Core Habitat Research Articles

Sensitivity of insectivorous bat foraging guilds to urbanization and implications for sustainable development

Substantial urban expansion is expected in global biodiversity hotspots over the next decade, especially in Asia. One such hotspot is Sulawesi, Indonesia, which hosts a diverse array of wild mammals, including bats. While urbanization may threaten some bats, species are not uniformly sensitive to urbanization. Many bat species’ sensitivity to urbanization is associated with their foraging strategies (or foraging guild), but information from Asia, generally, is severely lacking. Here we address this knowledge gap regarding urban sensitivity among insectivorous, echolocating bats within the context of urban informal settlements around the city of Makassar, South Sulawesi. Globally and in Makassar, informal settlements often exist on the fringe of cities, forming an urban-undeveloped land interface. Consequently, they may present opportunities to support conservation for some bats, given a growing focus on nature-based sustainable development solutions to improve the lives of informal settlement residents. We examined how, among informal settlements across Makassar, relative activity of bat sonotypes (in lieu of taxonomic species) from different foraging guilds was related to environmental factors associated with urban expansion. We found bat activity was influenced by processes interacting across multiple spatial scales ranging from the landscape- (e.g., spatial location relative to dense development in the urban core) to local-level (e.g., particular environmental features within 500 m). Broadly, we found some foraging guilds had lower overall relative activity, as well lower activity within the urban core compared to the peri-urban zone, indicating differential sensitivity to urbanization among Makassar’s bats that matches findings elsewhere. However, intensity of both urban and peri-urban informal settlement habitat use by particular bats was driven by a combination of landscape- and local-scale features. At the local scale, tree cover and inland water area frequently influenced sonotype activity in settlements, including urban core habitat use by urban-sensitive bats. Our work demonstrates that, especially if coordinated across broader spatial scales, local nature-based upgrades in informal settlements incorporating diverse green and blue spaces have the potential to enhance suitability of urban zones for both bats and for people.

On the elephant trails: habitat suitability and connectivity for Asian elephants in eastern Indian landscape.

Identifying suitable habitats and conserving corridors are crucial to the long-term conservation of large and conflict-prone animals. Being a flagship species, survival of Asian elephants is threatened by human-induced mortality and habitat modification. We aimed to assess the habitat suitability and connectivity of the Asian elephant Elephas maximus Linnaeus, 1758 habitat in the state of Odisha in eastern India. We followed the ensemble of spatial prediction models using species presence data and five environmental variables. We used least-cost path and circuit theory approaches to identify the spatial connectivity between core habitats for Asian elephants. The results revealed that normalized difference vegetation index (NDVI; variable importance 42%) and terrain ruggedness (19%) are the most influential variables for predicting habitat suitability of species within the study area. Our habitat suitability map estimated 14.6% of Odisha's geographical area (c. 22,442 km2) as highly suitable and 13.3% (c. 20,464 km2) as moderate highly suitable. We identified 58 potential linkages to maintain the habitat connectivity across study area. Furthermore, we identified pinch points, bottlenecks, and high centrality links between core habitats. Our study offers management implications for long-term landscape conservation for Asian elephants in Odisha and highlights priority zones that can help maintain spatial links between elephant habitats.

Looking for reliable species distribution models for low‐density cetacean species: Compared effectiveness of SDMs for G. griseus, G. melas, Z. cavirostris in the Mediterranean Sea based on long‐term fixed‐transect data

Abstract The EU regulative framework for the protection of marine biodiversity and habitats requires the assessment of species' conservation status and the identification of core habitats to design adequate conservation and management plans. However, the identification of distribution range and habitat‐use of pelagic large‐range, migratory species, such as cetaceans, is challenging. Species distribution models (SDMs) are increasingly used in conservation planning to identify species priority areas. However, the quality of SDMs varies widely depending on the representativeness of data and the appropriateness of the modelling techniques. Since 2007, the Fixed Line Transect Mediterranean Monitoring Network (FLT Med Net) has been continuously monitoring cetaceans throughout the year in the Mediterranean basin using passenger ferries as observation platforms that perform repetitive surveys along fixed trans‐border transects. With the aim of defining a standard analytical approach, the data collected by the FLT Med Net on rarer Mediterranean cetacean species (i.e., Grampus griseus, Globicephala melas, Ziphius cavirostris) are used here to assess the performance of commonly used SDMs, including GLM, GAM, GAM‐Negative Binomial, GAM‐tweedy, MaxEnt and Random Forest. Models were built and evaluated using a total of 296 FLT Med Net sighting data and cross‐validated using 145 independent data points. Under testing conditions, almost all methods exhibited good performance, with Random Forest being the best model in several cases. However, when evaluated with the independent dataset, many models yielded inconsistent results or notably low performance. Only MaxEnt demonstrated consistent efficiency and reliability in both cases, showing results less affected by unequal sampling or small sample size. Results confirm the importance of robust standard SDM approaches based on representative data such as the FLT Med Net data to identify reliable priority areas for the species and to assess the long‐term coherence and effectiveness of spatial protection measures.

