Austral Ecology最新文献

Locusts are globally recognized as major pest threats. In the first half of the 20th century, the South American locust caused great economic losses. After the implementation of preventive management, large-scale upsurges ceased. In 2015, resurgence of S. cancellata led to swarms affecting northern Argentina, Paraguay, and Bolivia, prompting control agencies to address an almost forgotten problem. After six decades without a major locust outbreak, there were limited and outdated studies on this species. This study aims to identify key environmental factors associated with the spatial distribution of S. cancellata oviposition sites. We focus on explanatory variables that represent physical and chemical properties of soil and vegetation cover. To understand the relationships between each potential explanatory variable and the presence-absence of S. cancellata oviposition sites, we first performed regression analyses applying a linear and quadratic structure for each explanatory variable. Then, we performed comparisons of logistic regression models in a multi-model inference framework, where CAIC and weights of evidence were analysed. Our results show that the South American locusts chose to lay their eggs in areas with a low proportion of natural forest and flooded grasslands and a high proportion of non-vegetated areas, where the soils are flat, with neutral pH, and low salinity. We also determined that an increase in the proportion of cultivated areas is associated with an increase in the probability of breeding presence of this species. The locust's habitat falls within the Dry Chaco, a global deforestation hotspot, evidencing a rapid replacing of forests for plantations. Since both the diminish of forest and the increase in cultivated areas are associated with an increase in oviposition sites, we consider that breeding areas will likely increase. The results found herein can be used to map the potential breeding habitats to help preventive management against the South American locust.

Vertebrates' roadkill impacts many species in natural areas. However, data on this topic in the Amazon domain are still scarce, especially within protected areas. In this study, we analysed data from 2 years of monitoring amphibians, reptiles, mammals and birds' roadkill on five types of terrestrial transport infrastructure in a protected area in the Brazilian Amazon. We tested which vertebrate classes and feeding guilds were most recorded, the influence of seasonality and the spatial pattern of roadkill. In the studied area, 2795 roadkills were recorded, with amphibians suffering the most casualties. Most of the roadkills occurred during the rainy season (57%). Correcting the roadkill data using observer efficiency and carcass persistence time data, we concluded that mortality rates might be underestimated by up to 40 times when compared to raw data. There was no significant difference between feeding guilds concerning the number of fatalities, and rainfall and temperature significantly affected the roadkill pattern of all vertebrate classes. The spatial pattern of roadkill varied between traffic routes and vertebrate class types. The results indicate that amphibians are the most common victims of roadkill, although they are neglected in many roadkill monitoring. Consequently, mitigation strategies should prioritize periods with the highest mortality rates, as rainfall and temperature influence the frequency of these accidents. In addition, different classes of vertebrates have different patterns of impact concentration along traffic routes, which makes mitigation planning more complex. Therefore, planning to reduce vertebrate deaths from roadkill must consider each taxon's particularity and seasonality.

Prescribed burning is the primary method used to reduce wildfire risk in a range of ecosystems globally. Knowledge of how animal populations respond to prescribed burns is essential for designing fuel management plans that are sensitive to ecological values. We conducted a before–after, control-impact experiment in the temperate jarrah forest ecosystem of south-western Australia to examine how reptiles respond to season of burning (spring or autumn) and time since burning (0–5 years). Through pitfall trapping at 10 survey grids over 7 years, we captured 1808 reptiles from 22 species. Bayesian mixed effects models revealed that six of the eight species analysed showed either a decrease or increase in capture rate at burnt compared to unburnt sites, and most of these effects only occurred within the first 2 years post fire. Species richness showed a weak negative response to one autumn burn and no relationship with time since fire. Fire effects were more common in autumn compared to spring burns, which is likely a reflection of differing fire severities. These results suggest that prescribed burning can temporarily reduce habitat suitability and abundance for some species, particularly those that rely on leaf litter for shelter and foraging. Our findings emphasise the dynamic nature of reptile responses to prescribed burns and underscore the importance of considering both fire seasonality and recency of burning in wildlife management plans.

Migratory patterns of the catfish Genidens genidens in four estuaries along the Brazilian Atlantic coast are reconstructed from otolith Sr/Ca, a salinity proxy, to test estuarine-dependency. To facilitate interpretation of this proxy in otolith core-to-edge profiles, a Sr/Ca Reference Value for High Salinity (RVHS_Sr/Ca) of 4.88 mmol/mol was established experimentally, from fish specimens reared in water with a salinity level (33 psu) between estuarine and high salinity (marine) water. All wild specimens exhibited otolith Sr/Ca values higher than RVHS_Sr/Ca, suggesting that G. genidens utilizes environments with marine salinity. Our results reveal highly variable environmental histories, with at least five major habitat usage patterns. Most distinctive among these, we find that (a) fish from Paranaguá Estuarine Complex (PEC) exhibit high intraindividual heterogeneity; (b) most fish (57%) from Guanabara Bay (GB) exhibit prolonged exposure to very high salinities, often exceeding 36.5 psu levels found in some shelf sectors; and (c) some fish from Paraiba do Sul River, GB and PEC exhibit Sr/Ca values below RVHS_Sr/Ca consistent with estuarine residence. These results suggest that G. genidens is not strictly estuarine-dependent.

