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Urbanization threatens bird populations globally, however many urban habitats present important refugia for wildlife in this rapidly changing landscape. Additionally, birds at the periphery of their global range are more prone to landscape changes and thus these distributions are good indicators of the effects of urbanization on diversity; e.g., bird populations and communities of Cork City, Ireland. The aim of this study was to evaluate effects from urbanization on bird densities (birds/ha), species richness, and species composition throughout Cork City. I surveyed 32 points selected with a stratified random sample within commercial areas, residential habitats, and green spaces throughout Cork City during four breeding seasons between 2016-2019. Species richness was highest in green spaces with 18-34 species; whereas residential habitats had 14-27 species and commercial areas had 9-20 species. The most densely populated species citywide were rock pigeons (5.4-9.1 birds/ha), Eurasian jackdaws (2.9-3.8 birds/ha), rooks (4.5-6.4 birds/ha), European starlings (3.4-5.3 birds/ha), Eurasian blackbirds (2.4-3.6 birds/ha), and house sparrows (2.7-4.5 birds/ha). Overall a lack in urban green space surrounding survey points was most strongly associated with reduced species richness and population estimates. Also, both species richness and population densities tended to be higher in regions with less noise pollution and farther from the urban core. Ultimately these results corroborate other studies stressing the importance of urban green spaces for conserving biodiversity in cities. This is particularly important for the birds of Cork City given that these urban habitats are at the western edge of these species' distributions. [ABSTRACT FROM AUTHOR]

Birds have been shown to be an effective means of identifying priority areas for conservation action and mitigation measures. A field survey of birds at Ekonde and Owala dams in Osun State, Nigeria was conducted between March and June 2018 to determine the species diversity, abundance and feeding guilds. Data were collected using line transect method. The birds sighted during the survey were categorized based on their species, migratory/ non-migratory status, and feeding guild. Mean bird density within the two dams was determined and compared using t-test, and species diversity indices were analyzed using PAST software. A total of 2,152 birds from 67 species (33 families and 12 orders) were recorded where Ekonde dam had 1,286 birds (59.76%) and Owala dam had 866 (40.24%). In Ekonde dam, Vanellus spinosus was the most abundant species (n = 72, 8.31%), while at Owala dam, Oriolus nigripennis was the most abundant (n = 204, 15.86%). Bird density was apparently higher at Ekonde dam (51.44 birds/km2) than Owala dam (30.95 birds/km2), yet there was no significant difference (t value=1.679; p= 0.097). At Ekonde dam, Black-winged oriole had the highest density (8.16 birds/km2) while at Owala dam Spur-winged lapwing had the highest density (72 birds/km2). Shannon diversity index and evenness were higher at Ekonde dam (3.702 and 0.862) than at Owala dam (3.102 and 0.654). The birds were categorized into 10 and 8 feeding guilds in Owala and Ekonde dam respectively. Most reported species were insectivores (27, 33%) and carnivores (15, 19%). It can be suggested that as two dams have high avian richness, these can be sites for avian conservation and avitourism if properly managed. It is therefore recommended that strategy for avian conservation be incorporated into the dam management program for sustainability of the ecosystem.

Riparian habitats provide refuge for unique plant and animal assemblages. Many riparian habitats in arid ecosystems have lost most of their vegetation and associated fauna, due to a reduction of their original extension by land transformation. Using a case study from the subtropical desert of Peru, we quantified avian richness, diversity and abundance of resident species in twelve sites with a varying degree of anthropogenic impact, using an anthropogenic index (A.I.) as a proxy of alteration of the original vegetation. Sites with lower values of A.I. were those with the highest percentage of riparian cover. We found that species richness was higher at sites with a higher percentage of riparian vegetation (low A.I.), although bird diversity did not differ between sites. Five bird species, mostly insectivorous passerines, showed higher abundances at sites with low A.I., suggesting that less riparian cover is associated with lower abundances of such species. Despite its conspicuous presence, the Slender‐billed Finch, an endemic species recorded at all sites, was found at lower abundances when riparian vegetation was scarcer. Only one species showed the opposite trend, the Rufous‐collared sparrow, a dietary generalist songbird, which was more abundant at sites with higher A.I. Other 20 species analysed showed no trend. Moreover, several species had few records precluding a formal statistical analysis. This study offers valuable data on the negative impact that the loss of native vegetation could have on riparian communities of subtropical ecosystems, for which no other long‐term data exist. The protection, management and restoration of riparian strips should be a priority for bird conservation in human‐modified environments, particularly for those in developing countries. Abstract in Spanish is available with online material. [ABSTRACT FROM AUTHOR]