Determinants of livestock depredation risk by Persian leopards in southern Iran

Human-wildlife conflict is a major conservation challenge worldwide, with negative consequences for people and wildlife alike. Large carnivores, despite their key role in ecosystem functioning, are persecuted throughout their ranges as a response to perceived or actual risks to livestock and humans. To promote human-carnivore coexistence, a better understanding of the determinants of conflict is necessary. A range of factors have been hypothesized to influence livestock depredation risk, including carnivore habitat suitability and connectivity, prey availability, and anthropogenic factors. Yet, the relative importance of these factors is often unclear. We analyzed and mapped livestock depredation risk for the Persian leopard (Panthera pardus tulliana) in southern Iran using a species distribution modeling framework. We used livestock depredation reports and interviews (n = 199) from 25 randomly selected villages together with predictors capturing leopard habitat suitability, movement corridors, wild and domestic prey, and anthropogenic pressure. Our leopard habitat suitability and connectivity analyses predicted 28 core habitat patches (>250km2) associated with mountainous and conserved areas, with partly severed corridors between them. Our risk mapping indicated that the chance of livestock depredation increased in areas with higher leopard habitat suitability. Conversely, depredation risk was lower in areas with more wild prey. We predicted the highest depredation risk in about 12 % of the landscape where urgent conflict mitigation measures would be most beneficial. More generally, our study shows that while conservation areas provide refuge for carnivores, these areas can also lead to higher levels of conflict, hence mitigation measures should be prioritized in their surroundings.

Using power analysis and spatial prioritization to evaluate the design of a forest bird monitoring programme

Abstract Biodiversity monitoring programmes should be designed with sufficient statistical power to detect population change. Here we evaluated the statistical power of monitoring to detect declines in the occupancy of forest birds on Christmas Island, Australia. We fitted zero-inflated binomial models to 3 years of repeat detection data (2011, 2013 and 2015) to estimate single-visit detection probabilities for four species of concern: the Christmas Island imperial pigeon Ducula whartoni, Christmas Island white-eye Zosterops natalis, Christmas Island thrush Turdus poliocephalus erythropleurus and Christmas Island emerald dove Chalcophaps indica natalis. We combined detection probabilities with maps of occupancy to simulate data collected over the next 10 years for alternative monitoring designs and for different declines in occupancy (10–50%). Specifically, we explored how the number of sites (60, 128, 300, 500), the interval between surveys (1–5 years), the number of repeat visits (2–4 visits) and the location of sites influenced power. Power was high (> 80%) for the imperial pigeon, white-eye and thrush for most scenarios, except for when only 60 sites were surveyed or a 10% decline in occupancy was simulated over 10 years. For the emerald dove, which is the rarest of the four species and has a patchy distribution, power was low in almost all scenarios tested. Prioritizing monitoring towards core habitat for this species only slightly improved power to detect declines. Our study demonstrates how data collected during the early stages of monitoring can be analysed in simulation tools to fine-tune future survey design decisions.

Identifying umbrella and indicator species to support multispecies population connectivity in a Himalayan biodiversity hotspot

