Avian Biodiversity Research Articles

Avian biodiversity assessment studies in a Neotropical wetland – the combination of sampling methods makes the difference

In studies of avian diversity, many different methods have been applied. Since methodological approaches may affect research results, the choice of a given methodology must be consistent with the scientific objectives. The aim of this study was to investigate how different methodologies with their intrinsic limitations help detect and monitor birds to evaluate how they complement each other in the survey of species. Three different assessment methods, mist nets, point counts, and autonomous acoustic recordings were used to serve this purpose in a study of different Pantanal habitats, such as savannas and forests. The point counts detected more species (126 species) than the two other methods autonomous acoustic recordings (113 species) and mist nets (79 species). We observed significant differences in the number of species detected by mist nets and the other two methods. Each survey method identified exclusive species. When comparing habitats, all three methods showed significant differences in bird species composition. Savannas were richer in bird species than forests, and replacement was the main driver responsible for the differences in beta diversity between the habitats. The three methodologies, when applied together, proved to be complementary in avian species detection.

Passive monitoring of avian habitat on working lands.

Intensive agricultural landscapes are a challenge for wildlife managers, policy makers, and landowners hoping to increase the diversity of desired wildlife species, such as grassland birds, which require urgent conservation action. In intensive agricultural landscapes, like those of the midwestern USA, most land area is privately owned and operated and managed primarily for production. Conducting ecological research in intensive agricultural landscapes thus requires collaborative approaches aimed at farm owners and operators. Recent advances in acoustic data collection and high-resolution habitat mapping, including low-cost acoustic recorders and satellite remote sensing, may be well positioned to address this challenge by enabling expanded assessments and monitoring of wildlife populations and habitats across regions. This study examined fine grain habitat characteristics and their relationship with avian biodiversity in intensive agricultural landscapes at 44 agricultural sites across Iowa, USA. Passive acoustic monitoring and manual identification of bird species allowed for measurement of vocalizing bird richness. High resolution mapping of noncrop vegetation provided detailed information on small noncrop vegetation habitat complexes within row-crop agriculture. Measures of image texture provided characterizations of compositional heterogeneity within noncrop vegetation. General linear Poisson modeling demonstrated robust associations between noncrop vegetation and vocalizing bird richness, yet variation in grassland bird richness was not well predicted by noncrop vegetation. Noncrop vegetation texture demonstrated potential as a predictor of vocalizing bird richness, though not better than or when combined with noncrop vegetated area, indicating it may not be an independent measure of habitat quality. Passive acoustic monitoring resulted in useful data at 44 out of 60 originally selected sites, with some lost to failed recorders and/or collaboration issues. Challenges remain in detecting habitat characteristics that promote grassland birds in row crop landscapes. Working toward probabilistic research design across privately owned working landscapes and incorporating more detailed management practice information would improve the transferability of this approach to farmland management and policy.

Bird Biodiversity and Ringing Data Analysis at Shakpak Pass in the Tanirtau (2017-2022)

The Shakpak Pass, located in the foothills of the Western Tien Shan, is a significant migration route for birds. This work presents the ringing data collected between 2017 and 2022, providing insights into the diversity, abundance, and seasonal occurrence of bird species at the pass. The study reveals several key findings, including the identification of rare species, the documentation of migration patterns for both passerine and non-passerine species, and the notable reappearance of a species that had been absent for an extended period. These results deepen our understanding of avian ecology and biodiversity and underscore the importance of long-term monitoring efforts for effective conservation strategies.

