Bird Abundance Research Articles

Species diversity, relative abundance, and distribution of avifauna in different habitats within Lewi Mountain, Awi zone, Ethiopia

Almost all habitats on the planet are home to birds, from the lowest deserts to the highest mountains. Birds have proved to be excellent indicators of biodiversity or productivity as they are easily observed and are relatively well known compared to other animals. Although bird species are distributed across the globe, habitat destruction, fragmentation, and loss have adversely affected their survival and distribution. Therefore, this study is an attempt to prepare a baseline data on avifaunal diversity with their relative abundance and species richness in different habitats within Lewi Mountain Awi zone, Ethiopia from December 2018 to October 2020, including both the wet and dry seasons. The sampling sites were stratified based on land cover features, and transect count techniques were employed. The data were summarized per season and habitat type in the excel spreadsheet throughout the study period. In this study, one-way ANOVA was used to determine the effect of habitat type on species diversity and abundance. T-tests are also use to analyze bird populations among seasons. A total of 1591 individuals, 56 bird species belonging to 29 families and 12 orders were identified during the two seasons. The Wetland habitat had the highest species diversity index (H’ = 3) with high evenness index (J = 0.88) during the dry season followed by the open shrubs habitat (H’ = 2.97) with the highest evenness index (J = 0.95). The settlement had the lowest species diversity (H' = 2.17) and the lowest evenness index (J = 0.8) in the same season. During the wet season, disturbed forests recorded the highest Shannon-Weiner diversity index (H’ = 3.2) with the highest evenness (J = 0.92) followed by Wetland habitat (H’ = 2.97) with high evenness index (J = 0.87). During dry and wet seasons, the abundance of birds' species in different habitat types did not differ significantly (F = 1.91, p = 0.193, dƒ = 3) and (F = 1.579, p = 0.199, dƒ = 3), respectively. From all studied habitats, the overall mean abundance of bird species between dry and wet seasons was significantly different (F = 3642, P ≤ 0.001, dƒ = 1). In conclusion, settlement had the lowest species diversity and the lowest evenness index in the research area for the entire season. The habitats are important to the conservation of birds, so good habitat management is required, such as minimizing agricultural expansion and overgrazing, demarcating the forest habitats for wild species only, and creating awareness among local communities.

Drivers of the changing abundance of European birds at two spatial scales.

Detecting biodiversity change and identifying its causes is challenging because biodiversity is multifaceted and temporal data often contain bias. Here, we model temporal change in species' abundance and biomass by using extensive data describing the population sizes and trends of native breeding birds in the United Kingdom (UK) and the European Union (EU). In addition, we explore how species' population trends vary with species' traits. We demonstrate significant change in the bird assemblages of the UK and EU, with substantial reductions in overall bird abundance and losses concentrated in a relatively small number of abundant and smaller sized species. By contrast, rarer and larger birds had generally fared better. Simultaneously, overall avian biomass had increased very slightly in the UK and was stable in the EU, indicating a change in community structure. Abundance trends across species were positively correlated with species' body mass and with trends in climate suitability, and varied with species' abundance, migration strategy and niche associations linked to diet. Our work highlights how changes in biodiversity cannot be captured easily by a single number; care is required when measuring and interpreting biodiversity change given that different metrics can provide very different insights. This article is part of the theme issue 'Detecting and attributing the causes of biodiversity change: needs, gaps and solutions'.

Assessing bird diversity in Neotropical rainforests: A comparative study of camera traps and mist nets reveals complementary sampling approaches

Abstract Different sampling methods are used to study bird diversity in the tropics, mist nets being one of the most common approaches. However, camera traps have been used for this purpose in the last 20 years. We compared the performance of mist nets and camera traps in sampling the diversity of understory and sub-canopy birds in a Neotropical rainforest. Given its high biodiversity, obtaining accurate bird diversity estimates in these forests is a challenging task. We sampled secondary forest patches in the Colombian central Andes between 2019 and 2021. We compared the effectiveness of both methods based on six comparison criteria (body size, foraging stratum, detection difficulty, habitat specialization, population trend, and migratory status). We recorded a total of 99 bird species: 92 species were captured using mist nets and 37 species using camera traps; 30 species were detected using both methods (mainly generalist and abundant birds). Mist net’s effectiveness was 83%, while camera trap effectiveness was 68%. Differences in sampling effectiveness were mainly determined by body size, as small birds were captured using mist nets, while camera traps often recorded large birds. However, detection difficulty and habitat specialization were also relevant. Camera traps effectively recorded ground-dwelling species that were not captured in mist nets. In contrast, those birds that forage in the sub-canopy stratum were mainly captured in the mist nets but not detected in camera traps. Although both methods detected different species, we found similar patterns regarding estimated species richness among different categories of body size, detection difficulty, population trend, and behavior, but not for habitat specialization. As both methods have advantages and limitations, using mist nets and camera traps together would improve bird diversity estimations. We urge investigators to explore canopy ecology with camera traps, as they provide long-term information that cannot be obtained with other methods.