Biological invasions are the second most important cause of species extinction. Aided by processes such as transportation and urbanization, exotic species can establish and spread to new locations, causing changes in the function and structure of ecosystems. The House Sparrow is a widespread and highly abundant landbird associated to human presence. Previous studies performed in urban landscapes have suggested that this species could be acting, in synergy with urbanization, as a potential threat to native urban avian assemblages. In this study we assessed the relationship between House Sparrow density and native bird species richness in a region where the sparrows are scarce and sparsely distributed. We surveyed bird assemblages in and around four small-sized human settlements, considering three conditions in relation to House Sparrow presence: urban invaded, urban non-invaded, and non-urban non-invaded. To assess the potential detrimental role of House Sparrows on native bird species richness, we measured, additionally to sparrow densities, 20 predictor variables that describe vegetation structure and complexity, as well as urban infrastructure and human activities across four seasons of 1 year. Our results show that maximum shrub height was positively related to bird species richness, built cover was negatively associated with it, and House Sparrow invaded sites were related to a significant decrease of bird species richness, with increasing richness loss when more sparrows were present. Thus, we here provide evidence that urban areas can act in synergy with the presence of House Sparrows (even in low densities) in the urban-related species richness decline pattern. [ABSTRACT FROM AUTHOR]

Parrots stand out among birds because of their poor conservation status and the lack of available information on their population sizes and trends. Estimating parrot abundance is complicated by the high mobility, gregariousness, patchy distributions, and rarity of many species. Roadside car surveys can be useful to cover large areas and increase the probability of detecting spatially aggregated species or those occurring at very low densities. However, such surveys may be biased due to their inability to handle differences in detectability among species and habitats. We conducted 98 roadside surveys, covering > 57,000 km across 20 countries and the main world biomes, recording ca. 120,000 parrots from 137 species. We found that larger and more gregarious species are more easily visually detected and at greater distances, with variations among biomes. However, raw estimates of relative parrot abundances (individuals/km) were strongly correlated (r = 0.86–0.93) with parrot densities (individuals/km2) estimated through distance sampling (DS) models, showing that variability in abundances among species (>40 orders of magnitude) overcomes any potential detectability bias. While both methods provide similar results, DS cannot be used to study parrot communities or monitor the population trends of all parrot species as it requires a minimum of encounters that are not reached for most species (64% in our case), mainly the rarest and more threatened. However, DS may be the most suitable choice for some species-specific studies of common species. We summarize the strengths and weaknesses of both methods to guide researchers in choosing the best–fitting option for their particular research hypotheses, characteristics of the species studied, and logistical constraints.

The function of the buffer zone of nature reserve is seldom evaluated in wildlife conservation. National Yancheng Rare Birds Nature Reserve is the largest coastal nature reserve in China. The environmental capacity of its core zone of 225.96 km² area is approaching saturation, and more and more birds have begun to utilize the buffer zone. We conducted a line transect survey in December 2010 to estimate bird density and evaluate the importance of the buffer zone. As a result, 34 protected species among the 4975 individuals were sighted, including 127 red-crowned cranes (Grus japonensis) and 868 common cranes (Grus grus). The overall density of protected species, winter migratory species, and resident birds was 1244.60 individuals/km², 396.88 individuals/km² and 758.94 individuals/km² respectively. The woodland, aquaculture, and farmland with >200 individuals/km² each signified the vital habitat of birds. Comparatively, density in the original habitat (woodland) is relatively higher than that in artificial habitats (aquaculture and farmland), which reached 81.0%, 13.9% higher than aquaculture and farmlands. These observations suggest that the northern buffer zone comprises of vital habitats for bird population. We recommend that priority should be given to the northern buffer zone to preserve the original habitat, whereas conversion of the original habitat to aquaculture and farmland use should be given great concern. [ABSTRACT FROM AUTHOR]

Due its unique topography and climatic conditions Pothwar plateau of Pakistan is famous for hosting important floral and faunal diversity of Pakistan but no report is available on the current status and population dynamics of bird species in this area. In this study the number and species richness of birds associated with different agricultural landscapes on the plateau were estimated. The study was conducted in 4 selected study sites (10×10 ha each) based on monthly visual surveys over 2 years. Two of the sites were drier where wheat and groundnut were the main crops whereas the other two sites were located close to rain water ponds where wheat, maize and millet were cultivated. A total of 29 bird species were recorded, of which 24 were residents while the remaining 5 were winter visitors. Both bird density and species richness decreased during summer (May-July) at all sites across the 2 years. Comparing sampling sites on the basis of cropping system and water availability showed that more bird species, especially the over-wintering species, were found at sites close to water resources. Thus the higher number of species in areas with a wheat-maize/millet cropping system was probably due to water availability. [ABSTRACT FROM AUTHOR]

Sapo National Park was the first established and is the largest national park in Liberia and contains the secondlargest area of primary tropical rainforest in West Africa. However, little is known about the distribution, population density, and ecology of threatened birds occurring in the park. In this study, we assessed the population status and distribution of birds of global conservation concern occurring in the park. Between April and June 2014, we surveyed 17 line transects of 2 km each in and around Sapo National Park, using Distance Sampling. We recorded eight of the 13 globally threatened birds in Liberia, including Gola Malimbe Malimbus ballmanni (Endangered), Timneh Parrot Psittacus timneh (Endangered) and Yellow-bearded Greenbul Criniger olivaceus (Vulnerable). The results of this study provide the first baseline information on the status of these species in the park and also show the importance of Sapo National Park in the conservation of not only birds but also biodiversity in general in Liberia and West Africa. [ABSTRACT FROM AUTHOR]