Successful conservation hinges on the reliable prediction and prioritisation of population core habitats and dispersal corridors. However, reliance on single-species connectivity has produced mixed results and, in most cases, failed to protect other species under the appealing but often unfulfilled guise of umbrella protection. The main objectives of this study were: (1) to identify core habitats and dispersal corridors for population connectivity of 15 terrestrial mammal species across Bhutan, (2) to identify indicator species of wildlife connectivity, (3) to prioritise core areas and dispersal corridors for the focal umbrella and indicator species, (4) to develop composite multispecies connectivity maps and evaluate the effectiveness of the existing protected area network. We used kernel density (KD) to identify core habitat areas and factorial least-cost path (LCP) to map dispersal corridors. We used correlation and cluster analyses to identify umbrella and indicator species, and quantitative ranking to prioritise core areas and corridors for these focal species. Finally, we produced maps of multispecies core areas and corridors, and identified gaps in the existing protected area network (PAN). We found that ungulates were generally more effective than carnivores in serving as umbrella species for core habitat protection, with Asian elephant (Elephas maximus) emerging as the most effective umbrella for core habitats and muntjac (Muntiacus muntjac) for dispersal corridors. We identified six focal connectivity indicator species in Bhutan: tiger (Panthera tigris), dhole (Cuon alpinus), clouded leopard (Neofelis nebulosa), Asiatic black bear (Ursus thibetanus), Asian elephant, and sambar deer (Rusa unicolor). Most indicator species’ core areas and dispersal corridors outside the PAN were in southern Bhutan, indicating opportunities for increased multispecies connectivity through expanding protected area network in this region. A total of 40% of multispecies core areas and 24% of dispersal corridors were under PAN, with large parts of Bhutan offering suitable core areas and corridors for multispecies conservation. Core areas and corridors of the 15 considered species only partially overlapped, stressing the importance of multi-species consideration in designating wildlife corridors.

Mapping conservation priorities for wild yak (Bos mutus) habitats on the Tibetan Plateau, China

The wild yak (Bos mutus) is a cold-tolerant herbivore native to the Tibetan Plateau and has been categorized as vulnerable by the International Union for Conservation of Nature and Natural Resources. Low population densities within currently fragmented habitats and unclear landscape conservation priorities warrant attention. Herein, we employed the maximum entropy (MaxEnt) model using over 900 wild yak occurrence records to model wild yak habitat suitability. Our analysis revealed unprotected wild yak landscapes covering 30.79 % of the habitat area, indicating a conservation gap between protected areas (PAs) and wild yak habitats. To protect metapopulation dynamics and mitigate high risks of poaching, habitat degradation and fragmentation, resource competition, and degenerated genetic characterization of wild yaks in fragmented and degraded habitat, we identified eight habitat patches as landscape conservation units (LCUs) and 14 linkages among the LCUs, enhancing the connectivity between LCUs to decrease negative effects of genetic threats. A centrality analysis demonstrated that Changtang, Arjinshan, and Hoh Xil national nature reserves and their linkages are all critical for the maintenance of habitat connectivity. Here, we suggest that habitat- and LCU-specific conservation strategies should be highlighted during the establishment of PAs and transboundary cooperation. Ultimately, our results can assist conservationists and land managers in comprehending wild yak distribution, movement, and habitat requirements, as well as for the development of effective protection strategies. Furthermore, the combined modeling method (MaxEnt–Zonation–InVEST) could be utilized as a component for identifying conservation priorities and linkages between core patches for species and assessing the efficiency of PAs, core habitats, and corridors in achieving conservation goals. Our study can provide a framework in identifying priority conservation and connectivity between habitat patches to facilitate effectively conservation and genetic resilience for endangered species in fragmented habitats.

A grazer's niche edge is associated with increasing diet diversity and poor population performance.

The core-periphery hypothesis predicts niche cores should be associated with greater survivorship, reproductive output and population performance rates than marginal habitats at niche edges. However, there is very little empirical evidence of whether niche centrality influences population trends in animals. Using the Cape mountain zebra (Equus zebra zebra) as a model system, we evaluated whether niche centrality is associated with population trends, resource availability and diet across a core-periphery gradient. Population growth rates and density progressively declined towards niche peripheries. Niche peripheries were resource-poor and Cape mountain zebra consumed more phylogenetically diverse diets dominated by non-grass families. In core habitats they consumed grass-rich diets and female reproductive success was higher. This combination of spatial niche modelling and functional ecology provides a novel evaluation of how bottom-up resource limitation can shape species distributions, population resilience and range change and can guide conservation management.