Editorial: Avian biodiversity collapse in the Anthropocene: drivers and consequences

Editorial: Avian biodiversity collapse in the Anthropocene: drivers and consequences

Relating biodiversity with health disparities of human population: An ecological study across the United States

Understanding biodiversity's contributions to human health is the first step toward fostering synergies between biodiversity conservation and health promotion - two major targets of UN's Sustainable Development Goals. The One Health approach acknowledges the health of people and biodiversity are interconnected and facing common threats. In this study, we aimed to unveil the geographical association between avian biodiversity and population health across the US. In this ecological study, we combined citizen science bird data from eBird, population health data from the Institute for Health Metrics and Evaluation, and county-level statistics of population characteristics, including socio-economics, healthcare service etc. Multivariate linear regression analyses were performed between bird biodiversity (measured by rarefied species richness of birds), key indicators of general public health (e.g., cause-specific mortality rate), and socio-economic health determinants of 2751 US counties. We found that a higher number of bird species was significantly associated with longer life expectancy after confounding adjustment (regression coefficient (95% CIs), 0·005 (0·003, 0·008)). Bird species richness calculated using the rarefied method consistently accounted for variance in age-specific mortality risks in both very young and old age groups (R2 from 2% to 4%). Rarefied species richness of birds was negatively correlated with the majority of cause-specific deaths (12 out of 21 mutually exclusive causes of death), indicating a general synergy effect between biodiversity and human health. The associations with the top causes of deaths were regarded as highly significant, with considerable effect sizes, for example, for cardiovascular diseases (regression coefficient (95% CIs), −0·242 (−0·311, −0·174)). Our findings show human health is inseparable from the health of the shared environment and the well-being of all species. Bird species richness offers a valuable means to understand large-scale relationships between human health and the health of the environment. To enable equitable sharing of biodiversity's benefits to human health, more efforts should be made to understand two-way socio-ecological mechanism underlying human–biodiversity interactions.

Potential of agroforestry orchards as a conservation set-aside initiative in industrial rubber tree and oil palm plantations for avian biodiversity

Potential of agroforestry orchards as a conservation set-aside initiative in industrial rubber tree and oil palm plantations for avian biodiversity

Management of U.S. Agricultural Lands Differentially Affects Avian Habitat Connectivity

Despite frequently being implicated in species declines, agricultural lands may nonetheless play an important role in connecting wildlife populations by serving as movement corridors or stopover sites between areas of high-quality habitat. For many North American bird species, agricultural intensification over the past half century has substantially impacted populations, yet recent studies have noted the potential for supporting avian biodiversity on agricultural lands through the promotion of functional connectivity. To support avian conservation efforts on agricultural lands across the United States, we used publicly available data from eBird to quantify and map the effects of agriculture on habitat suitability (using random forest models) and functional connectivity (via circuit theory) for three focal species that have experienced agriculture-linked declines or range contractions in recent decades: Greater Sage-grouse (Centrocercus urophasianus), American Black Duck (Anas rubripes), and Bobolink (Dolichonyx oryzivorus). Our analysis drew on novel, remotely sensed estimates of agricultural management intensity to quantify the effects of management practices on avian habitat and movement, revealing complex, species-specific relationships between agriculture and habitat value for the three focal species. Rangelands and croplands exhibited relatively high connectivity values for Greater Sage-grouse and Bobolink, respectively, mirroring these species’ strong habitat preferences for open sagebrush and cultivated grasslands. By contrast, American Black Duck migratory connectivity was low on all agricultural cover types. Mapping our model results across each species’ geographic range in the U.S. revealed key areas for agricultural management action to preserve high-quality habitat and connectivity, and we link these spatial recommendations to government incentive programs that can be used to increase wildlife-friendly management on U.S. agricultural lands.

How has bird biodiversity changed over time? A review across spatio-temporal scales

