Understanding the fundamental drivers of large-scale species co-occurrence is a critical issue in ecology and conservation research. Here, we assessed foraging guilds, habitat type and disturbances as drivers of bird ...Understanding the fundamental drivers of large-scale species co-occurrence is a critical issue in ecology and conservation research. Here, we assessed foraging guilds, habitat type and disturbances as drivers of bird species co-occurrence in Ghana's Central Region over six months. Birds were sampled in 120 points across six different habitat types (farmland, forest reserve, urban area, coastal savannah, wetland, and mangrove), using the point-centred count technique. In total, 4060 individuals belonging to 216 species were recorded across all six habitat types. We found that co-occurring species were more similar in their foraging behaviour and habitat association. About 60% of the birds were found to co-occur randomly, 15% co-occurred negatively, and 25% co-occurred positively. Carnivores like the Black Heron (Egretta ardesiaca) and Spur-winged Lapwing (Vanellus spinosus) randomly co-occurred with other guild groups and were dominant in the mangroves and wetlands. Frugivores from forest reserves had only a 25% chance of randomly co-occurring with other birds and about a 60% chance of positively co-occurring with other birds. Our findings suggest that foraging guilds and habitat type are major factors driving bird co-occurrence and community assemblages in this West African suburban region.展开更多
Increasing human activity is altering the struc-ture of forests,which affects the composition of communi-ties,including birds.However,little is known about the key forest structure variables that determine the richnes...Increasing human activity is altering the struc-ture of forests,which affects the composition of communi-ties,including birds.However,little is known about the key forest structure variables that determine the richness of bird communities in European temperate oak forests.We,there-fore,aimed to identify key variables in these habitats that could contribute to the design of management strategies for forest conservation by surveying 11 oak-dominated forest sites throughout the mid-mountain range of Hungary at 86 survey points to reveal the role of different compositional and structural variables for forest stands that influence the breeding bird assemblages in the forests at the functional group and individual species levels.Based on decision tree modelling,our results showed that the density of trees larger than 30 cm DBH was an overall important variable,indi-cating that large-diameter trees were essential to provide diverse bird communities.The total abundance of birds,the foliage-gleaners,primary and secondary cavity nest-ers,residents,and five specific bird species were related to the density of high trunk diameter trees.The abundance of shrub nesters was negatively influenced by a high density of trees over 10 cm DBH.The density of the shrub layer positively affected total bird abundance and the abundance of foliage gleaners,secondary cavity nesters and residents.Analysis of the co-dominant tree species showed that the presence of linden,beech,and hornbeam was important in influencing the abundance of various bird species,e.g.,Eur-asian Treecreeper(Certhia familiaris),Marsh Tit(Poecile palustris)and Wood Warbler(Phylloscopus sibilatrix).Our results indicated that large trees,high tree diversity,and dense shrub layer were essential for forest bird communities and are critical targets for protection to maintain diverse and abundant bird communities in oak-dominated forest habitats.展开更多
The process of agricultural intensification has led to significant reductions in biodiversity globally.Previous studies examined the role of semi-natural habitats within agroecosystems in supporting bird communities,b...The process of agricultural intensification has led to significant reductions in biodiversity globally.Previous studies examined the role of semi-natural habitats within agroecosystems in supporting bird communities,but few have considered the effects of landscape agricultural intensity on avian conservation potential of seminatural habitats.Here,we disentangle the relative effects of semi-natural habitats within different landscape agricultural intensities on bird community composition in central and eastern Jilin Province,China.We established 322 sampling sites distributed across low,middle,and high landscape agricultural intensities,with 103,118,and 101 sites respectively.Each sampling site was visited two times in May and June 2023 to test the dissimilarities in bird composition between different landscape agricultural intensities.We found that middleintensity agriculture supported the highest bird diversity in most cases,but low-intensity plays an important role in maintaining insectivorous birds.We used generalized linear models and model selection to assess the relative impacts of semi-natural habitats on bird community along agricultural intensity respectively.Our results showed that the effects of agriculture on bird communities were predominantly influenced by the amount of semi-natural habitats,with effects that differ in accordance with the level of landscape agricultural intensity.Priority should be given to preserve or/and plant these semi-natural habitats in middle-intensity agriculture due to the stronger effect sizes on bird diversity.Specifically,we suggested preserving and promoting woodlands and shrubs in high-intensity agriculture,and simultaneously increasing crop diversity to protect bird diversity in agriculture landscapes in the context of increasing crop intensification globally.展开更多
Soil samples were collected with distance at 5, 20, 40, 80, 160, and 320 m from the Shen-Ha （Shenyang-Harbin） Highway, Northeast China, to investigate the effect of heavy metals of highway origin on soil nematode gu...Soil samples were collected with distance at 5, 20, 40, 80, 160, and 320 m from the Shen-Ha （Shenyang-Harbin） Highway, Northeast China, to investigate the effect of heavy metals of highway origin on soil nematode guilds. The contents of soil Pb, Cu, Zn, and the nematode community structure were analyzed. The results showed that the contents of total and available Pb, Ca, Zn varied significantly with the different distances from the highway. Pb was the main pollutant in the soils in the vicinity of Shen-Ha Highway. The zone from 20 to 40 m away from the highway was the most polluted area. The highest abundance of soil nematodes was found at 5 m while the lowest at 20 m away from the highway. Thirty six genera of nematodes belonging to 23 families were identified. Nematode guilds having different responses to soil heavy metals were classified into four types. Soil nematode guilds may act as a prominent indicator to heavy metal pollution of highway origin.展开更多
The Naf River estuary is one of the most productive ecological ecosystems in Bangladesh providing an important feeding area for fishes and other aquatic animals.However,detailed information on macrobenthic communities...The Naf River estuary is one of the most productive ecological ecosystems in Bangladesh providing an important feeding area for fishes and other aquatic animals.However,detailed information on macrobenthic communities is rarely available in this area.Our study focused on the seasonal and spatial variability of macrobenthic community structure with their biomass and functional guilds.In total,fortyseven taxa were identified under nine major groups and seven functional feeding guilds.Among macrobenthic taxa,Polychaeta was dominant in both seasons and all over the estuary contributing 60%of total benthos.The mean abundance of macrobenthos was higher during the pre-monsoon(2 972±1 994 inds./m^2)than the monsoon(1 572±361 inds./m^2)being maximum at mid-estuary region and minimum at upper and lower estuary regions.Of the diversity indices,density(P=0.01,P=0.003),the number of taxa(P=0.000 3,P=0.000 9)and Margalef′s Index(P=0.000 4,P=0.001)of macrobenthos were significantly different among stations and seasons.Shannon-Weiner index(P=0.009,P=0.12)and Pielou’s evenness index(P=0.03,P=0.14)had significant differences among stations but not among seasons.Cluster analysis suggested that distribution of macrofauna is strongly influenced by seasonality.Among the feeding types,carnivorous were found to be dominant at the upper and mid-estuarine regions,and herbivorous were at lower estuarine regions.Carnivorous species were dominant in both seasons.Omnivores have shown to be the most abundant feeding type in terms of biomass though herbivores were highest during monsoon.展开更多
