Austral Ecology最新文献

Achelous spinimanus, a species of swimming crab found along the Western Atlantic from the USA to Brazil, inhabits coastal areas up to 90 m deep across various substrates. While these crabs are known to be omnivorous, the extent of their predatory behaviour remains unclear. This note documents the first record of A. spinimanus actively preying on live fish. In the observed interaction, the fish was still alive and moving its operculum and mouth while being eaten. The observation was made during a night dive at Ilha dos Porcos, Arraial do Cabo, Brazil, where a crab was seen preying on a live Malacoctenus zaluari. The behaviour suggests that A. spinimanus may employ sit-and-wait strategy, utilizing its strong chelipeds for capturing prey. Such records are crucial for understanding the trophic dynamics and ecological roles of marine species, emphasizing the importance of both scientific and citizen science contributions to biodiversity knowledge. This finding also underscores the importance of further research on the feeding and behavioural ecology of portunids.

Floral syndromes can be a useful tool for predicting the identity of pollinators from floral morphology. However, the reliability of floral syndromes are still debated in the literature, and can often result in effective pollinators being overlooked. Pollination by moths has historically been associated with a floral syndrome comprising white tubular flowers that are heavily scented at night, but there have been few experimental tests of this association. To test whether moths preferentially land on flowers that are white and tubular, we allowed two moth species (Agrotis ipsilon (Hufnaggel, 1766) and Ichneutica mutans (Walker, 1857)) to choose freely between three plant species (Vaccinium corymbosum, Ericaceae, Pittosporum tenuifolium, Pittosporaceae, and two forms of Leptospermum scoparium, Myrtaceae) which represent four different floral morphologies. Anthers on the flowers were marked with fluorescent powder dye (pollen-tracker), with the presence of pollen-tracker on moth bodies after the experiment indicating floral visitation. We detected no floral preferences for any of the plant species by either moth species, suggesting moths will visit flowers that lack features associated with the syndrome even when in the presence of white, tubular flowers which might be predicted to be more attractive to moths. We also examined moth bodies to determine where pollen-tracker was carried most often and if this varied among the floral types. Our results indicate that some moth body parts may be more important than others for pollen transfer, depending on the morphology of the flowers visited. After visiting tubular flowers (Vaccinium and Pittosporum), pollen-tracker was most often located on the proboscis, but after visiting open-access flowers (Leptospermum) pollen-tracker was most often located on the legs. Future studies looking at the presence of pollen on moth bodies should consider this and ensure the entire moth body is examined for the presence of pollen.

Exotic vines threaten biodiversity causing damage to forest structure. We investigated the distribution of exotic vines across different patchily distributed plant communities. We surveyed patches of 12 threatened, mesic forest communities along the coastal plain in New South Wales, Australia to determine how exotic and native vine distribution and density were influenced by characteristics of forest patches and neighbouring land use. Vine density and stem widths were measured in quadrats in the edge and interior of patches. Canopy cover, number of dead trees, area to perimeter ratio and surrounding land use were recorded for each patch. Our results show that exotic vine assemblages were influenced by anthropogenic land use surrounding patches but not influenced by community type. Most exotic vine species were present across the whole region where surveys were undertaken. Exotic vines species were sometimes at high densities but had smaller stem widths than native species and there was no change in density from the edges into the interior. Araujia sericifera and Ipomoea cairica were the most prevalent exotic species and together with the fast edge growing Anredera cordifolia are of key concern. In contrast, native vine assemblages were species rich, with some individuals having large stem widths suggesting greater age and we found species composition varied with plant community type. Native vines showed continual recruitment and appeared more specialized to the attributes of each plant community. Surrounding anthropogenic land uses (residential, agricultural and industrial) were the most important factors predicting invasion of exotic vines and were more important than the length of edges. This suggests that the surrounding matrix characteristics were influencing degradation of the interior of these patches, rather than exotic vines invading along an invasion front from the edge. Exotic vines need to be controlled across the entirety of patches, rather than a focus on edge control practices.

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.