Empirical quantification of biodiversity changes remains a challenge even in well surveyed groups such as birds. This may be because the change depends on spatio-temporal scales, specifically on spatial grain (i.e. average unit of area of the sampling or the analysis), geographic extent (i.e. size of the area of interest), temporal grain (i.e. average unit of duration of the sampling or the analysis), and temporal extent (i.e. length of the time series). Further, different metrics of biodiversity may exhibit different trends. Here we review the literature assessing the temporal trends of avian biodiversity from ca. 1900 AD to present, focusing on studies summarising trends across many locations within a larger region (i.e. spatially replicated). From each study we extracted direction of average trend (increase, decrease, stable), spatial and temporal grains and extents at which the trends have been assessed, metrics of biodiversity, and location. We then discuss the trends as a function of the spatio-temporal grains and extents they are defined at. We found 59 trends of 12 metrics, where each trend is an average of trends from multiple sites (spatial replicates). There was a tendency of biodiversity metrics to increase at local and regional spatial scales, and to decrease globally. We thus confirmed that biodiversity dynamics can have opposite trends at different spatial scales. Concerning temporal grain, it was poorly documented across the studies, with inconsistent and/or confusing definitions. We suggest a common framework to better understand the link between temporal scales and biodiversity dynamics. We have also identified underrepresented regions (those outside North America and Europe), periods (those before the 70′s), and biodiversity metrics that need further attention. We highlight the importance of considering both spatial and temporal scaling jointly in any assessment of biodiversity change, and provide guidelines for specifying spatio-temporal features (i.e. grain, lag and extent) effectively both in birds, and in other taxa.

A regional integrated assessment of the impacts of climate change and of the potential adaptation avenues for Quebec's forests

Regional analyses assessing the vulnerabilities of forest ecosystems and the forest sector to climate change are key to considering the heterogeneity of climate change impacts as well as the fact that risks, opportunities, and adaptation capacities might differ regionally. Here we provide the Regional Integrated Assessment of climate change on Quebec's forests, a work that involved several research teams and focused on climate change impacts on Quebec's commercial forests and on potential adaptation solutions. Our work showed that climate change will alter several ecological processes within Quebec's forests. These changes will result in important modifications in forest landscapes. Harvest will cumulate with climate change effects to further alter future forest landscapes, which will also have consequences on wildlife habitats (including woodland caribou habitat), avian biodiversity, carbon budget, and a variety of forest landscape values for Indigenous peoples. The adaptation of the forest sector will be crucial to mitigate the impacts of climate change on forest ecosystem goods and services and improve their resilience. Moving forward, a broad range of adaptation measures, notably through reducing harvest levels, should be explored to help strike a balance among social, ecological, and economic values. We conclude that without climate adaptation, strong negative economic and ecological impacts will likely affect Quebec's forests.

Using stable isotopes to measure the dietary responses of Costa Rican forest birds to agricultural countryside

How human modification of native habitats changes the feeding patterns and nutritional ecology of tropical birds is critical to conserving avian biodiversity, but tropical bird diets are laborious to investigate using the traditional methods of diet analysis. Stable isotope analysis provides a cost-effective and efficient proxy to identify general foraging patterns, especially when dietary shifts spanning multiple trophic levels have occurred due to ecosystem disturbance or transformation. To characterize the diets of forest bird species that persist in tropical agricultural countryside, we compared feather carbon (δ13C) and nitrogen (δ15N) isotope values of four species caught and radio-tracked in a 270 hectare forest reserve, smaller forest remnants (including mature forest, secondary forest, and riparian strips), and coffee plantations in mid-elevation (ca. 800–1,400 m) southern Costa Rica. Bird habitat choice had a significant effect on diet composition as revealed by δ13C and δ15N values. Three of the four species studied showed evidence of significantly reduced consumption of invertebrates in coffee plantations, with the isotope values of two species (Tangara icterocephala and Mionectes oleaginous) indicating, by comparison, nearly a doubling of invertebrate consumption in forest remnants. Our results suggest that coffee plantations are deficient in invertebrates preferred by forest generalist birds that forage in both native forest remnants and coffee plantations. In this region, typical of mountainous American tropics, small forest remnants and a larger forest reserve provide critical dietary resources for native forest birds that utilize the agricultural countryside.

