Search Results (153)

Obtaining reliable estimates of population sizes and their temporal trends is essential for assessing the conservation status and guiding the management of threatened species. Parrots (order Psittaciformes) are among the most diverse yet most threatened groups of birds worldwide, but information on their population sizes remains scarce. Their ecological traits and low densities complicate the application of widely used distance sampling methods for estimating population densities, which correct for declining detectability with increasing distance. Researchers have proposed simple encounter rates—the number of birds or groups detected per hour of observation during casual walks—as an alternative approach to address these limitations when estimating the abundance of rare species. Previous studies of the globally endangered African grey parrot (Psittacus erithacus) demonstrated that encounter rates derived from walk transects serve as reliable surrogates for densities estimated using distance sampling models. In this study, we evaluated whether car surveys and point counts, two other commonly used methods for estimating bird abundance, produce encounter rates comparable to those obtained from walk transects, thereby allowing greater methodological flexibility. To this end, we conducted a nationwide survey of African grey parrots in Equatorial Guinea using walk transects, car transects, and point counts (199 surveys, 1973 km, 192 h), which yielded 1166 encounters and 2972 recorded individuals. Three aspects of parrot detectability (the frequency of aural and visual detections, whether birds were perched or in flight, and detection distances) did not differ among the three survey methods. Encounter rates and the number of individuals observed per hour varied among sampled regions but did not differ among survey methods. These findings support the use of the three methods, either individually or in combination, to estimate the abundance of this globally endangered species and provide a basis for testing and applying this approach to other parrot species and geographic regions. Full article

Grasslands occupy 24% of the Earth’s surface. In most areas of the world these are either destroyed, fragmented or converted into cultivated fields. In Africa, their biodiversity is still insufficiently known. This study reports on the avian assemblages associated with grasslands in South African Highveld and Lesotho Drakensberg. Special attention was paid to the species richness, diversity, and population densities and dominance of particular species. Birds were counted by means of the Line Transect Method in three distinguished grassland types: Dry Cymbopogon-Themeda Grassland (transect length: 28 km), Wet Cymbopogo-Themeda Grassland (27 km) km, and Mountain Themeda-Festuca Grassland (31 km). In total, 86 bird species were recorded. While cumulative dominance was similar between the Dry and Wet Grassland (61–65%), these two were much different from that in the Mountain Grassland (46%). However the dominance index was similar in all three grassland types compared (0.25–0.33). Only one species, the long-tailed widow Euplectes orix was a common dominant species for all three grassland types. African stonechat, wing-snapping cisticola Cisticola ayresii, Levaillant’s cisticola Cisticola tinniens and yellow bishop Euplectes capensis were dominant only in the Mountain Grassland; northern black korhaan Afrotis afroides and the eastern clapper lark Mirafra fasciolata—only in the Dry and Wet Grassland; ostrich Struthio camelus, cloud cisticola Cisticola textrix, African quailfinch Ortygozpiza atricollis and pied starling Spreo bicolor—only in the Dry Grassland, while the helmeted guineafowl Numida meleagris, zitting cisticola Cisticola juncidis and African pipit Anthus cinnamomeus—only in the Wet Grassland. Despite these obvious differences in dominance and population densities of species, Diversity and evenness indices were similar in all three grassland types. Shannon’s Diversity Index (H′) varied between 1.22 and 1.35; Simpson Diversity Index between 0.91 and 0.94, while Pielou’s Evenness Index (J′) varied between 0.33 and 0.36. However, Sørensen Similarity Index between the three grassland types was low, ranging between 0.07 and 0.26. Proportions of ecological guilds were similar in the Dry and Wet Grassland but differed from mountain Grassland. In comparison with other tropical grassland, avian communities in southern Africa are characterized by higher species richness and higher its variance between particular grassland types. Full article