Remote Sensing and Ecological Variables Related to Influenza A Prevalence and Subtype Diversity in Wild Birds in the Lluta Wetland of Northern Chile.

The Lluta River is the northernmost coastal wetland in Chile, representing a unique ecosystem and an important source of water in the extremely arid Atacama Desert. During peak season, the wetland is home to more than 150 species of wild birds and is the first stopover point for many migratory species that arrive in the country along the Pacific migratory route, thereby representing a priority site for avian influenza virus (AIV) surveillance in Chile. The aim of this study was to determine the prevalence of influenza A virus (IAV) in the Lluta River wetland, identify subtype diversity, and evaluate ecological and environmental factors that drive the prevalence at the study site. The wetland was studied and sampled from September 2015 to October 2020. In each visit, fresh fecal samples of wild birds were collected for IAV detection by real-time RT-PCR. Furthermore, a count of wild birds present at the site was performed and environmental variables, such as temperature, rainfall, vegetation coverage (Normalized Difference Vegetation Index-NDVI), and water body size were determined. A generalized linear mixed model (GLMM) was built to assess the association between AIV prevalence and explanatory variables. Influenza positive samples were sequenced, and the host species was determined by barcoding. Of the 4349 samples screened during the study period, overall prevalence in the wetland was 2.07% (95% CI: 1.68 to 2.55) and monthly prevalence of AIV ranged widely from 0% to 8.6%. Several hemagglutinin (HA) and neuraminidase (NA) subtypes were identified, and 10 viruses were isolated and sequenced, including low pathogenic H5, H7, and H9 strains. In addition, several reservoir species were recognized (both migratory and resident birds), including the newly identified host Chilean flamingo (Phoenicopterus chilensis). Regarding environmental variables, prevalence of AIV was positively associated with NDVI (OR = 3.65, p < 0.05) and with the abundance of migratory birds (OR = 3.57, p < 0.05). These results emphasize the importance of the Lluta wetland as a gateway to Chile for viruses that come from the Northern Hemisphere and contribute to the understanding of AIV ecological drivers.

Population and Productivity of the Critically Endangered White-Rumped Vulture (Gyps bengalensis) in the Argha Important Bird and Biodiversity Area, Nepal

ABSTRACT The White-rumped Vulture (Gyps bengalensis) is an accipitrid vulture native to Asia. Once known as the world's most abundant large bird of prey, its population declined dramatically across its range during the 1990s. As a result, it is listed on the International Union for the Conservation of Nature (IUCN) Red List as critically endangered. From 2010 to 2021, we monitored two breeding colonies of White-rumped Vultures in the Argha Important Bird and Biodiversity Area, Arghakhanchi District, in the western mid-hill region of Nepal. We visited the colonies at least three times in each breeding season during November, February, and April and calculated nesting success. We estimated annual trends in number of occupied nests (i.e., nesting activity, egg, nestling, or adult in incubation posture), number of fledglings, and productivity (i.e., young fledged per occupied nest). The number of occupied nests, fledglings, and productivity were analyzed separately using identical models. Although the number of occupied nests appeared to increase, the credible interval of the growth rate (r) overlapped zero (r = 0.05, 95% CRI = −0.06–0.16). The number of fledglings (r = 0.04, 95% CRI = −0.04–0.16) and productivity (r &amp;lt; 0.01, 95% CRI = −0.08–0.09) appeared stable. Our findings are encouraging because they suggest stable population and productivity levels in the two breeding colonies of this critically endangered bird. However, our survey covered a small portion of the global population over a single generation of the species. We recommend coordinated, widespread, and long-term monitoring of vultures across South Asia.

