Animal Conservation最新文献

Given the current biodiversity crisis, understanding how animals move across a landscape dotted with different anthropogenic threats and the consequences of those threats for animals is paramount to devising evidence-based conservation interventions. Vultures roam across large areas and are highly exposed to poisoning, which represents a particularly damaging form of wildlife crime. In this study, we introduce a framework for quantifying the exposure to threats and illustrate an example of poisoning risk as a threat in an endangered African vulture species, the Lappet-faced Vulture (Torgos tracheliotos). We combined GPS tracking data of 19 individuals collected between 2012 and 2022 with food availability and spatial threat maps of both intentional (poachers directly targeting vultures) and unintentional (farmers aiming to kill carnivores, with vultures being secondarily affected) poisoning across most of Southern Africa. We identified poisoning hotspots in northern Botswana and south-eastern Namibia. These areas were also associated with a high number of vulture mortalities, providing additional support for poisoning risk. Northern Botswana and areas at the border between Botswana and South Africa were characterized by high food availability, potentially amplifying the mortality rate by attracting vultures from surrounding areas. Our results offer valuable insights for regional vulture conservation, together with a methodological framework for quantifying and mapping the spatial exposure to threats for mobile species of conservation concern, enabling improved targeting of conservation actions.

Land-use change is one of the main threats to biodiversity at the global level, and subtropical dry forests are not exempt from such a threat. Recent studies suggest that species can become extinct with a considerable time lag, even if no further habitat loss occurs. Hence, there may be an extinction debt, which poses a great challenge to conservation. Here, we analyzed the response of taxonomic and functional richness of forest and understory specialist birds to 30 years (data from 1989, 2004 and 2019) of land-cover and land-use changes in the Chaco Serrano forest of central Argentina. Our results showed the occurrence of extinction debt in both forest and understory specialist birds, with such debt being greater in forest specialist birds. Results for species trait debt were inconclusive. We also found evidence that birds are not equally sensitive to land-use change, indicating a species-specific response. We conclude that the current presence of some large native forest patches and an intermediate degree of isolation in the region might be prolonging the persistence of some bird species and traits. Moreover, ecological legacies can strongly affect the current species distribution pattern and the permanence of functional traits in fragmented landscapes. These findings should be considered in conservation planning.

Assessing trends in population abundance and demographics is crucial for managing long-lived and slow-reproducing species. Obtaining demographic data, and age-structure information, is challenging, notably for cetaceans. To address this, we combined Unoccupied Aerial System (UAS; drone) photogrammetry data with long-term (>20 years) photo identification data to assess the age-structure of the critically endangered sub-population of common bottlenose dolphins (Tursiops truncatus) of the Gulf of Ambracia, Greece. We compared our findings with two extensively studied non-endangered bottlenose dolphin populations (T. aduncus in Shark Bay, Australia, and T. truncatus in Sarasota Bay, USA). Using a log-linear model, we estimated the total body lengths (TL) of 160 known-aged dolphins between 2021 and 2023 from blowhole-to-dorsal-fin distance (BHDF) measurements collected during surfacing. Subsequently, we tested four growth models to establish an age-length growth curve. We assessed the sub-population's age-structure using three methods: (1) UAS-derived TL estimates, (2) age-length growth curve and (3) long-term monitoring data (i.e. actual age-structure). UAS-measured TL (247.6 ± 32.2 cm) and UAS-estimated TL (246.0 ± 34.7 cm) of the Greek sub-population showed no differences. The Richards Growth model suggested an asymptotic length of 258.5 cm. In Greece, resulting age-structure estimates across the three methods revealed no significant differences (P > 0.1). The Gulf of Ambracia and Shark Bay populations shared similar age-structures, while Sarasota had higher proportions of 2–10 year-olds and lower proportions of 10+ year-olds. All populations had a comparable proportion of 0–2 year-olds (~14%), indicating a similar reproductive rate. Our findings suggest stability in the Greek sub-population; however, additional monitoring of reproductive parameters is essential before concluding its status. We demonstrated the effectiveness of UAS-photogrammetry in rapidly quantifying population age-structure, including scenarios with limited or no demographic data. This technique shows promise for enhancing precision, timeliness, cost-effectiveness and efficiency in population monitoring and informing timely conservation management decisions.