Fire shapes ecological diversity, but its influence on bird communities is poorly understood. Fire is often considered crucial to management of savanna systems. Here, we assess effects of fire on bird species richness and density after a wildfire in September 2021, in an arid South African savanna where fire is infrequent. Point counts initially surveyed in 2004 now occurred in burnt and unburnt habitats, and were revisited five times across seasons from December 2021 to January 2023. This enabled identification of interaction effects of change over time and with fire from linear models using site and survey as predictor variables in a Before-After Control-Impact (BACI) framework. Patterns of bird species richness were explored using subsets of repeated points and those of summer to autumn surveys. To explore fire impacts on bird density, we used 'Distance Sampling' using additional surveys. Although total species richness during counts did not differ between survey periods and burnt and unburnt areas, densities of all birds were ca. 50% higher in unburnt veld relative to burnt, with this difference driven mostly by granivores. Three of 24 common species were significantly negatively influenced by fire. Fires may profoundly affect this arid zone bird community, a finding that would be overlooked if only species richness had been considered, and densities not accounted for. Fire, although potentially positive for biodiversity in mesic savannas, may negatively impact multiple taxa in arid savannas, which have a very different evolutionary and ecological history to that of more mesic savannas. These differences must be considered in management strategies. • Massive wildfire impact on avian communities in arid savanna: Bird density varied, but species richness remained unchanged in burnt vs. unburnt areas. • Granivorous species were negatively impacted by the fire, indicating the importance of considering dietary guilds alongside species richness when assessing fire effects. • While species richness alone may not reflect the true ecological effects of fire, turnover in species composition was observed, suggesting wildfire events in arid savanna's are subtle yet profound. [ABSTRACT FROM AUTHOR]

Abstract Ichthyophagous birds aggregate at cage fish farms attracted by caged and associated wild fish. Spatio-temporal variability of such birds was studied for a year through seasonal visual counts at eight farms in the western Mediterranean. Correlation with farm and location descriptors was assessed. Considerable spatio-temporal variability in fish-eating bird density and assemblage structure was observed among farms and seasons. Bird density increased from autumn to winter, with the great cormorant being the most abundant species, also accounting largely for differences among farms. Grey heron and little egret were also numerous at certain farms during the coldest seasons. Cattle egret was only observed at one farm. No shags were observed during winter. During spring and summer, bird density decreased markedly and only shags and little egrets were observed at only a few farms. Season and distance from farms to bird breeding/wintering grounds helped to explain some of the spatio-temporal variability. Highlights • Spatio-temporal variability of ichthyophagous birds was assessed at eight Mediterranean cage fish farms. • Great cormorant, shag, grey heron, little egret and cattle egret density at farms was studied. • Bird density showed a marked seasonal pattern: highest density occurred in autumn and winter. • Differences between farms were related to the proximity of natural breeding/wintering areas. [ABSTRACT FROM AUTHOR]

Non-native species or invasive species have been a threat to the global biodiversity. Avian communities are widely spread from the forest to the urban areas. Impacts of invasive avian communities in the urban areas have not been greatly explored in Sarawak. This study attempts to investigate the effect of invasive birds towards the native species within the urban avian community. The birds were surveyed using transects from October 2015 until September 2016 (12 months). The common species recorded were Asian glossy starling, Common myna, Eurasian tree sparrow, Intermediate egret, Javan myna, Longtailed shrike and Little egret, Pink-necked green pigeon, Rock pigeon, Spotted dove, White-breasted waterhen, White-breasted woodswallow, Yellow-vented bulbul and Zebra dove. The invasive species consist of the Eurasian tree sparrow, Rock pigeon, Zebra dove, Common myna. In general, these species became a threat to the native hollow-nesting species. Here we estimated the relative density of exotic species in urban bird assemblage. Proper and careful management of this invasive species is much needed in order to prevent the native species being pushed out or eliminated from the urban bird communities. [ABSTRACT FROM AUTHOR]

Observamos 205 especies de aves en la Península de Osa. La distribución geográfica de la mayoría de las especies de bosque en la península es discontinua (e.g., Corapipo altera y Tangara guttata), aún dentro de grandes áreas de bosque continuo, lo cual indica la posible adaptación de las especies a habitats, microhabitats, estratos y dietas particulares dentro del bosque. Las aves utilizan los estratos del bosque en diferente proporción lo que resulta en tres diferentes patrones: aves de sotobosque (e.g., Arremon aurantiirostris y Habia atrimaxillaris), aves de subdosel (e.g., Cacicus uropygialis y Euphonia imitans) y aves que utilizan diferentes estratos en similar proporción (e.g., Dendrocincla anabatina). La mayoría de estas especies de bosque se alimentan de insectos y frutos. La densidad y la abundancia relativa son muy bajas para la mayoría de las especies, con más de 90% de las especies con menos de un individuo por hectárea o kilómetro de transecto recorrido. Este conjunto de características hacen que esta avifauna sea muy sensible a la destrucción y fragmentación del bosque.Distribution and density of avifauna in Península de Osa, Costa Rica (1990-1991). We recorded 205 bird species at the Península de Osa. The geographical distribution of most forest bird species within the peninsula is discontinuous (e.g., Corapipo altera and Tangara guttata), even within large forest tracts, indicating the adaptation of species to particular habitats, microhabitats, strata and/or diet within the forest. Birds use the forest strata in different proportion resulting in three different patterns: understory birds (e.g., Arremon aurantiirostris and Habia atrimaxillaris), supdosel birds (e.g., Cacicus uropygialis and Euphonia imitans), and birds that use several strata in similar proportion (e.g., Dendrocincla anabatina). Most of these forest birds feed upon insects and fruits. The density and relative abundance is very low for most species, with more than 90% of the species having less than an individual per hectare or kilometer of transect. These characteristics make this avifauna highly susceptible to deforestation and forest fragmentation. Rev. Biol. Trop. 57 (Suppl. 1): 323-332. Epub 2009 November 30.