Abundance of Non-Native Birds in the City: Spatial Variation and Relationship with Socioeconomics in a South American City.

Cities commonly support a high abundance of non-native species that can affect both wildlife and human health; however, their distribution across the urban environment and their relationship with socioeconomics are not well documented. Here, we map the abundance of three non-native birds in a Latin American city-domestic pigeon (Columba livia f. domestica), house sparrow (Passer domesticus), and monk parakeet (Myiopsitta monachus)-and investigate the effect of socioeconomics on their abundance. We found that C. livia f. domestica exhibited a random distribution of abundance across the city but reached its greatest abundance in low-income areas. P. domesticus exhibited an aggregated distribution of abundance, being most abundant in the southern and western areas of the city and in low-income areas. M. monachus exhibited an aggregated distribution of abundance, being most abundant in the northeastern part of the city and reaching its greatest abundance in high-income areas. Low-income areas likely provide high abundance of food, shelter, and nesting sites for both C. livia f. domestica and P. domesticus, whereas high income areas have greater tree cover and larger trees in which M. monachus can build communal nests. Our study finds that the abundance of non-native birds varies across the city and between socioeconomic groups; therefore, targeted management is needed in different city zones to limit negative effects on native species and prevent zoonotic diseases.

Airborne and Underwater Noise Produced by a Hovercraft in the North Caspian Region: Pressure and Particle Motion Measurements

The measurements of airborne and underwater noise radiated by a Griffon BHT130 hovercraft were conducted in the Ural-Caspian Channel and in the North Caspian Sea. This type of hovercraft is being used for all-season cargo and crew transportation to oil and gas platforms within the environmentally sensitive area of the Ural River estuary known for its abundant bird and fish fauna. Several field campaigns were organized from 2017 to 2022 to measure and analyze acoustic noise levels simultaneously in the air and underwater at various sites and hovercraft speeds. Airborne noise levels were estimated according to ISO 2922:2020, 2021. Underwater noise study included not only acoustic pressure recordings but also particle velocity measurements with a self-designed pressure gradient sensor (PGS), which is important since the hearing of the majority of fish perceives the sound in terms of particle motion. This study is the first to report the particle velocity levels formed underwater during hovercraft passages. The minimum levels of underwater noise, 100 dB re 1 µPa (pressure), 45 dB re 1 nm/s (particle velocity), and airborne noise, 93 dBA re 20 µPa (pressure), normalized to a distance of 25 m were observed for the hovercraft passages at a cruising speed of 7–15 m/s. Thus, this speed interval can be recommended as an optimum to minimize an acoustic impact on ornitho- and fish fauna. The directivity of the hovercraft noise was estimated for the first time and utilized for noise mapping of the Ural-Caspian Channel. The possible hydrodynamic effect of a passing hovercraft is discussed.

Diversity, composition and conservation status of avian fauna in the forest and the wetland sites of Hastinapur wildlife sanctuary, India

Almost, in all flora and fauna, the species richness is affected by environmental changes; hence it is important to survey regularly to understand the current composition and diversity of different wildlife species in an ecosystem. The present study surveyed to assess the species distribution, conservation status, abundance and diversity of birds using the point count method, at two different habitats, a wetland (BhikundJheel; BJ) and a forest (Arjun Van; AV) in Hastinapur wildlife sanctuary, India. We surveyed early in the morning (before and after sunrise) and evening (before sunset) for 20 min at every point from January 2019 to April 2019. A total of 96 bird species were recorded, which belong to the 40 families and 15 orders. Out of 96 species, we recorded 67 resident bird species and 29 migratory bird species. The number of bird species specific to the type of habitat was higher in BhikundJheel than those in Arjun Van. The species richness and abundance were higher in the wetland (81; 5605)than in the forest habitat(45; 1716); however, evenness (J’) and diversity [Shannon-Weiner (H’) and Simpson diversity (D)]indices were higher in the forest habitat (J’: 0.827, H’: 3.420, D: 0.960) than in the wetland habitat (J’: 0.669, H’: 2.940, D: 0.827). Overall, we found that in the wetland habitats had more species richness than in the forests.