Direct and indirect effects of agricultural land cover on avian biodiversity in eastern Canada

Agriculture is one of the largest threats to global biodiversity. However, most studies have focused only on the direct effects of agriculture on biodiversity, and few have addressed the indirect effects, potentially over or under-estimating the overall impacts of agriculture on biodiversity. The indirect effect is the response not to the agricultural cover types or operations per se, but instead, to the way that agriculture influences the extent and configuration of different types of natural land cover in the landscape. We used structural equation modelling (SEM) to evaluate the direct, indirect, and total effects of agriculture on species richness of three bird guilds: forest birds, shrub-edge birds, and open country birds. We found that forest bird richness was driven by the negative indirect effect of cropland via forest loss. Shrub-edge and open country bird richness increased with the amount of agriculture land covers; however, importantly, we found negative indirect effects of agriculture on both guilds via a reduction in more natural land covers. This latter result highlights how we would have over-estimated the positive effects of agriculture on shrub-edge and open country bird richness had we not measured both direct and indirect effects (i.e., the total effect size is less than the direct effect size). Overall, our results suggest that a bird-friendly agricultural landscape in our region would have forest that is configured to maximize forest edge, and a high proportion of perennial forage within the agricultural portion of the landscape.

Even minor logging road development can decrease the functional diversity of forest bird communities: Evidence from a biodiversity hotspot

Although the effects of major roads and highways on biodiversity have received considerable attention, there is a lack of research considering how smaller and less-used roads might also impact wildlife, especially during the initial re-used development phase of abandoned roads, despite these minor roads being much more extensive and pervasive. Here, we examined how even minor redevelopment of former-abandoned logging roads can impact bird community alpha and beta diversity indices at the taxonomic, functional, and phylogenetic levels in a biodiversity conservation hotspot in central China. The minor redevelopment (i.e., re-paved) of former-abandoned roads generally reduced bird alpha and beta diversity compared to undeveloped abandoned roads, especially at the functional level. Compared with continuous-use roads, minor road redevelopment shows only a slight impact on avian diversity. Notably, compared to old-growth forest reference stands and undeveloped abandoned roads, minor road redevelopments have negative effects on the recovery process of avian diversity. Furthermore, the structure and composition of the high tree layer significantly affected avian functional and phylogenetic diversity, and low shrub layer vegetation mainly influenced taxonomic and phylogenetic diversity. To mitigate the effects of minor forest logging roads on avian biodiversity in priority biodiversity conservation areas, we propose the following: (1) roads that have fallen into disuse should be allowed and encouraged to re-naturalise; (2) roads should only be paved, and cleared back as strictly necessary, allowing grassy or gravel roads to suffice where possible; and (3) if road development is necessary, key umbrella tree species should be planted deliberately to support maximal community diversity and to maintain ecosystem functions and processes.

Effectiveness of acoustic indices as indicators of vertebrate biodiversity

Effective monitoring tools are key for tracking biodiversity loss and informing management intervention strategies. Passive acoustic monitoring promises to provide a cheap and effective way to monitor biodiversity across large spatial and temporal scales, however, extracting useful information from long-duration audio recordings still proves challenging. Recently, a range of acoustic indices have been developed, which capture different aspects of the soundscape, and may provide a way to estimate traditional biodiversity measures. Here we investigated the relationship between 13 acoustic indices obtained from passive acoustic monitoring and biodiversity estimates of various vertebrate taxonomic groupings obtained from manual surveys at six sites spanning over 20 degrees of latitude along the Australian east coast. We found a number of individual acoustic indices that correlated well with species richness, Shannon’s diversity index, and total individual count estimates obtained from traditional survey methods. Correlations were typically greater for avian and total vertebrate biodiversity than for anuran and non-avian vertebrate biodiversity. Acoustic indices also correlated better with species richness and total individual count than with Shannon’s diversity index. Random forest models incorporating multiple acoustic indices provided more accurate predictions than single indices alone. Out of the acoustic indices tested, cluster count, mid-frequency cover and spectral density contributed the greatest predictive ability to models. Our results suggest that models incorporating multiple acoustic indices could be a useful tool for monitoring certain vertebrate groups. Further work is required to understand how site-specific variables can be incorporated into models to improve predictive capabilities and how to improve the monitoring of taxa besides avians, particularly anurans.