A large fire of 233 ha in Huascarán National Park in Peru provided an opportunity to compare plant and bird responses in burned and nearby unburned zones of the puna. Heights and live diameters of flagship Puya r...A large fire of 233 ha in Huascarán National Park in Peru provided an opportunity to compare plant and bird responses in burned and nearby unburned zones of the puna. Heights and live diameters of flagship Puya raimondii rosettes(assigned to four broad developmental phases), plant communities(66 species in 24 families and nine growth forms) and bird communities(77 species in six trophic guilds) were monitored after the fire. Although no mortality was observed, Puya raimondii plants were affected by the fire, losing approximately 60% of their photosynthetic area across all developmental phases, but recovered quickly during the first two years after fire. The comparison of Puya rosette recovery after fire was complicated by the changes in live rosette diameter for unburned plants, which showed plasticity of photosynthetic area linked to seasonal and annual fluctuations in precipitation in this relatively dry environment(decreased by 26% for mature adult plants over the study period). Fire caused an immediate change in the density, biomass and composition of vegetation. Although the species present remained similar, their abundances changed significantly immediately after the fire, with notable reductions in dominant tussock grasses. This provided opportunities for other plants, resulting in higher postfire diversity of plant species, genera, families and growth forms. In turn, the changes in vegetation after fire affected the composition of birds according to their trophic guild. Granivores largely disappeared,generalists were mostly unaffected, and other guilds showed a more complex response. As the vegetation recovered, most displaced birds returned within approximately one year.展开更多
Niche theory predicts that closely related and ecologically similar species with overlapping distribution ranges can coexist through resource partitioning that limits interspecific competition.However,studies examinin...Niche theory predicts that closely related and ecologically similar species with overlapping distribution ranges can coexist through resource partitioning that limits interspecific competition.However,studies examining the mechanisms promoting coexistence of top predators at a large geographical scale are still scant.Here,we describe the foraging ecology of 3 sympatric owl species(Northern long-eared owl[Asio otus],Tawny owl[Strix aluco],Eurasian eagle owl[Bubo bubo])in the Mediterranean Basin.We review 160 studies reporting diet information(212,236 vertebrate preys)and investigate among-species differences in diet metrics(diversity,evenness,prey size,and proportion of mammals)and their variation along geographical and environmental gradients.Moreover,we test whether diet metrics differ in presence or absence of the other predators.All the 3 species mainly rely on small mammals,but they significantly differ in diet metrics.The smallest predator(i.e.,long-eared owl)shows a higher level of specialism on small mammals(highest proportion but lowest diversity of mammals in the diet)compared to the larger ones.In addition,mean prey size significantly increases with predator body size(long-eared owl<tawny owl<eagle owl).Finally,interspecific competition results in an increase of diet diversity and evenness in the long-eared owl,and species’diet also varies in response to environmental factors.The 3 species thus segregate along several dietary niche axes over a large spatial scale and according to both morphological characteristics(i.e.,body size)and environmental variables.Such dietary niche segregation may adaptively buffer interspecific competition costs,ultimately allowing coexistence.展开更多
The loss and degradation of wetlands have adversely affected waterbirds, which depend on wetland habitats. Interspecific competition has an important effect on habitat utilization of wintering waterbirds. Resource uti...The loss and degradation of wetlands have adversely affected waterbirds, which depend on wetland habitats. Interspecific competition has an important effect on habitat utilization of wintering waterbirds. Resource utilization, including partitioning, in degraded wetlands has become a hot issue in ecological studies of wintering waterbirds. In order to have an insight into the habitat utilization and resource partitioning between a Hooded Crane(Grus monacha) population and the guild of three goose species, i.e., Anser fabalis, A. albifrons and A. erythropus wintering in lake wetlands, we carried out a study at Shengjin Lake National Nature Reserve from November 2011 to April 2012. We surveyed the Hooded Cranes and goose guild foraging in various habitats during the wintering periods with a combined method of fixed route searching and fixed site observations. Resource partitioning was studied by means of calculating habitat utilization rates and the width and overlap of spatial niches. The results showed that the habitat utilization rate and the width of spatial niches of the Hooded Crane population and goose guild shifted with the season. The habitat utilization rates of the cranes in grasslands were high at all three wintering stages. The habitat utilization rates were 0.454, 0.435 and 0.959 respectively for the Hooded Cranes and 0.627, 0.491 and 0.616 for the goose guild. This suggests that the overlap in grasslands was higher between cranes and goose guild. Most habitats were accessible at the middle stage, so the width of the spatial niche of the cranes(1.099) and goose guild(1.133) both reached their peak at this stage. The greatest niche overlap was 0.914 for these two groups at the late stage, followed by 0.906 at the middle stage and the smallest was 0.854 at the early stage. Ecological response to the changes in habitats of wintering waterbirds was clearly shown in the dynamic variations of the niche of both the Hooded Cranes and the three goose species. Coexistence among waterbirds was achieved by regulation of niche width to reduce niche overlap and relieve interspecific resource partitioning.展开更多
The spatial and temporal characteristics of trophic structure of fish communities in the southern Huanghai Sea were examined based on the data sampled from bottom trawl surveys conducted during the autumn of 2000 and ...The spatial and temporal characteristics of trophic structure of fish communities in the southern Huanghai Sea were examined based on the data sampled from bottom trawl surveys conducted during the autumn of 2000 and the spring of 2001. Hierarchical agglomerative cluster method and bootstrap randomization were used to identify significant trophic groups for each fish assemblage in the southern Huanghai Sea. A total of six major trophic groups were identified within this system, which classified predators based upon location in the water column or prey size （ i. e. , benthic to pelagic predators or fish to small invertebrate prey predators）. The similarity level used to identify significant trophic groups in each assemblage ranged from 24% to 34%. Although planktivores were the dominant trophic group in each assemblage （60% - 79% ）, there were spatial and temporal variations in the trophic structure, which reflected the differences in the abundance and availability of dominant preys. Simplified food webs were constructed to evaluate the most important trophic relationships between the dominant prey taxa and the fishes in each assemblage within this system. Although there were some differences in the key prey species among different food webs, pelagic prey items （mainly euphausiids and copepods） represent the most important energetic link between primary producers and higher trophic level predators. The trophic level for most fishes was between 3 and d, and the weighted mean trophic level for each assemblage ranged from 3.3 to 3.4. Compared with previous study in the mid-1980s, there was an obvious downward trend in the trophic level for most fish species, which resulted mainly from the fluctuation in key prey species in the Huanghai Sea. The decrease in the importance of Japanese anchovy seems to be offset by other abundant prey species such as Euphausia pacifica and copepods （ mainly Calanus sinicus ） .展开更多