A synthesis of the current state of marine biodiversity knowledge in the Isles of Scilly, UK

Abstract Synthesising knowledge on the health of marine ecosystems and the human activities is crucial to informing holistic marine management. In many coastal states, however, research is conducted in an ad hoc manner and rarely compiled into accessible repositories making it challenging for marine managers to identify knowledge gaps when allocating resources. Here we conduct a structured review of existing literature to identify the current state of marine and coastal knowledge in the Isles of Scilly, an oceanic archipelago in the UK. The archipelago's marine flora and fauna are biogeographically unique in the Northeast Atlantic, with a distinct mosaic of warm and cold temperate habitats and species and are also considered a rare example of a near pristine marine environment in the otherwise highly degraded Northeast Atlantic Ocean. We found 150 sources relating to the marine biodiversity and relevant human activities in the Isles of Scilly with increasing diversification of research topics in recent years. Sources however remain dominated by specific taxa and habitats, suggesting the Isles of Scilly would particularly benefit from future research into: (1) anthropogenic impacts associated with warming waters and intense seasonal vessel activity; (2) development of repeatable survey protocols that can underpin long-term, ecosystem-based monitoring and management (notably for reef and sediment habitats and the European spiny lobster); and (3) data gaps associated with marine teleost fish and elasmobranch communities including identifying core habitat. This review can therefore act as a baseline biological synthesis for the region and importantly, can inform future research priorities.

Predicted Climate Change Impacts on Distribution and Habitat Structure of Forest Ungulates in Southwest China

Climate change will impact the distribution of species and their preferred habitat, thereby influencing the ecological processes intrinsic to these species. To investigate these phenomena, we analyzed the habitat distribution, structure, and connectivity of 6 forest ungulate species in Southwest China under current and future climate scenarios. Habitat projections indicate that forest ungulates will migrate to the southwest at higher elevations and the northwest at higher latitudes and elevations in the study area under climate change. The extent to which climate change affects the 6 forest ungulates is quite different. By 2050, there will still be a certain range of habitats for migration in the study area, but the habitat quality of species will have decreased to varying degrees after migration. By 2070, most forest ungulates will begin to experience significant habitat loss and habitat quality decline. The migration of species habitat also leads to a change in species habitat structure. Habitat landscape quality declines for most forest ungulate species. The loss of patches at the junction habitat has a huge impact on species habitat connectivity. The number and distance of corridors between the marginal habitat patches and the core habitat patches increase to a certain extent. To better achieve biodiversity conservation, we should strengthen the restoration and connectivity management of fragmented habitats to protect and restore the current habitats of species. Examples include the management of specific key areas and the establishment of large-scale integrated protected areas such as the Giant Panda National Park.

Sitatunga (Tragelaphus spekii) food sources and habitat use in Marsh–Savannah‐cultivation mosaics

AbstractWetland conversion threatens wetland specialists by reducing their core habitat. The sitatunga is a wetland specialist with declining populations. However, knowledge of sitatunga ecology and threats is limited, particularly outside protected areas. We examined sitatunga food sources, and habitat use in undisturbed Marshes and Marsh–Savannah transition blocks, and a Cultivated (disturbed) block in River Mayanja wetland, central Uganda. We recorded indirect indices and sightings of sitatunga along a 10 km transect in each block, and surveyed food sources in 34 plots along the transects. Our results indicate that the indices and sightings of Sitatunga had lower relative frequency in the Cultivated than in the Marshes and Marsh–Savannah transition blocks. Sitatunga feed on 39 plant species in 13 families and six growth forms; grasses, herbs, sedges, climbers, shrubs and water weeds. Cyperus papyrus, Echinochloa pyramidalis, Leersia hexandra accounted for 58% of sitatunga food sources. There were more individuals and species with Sitatunga feeding activity in the Marshes and Marsh–Savannah transition blocks than in the Cultivated block. Our results show that sitatunga habitat use and food sources are constrained in disturbed habitats while threats are intensified. To maintain wetland integrity and stability of sitatunga populations, stakeholders need to address wetland encroachment.

Divergent responses of highly migratory species to climate change in the California Current