Globally, agriculture is the greatest source of threat to biodiversity, through both ongoing conversion of natural habitat and intensification of existing farmland. Land sparing and land sharing have been suggested as alternative approaches to reconcile this threat with the need for land to produce food. To examine which approach holds most promise for grassland species, we examined how bird population densities changed with farm yield (production per unit area) in the Campos of Brazil and Uruguay. We obtained information on biodiversity and crop yields from 24 sites that differed in agricultural yield. Density-yield functions were fitted for 121 bird species to describe the response of population densities to increasing farm yield, measured in terms of both food energy and profit. We categorized individual species according to how their population changed across the yield gradient as being positively or negatively affected by farming and according to whether the species' total population size was greater under land-sparing, land-sharing, or an intermediate strategy. Irrespective of the yield, most species were negatively affected by farming. Increasing yields reduced densities of approximately 80% of bird species. We estimated land sparing would result in larger populations than other sorts of strategies for 67% to 70% of negatively affected species, given current production levels, including three threatened species. This suggests that increasing yields in some areas while reducing grazing to low levels elsewhere may be the best option for bird conservation in these grasslands. Implementing such an approach would require conservation and production policies to be explicitly linked to support yield increases in farmed areas and concurrently guarantee that larger areas of lightly grazed natural grasslands are set aside for conservation. [ABSTRACT FROM AUTHOR]

Copyright of Ardeola is the property of Sociedad Espanola de Ornitologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Species–specific habitat preferences, density and species richness of bird communities in Teneriffe (Canary Islands) Bird distribution and abundance are described and analyzed in Teneriffe (Canary Islands). Inter–habitat differences in density, diversity and species richness are shown in table 1. Figure 2 shows the main determinants of bird species richness in Teneriffe, and tables 2 and 3 and figure 3 show the species–specific patterns of spatial variation abundance (more detailed for Anthus berthelotii, Fringilla coelebs canariensis, Fringilla teydea, Parus caeruleus teneriffae, Phylloscopus canariensis, Regulus teneriffae, Serinus canarius and Turdus merula cabrerae). Deeply transformed environments due to human impact (urban habitats, agricultural mosaics, banana plantations) have high bird densities and species richness, even higher than those measured in native, unmodified habitats such as laurel forests or mature pinewoods. Urban environments in Teneriffe are very permeable to native bird fauna, as they have been occupied by many widespread endemic species/subspecies. Many of the endemic, well defined species or subspecies of island birds have high population densities within native, untransformed habitats. Density compensation and niche expansion is not a common phenomenon in the avifauna of Teneriffe. Nevertheless, all species/subspecies broadening the inter–habitat or altitudinal distribution are endemic of the Canary Islands.

A change in bird density within a captive flock of Sicalis flaveola pelzeni (Sclater, 1872) affected the decision to join a group. Ruling out inter-individual differences and maintaining constant the size of a food patch, birds were found to fly more often to the food source and spend a longer time in its environs when kept in greater groups.

The Milanino is an Italian chicken breed included in a conservation project run by the University of Milan. It is characterized by good fertility, heavy body weights, high adaptation ability to adverse climate conditions, and disease resistance. Because of these characteristics, the Milanino could represent an important genetic resource for alternative production systems. This research was aimed at studying the effect of bird density on growth and slaughter performance, as well as stress response in Milanino chickens kept in outdoor pens. One hundred and sixty Milanino chickens were randomly assigned to 2 experimental groups kept at different densities (2 m²/bird and 8 m²/bird) and were slaughtered at 185 days of age. Growth and slaughter performance and stress condition were recorded. The interaction bird density * sex * age significantly affected body weight and an opposite trend was found between females and males: heavier females were found in the high-density group, while heavier males were found in the low-density group. Bird density did not affect carcass weight data. The stress marker (H/L ratio) was significantly higher in birds kept at the higher density (2 m²/bird). In conclusion, the Milanino provided satisfactory growth performance with different rearing density but the lower density, 8 m²/bird, should be preferred to minimize welfare problems for male birds. [ABSTRACT FROM AUTHOR]