Background: Edge effects cause changes in bird community richness, abundance, and/or distribution within a landscape, but the avian guilds most influenced can vary among regions. Although Southeast Asia has the highes...Background: Edge effects cause changes in bird community richness, abundance, and/or distribution within a landscape, but the avian guilds most influenced can vary among regions. Although Southeast Asia has the highest rates of deforestation and projected species loss, and is currently undergoing an explosive growth in road infrastructure, there have been few studies of the effects of forest edges on avian communities in this region.Methods: We examined avian community structure in a dry evergreen forest in northeastern Thailand adjacent to a five-lane highway. We evaluated the richness and abundance of birds in 11 guilds at 24 survey points on three parallel transects perpendicular to the edge. At each point, 10-min surveys were conducted during February-August 2014 and March-August 2015. Vegetation measurements were conducted at 16 of the bird survey points and ambient noise was measured at all 24 survey points.Results: We found a strongly negative response to the forest edge for bark-gleaning, sallying, terrestrial, and understory insectivores and a weakly negative response for arboreal frugivore-insectivores, foliage gleaning insectivores, and raptors. Densities of trees and the percentage canopy cover were higher in the interior, and the ambient noise was lower. In contrast, arboreal nectarivore-insectivores responded positively to the forest edge, where there was a higher vegetation cover in the ground layer, a lower tree density, and a higher level of ambient noise.Conclusion: Planners should avoid road development in forests of high conservation value to reduce impacts on biodiversity. Where avoidance is impossible, a number of potential mitigation methods are available, but more detailed assessments of these are needed before they are applied in this region.展开更多
The Yangtze River floodplain is critical for migratory waterbirds along the East Asian-Australasian Flyway (EAAF). Greater awareness of its global importance is urgently needed to ensure waterbird populations remain i...The Yangtze River floodplain is critical for migratory waterbirds along the East Asian-Australasian Flyway (EAAF). Greater awareness of its global importance is urgently needed to ensure waterbird populations remain in favourable conservation status, as well as the enhancement of wider wetland biodiversity within this region. The designation of protected wetland areas and building a green ecological corridor in the Yangtze floodplain is now becoming a critical issue of interest to the Chinese government. Priority sites in this area were identified based on the criteria used to identify sites that qualify as Wetlands of International Importance (Ramsar Sites) and Important Bird and Biodiversity Areas (IBAs) by using multi-source data. The results show that 140 of the sites surveyed are priority sites. The Importance Index (/) for the whole floodplain decreased slightly from 2001–2005 and an unbalanced distribution pattern is evident with Jiangxi and Hunan provinces significantly higher than the other provinces in the floodplain. Although more than 60% of the priority sites are currently located outside protected areas, the average Conservation Effectiveness Index (C) of the whole floodplain is 75.6%, which suggests the coverage of protected areas for most wintering waterbird population is reasonable. Conservation of the Yangtze River floodplain needs to be further strengthened due to declining waterbird abundances and the mismatch between the distribution of protected areas and their importance for wintering waterbirds. A comprehensive system for priority site identification and protection and scientific review is needed. Multi-sourced data from regular, systematic and coordinated monitoring of waterbird distribution and abundance across the EAAF, as well as national scale citizen science programmes are also critically important.展开更多
Background: The guild concept is useful for understanding the community structure in a land-bridge island system,but most fragmentation studies have focused only on the importance of island area and isolation, other i...Background: The guild concept is useful for understanding the community structure in a land-bridge island system,but most fragmentation studies have focused only on the importance of island area and isolation, other island attributes such as perimeter-area ratio(PAR) were overlooked or understudied.Methods: We have adopted a guild approach to investigate the impacts of island attributes on bird guild richness on a set of 41 recently isolated land-bridge islands in the Thousand Island Lake(TIL), China.Results: We found insectivores had the largest number of species(34 species), fol owed by understory foraging guilds(28 species), omnivores(27 species) and canopy guilds(25 species). Furthermore, our data showed that migrants and residents responded equal y to island area, insectivores and understory guilds were sensitive to island area but omnivores and canopy guilds were not very sensitive. Most guild richness was determined by island area, except for omnivores and canopy guilds.Conclusions: Although PAR or habitat diversity found to be important for bird species richness, our results highlight the importance of island area in maintaining bird diversity in fragmented island systems.展开更多
Background:As an important player during food digestion,gut microbiota has attracted much attention in diet adaptation studies in birds.Microbiota extracted from feces has been widely used as a proxy for gut microbiot...Background:As an important player during food digestion,gut microbiota has attracted much attention in diet adaptation studies in birds.Microbiota extracted from feces has been widely used as a proxy for gut microbiota.Although several methods have been developed for microbial DNA extraction,their performances in the bird feces have not been systematacially evaluated yet.Methods:In this study,we applied three DNA extraction methods(Qiagen,MoBio and Bead)to extract DNA from feces of three avian dietary guilds(granivore,omnivore and carnivore),sequenced V4 region of 16S rRNA gene for each extract and evaluated the performances of DNA yield,DNA integrity,microbial composition,cell lysis capacity and alpha diversity for the three methods on each dietary guild.Results:Bead method was the best on the performance of both DNA yield and DNA integrity regardless of dietary guild.In granivore,microbial relative abundance at both species and phylum levels,alpha diversity and cell lysis capacity were comparable among all methods.In omnivore,Qiagen had the best performance on alpha diversity,fol-lowed by Bead and MoBio.There were small variations on microbial relative abundance at both species and phylum levels among different extraction methods.MoBio exhibited the best performance on cell lysis capacity.In carnivore,considerable variations were found on microbial relative abundance at both species and phylum levels.Qiagen had the best performance on alpha diversity,followed by MoBio and Bead.MoBio had the highest cell lysis capacity.Conclusions:DNA yield and integrity have no obvious impact on microbial composition,alpha diversity or cell lysis capacity.The microbiota results(e.g.,microbial composition,cell lysis capacity,alpha diversity)obtained from differ-ent methods are comparable in granivorous avian species but not in omnivorous or carnivorous birds.Either method could be used in granivore microbiota studies.For omnivores and carnivores,we recommend Qiagen method when the research purpose is microbial diversity and MoBio when gram-positive bacteria is the research target.展开更多