Abundance and Behavior of Migratory Birds in a Mangrove and Salt Marsh Ecosystem in Guyana, South America

Abundance and Behavior of Migratory Birds in a Mangrove and Salt Marsh Ecosystem in Guyana, South America

Landowner and biologist perceptions of game bird predators and management

AbstractNest survival has been identified as one of the most influential vital rates causing population change in game birds, and depredation, often influenced by habitat loss and fragmentation, is the primary cause of nest failure of upland game birds. We were interested in quantifying and comparing the perspectives of landowners and biologists in South Dakota regarding complex predator‐prey interactions to improve communication and management efficacy. We developed a questionnaire regarding the following: 1) general attitude statements about game bird species; 2) perceived impacts of 9 factors (e.g., development, pollution, predators) and 13 potential predators on game bird abundances; and 3) attitude statements regarding use of lethal predator control and nesting habitat management practices. A cluster analysis using landowner attitude statements about predator management identified 3 landowner segments that had strong (most supportive; 37%), moderate (moderately supportive; 35%), or weak (least supportive; 28%) attitude statements about lethal predator control. Landowner segments most supportive and moderately supportive of predator control rated predators as the primary negative factor impacting game bird abundances and agreed that predators were the primary cause of game bird abundance declines, whereas the landowner segment least supportive of predator control rated habitat loss as the top factor and disagreed that predators were the primary cause of game bird declines. Biologists rated habitat loss as the top factor negatively impacting game bird abundances and disagreed that predators were the primary cause of game bird abundance declines. Thus, when considering the effectiveness of strategies to reduce nest depredation, most landowners focused on the direct cause of nest failures (predators), whereas biologists focused on an indirect cause (habitat loss). Perception differences among these groups emphasizes the need for better communication on proximate and ultimate factors affecting game bird populations and how these differences may impact management decisions.

Bird population dynamics during the regenerative succession of mossy pine woodland in southwestern Belarus

Disturbed forest ecosystems are characterized by significant spatial and temporal changes. As a part of the study on bird communities, changes in bird abundance during the secondary succession of a cleared mossy pine woodland in southwestern Belarus were investigated. The purpose of the work was to determine the inter-annual dynamics of bird species abundance and to assess the variability of individual species abundance during the secondary succession of the mossy pine woodland. The material was collected in 2000–2019. Line transects were set to conduct bird counts in ecosystems at different stages of succession. For the data processing, generally accepted methods of statistical analysis were used. The species diversity of birds was found to increase from 8 to 42 species, the overall abundance from 171.7 to 587.1 birds/km2 during the succession (6 stages, from 1 to 90 years in age). The abundance of species (birds/km2) and inter-annual variability during 11 seasons were determined. The coefficient of variation (CV) was the highest (71.00–82.50%) for species whose abundance did not exceed 1.0 birds/km2. The average abundance of species varied considerably, e.g., among passerines at the 80–90-year old stage from 1.1 birds/km2 (Little Flycatcher) to 153.7 birds/km2 (Chaffinch). Bird populations with high abundance turned out to be the most stable, for example at the last two successional stages the CV of the Chaffinch is 6.02 and 7.16%. For species with average abundance the variability is found to be low or medium (varies from 11.90 to 36.20%), for species with low abundance the CV varies from 17.68 to 82.50%. All six stages of succession were dominated by nesting migratory birds, which account for 75.0% of the species in the first stage of succession to 52.4% in the fifth and sixth stages. Near and distant migrants form the basis of the bird community at all stages. Populations of sedentary species and distant migrants are more stable than those of near migrants.

Quantitative Distribution of the Flying Fish (Exocoetidae), Marine Mammals, Birds, and Sea Turtles in the Northern Part of the Central Atlantic Ocean (Results Obtained in the Research Cruises nos. 43–45 of the R/V “Akademik Nikolaj Strakhov”)

The results of visual assessments of the flying fish (Exocoetidae), marine mammals, birds, and sea turtles, carried out mainly in the northern part of the Central Atlantic Ocean both during the ship was under way and at stations, are presented. Schematic maps of the quantitative distribution of the detected animals and of the specific biomass of the flying fish are provided. In terms of abundance and biomass of the flying fish, the studied region of the Atlantic south of 30° N is one of the most productive in the World Ocean, no signs of decreasing productivity have been found when compared with data obtained earlier. Tremendous abundance of gulfweed (Sargassum) in the study area is expected to have a positive effect on the abundance of birds and four-winged flying fish (subfamily Cypselurinae); at the same time, it apparently had a negative impact on the abundance of two–winged flying fish (genus Exocoetus). As a result, four-winged flying fish began to significantly predominate in the study area replacing the two-winged flying fish that dominated by abundance for almost a century. The relationships between the abundance of the flying fish and birds and some environmental parameters have been studied. An attempt has been made to assess the influence of various environmental factors on the quantitative distribution of the flying fish and birds using mathematical models.