Copyright of Avian Conservation & Ecology is the property of Resilience Alliance and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Wildfire Is an Important disturbance regime that can structure wildlife communities and their habitats for many years. Using a before-after-control-Impact framework, we evaluated the effect of the Quartz Fire on a mixed broadleaf-conifer forest and associated bird community In southwestern Oregon, USA, over 10 yr. To assess whether fire severity explained changes better than simply whether an area was burned, we used a tiered sampling approach by comparing unburned control points with either all burned points combined (burned) or those same points partitioned by severity level (low, moderate, high). As expected, overall tree cover decreased while cover of shrubs Increased In response to greater fire severity. This pattern was most pronounced In hlgh-severlty areas, where tree cover declined by 40% and remained depressed, but shrub cover recovered from 10% the year following fire to 75% by year 6. Ordinations of bird species density showed turnover In community composition In all burned areas combined, as well as In moderate-severity areas, shifting to a shrub-associated community 9 yr postflre. For Individual species, annual density variations were best explained by fire for 14 of 37 species, with fire severity providing the best-fitting model for 7 species. Of those 7 species, 3 declined and 4 Increased with greater severity. When grouped Into guilds, flycatchlng foragers and shrub nesters Increased with greater fire severity. Our results Illustrate the Importance of mixed-severity wildfire In creating diverse vegetation structure and composition that supports distinct bird communities for at least a decade following fire. [ABSTRACT FROM AUTHOR]

Tropical mangroves are one of vital coastal systems which support migratory and resident waterbird species round the year. Globally the potential of mangrove habitats in relation to support waterbirds is poorly understood. We examined density of waterbirds in five different habitats: mudflats, open water, emerging mangroves, well-grown mangroves and adjacent agriculture lands of Pichavaram mangroves of southeast coast of India between the years 2004 and 2007. Among the habitats, the density of waterbirds was high in the mudflats followed by agriculture land, emerging mangroves, open water and well-grown mangroves. The work suggested on improvement of the habitats for supporting considerable density of the waterbirds. [ABSTRACT FROM AUTHOR]

Biological invasions are a major threat to native species. The red-bellied tree squirrel Callosciurus erythraeus was introduced in Luján, Argentina, in 1970, where it spread rapidly. Squirrels can affect birds through nest predation, interference and competition for food and nesting sites. We aimed to compare community composition, density and richness of birds in forested areas within and outside the range distribution (680 km2 in 2004) of the main population of these squirrels in the country. We selected seven paired sites (each pair had similar vegetation structure and composition) and other 14 sites, half in each condition (with and without squirrels). In each of these 28 sites, we did 4-5 point counts during spring-summer 2008-2009, recording all bird individuals that were seen/heard <10-20 m from the observer. Species richness was rarefied to the smallest number of point counts per site. Community composition differed among sites with and without squirrels, particularly for paired sites. We found no differences in bird density though species richness was higher for paired sites without squirrels. To assess if squirrels do consume bird eggs and if they have any egg-size preference, we conducted cafeteria experiments offering fruit and three eggs of different sizes to individual squirrels kept in a large cage (3×2×2m) for < 24 h. Few squirrels (2/25) consumed the eggs. Our results suggest that squirrels could negatively affect some bird species but not through nest predation. [ABSTRACT FROM AUTHOR]

Conversion of grasslands into crops is a major factor leading to the decline of grassland birds. Cattle ranching represents another disturbance to natural grasslands, but may be less detrimental to grassland birds. We studied the diversity, density, and composition of bird species in Brazilian and Uruguayan grasslands under two different land use types: cattle ranching on seminatural grasslands, and soybean fields with interspersed patches of grassland. Cattle sites had higher species richness (n = 75 species) than soybean sites (n = 57 species). Most birds showed higher densities in cattle sites, but some common and habitat-generalist species were more abundant in soybean sites. Species composition did not differ significantly with land use. The generalist Eared Dove (Zenaida auriculata), however, was strongly associated with soybean sites. Among species of conservation interest, either regionally or globally, all had higher densities in cattle sites, highlighting the importance of maintaining these ranching areas. The persistence of grassland birds in soybean fields may be related to the presence of seminatural grassland patches within soybean crops. [ABSTRACT FROM AUTHOR]

Habitat fragmentation is one of the most studied topics in ecology but our knowledge is still limited particularly concerning matrix effects on species distribution in a human-dominated landscape. We tested the ability of random sampling hypothesis, colonization-extinction dynamics and matrix-related concepts to explain the variation in species richness, total bird density and community composition in old-forest bird assemblages in two contrasting landscapes. We collected data on breeding bird abundances from 66 old-growth forest reserves in NE Finland and six larger areas in adjacent Russian Karelia using the line transect method. In Finland, protected old-forest patches are embedded in a matrix dominated by young regeneration stands. In Russia, study areas were situated in continuous, old forest dominated landscapes. Bird assemblages in old-forest patches embedded in human-modified matrix in Finland were not random samples from Russian bird assemblages. In the Finnish assemblages, species richness was lower and total bird density higher. Species richness declined with increasing distance (isolation) to Russia. Bird assemblages in large forest reserves in Finland close to Russia were structurally more similar to assemblages in the continuous reference landscape than those in small and more distant reserves. The results support the idea that several mechanisms related to colonisation-extinction dynamics and to matrix resource availability influence species distribution in fragmented landscapes but in species-specific ways. We conclude that even though small and isolated protected areas may foster high relative bird species density their ecological integrity is compromised, and therefore, improving matrix quality around reserves may lead to considerable conservation benefits. [ABSTRACT FROM AUTHOR]