Understanding how animals respond to fire is crucial for conservation efforts in fire-prone regions across the world. How fire affects animal movement is of particular interest, as it determines access to resources, exposure to risks, and connectivity of populations. We report on observations of the movement patterns and habitat selection of two northern quolls (Dasyurus hallucatus, an endangered marsupial predator), one male and one female, in the Pilbara region of Western Australia. We employed GPS tracking and integrated step selection functions to analyse habitat preferences in relation to fire, and used accelerometry data to assess the energetic costs of using burnt areas. The male northern quoll avoided recently burnt areas, likely due to increased energetic demands and predation risks during the breeding season. In contrast, the female northern quoll neither avoided nor preferred burnt areas, but showed a preference for rocky areas. The female appeared to move through burnt areas to access suitable breeding habitat. The movement patterns observed in the two individuals might reflect a broader pattern of sex-specific responses to fire, but further research is required to confirm how general the pattern is. Our observations indicate that fire can influence northern quoll movement, with female dependence on rocky areas increasing use of suboptimal habitats, and male avoidance of burnt areas raising potential implications for breeding dispersal and population dynamics. Given the expected increases in fire size and frequency, further research on northern quoll responses to fire in the Pilbara is needed to determine if the pattern we observed is consistent across the broader population.

Sampling of environmental DNA (eDNA) and high-throughput sequencing is emerging as an effective biodiversity assessment method in aquatic systems and may have utility for biodiversity inventory in terrestrial environments. Rock pools (gnammas) on granite inselbergs support a rich community of aquatic organisms and are culturally important to Indigenous peoples worldwide. However, the application of eDNA to survey rock pool biodiversity are undocumented. In a collaborative study with traditional owners, we explore the application of eDNA metabarcoding and traditional sampling methods to document and compare species richness and composition of eukaryotes from 15 rock pools (pits and pans) on granite inselbergs in southeastern Australia. We detected 116 taxonomic units, 81 assignments from eDNA sequencing and 35 species (23 rotifers and 12 microcrustaceans) using microscopic analysis. eDNA detected a broad range of taxa not previously documented from rock pools in Australia, although significantly more zooplankton (rotifers and microcrustaceans) were detected under a microscope, including several rare species and two undescribed species of rotifer. Brachionus calyciflorus and B. angularis were the only rotifer species assigned to species level through eDNA sequencing and were detected using both methods. We found no significant difference in mean species richness between rock pool types; however, species composition differed significantly between pits and pans. This study highlights the value of using eDNA to document biodiversity of ephemeral aquatic habitats in terrestrial ecosystems but reveals the general lack of reference sequence data for microorganisms, underscoring the value of using traditional sampling and taxonomic assignment methods.

Dietary data are vital for understanding species' resource requirements and ecological roles and supporting conservation efforts. The Blue-headed Macaw, Primolius couloni, is a vulnerable and endemic species in the Amazon. Due to their rarity, elusive nature, complex forest canopy habitat, and occurrence in remote areas, we minimally know their dietary habits. To address this gap, we analysed photographs of Blue-headed Macaws posted on wildlife-focused social media platforms, specifically targeting images that capture foraging behaviour on plants. Photographs depicting the same foraging were included only once, and those where the plants were not identified were discarded. By doing so, we identified 36 distinct foraging events (or photos), primarily taken between July and October, concentrated in specific locations in Peru and Brazil, a potential seasonality in foraging. We documented 27 food plant species and items such as nectar (n = 9 photos), pulp (8), seeds (7), buds, bark (5 each), aril, and leaves (n = 1 photo each). Notably, floral resources, including nectar, are a potentially important food in the driest months. Using Levin's Index (Ba), we identified a broad dietary niche, indicating a generalist feeding strategy with a wide variety of plant species (Ba = 0.69) and food items (Ba = 0.88). Additionally, the study revealed interactions such as florivory, seed predation, bark consumption, and potential mutualistic roles like pollination and seed dispersal. Our photo-centric approach here expanded the known dietary spectrum of the Blue-headed Macaw from four to 31 plant species, offering new insights for conservation strategies. We recommend the preservation of identified food plants and suggest using these data to inform habitat restoration efforts that support the macaws' dietary needs and ecological functions. Future research should focus on continuous monitoring of these food plants to deepen our understanding of seasonal foraging trends and ecological interactions and refine conservation approaches.