Predator–prey relationships can influence community processes, and a rich prey spectrum is important to favour carnivore conservation, as well as to buffer single prey towards intensive predation. Antipredator behavioural responses can occur and can be dynamic in time and space, which may generate counter-responses in predators. However, data are scarce on their role in modulating carnivore diet and behaviour. Data are especially needed for European landscapes that are largely anthropized and have been recently recolonized by large carnivores. In a protected area in central Italy recently recolonized by the wolf and hosting a rich community of wild ungulates, we studied the interactions between this predator and three ungulate species. At the initial stage of wolf recovery, the fallow deer and the wild boar were the main prey, while the roe deer was a minor food item. Through camera-trapping and predator food habits, we assessed temporal changes in wolf–prey relationships throughout 5 years (2017–2022). Wolf detection rates were spatially associated with those of fallow deer and wild boar, but shrub cover was positively related to predator and negatively to prey, suggesting possible prey avoidance of sites with lower visibility and greater predation risk. Throughout the years, the fallow deer increased its diurnal activity, with a decreasing temporal overlap with the predator. The wolf showed crepuscular/nocturnal activity, with an increased synchronization with the wild boar, which replaced the fallow deer as first prey. No support for major spatiotemporal responses was reported for wild boar and roe deer. With the ongoing recovery of carnivores across Europe, conservation priorities may emphasize the need to maintain an efficient ecological role of predators. Our results support the role of antipredator responses in modulating predator behaviour and diet and emphasize the importance of a diverse spectrum of wild prey to ensure the conservation of the ecological role of carnivores.

Animals often rely on the presence of multiple, spatially segregated cover types to satisfy their ecological needs; the juxtaposition of these cover types is called landscape complementation. In ecosystems that have been homogenized because of human land use, such as fire-suppressed forests, management activities have the potential to increase the heterogeneity of cover types and, therefore, landscape complementation. We modeled changes to California spotted owl (Strix occidentalis occidentalis) nesting/roosting habitat, foraging habitat and habitat co-occurrence (i.e. landscape complementation) within a 971 245-ha forest landscape restoration project area, the Tahoe-Central Sierra Initiative (TCSI) landscape, through mid-century as a function of fuels reduction, fire and climate change. Compared to a minimal management scenario, accelerated management within the TCSI landscape was predicted to increase the number of potential 400-ha spotted owl territories containing a high degree of landscape complementation (defined as containing >20% nest/roost habitat and >20% foraging habitat) at lower elevations (<5000 ft.) by an average of 90 to 118 territories by 2050, depending on the climate scenario examined. At higher elevations (>5000 ft.), potential benefits of treatments to spotted owl nesting/roosting and foraging habitat were less evident, but accelerated management did not result in habitat loss. Our results suggest that accelerated fuels reduction and forest restoration treatments within this large landscape are expected to benefit spotted owls by improving the spatial juxtaposition of nesting/roosting and foraging cover types by 2050 compared to a minimal management scenario. Fuels reduction and forest restoration in this landscape thus can both increase the resilience of forest ecosystems to disturbances as well as benefit the habitat of a sensitive old-forest species.

Human-mediated animal movement can expose wildlife populations to novel environments. Phenotypic plasticity can buffer against the challenges presented by novel environments, while adaptation to local ecosystems may limit resilience in novel ecosystems. Outbreeding depression during the mixing of disparate gene pools can also reduce reproductive success after long-distance movement. Here, we use a ‘common-garden’ population of gopher tortoises (Gopherus polyphemus), translocated from numerous sites across the state of Florida, USA, to a mitigation site in the north-west (panhandle) region to assess whether geographic origin, outbreeding effects, and behavioral plasticity influence reproductive success in this threatened keystone species. We found that females from north-east Florida produced clutches with lower hatching success than females from other regions. We detected regional differentiation in nest site selection behavior in the common environment of the translocation site, though these differences did not mediate the regional effect on hatching success. We also found evidence for outbreeding depression: hatching success declined with increasing parental geographic and genetic distances, dropping from 93% to 67% across the range of observed parental genetic distances. Together, these results suggest that newly admixed populations may suffer reproductive costs due to historical population differentiation, and that undetected outbreeding depression could significantly hamper conservation efforts for this species and others undergoing a variety of human-mediated movements.