Highlights: [•] Observer, day, time, and temperature had species-specific effects on detection probability. [•] Habitat, landscape, and fire history factors affected bird densities more than management type. [•] Savanna and woodland support further breeding habitat for woodland and early-successional birds. [•] Open-adapted birds were not supported at restored sites in this forested landscape. [ABSTRACT FROM AUTHOR]

Avian communities in cloud forests have high levels of endemism and are at major risk given the accelerated rate of habitat fragmentation. Nevertheless, the response of these communities to changes in fragment size remains poorly understood. We evaluated species richness, bird community density, community composition, and dominance as indicators of the response to fragment size in a fragmented cloud forest landscape in central Veracruz, Mexico. Medium-sized fragments had statistically higher than expected species richness and more even communities, which may be a reflection of the intermediate disturbance hypothesis, in which medium-sized fragments are exploited by both forest and disturbance-associated species. Bird density also reached higher values in medium-sized fragments, which may indicate a carrying capacity in this habitat. However, large cloud forest fragments had a distinct taxonomic and functional composition, attributable to an increased number of understory insectivore species and canopy frugivores. By comparison, omnivorous species associated with human-altered habitats were more abundant in smaller fragments. Hence, although medium-sized cloud forest fragments had higher species richness and high bird density, large forest tracts maintained a distinct avian community composition, particularly of insectivorous and frugivorous species. Furthermore, the underlying response to fragmentation can only be properly addressed when contrasting several community attributes, such as richness, density, composition, and species dominance. Therefore, cloud forest conservation should aim to preserve the remaining large forest fragments to maintain comprehensive avian communities and avoid local extinctions.

Highlights: [•] We studied avian abundance and nest survival with experimental forest management. [•] Mature forest species declined on even-aged, uneven-aged, and no-harvest sites. [•] Early successional species peaked 7–8years post-harvest before declining. [•] Nest survival did not differ with forest management. [•] More frequent even-aged harvests on fewer stands could benefit avian diversity. [Copyright &y& Elsevier]

Mangroves are threatened worldwide yet they host diverse avian assemblages, especially in Australia. We examined the diversity, density and habitat use of birds in northern Australian mangroves to determine the influence of habitat patch-size and floristic composition on the structure of mangrove bird assemblages. Birds were surveyed using line transects in 13 mangrove patches. A total of 70 species was encountered, with a mean density of 11.7 individuals ha[sup -1], including 11 of 12 known mangrove-dependent species. Many species were strongly associated with, and indicative of, a specific mangrove plant zone, emphasising the importance of the number of zones to bird diversity at a site. Of six functional guilds, the insectivores were most dominant, followed by nectarivores. Accordingly, avian assemblage structure was influenced by mangrove flowering phenology. Large mangrove patches supported fewer species than many smaller patches of equivalent combined area, and species richness was independent of area. In addition, there was no density compensation or a density-area relationship, implying that assemblages are not saturated with species and species interactions do not determine assemblage structure. In order of increasing importance, avian assemblage structure in mangroves is determined by the type and diversity of mangrove zones, the timing of mangrove flowering and the nature of the matrix surrounding mangroves. [ABSTRACT FROM AUTHOR]

We repeated bird and vegetation surveys in 1991-1992 and 2005-2006 among young managed stands and old-growth forests in southeast Alaska to evaluate whether pre-commercial thinning of managed stands influenced the bird community. We compared decadal changes in bird densities and forest vegetation among 3 stand types: managed stands originating from clearcuts 35 years ago that were left untreated (unthinned), managed stands thinned at uniform spacing (thinned), and old growth with no prior timber harvest. We did not detect differences in decadal trends in avian densities between thinned and unthinned stands for 15 of 16 common bird species using a repeated-measures design. Thinning did not result in greater recruitment of overstory-nesting species as predicted. This was likely because of 1) similar increases in tree heights ( ${\bar {x}}$ = 9-10 m) and canopy cover ( ${\bar {x}}$ = 29-43%) between unthinned and thinned stands across decades and 2) the relatively young successional stage of these stands, which had only begun to recruit medium and large size conifers (dbh ≥ 36 cm). Decadal trends in densities of most (88%) understory-nesting bird species did not differ between thinned and unthinned stands. Shrub cover decreased by 22% and 31% across decades in thinned and unthinned stands, respectively. Bird community composition in managed stands reflected the general decadal changes in forest vegetation with a shift in dominance from understory species in the early 1990s (80-85% of total bird density) to an equal abundance of understory (45-54%) and overstory species in the mid-2000s. The latter was more similar to old-growth stands, which were dominated by overstory species (67-71%). Overstory-nesting birds in old growth increased in density by 49% across decades. Densities of cavity-nesting species remained unchanged in managed stands and less than densities in old growth across decades, possibly because of a lack of large trees and snags for nest sites. Overall, thinning of clearcut stands, the primary silvicultural system in the region, had few measurable benefits to birds nearly 20 years after treatment. Monitoring over the 70-100-year harvest rotation may be necessary to fully test whether thinning accelerates succession of bird communities in clearcut stands. However, partial harvests that retain large trees and snags should also be explored as alternatives to better maintain late-succession avifauna throughout the harvest rotation in southeast Alaska. © 2012 The Wildlife Society. [ABSTRACT FROM AUTHOR]