AbstractAimMarine biodiversity faces unprecedented threats from anthropogenic climate change. Ecosystem responses to climate change have exhibited substantial variability in the direction and magnitude of redistribution, posing challenges for developing effective climate‐adaptive marine management strategies.LocationThe California Current Ecosystem (CCE), USA.MethodsWe project suitable habitat for 10 highly migratory species in the California Current System using an ensemble of three high‐resolution (~10 km) downscaled ocean projections under the Representative Concentration Pathway 8.5 (RCP8.5). Spanning the period from 1980 to 2100, our analysis focuses on assessing the direction and distance of distributional shifts, as well as changes in core habitat area for each species.ResultsOur findings reveal a divergent response among species to climate impacts. Specifically, four species were projected to undergo significant poleward shifts exceeding 100 km, and gain habitat (~7%–60%) in response to climate change. Conversely, six species were projected to shift towards the coast, resulting in a loss of habitat ranging from 10% to 66% by the end of the century. These divergent responses could typically be characterized by the mode of thermoregulation (i.e. ectotherm vs. endotherm) and species' affiliations with cool and productive upwelled waters that are characteristic of the region. Furthermore, our study highlights an increase in niche overlap between protected species and those targeted by fisheries, which may lead to increased human interaction events under climate change.Main ConclusionsBy providing valuable species distribution projections, our research contributes to the understanding of climate change effects on marine biodiversity and offers critical insight and support for developing climate‐ready management of protected and fished species.

Fine-scale spatial variability of marine acoustic environment corresponds with habitat utilization of Indo-Pacific humpback dolphins in Hong Kong waters

Acoustic properties of the underwater environment are important in maintaining biological processes of various marine organisms. However, with the increasing level of underwater noise in the global ocean, there is a growing need to better understand how marine animals use soundscape cues in their habitat selection. Indo-Pacific humpback dolphins (Sousa chinensis) inhabiting the Pearl River Estuary, southeast China, live in one of world’s most developed and noisiest coastal environment and are subjected to many sources of anthropogenic noise. To investigate whether spatial variability of underwater soundscape corresponds with their habitat utilization, we collected daytime underwater recordings in western Hong Kong waters from mid-2016 to mid-2018, and quantified the spatial pattern of marine acoustic environment and its differing characteristics in a fine spatial scale. We developed a framework of soundscape information retrieval to investigate spectral features that may facilitate identification of dolphins’ core habitats. Our findings reveal that a spectral feature, which peaks at 2 kHz, is a reliable predictor of humpback dolphin core habitat. Further modelling of spatial and seasonal variations of underwater soundscape demonstrates that the relative strength of this spectral feature is positively correlated with the sighting rates of humpback dolphins throughout the year. Although the source of the 2 kHz feature remains unknown, it is likely associated with humpback dolphins’ prey. We suggest that underwater acoustic environment represents an important component in evaluating the quality and suitability of coastal habitats for the daily needs of this threatened dolphin species. Local and regional conservation authorities should include habitat-specific baseline soundscape data when developing conservation management strategies.

Research activity induces change in nest position but does not affect nest success in a vulnerable babbler

AbstractStudies show that birds cognize human disturbance as a potential predation risk. However, the responses of breeding birds to long‐term continuous disturbance by research activities and whether researcher disturbance affects the fitness of target species remain poorly understood. In this study, we used field observation data collected over 6 years to assess the potential impacts of research activities on nest‐site selection and nest success of the Emei Shan Liocichla (Liocichla omeiensis), a vulnerable babbler species endemic to Southwest China. Our results showed that Emei Shan Liocichlas tended to nest in taller nesting plants or the higher parts of nesting plants to increase nest‐site height following researcher disturbance. The average height of Emei Shan Liocichla nests increased by 52.2% over the 6‐year study period, from 129.8 ± 9.2 cm in 2009 (n = 11) to 197.5 ± 12.1 cm in 2015 (n = 18). While some pairs adopted a different strategy, placing their nests in Rosaceae plants with thorns instead of the bamboo Chimonobambusa szechuanensis (the favored nesting plant of the Emei Shan Liocichla) under high interference pressure, which made it more difficult for researchers to approach their nests. There were no significant differences both in clutch size and nest success between the low‐ and high‐disturbance groups. The study revealed the behavioral response pattern of breeding Emei Shan Liocichlas to researcher disturbance, which will contribute to conservation of this threatened songbird and the knowledge of reproductive strategies of birds. Developing specific guidelines for fieldwork and strengthening visitor management within its core habitat of Emei Shan Liocichla during breeding period should be considered.