Drivers of power line collisions and electrocutions of birds in Nepal.

Among the several anthropogenic factors, power lines are increasingly regarded as one of the most significant hazards to bird species, primarily owing to collisions and electrocutions. Nepal has comparatively fewer studies on the impact of power line collisions and electrocution on birds compared with developed nations. From November 2021 to May 2022, we assessed the effect of power line collisions and electrocutions on the mortality of birds in the Putalibazar Municipality of the Syangja district of Nepal. We established 117 circular plots in diverse habitats, including agricultural lands, forests, settlements, and river basins, along a 30.6 km long distribution line. Within 18 plots, we detected 43 fatalities of 11 species (17 individuals of six species due to collision and 26 individuals of eight species due to electrocution). House Swift (Apus nipalensis) and Common Myna (Acridotheres tristis) were the primary victims of the collision, whereas House Crow (Corvus splendens) and Rock Pigeon (Columba livia) were frequently observed electrocuted. We also recorded the electrocution of the critically endangered White-rumped Vulture (Gyps bengalensis). The total rate of bird power line collisions per kilometer was 0.55 birds, while the total electrocution rate per 10 poles was 2.22. The bird abundance, distance to agricultural regions, and proximity to human settlements were found to have a strong relationship with the mortality of birds caused by power lines. In order to reduce power line collisions and electrocution fatalities, we recommend conducting a detailed bird population study prior to determining the route of distribution lines.

Regional Context for Balancing Sagebrush- and Woodland-Dependent Songbird Needs with Targeted Pinyon-Juniper Management

In the western United States, pinyon-juniper woodlands have expanded by as much as sixfold among sagebrush landscapes since the late 19th century, with demonstrated negative impacts to the behavior, demography, and population dynamics of species that rely on intact sagebrush rangelands. Notably, greater sage-grouse (Centrocercus urophasianus) are unable to tolerate even low conifer cover, which can result in population declines and local extirpation, whereas removing expanding conifer cover has been demonstrated to increase sage grouse population growth rates and sagebrush obligate songbird abundance. Yet conifer management among sagebrush landscapes has been met with concerns about unintended impacts to species that rely on conifer woodlands, notably the pinyon jay (Gymnorhinus cyanocephalus), whose population declines are distinctive among birds breeding in pinyon-juniper woodlands. Spatial models of bird abundance can help management prioritize future actions in light of multiple species requirements, while also providing a framework to retroactively test the impact of past treatments. We used Breeding Bird Survey data to model indices to abundance in relation to multiscale habitat features including landcover, fire, topography, and climate variables for nine songbird species reliant on sagebrush and pinyon-juniper woodlands for breeding. Predictive maps allowed us to also examine the overlap of conifer management conducted by the Sage Grouse Initiative (SGI), which targets management of early successional conifers among priority sage-grouse habitats, with predicted indices to abundance of songbirds. Our findings demonstrate that targeted sage grouse habitat restoration under SGI was not at odds with protection of pinyon jay populations. Rather, conifer management has largely occurred among northern sagebrush landscapes where models suggest that past cuts likely benefit Brewer's sparrow and sage thrasher while avoiding pinyon jay habitats.

Large-scale correlations between gamebird release and management and animal biodiversity metrics in lowland Great Britain.