Abstract: In Argentina, the rapid expansion and intensification of row crop production that has occurred during the last 20 years has resulted in the loss of habitat and spatial heterogeneity in agroecosystems. One of the principal effects of industrialized row crop production is the loss of avian diversity and associated ecosystem services that benefit crop production. To better understand the response of bird species to the intensification and expansion of row crop agriculture in Argentina, and the potential effects on the provision of ecosystems services, we analyzed the relationship between short- and long-term changes in agricultural land use on the densities of six bird species (Milvago chimango, Caracara plancus, Tyrannus savana, Zenaida auriculata, Molothrus bonariensis, and Sturnella supercilliaris) using data from a large-scale, long-term avian monitoring program in central Argentina. Species densities responded individually to long-term landuse changes; T. savana and M. chimango densities were positively related to an increase in the annual cropping area, whereas C. plancus and S. supercilliaris were positively related to the area of non-plowed fields. M. bonariensis and Z. auriculata (considered crop pests) showed a weak relationship with land use. None of the species exhibited response to short-term changes in land-use. Although generalist species can apparently adapt to a diversity of open habitats, species that provide pest control services were also related to semi-natural habitats and thus likely to suffer from land transformation associated with intensive agricultural management. Our results, as well as those found in similar systems, denote strong inferential evidence that the disappearance of remnants of natural and semi-natural habitats in heavily transformed agricultural landscapes will have a substantial negative effect on the provision of pest control services provided by avian abundance and diversity. [Copyright &y& Elsevier]

The article discusses a study which determined the correlation between temporal variation in bird and resource abundance and the elevational gradient in Hawaii. It documents patterns of nectar availability and nectarivorous bird abundance at nine study sites across an 1,800-meter elevational gradient in Hawaii and shows that variability in bird abundance was generally best modeled as a function of elevation, season and flower density. It is concluded that low-elevation forests in Hawaii may be the first example of an ecological trap based on disease.

Abstract: Alternative silvicultural approaches to timber management, such as regeneration treatments with different degrees of stand retention, may mitigate negative effects of clear-cutting or shelterwood cuts in forested ecosystems, including changes in old-growth forest bird communities. The aims of this work were: (a) to compare bird species richness and densities among different silvicultural designs with variable retention (dispersed and/or aggregated) and unmanaged primary forests, and (b) to assess temporal changes at community and species levels before and after treatments. A baseline avian survey was conducted prior to harvesting to evaluate canopy gap presence and forest stand site quality influences. Subsequent to harvesting, data on bird species richness and density were collected by point-count sampling during the summer season for 5 consecutive years (4 treatments×5 years×6 sampling points×5 counts). Bird species richness and density (15 species and 9.2individualsha−1) did not change significantly with forest site quality of the stands and canopy gap presence in unmanaged forests. However, both variables were significantly modified in managed forests, increasing over time to 18 species and reaching to 39individualsha−1. Inside the aggregated retention, bird communities were more similar to unmanaged primary forests than those observed within the dispersed retention or in clear-cuts. Opting for a regeneration method with dispersed and aggregated retention has great potential for managing birds in Nothofagus pumilio forests. This method retained enough vegetation structure in a stand to permit the establishment of early successional birds (at least in dispersed retention), and to maintain the bird species of old-growth forests which could persisted in the retention aggregates. [Copyright &y& Elsevier]

Oak savannas were historically common but are currently rare in the Midwestern United States. We assessed possible associations of bird species with savannas and other threatened habitats in the region by relating fire frequency and vegetation characteristics to seasonal densities of 72 bird species distributed across an open-forest gradient in northwestern Indiana. About one-third of the species did not exhibit statistically significant relationships with any combination of seven vegetation characteristics that included vegetation cover in five vertical strata, dead tree density, and tree height. For 40% of the remaining species, models best predicting species density incorporated tree density. Therefore, management based solely on manipulating tree density may not be an adequate strategy for managing bird populations along this open- forest gradient. Few species exhibited sharp peaks in predicted density under habitat conditions expected in restored savannas, suggesting that few savanna specialists occur among Midwestern bird species. When fire frequency, measured over fifteen years, was added to vegetation characteristics as a predictor of species density, it was incorporated into models for about one-quarter of species, suggesting that fire may modify habitat characteristics in ways that are important for birds but not captured by the structural habitat variables measured. Among those species, similar numbers had peaks in predicted density at low, intermediate, or high fire frequency. For species suggested by previous studies to have a preference for oak savannas along the open-forest gradient, estimated density was maximized at an average fire return interval of about one fire every three years. [ABSTRACT FROM AUTHOR]