The stable isotope ratios of nitrogen(δ^(15)N) and carbon(δ^(13)C) were applied in this study to analyze sediment carbon sources and primary food sources of epifauna in an oceanic mangrove forest in tropical North S...The stable isotope ratios of nitrogen(δ^(15)N) and carbon(δ^(13)C) were applied in this study to analyze sediment carbon sources and primary food sources of epifauna in an oceanic mangrove forest in tropical North Sulawesi, Indonesia. Proportional contribution of mangrove-derived carbon to the food sources was compared among epifauna belonging to different feeding guilds. The sediment in the mangrove site with a depleted δ^(13)C signature(-28.02‰± 0.24‰) mainly consists of mangrove-derived carbon. Analysis using Bayesian stable isotope mixing model in the R program shows that mangrove-derived carbon can dominate the food sources of a majority of the epifauna(11 out of the total 18 species), especially 2 sesarmid crabs Parasesarma semperi and Sesarma sp., crab Epixanthus dentatus, and snails Terebralia sulcata and Optediceros breviculum, which belong to various feeding guilds. Mangrove-derived carbon has a proportional contribution to the food sources of fiddle crab Tubuca coarctata and 3 littorinid snails(Littoraria spp.) close to that of suspended particulate organic matter. Three planktophagous bivalve species(Anadara antiquata, Anadara sp. and Callista erycina) were found to mainly feed on seagrass-derived materials. Mean proportional contributions of mangrove-derived carbon to the food sources were 50.15%, 59.60%, 46.20% and 27.58% for the carnivorous, omnivorous, phytophagous and planktophagous groups, respectively. The results suggest that mangrove-derived carbon can directly(via grazing plant tissues) or indirectly(via deposit feedings) make an important contribution to the food sources of epifauna in the oceanic mangrove forest where the allochthonous input of organic carbon is low.展开更多
Although fairy rings are widely observed,little is known about the community processes associated with them.Here,we studied fairy rings in a natural grassland in northern Mongolia by sampling soils outside(future stag...Although fairy rings are widely observed,little is known about the community processes associated with them.Here,we studied fairy rings in a natural grassland in northern Mongolia by sampling soils outside(future stage),directly under(present stage),and within(past stage)the rings,to represent different time stages during the expansion of fairy rings.Soil DNA was extracted for amplicon sequencing of the fungal ITS1 region.The present stage had reduced fungal diversity and different fungal communities toward the other stages.Most strikingly,there was an increase in the pathogenic fungus Gibberella baccata in the present stage of most rings and the saprotrophic fairy ring fungus Lepista luscina in several.However,no mushrooms of Lepista had been recorded from any of these rings during several years of observation.Known fairy ring fungi were not found in the present stage of every ring,even in some known rings to have previously displayed mushrooms of such species.It is possible that these fungi occurred or were more abundant at the unsampled leading edge of the ring.The increase in G.baccata is intriguing,but its importance,if any,is unclear.It is also unclear whether consortia of fungi or other microbes might be present in these rings.The absence or low abundance of the previously reported fairy ring fungal species suggests that their presence is transient,with rapid replacement by other fungi.No differences in soil parameters were found between the fairy ring stages,except for aluminum.There is a need for broader sampling,including analysis of non-fungal biota,to understand the functional diversity of fairy ring fungi and the consequences for plant communities.展开更多
Drivers of bird niche separation in temperate primeval forests have not yet been determined,due to the low number of intact forest sites.Here,we analyzed the general patterns of niche usage on trees by birds’assembla...Drivers of bird niche separation in temperate primeval forests have not yet been determined,due to the low number of intact forest sites.Here,we analyzed the general patterns of niche usage on trees by birds’assemblages.We tested how tree species affect the sharing of space in an assemblage of birds and their level of specialization.We conducted our study in the Białowieża primeval forest(NE Poland).During two breeding seasons,we observed bird positions on trees,divided into three vertical and six horizontal zones in 768 observation points.Based on the interaction networks framework we calculated the Kullback-Leibler distance d′as a metric of species specialization and the resource range RR index,which estimates the species’specificity based on the fraction of space utilized with a non-zero performance.The d′index was the highest in the lower understory for all parts of the tree on the basis of the position from the trunk.The RR index was the highest in the lower understory for all parts based on the position from the trunk.Regarding the tree species,the lowest d′index was observed in all tree species together,and hornbeam,whereas the highest in oak.At the tree species level,the RR index was the lowest for hornbeam.We show tree species importance in forest space sharing in the case of bird assemblages.Hornbeam,alder,and spruce are universal species that were used by birds almost entirely.In contrast,oak,lime,and maple were only partially used.Tree species with less complex structures could shape bird assemblages,as they could offer birds much fewer niches to realize.Therefore,we showed that high specialization and niche separation are drivers of high bird diversity.Consequently maintaining a diverse stand structure is crucial for biodiversity conservation.展开更多
This study of feeding guild fish from the same coast of subtropics helps to suggest conservation of fishery resources. A total of 2,537 specimens of Plotosus lineatus (Plotosidae) were collected from July 2013 to Marc...This study of feeding guild fish from the same coast of subtropics helps to suggest conservation of fishery resources. A total of 2,537 specimens of Plotosus lineatus (Plotosidae) were collected from July 2013 to March 2019 on the coast of Taiwan. The average total body length (TL) was 23.7 cm ± 4.7 cm and 20.3 cm ± 2.9 cm, and the average body weight (W) was 94.1 g ± 59.6 g and 56.6 g ± 30.8 g among 174 males and 630 females, respectively. The LWRs of male and female were ln(W)<sub>M </sub>= 3.2914 × ln (TL) −6.0395, and ln(W)<sub>F </sub>= 3.0917 × ln(TL) −5.3629. The male specimens were large than female in TL and W. The average OSW/TL ratios were 0.722 ± 0.044 and 0.649 ± 0.029 among 41 male and 49 female specimens, respectively. The OSW of the male head was wider than that of the female head (F = 91.5;p < 0.001), and the head widths of the male fish were significantly more than those of their female counterparts, causing the OSs to form granular protrusions. The average CFW/TL ratios were 0.198 ± 0.034 and 0.252 ± 0.032 among the male and female specimens, respectively. The CFW of the male specimens was narrower than that of the female specimens (F = 58.9;p < 0.001), and the CF gap of the male fish was narrower than that of the female fish. The P. lineatus exhibits significant sexual dimorphism. The average eggs number of each female was 2375.6 eggs/individual ± 1140.9 eggs/individual (N = 161). The major prey of P. lineatus were shrimps, crabs, and fishes;the total relative frequencies of occurrence of the prey were 57.1%, 32.6%, and 37.2%, respectively (N = 282), and their total relative abundance levels were 40.2%, 26.3%, and 25.8%, respectively (N = 445). Proper scientific knowledge management will improve the development of fisheries.展开更多
文摘Understanding the fundamental drivers of large-scale species co-occurrence is a critical issue in ecology and conservation research. Here, we assessed foraging guilds, habitat type and disturbances as drivers of bird species co-occurrence in Ghana's Central Region over six months. Birds were sampled in 120 points across six different habitat types (farmland, forest reserve, urban area, coastal savannah, wetland, and mangrove), using the point-centred count technique. In total, 4060 individuals belonging to 216 species were recorded across all six habitat types. We found that co-occurring species were more similar in their foraging behaviour and habitat association. About 60% of the birds were found to co-occur randomly, 15% co-occurred negatively, and 25% co-occurred positively. Carnivores like the Black Heron (Egretta ardesiaca) and Spur-winged Lapwing (Vanellus spinosus) randomly co-occurred with other guild groups and were dominant in the mangroves and wetlands. Frugivores from forest reserves had only a 25% chance of randomly co-occurring with other birds and about a 60% chance of positively co-occurring with other birds. Our findings suggest that foraging guilds and habitat type are major factors driving bird co-occurrence and community assemblages in this West African suburban region.