Background and Objectives: Bile leak is a common complication after hepatopancreatobiliary surgery, requiring timely management to prevent life-threatening outcomes. Endoscopic retrograde cholangiopancreatography (ERCP) is essential in treatment, but large data concerning optimal timing and technique selection are unavailable. This study evaluates whether the timing of ERCP influences healing and if different bile duct injuries affect outcomes. Materials and Methods: Data from a prospectively maintained database over 25 years (2001–2025) included 176 patients (M/F: 91/85, mean age 62) undergoing ERCP for bile leaks. Results: Most leaks followed cholecystectomy (n = 143, 81.5%). The median time from leak to ERCP was 7 days. Ten patients (5.7%) had complete common bile duct (CBD) transection—considered major leaks—requiring surgery. Among the 166 minor leaks, the cystic duct stump (40.1%) was the most common injury site, followed by the CBD (24.1%) and the gallbladder bed (15.4%). Healing occurred in 90.6%. Stent placement improved healing rates (93.9% vs. 75.9%, p = 0.007), with no difference between pig-tail and (Amsterdam) straight plastic stents (90% vs. 96%, p = 0.267). Retained CBD stones or CBD strictures did not affect outcomes. Leaks from the cystic duct stump had a 96.9% resolution rate, whereas gallbladder bed leaks healed in 88%. The median healing time was 2 days, unaffected by stent placement or ES alone (p = 0.842), but later ERCP correlated with longer healing (RR: 0.362, p < 0.001). Following a right aberrant bile leak, the time for healing was longer than in leaks from other sites. Conclusions: ERCP with stenting remains the first-line approach for minor bile leaks. Early ERCP accelerates healing, emphasizing the importance of prompt intervention. Full article

The mackerel fishery is Taiwan’s most productive coastal fishery sector, with the blue mackerel (Scomber australasicus) being its primary target species. Given the economic and ecological significance of this fishery, considerable attention has been devoted to assessing stock status and promoting sustainable use. Between 2021 and 2024, acoustic transect surveys were conducted in Yilan Bay during the blue mackerel spawning season, supplemented by hook-and-line sampling to confirm the identity of single-target acoustic signals. Acoustic detections within ±10 m of capture depth and ±10 min of capture time were used to establish a depth-compensated regression model linking target strength (TS) to fork length (FL). Validation revealed that over 80% of the hook-and-line samples were blue mackerel. After careful noise filtering, a depth-compensated regression model was established to relate TS to FL and sampling depth. The model incorporated both logarithmic body length and depth terms, effectively accounting for vertical variations in TS. The model improved alignment with biological sampling data by effectively accounting for depth-related variations in TS, thereby enhancing biomass estimation accuracy. Cross-validation with auction records from Nan-Fang-Ao Fishing Harbor confirmed that the acoustic biomass estimates closely mirrored commercial catch trends. These findings highlight the effectiveness of depth-compensated acoustic methodologies for obtaining reliable, fishery-independent spawning biomass estimates, supporting their continued application in long-term monitoring and spatial resource management. Full article

The Red Kite (Milvus milvus), a Western Palearctic raptor, experienced a severe population decline across its range during the 19th and 20th centuries, nearly disappearing as a breeding species in Spain. Although conservation and reintroduction efforts have facilitated recovery, information on its wintering ecology remains limited. We evaluated the population size and habitat selection of wintering Red Kites in and around the La Mancha Húmeda Biosphere Reserve (MHBR), Central Spain, and assessed whether survey route type affected detectability. Surveys comprised 325 vehicle-based line transects along paved roads and dirt tracks during the winters of 2021–2022 and 2022–2023, and the 2022 breeding season. Detection rates and density did not differ between route types. Across 212 winter transects, we recorded 124 individuals, with none detected during 113 breeding season transects. Density estimates were consistent across winters (1.3–1.4 individuals/km²), yielding a population estimate of approximately 1430 individuals. Habitat analysis indicated clear selection for open agricultural mosaics dominated by fallow land and vineyards, while rugged terrain was avoided. These results identify MHBR as an important wintering area. Yet, super-intensive agriculture is a poor habitat due to its uniformity. Enhancing heterogeneous open landscapes, including farmland, is essential for Red Kite colonization and expansion. Full article

Against the backdrop of advancing ecological civilization and increasing public interest in reconnecting with nature, this study examines fireflies—iconic insects cherished for their natural charm—as valuable landscape resources. This study was conducted in Dalingshan Forest Park, Dongguan (Pearl River Delta), using the Forest Science Trail as a sampling site. Surveys combining line transect and point count methods were employed to analyze firefly species composition, adult activity patterns, and flight characteristics. Key findings include: (1) Four species were identified—Asymmetricata circumdata, Pygoluciola qingyu, Aquatica analis, and Luciola satoi—three of which were observed along the trail; (2) Adults appeared sporadically after 19:00, with peak activity occurring between 19:30 and 20:00, showing minor interspecific variation; (3) Although flight height varied slightly among species, most activities concentrated within 0–1.5 m, corresponding to herbaceous and shrub layers; (4) Distinct flight patterns were observed: A. circumdata displayed prolonged intermittent flights, while P. qingyu and L. satoi exhibited shorter perching-based flights. These results provide a scientific basis for firefly habitat conservation, biodiversity promotion, and the sustainable integration of firefly landscapes into nature education and ecotourism. Full article