Increasing housing density is an important component of global land transformation, with major impacts on patterns of biodiversity. However, while there have been many studies of the changes in biodiversity across rural–urban gradients, which are influenced in large part by housing densities, how biodiversity changes across the full range of regional variation in housing density remains poorly understood. Here, we explore these relationships for the richness and abundance of breeding birds across Britain. Total richness, and that of 27 urban indicator species, increased from low to moderate household densities and then declined at greater household densities. The richness of all species increased initially faster with household density than did that of the urban indicator species, but nonurban indicator species richness declined consistently after peaking at a very low housing density. Avian abundance showed a rather different pattern. Total abundance and that summed across all urban indicator species increased over a wide range of household densities, and declined only at the highest household densities. The abundance of individual urban indicator species generally exhibited a hump-shaped relationship with housing density. While there was marked intraspecific variation in the form of such relationships, almost invariably avian abundance declined at housing densities below that at which the UK government requires new developments to be built. Our data highlight the difficulties of maintaining biodiversity while minimising land take for new development. High-density housing developments are associated with declines in many of those species otherwise best able to exploit urban environments, and those components of native biodiversity with which human populations are often most familiar. [ABSTRACT FROM AUTHOR]

Forestry operations in jarrah forests of south-western Australia use two types of selective logging, gaps which remove 85–95% of basal area and shelterwoods which remove 40–60% of basal area. These operations create considerable lengths of forestry edge (edges between logged and unlogged forest) each year, but their impact on the avifauna of the jarrah forest is unknown. Changes in bird density were examined along edges created by forestry operations in jarrah forests using a BACI design experiment. Bird densities were estimated on 1-ha plots that were surveyed three times per season, in three seasons both before and after logging. There was no evidence of edge effects at the community level; overall bird density and species richness did not changes along forestry edges. Scarlet robin ( Petroica multicolor) abundance increased significantly along both gap and shelterwood edges, relative to controls. Apart from a probably spurious increase in density along gap edges by red-winged fairy-wrens ( Malurus elegans), no other species showed a significant change in density along edges. There was also no difference in responses to gap and shelterwood edges, despite gaps removing more basal area than shelterwoods, suggesting that response to forestry edges in the jarrah forest may be threshold dependent, rather than increasing with increasing intensity of logging operations. Comparisons with other studies examining density changes along forestry edges in south-western Australia suggest that density changes observed in this study are short-term in nature. The limited density change in avifauna along forestry edges is probably because selective logging practices were examined instead of clear-felling. Studies in the literature indicate that this pattern is likely to be true for many forest ecosystems. [ABSTRACT FROM AUTHOR]

Current management recommendations for grassland birds in North America emphasize providing large patches of grassland habitat within landscapes that have few forest or shrubland areas. These Bird Conservation Areas are being proposed under the assumption that large patches of habitat in treeless landscapes will maintain viable populations of grassland birds. This assumption requires that patch size and landscape features affect density and nesting success of grassland birds, and that these effects are consistent among years and regions and across focal species. However, these assumptions have not yet been validated for grassland birds, and the relative importance of local vegetation structure, patch size, and landscape composition on grassland bird populations is not well known. In addition, factors influencing grassland bird nesting success have been investigated mostly in small-scale and short-duration studies. To develop management guidelines for grassland birds, we tested the spatial and temporal repeatability of the influence of patch size and landscape composition on density and nesting success of 3 grassland passerines, after controlling for local-scale vegetation structure, climate, and—when analyzing nest success—bird density. We conducted our study during 4 years (1998-2001) in 44 study plots that were set up in 3 regions of the northern tallgrass prairie in Minnesota and North Dakota, USA. In these study plots we measured density and nesting success of clay-colored sparrows (Spizella pallida), Savannah sparrows (Passerculus sandwichensis), and bobolinks (Dolichonyx oryzivorus). Statistical models indicated that density was influenced by patch size, landscape, region, and local vegetation structure more so than by local vegetation structure alone. Both magnitude and direction of the response of density to patch size varied among regions, years, and species. In contrast, the direction of landscape effects was consistent among regions, years, and between Savannah sparrows and bobolinks. In each species, this landscape effect was independent of patch size. Nesting success was not clearly influenced by patch size or landscape composition, and none of the factors that influenced avian density also influenced nesting success in any of the 3 species. General statements on ‘optimal habitat’ for grassland birds should therefore be viewed cautiously. Instead, long-term studies in different regions as well as a deeper understanding of the local system are needed to determine which factors are most important for grassland birds in a particular area. [ABSTRACT FROM AUTHOR]

The shallow (1.5 m) Pulicat Lagoon in India supports a variety of migratory birds (125 species), especially flamingos and storks. Flamingo populations in this area are dominated byPhoenicopterus roseuis, and they are densely distributed in shallow areas and fringes of the lake where the water level is below 40 cm. Eighteen flamingo groups are distributed around the lagoon with ~750 individuals per group. Flamingo populations are greatest in places where fish, algal, and benthic faunal biomass are highest. Physiological adaptations and morphology of flamingo are important criteria for selecting feeding locations. [ABSTRACT FROM AUTHOR]

The article focuses on a study on the density of breeding bird in woodlots, citing differences in density at the edge and depth. It states use of measure of depth as the primary variable, which depends on distances to four woodlot edges, and mentions threats associated with species living at the edges. It notes analysis of two woods in eastern Pennsylvania, and cites that densities of the birds were affected by buildings at the edge of the woodlots.