基金supported part ia l l y by LIFE4Oak Forests Project LIFE16NAT/IT/000245)the RRF 2.3.121202200008 projectthe MERLiN project funded under the European Commission H2020 Programme(101036337 MERLiN H2020 LC GD 2020)。
文摘Increasing human activity is altering the struc-ture of forests,which affects the composition of communi-ties,including birds.However,little is known about the key forest structure variables that determine the richness of bird communities in European temperate oak forests.We,there-fore,aimed to identify key variables in these habitats that could contribute to the design of management strategies for forest conservation by surveying 11 oak-dominated forest sites throughout the mid-mountain range of Hungary at 86 survey points to reveal the role of different compositional and structural variables for forest stands that influence the breeding bird assemblages in the forests at the functional group and individual species levels.Based on decision tree modelling,our results showed that the density of trees larger than 30 cm DBH was an overall important variable,indi-cating that large-diameter trees were essential to provide diverse bird communities.The total abundance of birds,the foliage-gleaners,primary and secondary cavity nest-ers,residents,and five specific bird species were related to the density of high trunk diameter trees.The abundance of shrub nesters was negatively influenced by a high density of trees over 10 cm DBH.The density of the shrub layer positively affected total bird abundance and the abundance of foliage gleaners,secondary cavity nesters and residents.Analysis of the co-dominant tree species showed that the presence of linden,beech,and hornbeam was important in influencing the abundance of various bird species,e.g.,Eur-asian Treecreeper(Certhia familiaris),Marsh Tit(Poecile palustris)and Wood Warbler(Phylloscopus sibilatrix).Our results indicated that large trees,high tree diversity,and dense shrub layer were essential for forest bird communities and are critical targets for protection to maintain diverse and abundant bird communities in oak-dominated forest habitats.
基金supported by the project China Postdoctoral Science Foundation under Grant No.2024M760408the project Research on Artificial Recruitment,Rescue and Breeding of Scaly-sided Merganser from Jilin Forestry and Grassland Bureau and the Fundamental Research Funds for the Central Universities,China (2412024QD021)。
文摘The process of agricultural intensification has led to significant reductions in biodiversity globally.Previous studies examined the role of semi-natural habitats within agroecosystems in supporting bird communities,but few have considered the effects of landscape agricultural intensity on avian conservation potential of seminatural habitats.Here,we disentangle the relative effects of semi-natural habitats within different landscape agricultural intensities on bird community composition in central and eastern Jilin Province,China.We established 322 sampling sites distributed across low,middle,and high landscape agricultural intensities,with 103,118,and 101 sites respectively.Each sampling site was visited two times in May and June 2023 to test the dissimilarities in bird composition between different landscape agricultural intensities.We found that middleintensity agriculture supported the highest bird diversity in most cases,but low-intensity plays an important role in maintaining insectivorous birds.We used generalized linear models and model selection to assess the relative impacts of semi-natural habitats on bird community along agricultural intensity respectively.Our results showed that the effects of agriculture on bird communities were predominantly influenced by the amount of semi-natural habitats,with effects that differ in accordance with the level of landscape agricultural intensity.Priority should be given to preserve or/and plant these semi-natural habitats in middle-intensity agriculture due to the stronger effect sizes on bird diversity.Specifically,we suggested preserving and promoting woodlands and shrubs in high-intensity agriculture,and simultaneously increasing crop diversity to protect bird diversity in agriculture landscapes in the context of increasing crop intensification globally.
基金supported by the National NaturalScience Foundation of China (No. 30600087)the Scientific Research Startup Special Foundation on Excellent Ph.D Thesis and Presidential Award of Chinese Academyof Sciences (No. 2007356).
文摘Soil samples were collected with distance at 5, 20, 40, 80, 160, and 320 m from the Shen-Ha （Shenyang-Harbin） Highway, Northeast China, to investigate the effect of heavy metals of highway origin on soil nematode guilds. The contents of soil Pb, Cu, Zn, and the nematode community structure were analyzed. The results showed that the contents of total and available Pb, Ca, Zn varied significantly with the different distances from the highway. Pb was the main pollutant in the soils in the vicinity of Shen-Ha Highway. The zone from 20 to 40 m away from the highway was the most polluted area. The highest abundance of soil nematodes was found at 5 m while the lowest at 20 m away from the highway. Thirty six genera of nematodes belonging to 23 families were identified. Nematode guilds having different responses to soil heavy metals were classified into four types. Soil nematode guilds may act as a prominent indicator to heavy metal pollution of highway origin.
文摘The Naf River estuary is one of the most productive ecological ecosystems in Bangladesh providing an important feeding area for fishes and other aquatic animals.However,detailed information on macrobenthic communities is rarely available in this area.Our study focused on the seasonal and spatial variability of macrobenthic community structure with their biomass and functional guilds.In total,fortyseven taxa were identified under nine major groups and seven functional feeding guilds.Among macrobenthic taxa,Polychaeta was dominant in both seasons and all over the estuary contributing 60%of total benthos.The mean abundance of macrobenthos was higher during the pre-monsoon(2 972±1 994 inds./m^2)than the monsoon(1 572±361 inds./m^2)being maximum at mid-estuary region and minimum at upper and lower estuary regions.Of the diversity indices,density(P=0.01,P=0.003),the number of taxa(P=0.000 3,P=0.000 9)and Margalef′s Index(P=0.000 4,P=0.001)of macrobenthos were significantly different among stations and seasons.Shannon-Weiner index(P=0.009,P=0.12)and Pielou’s evenness index(P=0.03,P=0.14)had significant differences among stations but not among seasons.Cluster analysis suggested that distribution of macrofauna is strongly influenced by seasonality.Among the feeding types,carnivorous were found to be dominant at the upper and mid-estuarine regions,and herbivorous were at lower estuarine regions.Carnivorous species were dominant in both seasons.Omnivores have shown to be the most abundant feeding type in terms of biomass though herbivores were highest during monsoon.