Large-scale agricultural development has led to a significant reduction in wetland areas, resulting in habitat fragmentation for birds and biodiversity loss. Recently, the implementation of farmland abandonment policies has helped in the restoration of wetland areas. In order to understand the ecological effects of farmland abandonment, this study investigated the bird communities in the Naoli River National Nature Reserve (NRNNR) in the Sanjiang Plain after abandonment. The field surveys (line transect and point count methods) of bird community diversity in the abandoned areas of the NRNNR showed 92 bird species from 37 families and 16 orders, including 4 species of national first-class protected birds and 17 species of national second-class protected birds (accounting for a combined 22.83%). Additionally, the bird community diversity displayed annual variation in individual and species richness over time, and the diversity indices order was 2019 > 2020 > 2018 > 2016 > 2015. Bird species richness and individual abundance were significantly higher in meadow habitats as compared to other habitat types. With prolonged restoration time after farmland withdrawal, the Pielou evenness index of bird communities significantly decreased, while the total number of individual birds significantly increased (p < 0.05). The abandoned time showed a positive impact on waterbird richness, while the longer abandoned duration led to higher waterbird richness. In conclusion, long-term ecological restoration measures revealed a significant enhancement in bird diversity over time. Full article

Amazon River dolphins often form multi-species aggregations at water confluences. This study used a multi-year data set to examine dolphins, fish, and geomorphology at dolphin aggregations. Methods included dolphin transect surveys, dolphin point counts, net and line fish captures, side-scan sonar, and eDNA analyses at five dolphin aggregations and two control sites. Amazon River dolphins (Inia geoffrensis and Sotalia fluviatlis) are typically found at aggregation sites that occur at water confluences that have greater dolphin numbers than control sites. The confluences had riverbed depressions averaging six metres in depth where fish were concentrated. Pink river dolphins preferred to form aggregations in flooded forest tributaries and large rivers, while grey river dolphins preferred the larger rivers. There were eighty-nine fish species at the confluences within the size of fish consumed by dolphins, and a higher abundance of fish occurred in and around the aggregation sites compared to control sites. The number of dolphins present at the aggregation sites correlated with fish abundance. Dolphin life history, such as fishing, resting, raising calves, and social interactions, occur at the aggregation sites. The aggregation sites are important conservation areas of the endangered pink and grey river dolphins, and through their folklore, Indigenous people living at confluence sites assist in the conservation of the aggregations and have lived with dolphins at confluences for thousands of years, contributing to their survival. Full article

Bird–plant interactions are critical for maintaining biodiversity and ecosystem function, and represent a key research focus in modern ecology. Using the line transect method, we surveyed bird diversity and collected plant trait data in four habitat types in the southern zone of Fujian’s Meihuashan National Nature Reserve during October–December 2021 and July–August 2022. This study investigated how plant traits (tree height, diameter at breast height (DBH), canopy density fruit amount) influence the diversity of frugivorous birds (species richness, abundance, Shannon–Wiener, Pielou, Simpson) across four disturbed habitats—villages (residential areas), bamboo forests (economic plantations), unguarded broad-leafed forests (wild forests), and nurtured broad-leafed forests (managed forests)—during both summer (breeding season) and autumn–winter (fruiting season). The key findings revealed that (1) significant correlations between plant traits and bird diversity were exclusive to the fruiting season, with no associations found in summer; (2) during autumn–winter, the key plant traits driving bird diversity varied distinctively by habitat: tree height and canopy density were paramount in villages; both habitat structure (canopy density) and fruit amount were important in bamboo forests, whereas in both broad-leafed forests, a combination of tree structure (height, DBH, canopy density) and fruit amount determined bird abundance; (3) a significant interaction between season and habitat was detected for community evenness, indicating that habitat type modulates the seasonal effects on community composition. This study underscores that in human-modified landscapes, conserving habitat structural complexity and key resource plants is crucial for sustaining frugivorous bird diversity and its ecological functions. Conservation strategies must account for seasonal dynamics to be effective. Full article