Habitat loss, fragmentation, and degradation of habitats are among the most pervasive impacts on species persistence. Mammals may vary in their response to these impacts, both in abundance and in physiological parameters. Herein, we verified how habitat quality influenced the small mammal nutritional status and stress levels among five semi-deciduous forest remnants in the Brazilian Cerrado. To assess species' physiological responses, we used body condition as an indicator of nutritional status and neutrophil/lymphocyte (N/L) ratio as an indicator of chronic stress in Gracilinanus agilis and Rhipidomys macrurus. We sampled 264 animals belonging to the following species: G. agilis, Didelphis albiventris, Akodon montensis, Oligoryzomys spp., Rattus rattus, R. macrurus, Oecomys cleberi, Hylaeamys megacephalus, and three unidentified rodent species. We found no negative effect of reduced habitat quality on the body condition of G. agilis and R. macrurus, however, the N/L ratios of these species were lower only in high-quality habitats, demonstrating that this parameter is an accurate indicator of chronic stress. Based on preliminary analysis, we also reported an impoverished fauna, mainly dominated by generalist species, in low-quality habitats. Thus, we conclude that short-term reduction in habitat quality leads to increased stress levels, which can in turn lead to future population declines and culminate in biotic homogenization.

The fishing gear deployed by fishermen in seas and oceans throughout the world not only captures target species but also unintentionally ensnares non-target species, a phenomenon known as ‘by-catch’. This unintended capture of marine life can represent significant challenges for the fishing industry, with adverse impacts on both the environment and species such as sea turtles, marine mammals, seabirds and elasmobranchs, which may be injured or even killed. To address this problem, the fishing industry has implemented regulations and mitigation measures. In this literature review, we have examined 389 papers published between 2010 and 2022 that assess the effectiveness of these measures. Taking into account the fishing gear with which each group interacts the most, trawls for sea turtles, gillnets for marine mammals and longlines for seabirds and elasmobranchs, it has been demonstrated that ‘TEDs’ (Turtle Excluder Devices) are an effective measure for sea turtles, ‘pingers’ for marine mammals and ‘BSLs’ (Bird Scaring Lines), more commonly known as ‘tori lines’, for seabirds. The most complex case is that of elasmobranchs, and the most effective measure has yet to be discovered. This complexity arises from the ongoing targeted fishing of these species, resulting in less monitoring of their catches and, therefore, fewer surveys. Overall, we encourage the global implementation of these measures by the fishing industry in order to reduce by-catch in an attempt to ensure the future of many endangered species.

The need for effective conservation strategies to combat the ongoing biodiversity crisis is well recognised. Conservation translocations are an important and frequently used form of conservation management for species recovery. Despite this, the uncertainty prevalent throughout the translocation cycle often makes it challenging to determine whether translocations should be included in the suite of actions to achieve desired conservation outcomes. Further, the fundamental question of whether translocations should occur is seldom assessed as a formal decision. We applied a formal decision analysis for the conservation management of a highly threatened bird (karure | kakaruia | Chatham Island black robin | Petroica traversi) to evaluate whether translocation and/or other actions should be implemented for species recovery. The species' precarious status (<330 adults), combined with uncertainty about translocation outcomes, meant that for years, decision-makers were reluctant to act given the potentially severe consequences of translocation failure. We used structured decision-making in conjunction with population modelling to estimate the consequences of translocations and other actions across a range of objectives identified by Moriori and Ngāti Mutunga o Wharekauri (Indigenous Peoples of Rēkohu | Wharekauri | the Chatham Islands), the local community and government agencies. Structured decision-making facilitated an inclusive approach that ensured all participants were actively engaged in the decision-making process including the identification of the best management alternative while balancing multiple objectives. This process overcame the long-standing conservation impasse, resulting in rapid implementation of actions, including translocation, that would have otherwise been difficult to achieve. The preferred alternative across objectives involved multiple translocations, illustrating the vital role translocations have in the desired future management for the species. The methods used in our study can be readily applied in other species recovery programmes to help decision-makers navigate the complexities and uncertainties inherent in conservation decisions.

Over the past decade, the development of genetic and genomic tools for conservation management has come forward in leaps and bounds. Once considered a ‘nice to have’, genetic data are fast becoming an essential tool for informing and managing translocations. However, due to the complexity of the field, easily using genetic data for decision-making and monitoring remains beyond the reach of most managers and conservation biologists. In May 2020, we launched the Threatened Species Initiative (TSI), a programme designed to generate genomic resources for Australia's threatened species. Critical to the project is not only the generation of reference genomes and population genetic data but an online toolkit for conservation managers. The toolkit is a ‘one stop shop’ from collecting samples, to generating and analysing genetic data, to an easily interpretable genetic management report. A series of workflows and pipelines have been developed, including the TSI Biodiversity Portal, that uses point and click web interfaces to easily transfer raw sequence data and assemble genomes, transcriptomes and soon population genetics for management decisions. Here we present how the current toolkit works and provide case study examples for how it is being used to inform translocations and the management of threatened species.