Assessing landscape suitability and connectivity for effective conservation of two semi‐desert ungulates in Iran

AbstractConservation outside conservation areas (CAs) is more challenging due to increased exposure to human‐induced disturbances. Therefore, it is important to identify and designate new CAs that can protect core wildlife habitat patches, as well as key linkages to promote connectivity. We performed this study to identify and prioritize core habitat patches and corridors for two semi‐desert sympatric gazelles in Iran (i.e., goitered gazelle Gazella subgutturosa and jebeer gazelle G. bennettii) in order to propose the expansion of existing CAs. We used an ensemble distribution modeling approach based on three algorithms (random forest, maximum entropy, and generalized boosting models) for habitat suitability assessment and a combination of resistant kernel and factorial least‐cost path analysis for connectivity modeling. Our results revealed that distance to CAs, elevation, and annual mean temperature were the most influential variables for predicting the distribution of the two gazelle species. We identified 12 and six core habitat patches for goitered gazelle and jebeer gazelle, respectively with a minimum area of 210 km2. Core habitat patches were mainly occurred in the north of the central basin of Iran with a high priority for the conservation of both species. CAs protected up to half of core habitat patches for goitered gazelle and one‐third of core habitat patches for jebeer gazelle. Due to human‐induced disturbances (e.g., vehicle collisions and poaching) outside CAs, it is necessary to increase regular monitoring and establish new CAs based on the identified core habitat patches for the two gazelles. Our findings highlight opportunities of designating new CAs for wildlife habitat and corridors conservation and for promoting connectivity by limiting road impacts.

Optimizing efficiency and resilience of no-take marine protected areas for fish conservation under climate change along the coastlines of China Seas.

Climate change is one of the major threats to coastal fish biodiversity, and optimization of no-take marine protected areas (MPAs) is imminent. We predicted fish redistribution under climate change in coastal China Seas with joint species distribution modeling and prioritized areas for conservation with Zonation, for which we used core area zonation (CAZ) and additive benefit function (ABF). Based on our results, we devised an expansion plan of no-take MPAs. Under climate change, fish were redistributed northward along the coast. These redistributions were segmented by the Yangtze River estuary and its adjacent waters, indicating a possible biogeographical barrier. Under CAZ and ABF, significantly more fish habitat was conserved than under random prioritization (p<0.001, Cohen's d=-0.36 and -0.62, respectively). The ABF better represented areas with higher species richness, whereas CAZ better represented core habitats for species with narrow distributions. Without accounting for species redistribution, the expanded MPAs were mainly distributed in the northwest of the South China Sea, the East China Sea, the north of the Yellow Sea, and the west of the Bohai Sea. When accounting for species redistribution, the proposed MPAs were mainly distributed in the north of the Bohai Sea and southwest of the Yellow Sea, corresponding to the northern species redistributions. These MPAs conserved less habitat for fishes at present but protected more and better quality habitat for fishes in 2050 and 2100 than those MPAs that did not account for species redistribution, indicating improved fish conservation under climate change. Incorporating species redistribution and trade-offs between areas with high species richness and areas that contain habitats for rare species are suggested to address coastal fish conservation under climate change. This work provides valuable information for fish conservation and is a precursor to systematic conservation planning along the coastlines of China Seas.

The first baleen whale marine protected area proposed for Bryde's whales in the Beibu Gulf, China

AbstractThe establishment of marine protected areas (MPAs) for cetaceans is an important strategy to mitigate human disturbance and protect biodiversity. Despite abundant cetacean species, there are only a few MPAs dedicated to cetacean conservation in China, all of which are for inshore dolphins. Bryde's whales, the only nearshore baleen whale population in mainland China, are conflicting with intensive human activities, yet an effective conservation strategy is lacking. This study used species distribution models to analyze distribution patterns and suitable habitats of Bryde's whales in the Beibu Gulf and proposes the first baleen whale MPA in China. Our results showed Bryde's whales have a seasonal distribution pattern in the Beibu Gulf, and that the waters around Weizhou Island and the southeastern coast of Vietnam were their core habitats. The seasonal nighttime light data indicated a negative relationship between the number of ship lights and Bryde's whale sightings and suggest that Bryde's whales might be threatened by fisheries. We proposed an MPA based on the results, suggesting that the waters within 20 km around Weizhou Island should be declared a protected area. Furthermore, we recommend that anthropogenic activities in the waters around Weizhou Island are better managed to reduce negative impacts on marine life.

Spatial patterns of reproduction suggest marginal habitat limits continued range expansion of black bears at a forest-desert ecotone.