The ecological effects on populations of non-game species driven by the annual release and management of tens of millions of gamebirds for recreational shooting are complex and relatively poorly understood. We investigated these effects at a national scale, considering multiple taxa simultaneously. We used records from the UK National Biodiversity Network Atlas to compare animal species and diversity metrics previously suggested to be affected by behaviors of the released birds, or because resources or habitats are influenced by game management or both processes. We contrasted records from 1 km grid squares where gamebirds were reported released in Great Britain, and control squares with similar land cover but where no releases were reported. There were more records overall reported from release grid squares (RGS) compared with controls (CGS), perhaps due to greater reporting effort or greater biological richness. We found fewer foxes in RGS and fewest in grid squares with largest releases, but more carrion crows in RGS. We found no consistent effects for buzzards, ravens, jays, or magpies. There were more rodents and gray squirrels reported from RGS but no differences for reptiles. There were more butterflies but fewer beetles reported from RGS but no consistent patterns for Orthoptera or ground beetles considered common gamebird prey. Farmland and woodland birds exhibited higher abundance, richness, and diversity in RGS when considering absolute records, but woodland bird abundance and richness were lower when correcting for the relative number of records. These nationwide results, despite crude data resolution, reveal diverse effects of gamebird release and management at a national scale and across trophic levels, increasing some non-game animal populations while decreasing others. This should alert practitioners, opponents, and legislators that a focus on single taxa effects, either positive or negative, may obscure the simultaneous changes in other taxa.

Inventory and abundance of non-volant mammals and birds in the unprotected regions of the Mount Apo Range, Philippines

Wildlife, such as non-volant mammals and birds, play a vital role in the maintenance of ecosystem health. They are considered ecological engineers that influence forest vegetation. However, due to deforestation, habitat loss, and human persecution, its population status has declined over the years. This study aimed to conduct a species inventory and assess the relative abundance of non-volant mammals and birds in the unprotected regions of the Mt. Apo Range, Philippines, through camera trapping methods. Furthermore, the anthropogenic threats observed in the study areas were also documented. A total of 1,106 camera trap days were carried out in 2016 and another 500 days in 2020. Based on 260 independent sequences for both the 2016 and 2020 surveys, 12 species were identified, consisting of eight non-volant mammals and four birds. Among the identified species are the Endangered Philippine Brown Deer Rusa marianna &amp; Philippine Long-tailed Macaque Macaca fascicularis philippensis and the Vulnerable Giant Scops-owl Otus gurneyi &amp; the Philippine Warty Pig Sus philippensis. Video evidence of the Philippine Warty Pig Sus philippensis performing an important ecological role as an ecological engineer in the Philippine tropical forests were also captured for the first time. Another 61 independent sequences of unidentified rodents were detected in the camera traps, requiring further species monitoring techniques. Conservation must be strengthened beyond the protected landscapes of the Mt. Apo Range through community-based forest governance. This will ensure that the forest vertebrates are protected and conserved from further anthropogenic pressures.

Associations between farmland birds and fallow area at large scales: Consistently positive over three periods of the EU Common Agricultural Policy but moderated by landscape complexity

Abstract Fallow agricultural land provides habitat for threatened and declining farmland biodiversity. Policy change under the EU's Common Agricultural Policy (CAP) has been driving the area of fallows over the past decades. It is still unclear, whether positive relationships between farmland biodiversity and fallow area are general in time and space, and what landscape factors moderate them at large scales. We analysed associations between fallow area and species richness and abundance of 24 farmland birds in 3 years covering three CAP funding periods, by linking agricultural statistics at the district level to plot‐level bird data from a national‐scale monitoring scheme. We tested whether these relationships are moderated by species' habitat preferences and landscape configurational complexity, measured as the edge density of woody features. Species richness was positively associated with fallow area in all three funding periods. We found a hump‐shaped response along a gradient of increasing landscape configurational complexity. The associations between fallow area and species richness peaked at intermediate values of edge density. The associations between species abundance and fallow area varied among species, but there was strong support for positive and consistent associations in 15 (63%) of the studied species. There was little support for a moderating effect of landscape configurational complexity on the associations of fallow area and bird abundance. Policy implications. To support farmland biodiversity, we suggest promoting fallow land across all agricultural landscapes and anchoring respective ambitious targets in the CAP strategic plans. An increase of fallow land beyond minimum requirements through voluntary measures, such as eco‐schemes and agri‐environment schemes, should particularly target landscapes with intermediate configurational complexity.