基金supported by the Universidad Nacional Mayor de San Marcos: Resolución Rectoral (RR) N° 00883-R-06, project code 061001191RR N° 00914-R-07, project code 071001281and RR N°03556-R-19, project code D19120061。
文摘A large fire of 233 ha in Huascarán National Park in Peru provided an opportunity to compare plant and bird responses in burned and nearby unburned zones of the puna. Heights and live diameters of flagship Puya raimondii rosettes(assigned to four broad developmental phases), plant communities(66 species in 24 families and nine growth forms) and bird communities(77 species in six trophic guilds) were monitored after the fire. Although no mortality was observed, Puya raimondii plants were affected by the fire, losing approximately 60% of their photosynthetic area across all developmental phases, but recovered quickly during the first two years after fire. The comparison of Puya rosette recovery after fire was complicated by the changes in live rosette diameter for unburned plants, which showed plasticity of photosynthetic area linked to seasonal and annual fluctuations in precipitation in this relatively dry environment(decreased by 26% for mature adult plants over the study period). Fire caused an immediate change in the density, biomass and composition of vegetation. Although the species present remained similar, their abundances changed significantly immediately after the fire, with notable reductions in dominant tussock grasses. This provided opportunities for other plants, resulting in higher postfire diversity of plant species, genera, families and growth forms. In turn, the changes in vegetation after fire affected the composition of birds according to their trophic guild. Granivores largely disappeared,generalists were mostly unaffected, and other guilds showed a more complex response. As the vegetation recovered, most displaced birds returned within approximately one year.
文摘Niche theory predicts that closely related and ecologically similar species with overlapping distribution ranges can coexist through resource partitioning that limits interspecific competition.However,studies examining the mechanisms promoting coexistence of top predators at a large geographical scale are still scant.Here,we describe the foraging ecology of 3 sympatric owl species(Northern long-eared owl[Asio otus],Tawny owl[Strix aluco],Eurasian eagle owl[Bubo bubo])in the Mediterranean Basin.We review 160 studies reporting diet information(212,236 vertebrate preys)and investigate among-species differences in diet metrics(diversity,evenness,prey size,and proportion of mammals)and their variation along geographical and environmental gradients.Moreover,we test whether diet metrics differ in presence or absence of the other predators.All the 3 species mainly rely on small mammals,but they significantly differ in diet metrics.The smallest predator(i.e.,long-eared owl)shows a higher level of specialism on small mammals(highest proportion but lowest diversity of mammals in the diet)compared to the larger ones.In addition,mean prey size significantly increases with predator body size(long-eared owl<tawny owl<eagle owl).Finally,interspecific competition results in an increase of diet diversity and evenness in the long-eared owl,and species’diet also varies in response to environmental factors.The 3 species thus segregate along several dietary niche axes over a large spatial scale and according to both morphological characteristics(i.e.,body size)and environmental variables.Such dietary niche segregation may adaptively buffer interspecific competition costs,ultimately allowing coexistence.
基金supported by the National Natural Science Foundation of China(Grant No.31172117)the Graduate Student Innovation Research Projects of Anhui University(Grant No.yqh100118)the Anhui Academic and Technical Leader Fund
文摘The loss and degradation of wetlands have adversely affected waterbirds, which depend on wetland habitats. Interspecific competition has an important effect on habitat utilization of wintering waterbirds. Resource utilization, including partitioning, in degraded wetlands has become a hot issue in ecological studies of wintering waterbirds. In order to have an insight into the habitat utilization and resource partitioning between a Hooded Crane(Grus monacha) population and the guild of three goose species, i.e., Anser fabalis, A. albifrons and A. erythropus wintering in lake wetlands, we carried out a study at Shengjin Lake National Nature Reserve from November 2011 to April 2012. We surveyed the Hooded Cranes and goose guild foraging in various habitats during the wintering periods with a combined method of fixed route searching and fixed site observations. Resource partitioning was studied by means of calculating habitat utilization rates and the width and overlap of spatial niches. The results showed that the habitat utilization rate and the width of spatial niches of the Hooded Crane population and goose guild shifted with the season. The habitat utilization rates of the cranes in grasslands were high at all three wintering stages. The habitat utilization rates were 0.454, 0.435 and 0.959 respectively for the Hooded Cranes and 0.627, 0.491 and 0.616 for the goose guild. This suggests that the overlap in grasslands was higher between cranes and goose guild. Most habitats were accessible at the middle stage, so the width of the spatial niche of the cranes(1.099) and goose guild(1.133) both reached their peak at this stage. The greatest niche overlap was 0.914 for these two groups at the late stage, followed by 0.906 at the middle stage and the smallest was 0.854 at the early stage. Ecological response to the changes in habitats of wintering waterbirds was clearly shown in the dynamic variations of the niche of both the Hooded Cranes and the three goose species. Coexistence among waterbirds was achieved by regulation of niche width to reduce niche overlap and relieve interspecific resource partitioning.
基金The National Natural Science Foundation of China under contract No.30490233the National Basic Research Program ("973"Program) of China under contract Nos2006CB400608 and 2005CB422306
文摘The spatial and temporal characteristics of trophic structure of fish communities in the southern Huanghai Sea were examined based on the data sampled from bottom trawl surveys conducted during the autumn of 2000 and the spring of 2001. Hierarchical agglomerative cluster method and bootstrap randomization were used to identify significant trophic groups for each fish assemblage in the southern Huanghai Sea. A total of six major trophic groups were identified within this system, which classified predators based upon location in the water column or prey size （ i. e. , benthic to pelagic predators or fish to small invertebrate prey predators）. The similarity level used to identify significant trophic groups in each assemblage ranged from 24% to 34%. Although planktivores were the dominant trophic group in each assemblage （60% - 79% ）, there were spatial and temporal variations in the trophic structure, which reflected the differences in the abundance and availability of dominant preys. Simplified food webs were constructed to evaluate the most important trophic relationships between the dominant prey taxa and the fishes in each assemblage within this system. Although there were some differences in the key prey species among different food webs, pelagic prey items （mainly euphausiids and copepods） represent the most important energetic link between primary producers and higher trophic level predators. The trophic level for most fishes was between 3 and d, and the weighted mean trophic level for each assemblage ranged from 3.3 to 3.4. Compared with previous study in the mid-1980s, there was an obvious downward trend in the trophic level for most fish species, which resulted mainly from the fluctuation in key prey species in the Huanghai Sea. The decrease in the importance of Japanese anchovy seems to be offset by other abundant prey species such as Euphausia pacifica and copepods （ mainly Calanus sinicus ） .