Mongolian Lark as an indicator of taxonomic, functional and phylogenetic diversity of steppe birds

Biodiversity is declining at an unprecedented rate. Many grassland species have been lost and are now of conservation concern. Identifying efficient biodiversity indicators is a key pillar of the global conservation strategy. Mongolian Lark (Melanocorypha mongolica) is a charismatic bird species abound in Mongolian steppes, and recent studies demonstrated that this species share similar habitat requirements and likely co-occur with other grassland birds. We tested the hypothesis that Mongolian Lark would make a suitable indicator for different aspects of avian biodiversity. We made a large-scale bird survey in Inner Mongolia, and classified point counts into three groups based on different taxonomic, functional, and phylogenetic biodiversity measures. We identified species indicators of each group using the indicator value (IndVal) analysis, and examined the bird compositional difference among groups. Linear models were used for studying the patterns of occurrence of Mongolian Lark in relation to various biodiversity measures. Mongolian Lark showed the highest indicator value in comparison with other potential species indicators. Bird species richness is significantly higher at sites with Mongolian Lark, and its occurrence was negatively correlated with species abundance, functional richness, Rao's quadratic entropy and phylogenetic diversity. Mongolian Lark is therefore a suitable indicator species for avian biodiversity in Mongolian steppes. It is highly distinctive in flight and usually seen singly. The widespread distribution and charismatic appearance make it easy to monitor and adequate for citizen science, and may provide useful information on the paradigm of surrogacy in conservation ecology.

Assessing avian biodiversity in Swamithoppu saltpan with the fuzzy matrix approach

Fuzzy matrix is an invaluable tool in determining the biodiversity of a particular area. It is used to measure the species richness and abundance of a given area, as well as account for the presence of rare species. This study used fuzzy matrix analysis Initial Raw Data Matrix (IRDM), Average Quantity Dependent Data Matrix (AQDM), Refined Quantity Dependent Data Matrices (RQDMs), and Combined Effect Quantity Dependent Data Matrix (CEQDM) to determine the distribution and diversity of wetland birds in Samythoopu. The results showed that the maximum number of birds chose the sites of J1, J2,J3, S4, and S5, while the S2 point was identified as the most disturbed site and the birds were facing threats in sites including J4, S2, S3, S5, U1, U2, and U3. This fuzzy matrix can help predict the exact places with more anthropogenic disturbance to disturb the diversity and distribution of wetland birds.

Effects of land use change on the functional diversity and composition of mixed species avian flocks in the high tropical Andes of southern Ecuador

One of the greatest threats to biodiversity is land use change. Habitat alteration can have strong impacts on functional diversity, i.e., the range of biological traits within a suite of organisms. Mixed species avian flocks are integral to maintaining both taxonomic and functional diversity in tropical forests as they provide participants with greater foraging efficiency, reduced predation risks, and increased resiliency of species and ecosystems to environmental change. Our aim for this study was to determine the effects of land use change on the taxonomic and functional structures of mixed species avian flocks in and around Cajas National Park, Azuay Province in the tropical Andes of southern Ecuador by comparing non-native vegetation in agricultural plots and forest regenerating from historical use as pastureland to the largest intact primary forest in the region. We found no changes in species richness and diversity or functional richness of flocks across habitats, but we did find significant differences in species composition. Surprisingly, we found higher functional diversity and uniqueness of flocks in regenerating forest with more diverse and structurally complex vegetation, but native and non-native forests were functionally similar. We did, however, find significant differences in the community weighted means of four of five functional traits in different habitat types. Overall, the taxonomic and functional structures of mixed species flocks in this region seem relatively unaffected by land use change, indicating flocking as a beneficial strategy for species with higher sensitivities to disturbance in areas with anthropogenic activities. It is critical to maintain functional diversity in ecosystems, as a greater variety of functional traits and functional redundancy implies an efficient and more resilient ecosystem in the face of environmental change. Mixed species flocks provide membership benefits that may mitigate impacts of disturbance via land use change and thus can be considered essential units for conserving avian biodiversity.

