Austral Ecology最新文献

The sungazer (Smaug giganteus) is a strict grassland specialist lizard endemic to South Africa's highveld grasslands. It is currently listed as Vulnerable (IUCN) and is primarily threatened by anthropogenic activities. Because sungazers are habitat specialists, climate change may be detrimental to the species, considering their life-history traits, and the area of available suitable habitat. We assessed how climate change may impact the sungazers' geographic range by first producing an ecological niche model (ENM) for the species within a buffered region of its extent of occurrence (buffered EOO). The ENM was then projected to 2040, 2060, 2080 and 2100 under two climate change scenarios using Shared Socioeconomic Pathways (SSP); SSP245 (moderate-case) and SSP585 (worst-case). A mean ensemble of three global circulation models for each time period and scenario was used to create habitat suitability maps which were refined using a natural grassland variable overlay. Resulting maps were clipped to the sungazers' EOO and interpreted distribution. Within the interpreted distribution, models predicted an area of 10 198 km² of current suitable habitat. At this scale, future habitat suitability is predicted to remain relatively stable (area: 9910 km²; 3% decline) under SSP245 by 2100. However, a 24% decline (area: 7705 km²) in habitat suitability was predicted under SSP585. Within the buffered EOO, habitat suitability increased in south-western regions, which was more prominent under SSP585. Although this finding suggests that sungazers could track favourable conditions, their life history and low dispersal ability makes climate tracking unlikely. Because sungazers only occur in primary grasslands, regions dominated by agricultural activities, further land use developments are likely to affect the species survival. Thus, careful conservation management is essential, and we recommend the establishment of protected areas with cognizance of our predictions for current and future suitable habitat within the sungazers' interpreted distribution.

Prescribed burning is frequently used in savanna vegetation in Australia and worldwide. In north-east Queensland savanna burning has been proposed for the control of woody weeds including Cryptostegia grandiflora (rubbervine), an invasive shrub/vine of riparian savanna. However, burning as a management tool can have non-target impacts on ecosystems, particularly where associated with additional invasive species, such as the exotic stoloniferous grass species Bothriochloa pertusa (Indian couch). For this reason, an experiment was established to test for non-target impacts of prescribed burning on herbaceous vegetation. The experiment consisted of wet and dry season burning, and single and double burning treatments during a 4 year study. Annual herbaceous surveys were conducted, both before treatments applied, and then annually. We addressed alternative hypotheses, that (i) burning would exacerbate grazing impacts resulting in negative outcomes for native herbaceous vegetation, or alternatively (ii) burning would be neutral or beneficial to native herbaceous assemblages due to savanna co-evolution with fire. Burning treatments resulted in subtle but beneficial responses for native herbaceous vegetation. Native legume biomass, percent composition and percent frequency, and forb species richness, increased 4–5 months following wet season burning with above average rainfall. There was a delayed (8–18 months) positive response of burning (both wet and dry season) in percent composition of native grazing sensitive perennial grasses. There was a slight short-term decline in introduced perennial grass percent composition and biomass following treatment. Results were consistent with predominantly positive or neutral responses to prescribed burning. There was no evidence to support the hypothesis that invaded native savanna herbaceous assemblages declined with burning treatment applications. These results are discussed in relation to other savanna studies in northern Australia and to the role of fire in the maintenance of herbaceous vegetation in savanna biomes.

Altered fire regimes and the increased frequency and/or severity of wildfires are significant issues for fire-sensitive species. In the Austral summer of 2019/2020, Australia experienced one of the worst fire seasons in recorded history (known as the 2019/2020 megafires), affecting 12.6 million hectares of eastern Australia. The Endangered southern greater glider (Petauroides volans) inhabits large areas impacted by the 2019/2020 megafires. With increasing fire severity, frequency, and intensity, there is a need to understand where in the landscape southern greater gliders are most impacted by fire, and where the species is most likely to persist in fire-affected landscapes. This is challenging given the lack of systematic data collected for this species. Maximum entropy modelling (Maxent) is a type of species distribution model with good predictive performance for presence-only records. We used Maxent to model the distribution of the southern greater glider in the two years prior (2017–2019) and two years post (2020–2022) megafire across the East Gippsland region of Victoria, an area heavily affected by the 2019/2020 megafires. Whilst we found that the predicted short-term area of occurrence of the southern greater glider remained relatively stable in the two years after megafire, a large area of marginal habitat was considerably reduced. We interpret this result as a potential contraction of suitable habitat where southern greater gliders may become isolated. Post fire, higher elevation areas and locations that experienced comparatively lower fire severity and a lower fire frequency had a higher predicted occurrence of the southern greater glider. Understanding the role of fire in species survival is essential for effective biodiversity conservation and management of species. More comprehensive and systematic monitoring in suitable and unsuitable areas will enhance our understanding of the distribution of the southern greater glider, including areas subject to wildfire.

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.