基金supported by King Mongkut’s University of Technology Thonburi(Thailand)the National Science and Technology Development Agency(CPMO P-14-51347)supported by the Royal Golden Jubilee Ph.D.Program,Thailand(PHD/0036/2556)
文摘Background: Edge effects cause changes in bird community richness, abundance, and/or distribution within a landscape, but the avian guilds most influenced can vary among regions. Although Southeast Asia has the highest rates of deforestation and projected species loss, and is currently undergoing an explosive growth in road infrastructure, there have been few studies of the effects of forest edges on avian communities in this region.Methods: We examined avian community structure in a dry evergreen forest in northeastern Thailand adjacent to a five-lane highway. We evaluated the richness and abundance of birds in 11 guilds at 24 survey points on three parallel transects perpendicular to the edge. At each point, 10-min surveys were conducted during February-August 2014 and March-August 2015. Vegetation measurements were conducted at 16 of the bird survey points and ambient noise was measured at all 24 survey points.Results: We found a strongly negative response to the forest edge for bark-gleaning, sallying, terrestrial, and understory insectivores and a weakly negative response for arboreal frugivore-insectivores, foliage gleaning insectivores, and raptors. Densities of trees and the percentage canopy cover were higher in the interior, and the ambient noise was lower. In contrast, arboreal nectarivore-insectivores responded positively to the forest edge, where there was a higher vegetation cover in the ground layer, a lower tree density, and a higher level of ambient noise.Conclusion: Planners should avoid road development in forests of high conservation value to reduce impacts on biodiversity. Where avoidance is impossible, a number of potential mitigation methods are available, but more detailed assessments of these are needed before they are applied in this region.
基金Strategic Priority Research Program of the Chinese Academy of Sciences,No.XDA23040203National Natural Science Foundation of China,No.41701212STS Project of Chinese Academy of Sciences,No.KFJ-SW-YW026。
文摘The Yangtze River floodplain is critical for migratory waterbirds along the East Asian-Australasian Flyway (EAAF). Greater awareness of its global importance is urgently needed to ensure waterbird populations remain in favourable conservation status, as well as the enhancement of wider wetland biodiversity within this region. The designation of protected wetland areas and building a green ecological corridor in the Yangtze floodplain is now becoming a critical issue of interest to the Chinese government. Priority sites in this area were identified based on the criteria used to identify sites that qualify as Wetlands of International Importance (Ramsar Sites) and Important Bird and Biodiversity Areas (IBAs) by using multi-source data. The results show that 140 of the sites surveyed are priority sites. The Importance Index (/) for the whole floodplain decreased slightly from 2001–2005 and an unbalanced distribution pattern is evident with Jiangxi and Hunan provinces significantly higher than the other provinces in the floodplain. Although more than 60% of the priority sites are currently located outside protected areas, the average Conservation Effectiveness Index (C) of the whole floodplain is 75.6%, which suggests the coverage of protected areas for most wintering waterbird population is reasonable. Conservation of the Yangtze River floodplain needs to be further strengthened due to declining waterbird abundances and the mismatch between the distribution of protected areas and their importance for wintering waterbirds. A comprehensive system for priority site identification and protection and scientific review is needed. Multi-sourced data from regular, systematic and coordinated monitoring of waterbird distribution and abundance across the EAAF, as well as national scale citizen science programmes are also critically important.
基金supported by the National Natural Science Foundation of China (No. 31170397)the Fundamental Research Funds for the Central Universities
文摘Background: The guild concept is useful for understanding the community structure in a land-bridge island system,but most fragmentation studies have focused only on the importance of island area and isolation, other island attributes such as perimeter-area ratio(PAR) were overlooked or understudied.Methods: We have adopted a guild approach to investigate the impacts of island attributes on bird guild richness on a set of 41 recently isolated land-bridge islands in the Thousand Island Lake(TIL), China.Results: We found insectivores had the largest number of species(34 species), fol owed by understory foraging guilds(28 species), omnivores(27 species) and canopy guilds(25 species). Furthermore, our data showed that migrants and residents responded equal y to island area, insectivores and understory guilds were sensitive to island area but omnivores and canopy guilds were not very sensitive. Most guild richness was determined by island area, except for omnivores and canopy guilds.Conclusions: Although PAR or habitat diversity found to be important for bird species richness, our results highlight the importance of island area in maintaining bird diversity in fragmented island systems.
基金This study was supported by National Natural Science Foundation of China(No.31930013,31872240)the National Key Program of Research and Development,Ministry of Science and Technology(2016YFC0503200)Youth Innovation Promotion Association of Chinese Academy of Sciences(2020086)to SP.
文摘Background:As an important player during food digestion,gut microbiota has attracted much attention in diet adaptation studies in birds.Microbiota extracted from feces has been widely used as a proxy for gut microbiota.Although several methods have been developed for microbial DNA extraction,their performances in the bird feces have not been systematacially evaluated yet.Methods:In this study,we applied three DNA extraction methods(Qiagen,MoBio and Bead)to extract DNA from feces of three avian dietary guilds(granivore,omnivore and carnivore),sequenced V4 region of 16S rRNA gene for each extract and evaluated the performances of DNA yield,DNA integrity,microbial composition,cell lysis capacity and alpha diversity for the three methods on each dietary guild.Results:Bead method was the best on the performance of both DNA yield and DNA integrity regardless of dietary guild.In granivore,microbial relative abundance at both species and phylum levels,alpha diversity and cell lysis capacity were comparable among all methods.In omnivore,Qiagen had the best performance on alpha diversity,fol-lowed by Bead and MoBio.There were small variations on microbial relative abundance at both species and phylum levels among different extraction methods.MoBio exhibited the best performance on cell lysis capacity.In carnivore,considerable variations were found on microbial relative abundance at both species and phylum levels.Qiagen had the best performance on alpha diversity,followed by MoBio and Bead.MoBio had the highest cell lysis capacity.Conclusions:DNA yield and integrity have no obvious impact on microbial composition,alpha diversity or cell lysis capacity.The microbiota results(e.g.,microbial composition,cell lysis capacity,alpha diversity)obtained from differ-ent methods are comparable in granivorous avian species but not in omnivorous or carnivorous birds.Either method could be used in granivore microbiota studies.For omnivores and carnivores,we recommend Qiagen method when the research purpose is microbial diversity and MoBio when gram-positive bacteria is the research target.