The west coast of Korea is characterized by a macro-tidal environment, where beach exposure varies significantly with tidal levels, resulting in high spatial variability of beach width and erosion patterns. This study aims to establish an Erosion Control Line (ECL) for Mallipo Beach using long-term beach topographic data collected from 2009 to 2020. For each transect, beach width was statistically estimated for a 30-year return period by calculating the average and standard deviation of surveyed widths and applying the inverse function of the normal cumulative distribution. The variability of shoreline positions was analyzed as an indicator of shoreline sensitivity, allowing the identification of highly vulnerable sections. Based on these analyses, the ECL was derived for three tidal reference levels—Highest Water of Medium Tide (H.W.O.M.T), Highest Water of Neap Tide (H.W.O.N.T), and Mean Sea Level (M.S.L)—according to Korea Hydrographic and Oceanographic Agency (KHOA)’s tidal datums. When the H.W.O.N.T-based beach width was used to define the Target shoreLimit of Erosion Prevention (TLEP), several public facilities were found to fall within the erosion hazard zone. These findings underscore the need for institutionalized coastal setback policies in Korea and highlight the practical value of the proposed ECL method for managing erosion-prone zones. Full article

Urban forests provide many ecosystem services in urbanized landscapes, including biodiversity conservation. The sustainable management of urban forests requires a thorough understanding of biodiversity changes in the context of rapid urbanization. As biodiversity in rapidly changing urban areas is very dynamic, we need a better understanding of long-term biodiversity changes in urban forests. Birds are very good bioindicators of urban forest biodiversity because they are strongly habitat-sensitive. However, a major knowledge gap exists in long-term trends in bird diversity in temperate urban forests. This study analyzed a comparison of bird-species richness in a temperate Central European urban forest over a time span of 37 years. Bird-counts using the standard line-transect method conducted in 2023–2024 were compared with older field data from 1987 gained using the same method in a lowland hardwood floodplain forest in the Czech Republic. The results revealed significant faunistic similarities in the bird-species diversity of an urban forest during the 1987–2024 period. The high local alpha diversity of the bird community (42 nesting bird species) as well as the relatively high long-term stability in bird richness indicated the importance of the studied urban forest as a stable biodiversity refugium in a dynamic urbanized landscape. Therefore, urban forests can be considered very stable biodiversity refugia in dynamically changing urban areas. Full article

This study systematically documented macrofungal diversity in Beijing, China (field surveys conducted from 2020 to 2024) using line-transect and random sampling. A total of 1056 species were identified, spanning 2 phyla, 7 classes, 25 orders, 109 families, and 286 genera. The inventory includes 12 new species, 456 new records for Beijing, 79 new records for China, and comprises 116 edible, 56 edible–medicinal, 123 medicinal, and 58 poisonous species. Among these, 542 species were assessed against China’s Macrofungi Redlist, revealing eight species needing conservation attention (seven Near Threatened, one Vulnerable). Analysis revealed stark differences in dominant taxa between natural ecosystems (protected areas) and urban green spaces/parks. In natural areas, macrofungi are dominated by 31 families (e.g., Russulaceae, Cortinariaceae) and 47 genera (e.g., Russula, Cortinarius). Ectomycorrhizal lineages prevailed, highlighting their critical role in forest nutrient cycling, plant symbiosis, and ecosystem integrity. In urban areas, 10 families (e.g., Agaricaceae, Psathyrellaceae) and 17 genera (e.g., Leucocoprinus, Coprinellus) were dominant. Saprotrophic genera dominated, indicating their adaptation to decomposing organic matter in human-modified habitats and the provision of ecosystem services. The study demonstrates relatively high macrofungal diversity in Beijing. The distinct functional guild composition—ectomycorrhizal dominance in natural areas versus saprotrophic prevalence in urban zones—reveals complementary ecosystem functions and underscores the conservation value of protected habitats for maintaining vital mycorrhizal networks. These findings provide fundamental data and scientific support for regional biodiversity conservation and sustainable macrofungal resource development. Full article

