

The understanding of the resource use and partitioning of medium and large terrestrial mammals in anthropogenic environments such as road areas is crucial for comprehending ecosystem dynamics and reveals how species coexist and adapt to environmental changes. The aim of this work was to characterize trophic aspects of medium and large terrestrial mammals, including the quantification of resource use, variation in isotopic trophic niche breadth and overlap among sympatric species within a road zone influence in Uruguay. To this end, stable isotope ratios (δ¹³C and δ¹⁵N) were examined in hair samples collected from 57 individuals from road-killed animals including 9 medium and large mammals species, as well as potential resources. The isotopic results reflected a community that contains four trophic levels, with Galictis cuja as a predator while the species Dasypus hybridus and Subulo gouazoubira were in the primary consumer levels. Furthermore, the results showed varying degrees of isotopic trophic niche breadth, suggesting different feeding strategies and degrees of dietary specialization. Additionally, a high degree of overlap in resource use was observed among these sympatric species with the exception of Galictis cuja, suggesting that spatial and temporal differentiation in resource use could help to explain the coexistence patterns. Diet composition estimated using Bayesian stable isotope mixing models revealed that in most species, the basal food source was represented by a combination of natural grasslands of types C3 and C4. This trophic behaviour with the incorporation of diverse and variable food items helps to explain the occurrence of these species within this complex environment.

Predator exclosure reserves have become pivotal to conserving some threatened Australian mammalian fauna. However, the impact of predator exclosure reserves on resident (non-target) small vertebrates is less understood. Given the potential ecological consequences of fencing, and the contribution of small vertebrates to ecosystem processes, we investigated species' occupancy, and site colonization and extinction dynamics, inside and outside of a predator exclosure fenced area for nine small vertebrates (six reptile, three mammal). We conducted vertebrate surveying 4 years (2011–2014) pre- and 2 years (2015–2016) post-fence construction at the Australian Wildlife Conservancy Mt Gibson Sanctuary, in the semi-arid, critically endangered Wheatbelt Eucalypt Woodlands of Western Australia, to assess spatial and temporal trends in small mammal and reptile populations. Of nine species modelled, one reptile (Diplodactylus pulcher) decreased in occupancy inside of the fence following construction. We detected no negative impact of the predator exclosure fence on the remaining eight species. One native reptile species (Lerista kingi) and an introduced rodent (Mus musculus) increased occupancy inside (but not outside) the fenced area. Spatial and temporal occupancy inside and outside of the fenced area for all other modelled species was stable. Biotic (habitat) factors and stochastic interannual detectability were the most significant drivers of species' occupancy. Species-specific habitat associations were partially determined by site-based presence and absence probabilities. This suggests that the predator exclosure sanctuary either benefitted or had minimal impact on all but one modelled species. These results may be a useful reference for future fencing projects aimed at both conservation and land management.

Defaunation is an increasingly pervasive process, reaching ever larger spatial scales worldwide. We integrated data on thousands of putative local mammal assemblages across the Neotropics into 518 metacommunities to predict the phylogenetic trait-based effects of regional defaunation—here defined as meta-extirpation (i.e. extinction at the metacommunity level)—on dozens of putative ecosystem services (ESs). Further, based on 1029 real-world mammal assemblages coalesced into 236 metacommunities, we assessed the spatial extent of meta-extirpations across the Neotropics, while empirically quantifying losses in ESs in comparison with putative scenarios. Using observed data, we also sought to understand changes in the mean body size of metacommunities for different dietary guilds. We examined patterns of mammal diversity, evaluated the erosion of ESs based on ecological networks and measured the relationships between diversity metrics and ESs via dissimilarity arrangements and generalized linear models. Meta-extirpation regimes lead to a mean loss of 49.6% of the ESs provided by Neotropical mammals within metacommunities, whereas real-world meta-extirpations derived 47.2% of ES loss. We show that simulated meta-extirpations penalizing large-bodied species, induced the most severe losses in ESs. Regional-scale meta-extirpations lead to changes in the metabolic allometry and trophic structure of consumers, inducing significant metacommunity downsizing. We conclude that once-thriving mammal-mediated roles in natural ecosystems are fading, with significant consequences for human livelihoods. Many mammal populations have succumbed in several Neotropical ecoregions; so it is critical to protect representative fractions of Neotropical landscapes and regional species pools. Finally, we reinforce the appeal for effective conservation action, given that meta-extirpations are already a global reality.

Brushtail 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.

The incidence of wildlife roadkill significantly threatens the persistence of wildlife populations and disrupts the ecological functionality of ecosystems. This study investigates the impact of roadkills on wildlife in the Paraguayan Chaco, focusing on a 250-km segment of Route 9 ‘Dr. Carlos Antonio López’ between Villa Hayes and Pozo Colorado. We conducted a road survey for 15 months and recorded 2338 carcasses, identifying 87 species, with mammals (41.3%), reptiles (32.3%) and birds (19.8%) being the most observed groups. The species most frequently killed included Cerdocyon thous, Caracara plancus, Thamnodynastes hypoconia and Procyon cancrivorus. We also recorded species with conservation concern. Additionally, we estimated mortality rates by accounting for sampling errors such as carcass removal and searcher efficiency, revealing annual roadkill rates of 5183 mammals, 19 402 birds and 5020 reptiles on the 250 km per year. Spatial analysis using Ripley's K statistic and HotSpot Identification highlighted significant variation in roadkill distribution across different taxonomic groups and seasons, with 51 km of road identified as hotspots when analysing all groups together. Notably, there was minimal overlap in hotspot locations between seasons and taxonomic groups, emphasizing the need for targeted mitigation strategies. Our findings challenge previous macroecological assessments suggesting low roadkill rates in Paraguay, underscoring the importance of local studies in accurately assessing ecological impacts. This study provides critical baseline data for conservation efforts and calls for further research to develop and implement effective roadkill mitigation strategies in Latin America, especially in Chaco region.