基金supported by the National Key Technologies Research and Development Program of China (No. 2017YFC0506101)the China-ASEAN Maritime Fund ‘Monitoring and Conservation of the Coastal Ecosystems in the South China Sea’the National Natural Science Foundation of China (No. 31101876)。
文摘The stable isotope ratios of nitrogen(δ^(15)N) and carbon(δ^(13)C) were applied in this study to analyze sediment carbon sources and primary food sources of epifauna in an oceanic mangrove forest in tropical North Sulawesi, Indonesia. Proportional contribution of mangrove-derived carbon to the food sources was compared among epifauna belonging to different feeding guilds. The sediment in the mangrove site with a depleted δ^(13)C signature(-28.02‰± 0.24‰) mainly consists of mangrove-derived carbon. Analysis using Bayesian stable isotope mixing model in the R program shows that mangrove-derived carbon can dominate the food sources of a majority of the epifauna(11 out of the total 18 species), especially 2 sesarmid crabs Parasesarma semperi and Sesarma sp., crab Epixanthus dentatus, and snails Terebralia sulcata and Optediceros breviculum, which belong to various feeding guilds. Mangrove-derived carbon has a proportional contribution to the food sources of fiddle crab Tubuca coarctata and 3 littorinid snails(Littoraria spp.) close to that of suspended particulate organic matter. Three planktophagous bivalve species(Anadara antiquata, Anadara sp. and Callista erycina) were found to mainly feed on seagrass-derived materials. Mean proportional contributions of mangrove-derived carbon to the food sources were 50.15%, 59.60%, 46.20% and 27.58% for the carnivorous, omnivorous, phytophagous and planktophagous groups, respectively. The results suggest that mangrove-derived carbon can directly(via grazing plant tissues) or indirectly(via deposit feedings) make an important contribution to the food sources of epifauna in the oceanic mangrove forest where the allochthonous input of organic carbon is low.
基金supported by the PIRE Mongolia project funded by the U.S.National Science Foundation(OISE 0729786)supported by the Taylor Family-Asia Foundation Endowed Chair in Ecology and Conservation Biology,Mongoliasupported by a grant funded by the National Research Foundation of Korea(Nos.NRF-2018R1C1B6007755,NRF-2022R1F1A1066643)。
文摘Although fairy rings are widely observed,little is known about the community processes associated with them.Here,we studied fairy rings in a natural grassland in northern Mongolia by sampling soils outside(future stage),directly under(present stage),and within(past stage)the rings,to represent different time stages during the expansion of fairy rings.Soil DNA was extracted for amplicon sequencing of the fungal ITS1 region.The present stage had reduced fungal diversity and different fungal communities toward the other stages.Most strikingly,there was an increase in the pathogenic fungus Gibberella baccata in the present stage of most rings and the saprotrophic fairy ring fungus Lepista luscina in several.However,no mushrooms of Lepista had been recorded from any of these rings during several years of observation.Known fairy ring fungi were not found in the present stage of every ring,even in some known rings to have previously displayed mushrooms of such species.It is possible that these fungi occurred or were more abundant at the unsampled leading edge of the ring.The increase in G.baccata is intriguing,but its importance,if any,is unclear.It is also unclear whether consortia of fungi or other microbes might be present in these rings.The absence or low abundance of the previously reported fairy ring fungal species suggests that their presence is transient,with rapid replacement by other fungi.No differences in soil parameters were found between the fairy ring stages,except for aluminum.There is a need for broader sampling,including analysis of non-fungal biota,to understand the functional diversity of fairy ring fungi and the consequences for plant communities.
基金supported by the University of Natural Sciences and Humanities in Siedlce and the Institute of Dendrology,Polish Academy of Sciencesupport from the Foundation for Polish Science (FNP) from the START scholarship
文摘Drivers of bird niche separation in temperate primeval forests have not yet been determined,due to the low number of intact forest sites.Here,we analyzed the general patterns of niche usage on trees by birds’assemblages.We tested how tree species affect the sharing of space in an assemblage of birds and their level of specialization.We conducted our study in the Białowieża primeval forest(NE Poland).During two breeding seasons,we observed bird positions on trees,divided into three vertical and six horizontal zones in 768 observation points.Based on the interaction networks framework we calculated the Kullback-Leibler distance d′as a metric of species specialization and the resource range RR index,which estimates the species’specificity based on the fraction of space utilized with a non-zero performance.The d′index was the highest in the lower understory for all parts of the tree on the basis of the position from the trunk.The RR index was the highest in the lower understory for all parts based on the position from the trunk.Regarding the tree species,the lowest d′index was observed in all tree species together,and hornbeam,whereas the highest in oak.At the tree species level,the RR index was the lowest for hornbeam.We show tree species importance in forest space sharing in the case of bird assemblages.Hornbeam,alder,and spruce are universal species that were used by birds almost entirely.In contrast,oak,lime,and maple were only partially used.Tree species with less complex structures could shape bird assemblages,as they could offer birds much fewer niches to realize.Therefore,we showed that high specialization and niche separation are drivers of high bird diversity.Consequently maintaining a diverse stand structure is crucial for biodiversity conservation.
文摘This study of feeding guild fish from the same coast of subtropics helps to suggest conservation of fishery resources. A total of 2,537 specimens of Plotosus lineatus (Plotosidae) were collected from July 2013 to March 2019 on the coast of Taiwan. The average total body length (TL) was 23.7 cm ± 4.7 cm and 20.3 cm ± 2.9 cm, and the average body weight (W) was 94.1 g ± 59.6 g and 56.6 g ± 30.8 g among 174 males and 630 females, respectively. The LWRs of male and female were ln(W)<sub>M </sub>= 3.2914 × ln (TL) −6.0395, and ln(W)<sub>F </sub>= 3.0917 × ln(TL) −5.3629. The male specimens were large than female in TL and W. The average OSW/TL ratios were 0.722 ± 0.044 and 0.649 ± 0.029 among 41 male and 49 female specimens, respectively. The OSW of the male head was wider than that of the female head (F = 91.5;p < 0.001), and the head widths of the male fish were significantly more than those of their female counterparts, causing the OSs to form granular protrusions. The average CFW/TL ratios were 0.198 ± 0.034 and 0.252 ± 0.032 among the male and female specimens, respectively. The CFW of the male specimens was narrower than that of the female specimens (F = 58.9;p < 0.001), and the CF gap of the male fish was narrower than that of the female fish. The P. lineatus exhibits significant sexual dimorphism. The average eggs number of each female was 2375.6 eggs/individual ± 1140.9 eggs/individual (N = 161). The major prey of P. lineatus were shrimps, crabs, and fishes;the total relative frequencies of occurrence of the prey were 57.1%, 32.6%, and 37.2%, respectively (N = 282), and their total relative abundance levels were 40.2%, 26.3%, and 25.8%, respectively (N = 445). Proper scientific knowledge management will improve the development of fisheries.