Investigating altitudinal distribution patterns of species richness represents a fundamental research objective in biogeography and community ecology. Hainan Island has tropical rainforests ranging from sea level to >1800 m a.s.l., with various animal species, including reptiles such as geckos. Information on the altitudinal distribution patterns of animal diversity on Hainan Island is limited. Thus, from October 2020 to June 2023, we surveyed Gekkonidae species on Diaoluo Mountain and Jianfeng Ridge in the Hainan Tropical Rainforest National Park using a line transect method. The two study sites were divided into seven altitudinal zones at intervals of 150 m from 31 to 1080 m a.s.l. We tested correlations between abundance and species diversity indices and altitude. Five gecko species were identified. The endemic Gekko similignum mainly occurred at high-altitude areas on both mountains, whereas Hemidactylus frenatus occupied low-altitude areas. Gehyra mutilata had the lowest abundance among all species at all altitudes. Diaoluo Mountain exhibited a higher species diversity and abundance than Jianfeng Ridge. Geckos on Diaoluo Mountain were mainly distributed between 31 and 920 m a.s.l., presenting a bimodal distribution, with peaks appearing in altitudinal zones II (181–330 m a.s.l.) and VI (781–930 m a.s.l.). The gecko distribution on Jianfeng Ridge ranged from 31 to 948 m a.s.l., presenting a unimodal distribution, with a peak in altitudinal zone V (631–780 m a.s.l.). Full article

The Mapleton Falls National Park transmission line corridor in Queensland, Australia, has received a number of vegetation management treatments over the last decade to maintain and protect the infrastructure and to ensure continuous electricity supply. Recent treatments have included ‘mega-mulching’ (mechanical mastication of vegetation to a mulch layer) in 2020 and targeted herbicide treatment of woody vegetation, with the aim of reducing vegetation height by encouraging a native herbaceous groundcover beneath the transmission lines. We measured vegetation structure (cover and height) and composition (species presence in 15 × 2 m plots), at 12 transects, 90 m in length on the transmission line corridor, to determine if management goals were being achieved and to determine how the vegetation and fire hazard (based on the overall fuel hazard assessment method) varied among the treated corridor, the forest edge environment, and the natural forest. The results showed that vegetation structure and composition in the treated zones had been modified to a state where herbaceous plant species were dominant; there was a significantly (p < 0.05) higher native grass cover and cover of herbs, sedges, and ferns in the treated zones, and a lower cover of trees and tall woody plants (>1 m in height) in these areas. For example, mean native grass cover and the cover of herbs and sedges in the treated areas was 10.2 and 2.8 times higher, respectively, than in the natural forest. The changes in the vegetation structure (particularly removal of tall woody vegetation) resulted in a lower overall fuel hazard in the treated zones, relative to the edge zones and natural forest. The overall fuel hazard was classified as ‘high’ in 83% of the transects in the treated areas, but it was classified as ‘extreme’ in 75% of the transects in the adjacent forest zone. Importantly, there were few introduced species recorded. The results suggest that fuel management has been successful in reducing wildfire risk in the transmission corridor. Temporal monitoring is recommended to determine the frequency of ongoing fuel management. Full article

Identifying habitat characteristics is essential for conserving critically endangered species. When quantifying species habitat characteristics, ignoring data types may lead to misunderstandings about species’ specific habitat requirements. This study focused on the critically endangered Chinese pangolin in Guangdong Province, China, and divided the study area into 600 m × 600 m grids based on its average home range. The burrow number within each grid was obtained through line transect surveys, with burrow numbers/line transect lengths used as direct indicators of habitat utilization intensity. The relationships with sixteen environmental variables, which could be divided into three categories, including topographic, human disturbance and land cover composition, were quantified using the GAM method. We also converted continuous data into binary data (0, 1), constructed GAMs and compared them with habitat utilization intensity models. Our results indicate that the habitat utilization intensity model identified profile curvature and slope as primary factors, showing a nonlinear response to profile curvature (Edf = 5.610, p = 0.014) and a positive relationship with slope (Edf = 1.000, p = 0.006). The presence–absence model emphasized distance to water (Edf = 1.000, p = 0.014), slope (Edf = 1.709, p = 0.043) and aspect (Edf = 2.000, p = 0.026). The intensity model explained significantly more deviance, captured complex nonlinear relationships and supported higher model complexity without overfitting. This study demonstrates that habitat utilization intensity data provides a more ecologically informative basis for in situ conservation (e.g., identifying core habitats), and the process from habitat selection to habitat utilization should be integrated to reveal species’ habitat characteristics. Full article