Community science for enigmatic ecosystems: using eBird to assess avian biodiversity on glaciers and snowfields

Community science for enigmatic ecosystems: using eBird to assess avian biodiversity on glaciers and snowfields

Bird Community Composition and Functional Guilds Response to Vegetation Structure in Southwest Ethiopia

Shade coffee farms in southwest Ethiopia are known to host high levels of avian biodiversity. However, these farms vary in terms of forest management, which affects their understory, mid-story, crown cover, and canopy closure, and hence their structural complexity. Such differences in vegetation structure can potentially affect the survival of specialist bird species, and shade coffee farms may not equally contribute to avian biodiversity conservation. This study aimed to investigate how avian community composition, richness, and the relative abundance of different bird functional guilds relate to structural differences in vegetation shaped by forest management. Bird guild classification was based on bird species forest dependence, diet type, migration status, nest type, foraging, and nesting strata, and bird communities were surveyed using the Timed Species Counts (TSCs) method. Species turnover in bird communities was evaluated using detrended correspondence analysis and redundancy analysis, whereby multiple regression models were used to examine bird guild responses to vegetation structure. Total bird species richness and relative abundance did not respond to vegetation structure. However, the richness of forest specialists and understory foragers, and the relative abundance of mid-high foragers, all positively related to tree diameter at breast height (DBH) and crown cover, whereas the relative abundance of species with medium levels of forest dependency, mid-high/canopy foragers, and open-nesters were positively related to basal area and canopy cover. This study demonstrates that the relative value of shade coffee farms for avian biodiversity conservation depends on the type of forest management, and that bigger trees with larger crown cover provide a habitat of higher quality to habitat specialist birds.

Ecology and “bird-habitat” relationship in the cedar forest of Aurès mountain (Eastern Algeria)

Abstract This work aims to compile the birds breeding in the cedar forest of Aurès and to study the “Bird – Habitat” relationships. The data was collected using the progressive frequency sampling method that served as the basis for the diagnosis build on an analytical approach designed around three tools (mutual information, ecological profiles, modelling). Information theory tools allowed us to identify the indicator values of species as well as the most important descriptors. Habitat modelling has been prepared for species with a high indicator value. The logistic models are shown to be well adapted to the nature of the ornithological data. They related the occurrences of the species with the dendro-ecological descriptors. The 70 surveys carried out enabled us to identify 32 bird species. The ecological analysis revealed the most active descriptors and the species with high indicator value. The best-fitting models are those of Short-toed Treecreeper with positive effect of dead wood, density of trees and variability of distances between trees, and European Robin with negative effect of anthropization and general coverage, and positive effect of crown parametres. We conclude that promoting forest structural complexity by diversifying management regimes will be key to maintain avian biodiversity in cedar forests.

Avian diversity at Sonvad water reservoir in Dhule district (Maharashtra): An important wetland site for waterfowl

The avifauna of Sonvad water reservoir near Dhule (Maharasgtra) included a total of 220 species of birds from 61families and 21orders. The bird were classified by residential status, occurrence, feeding guild as well as on utilization of microhabitats. The sighting records show visits by at least 11 bird species (4.55%) of ‘Near Threatened’ species of the red-data book of International Union for Conservation of Nature. Common Pochard (Aythya ferina) is the only ‘Vulnerable’ species sighted occasionally in good numbers, while Egyptian Vulture (Neophron percnopterus) is the only ‘Endangered’ species sighted once. In view of the considerable avian biodiversity, Sonwad water reservoir is an important wetland for birds. It has the potential to develop into a bird sanctuary with suitable protection, adequate management and coordinated efforts of local and Government authorities.