Investigating spatial patterns of animal occupancy and reproduction in peripheral populations can provide insight into factors that form species range boundaries. Following historical extirpation, American black bears (Ursus americanus) recolonized the western Great Basin in Nevada from the Sierra Nevada during the late 1900s. This range expansion, however, has not continued further into the Great Basin despite the presence of additional habitat. We aimed to quantify whether reduced reproduction toward the range edge contributes to this range boundary. We analyzed black bear detections from 100 camera traps deployed across black bear distribution in western Nevada using a multistate occupancy model that quantified the probability of occupancy and reproduction (i.e., female bears with cubs occupancy) in relation to changes in habitat type and habitat amount toward the range boundary. We detected a strong effect of habitat amount and habitat type on the probability of black bear occupancy and reproduction. At similar levels of landscape-scale habitat amount (e.g., 50%), estimated probability of occupancy for adult bears in piñon-juniper woodlands near the range boundary was 0.39, compared to ~1.0 in Sierra Nevada mixed-conifer forest (i.e., core habitat). Furthermore, estimated probability of cub occupancy, conditional on adult bear occupancy, in landscapes with 50% habitat was 0.32 in Great Basin piñon-juniper woodlands, compared to 0.92 in Sierra Nevada mixed-conifer forest. Black bear range in the western Great Basin conforms to the center-periphery hypothesis, with piñon-juniper woodland at the range edge supporting ecologically marginal habitat for the species compared to habitat in the Sierra Nevada. Further geographic expansion of black bears in the Great Basin may be limited by lower occupancy of reproducing females in piñon-juniper woodland. Center-periphery range dynamics may be common in large carnivore species, as their dispersal ability allows them to colonize low-quality habitat near range edges.

Snapshots in time: quantifying dynamics of coastal vessel traffic in a dolphin hotspot

ABSTRACT Small vessels contribute substantially to coastal soundscapes, presenting myriad potential impacts on marine species and ecosystems, yet are challenging to monitor using standard tracking methods (e.g. AIS). Here, we present an automated camera system developed to quantify coastal vessel traffic in a core habitat for Hector’s dolphins (Cephalorhynchus hectori) within Akaroa Harbour, Aotearoa New Zealand. Analysis of 55,569 images taken during the austral summer of 2019/20 showed that traffic was highest around midday, on weekends, and in January. A mean of 41.9 vessel trips per day transited the area of core habitat. Vessel speeds estimated from photographs were assigned to 5-knot bins with 84% accuracy. Findings suggest vessel traffic in Akaroa Harbour has approximately doubled between 2006–2008 and 2020. Additionally, tours focused specifically on dolphins composed a significantly larger proportion of vessel traffic in 2020 than observed during 2006–2008. We validate the use of an automated camera system as a robust, novel, repeatable, and cost-effective tool for quantifying fluctuations in coastal vessel traffic. Such tools can provide baseline data and help assess impacts, and their use can guide management action.

Summer and winter surveys of deep waters of the Hellenic Trench, Greece, provide insights into the spatial and temporal distribution of odontocetes

The Mediterranean Sea provides habitat for globally threatened cetaceans. The Hellenic Trench is an Important Marine Mammal Area, providing core habitat for sperm whalesPhyseter macrocephalusand Cuvier’s beaked whalesZiphius cavirostris. Surveys have characterized distributions of these species in near-shore areas (&lt;2000 m deep). Sparse survey effort in deeper waters during winter has allowed speculation that it is not an important habitat in winter. We used passive acoustic monitoring from towed arrays to document cetaceans during summer and winter, covering 18366 km of trackline off the Peloponnese and Crete. We confirmed the acoustic presence of 5 odontocetes: sperm whales (n = 49 encounters; mean depth (x̄): 3360 m; range (R): 1250 to 4210 m), Cuvier’s beaked whales (n = 4;x̄: 3070 m;R: 1970 to 3770 m), Risso’s dolphinsGrampus griseus(n = 5;x̄: 3340 m;R: 2250 to 4440 m), striped dolphinsStenella coeruleoalba(n = 2;x̄: 2980 m;R: 2490 to 3470 m) and rough-toothed dolphinsSteno bredanensis(n = 1; 3650 m). We also encountered 224 unidentified delphinids, including a potential blackfish (3020 m). We confirmed that these species are present in the Hellenic Trench throughout the year. Given the impact of multiple threats on sperm and Cuvier’s beaked whales in the Hellenic Trench, we suggest that policymakers follow the precautionary approach in managing human activities in the area. Ongoing seismic surveys, hydrocarbon extraction and uncontrolled shipping could have potentially negative effects on these species at the population level and we advise caution in permitting such activities in future