Biodiversity and environmental stressors along urban walking routes

There is increasing focus on designing liveable cities that promote walking. However, urban walking routes can expose people to adverse environmental conditions that reduce health, well-being and biodiversity. Our primary objective is to assess how urban form is associated with environmental quality, including biodiversity, for people moving through urban spaces. We assess a range of environmental conditions that influence human health and biodiversity (temperature, noise and particulate pollution) and biodiversity of three taxa (trees, butterflies and birds) along 700 m public walking routes embedded in 500 m x 500 m grid cells across three UK towns. Cells are selected using random stratification across an urbanisation intensity gradient. Walking routes in more built-up areas were noisier and hotter; noise levels further increased in areas with more industrial land-use and large roads. There was no evidence of vegetation mitigating noise or temperature, but there was some evidence that increased vegetation cover mitigated small particulate pollution. Walking routes in more built-up environments had lower butterfly, bird and native tree species richness, and reduced butterfly abundance. Large roads were associated with reduced bird species richness and increased noise was associated with reduced bird abundance. Most specific measures of vegetation in the surrounding matrix (median patch size, structural complexity at 1.5 m resolution) were not detectably associated with biodiversity along walking routes, indicating minimal beneficial spill-over. Increased garden cover in the surrounding matrix was associated with less abundant and less species-rich butterfly communities. Our results highlight considerable heterogeneity in the environmental quality of urban walking routes and pedestrians’ potential to experience biodiversity along these routes, driven by reduced quality in areas with more built cover. A greater focus is needed on mitigating adverse effects of specific features of the built environment (roads, industrial areas, noise) surrounding walking routes to enhance the co-benefits of more biodiversity and healthier conditions for pedestrians.

Feasibility of urban bird occurrence and nest amount evaluation by the street-view image virtual survey.

Bird observation mainly relies on field surveys, which are time-consuming and laborious. In this study, we explored using street-view images in the virtual survey of urban birds and nests. Using the coastal city of Qingdao as the study area, 47 201 seamless spherical photos at 2741 sites were collected using the Baidu street-view (BSV) map. Single-rater-all photo checks and seven-rater-metapopulation checks were used to find inter-rater repeatability, the best viewing layer for BSV collection, and possible environments affecting the results. We also collected community science data for comparison. The BSV time machine was used to assess the temporal dynamics. Kappa square test, generalized linear model, redundancy ordination and ArcMap were used in the analysis. Different rater repeatability was 79.1% in nest evaluations and 46.9% in bird occurrence. A re-check of the different-rating photos can increase them to 92% and 70%. Seven-rater statistics showed that more than 5% sampling ratio could produce a non-significant different bird and nest percentage of the whole data, and the higher sampling ratio could reduce the variation. The middle-viewing layer survey alone could produce 93% precision of the nest checks by saving 2/3 of the time used; in birds, selecting middle and upper-view photos could find 97% of bird occurrences. In the spatial distribution, the nest's hotspot areas from this method were much greater than the community science bird-watching sites. The BSV time machine made it possible to re-check nests in the same sites but challenging the re-check of bird occurrences. The nests and birds can be observed more in the leafless season, on wide, traffic-dense coastal streets with complex vertical structures of trees, and in the gaps of tall buildings dominated by road forests. Our results indicate that BSV photos could be used to virtually evaluate bird occurrence and nests from their numbers, spatial distribution and temporal dynamics. This method provides a pre-experimental and informative supplement to large-scale bird occurrence and nest abundance surveys in urban environments.

Structure of breeding bird assemblages in the city of Windhoek, Namibia

The line transect method was employed to count birds in four urbanized habitats in the city of Windhoek, Namibia. Most counts were conducted during July-October, in 2012-2014. Twelve transects with a total length of c. 86 km were located in places representing major urban habitats: residential areas (city centre, suburbs in lowland, suburbs in highland, and city periphery), sport fields, and a modern industry area. In total, 80 bird species (excluding Palearctic visitors) were recorded. For all species, we calculated linear population densities and dominance. Six species were classified as dominant: house sparrow, red-eyed bulbul, Southern masked weaver, laughing dove, wattled starling and white-backed mousebird. Their cumulative numerical abundance comprised 54.2 % of all the breeding species. The group of dominant species varied markedly among transects. Granivores were the most important feeding guild, comprising more than half of all birds in Windhoek. Frugivores (26 %) were more numerous than insectivores (19 %). Birds nesting in trees and/or in shrubs comprised two thirds of all birds. Surprisingly, few differences in the structure of feeding and nesting guilds were recorded among the four urban habitats. Windhoek avifauna is similar in dominance structure to avifauna in other southern African cities and towns, where sparrows, doves/pigeons, bulbuls and mousebirds dominate, and with granivores being the main feeding guild. Species richness declines and bird abundance increases along urban gradient (towards the city centre).