Total Bird Density Research Articles

Factors Affecting the Winter Distribution of Birds in Forests at the Eastern Edge of Europe

We show for the first time the results of a study into the spatial distribution of birds in forests at the eastern edge of Europe (Republic of Tatarstan, Russia) and changes from early to late winter. A transect method was used to census randomly selected plots spread over a large geographical area in the winters 2018/9–2022/3. We used regression and ordination methods to assess the influence of key environmental factors on species richness, total density of birds, biological diversity, and the probabilities of occurrence of individual species. The most abundant bird species in early winter was the Willow Tit, and in the late winter was the Common Redpoll. Compared with the end of the 20th century, the number of wintering bird species has increased in the study area, likely due to climate warming. Species richness, total density, and the Shannon Index of diversity were higher in early winter than in late winter. Species richness and the Shannon Index were also higher at low elevations and in the west of the study region. Our research shows strong ecological-geographical differences in the preferences of individual bird species in the studied forests. However, almost without exception, birds had a higher probability of occurrence at lower elevation and toward the west.

Clear-cuts and warming summers caused forest bird populations to decline in a southern boreal area

Land use and climate change are the main drivers of biodiversity change. However, their relative roles in the decline of biodiversity are still insufficiently known. Climate change is expected to be globally most pronounced in the boreal biome, where another key driver affecting boreal species is forestry. In NW Europe almost all forest land outside protected areas is subject to systematic forest management practices including clear-cutting, thinning and replanting. In addition, a human-caused increase in herbivores, such as ungulates, may affect the forest vegetation structure and thereby also bird species. We studied population changes of a bird community in a southern boreal area in Finland over a period of 30 years and related changes in the bird community concerning both land use and climate variables. During the study the total bird density declined by 26%, i.e., 1%/year. Long-distance migrants and residents declined the most, both by 44%, and short-distance migrants by 29%, while partial migrants increased by 29%. Clear-cuts were the most important variable explaining the decline in the total bird density and the density change of long-distance and short-distance migrants and residents. In addition, the higher summer mean temperature was related to the decline of the total bird density and short-distance migrants, which were also moderately negatively affected by the ungulate density. The increase in partial migrants was mostly due to an increase in the numbers of two bird species, the great tit Parus major and the blue tit Cyanistes caeruleus, which have benefitted from human actions in many ways. As a whole, the bird community did not recover to the level that prevailed before the clear-cuts in the study period. This indicates that recolonisation and the recovery rate by birds in maturing young stands cannot fully compensate for the loss of birds resulting from the clear-cuts. Forest management practices should adopt more biodiversity-friendly methods, such as continuous cover forestry, to better maintain populations of forest birds.

Многолетняя динамика фауны и населения птиц аэропорта Челябинск (Баландино)

Over 30-year study period (1990–2021), 144 bird species, including 54 nesting species, were registered on the territory of the Chelyabinsk International Airport Balandino. Total bird population density varied from 147 ind./km² in 1990 to 215 ind./km² in 2020. In different years, dominant species in this area were Alauda arvensis, Motacilla flava, Saxicola rubetra, S. torquata, and Passer montana. In the first years of research, a significant decrease in the number of the most widespread species (Corvus frugilegus, C. monedula, Columba livia, Larus barabensis, L. canus, and L. ridibundus), crossing the airfield during seasonal and diurnal (forage) migrations, was revealed. This was caused both by decrease of population of some species (C. frugilegus) in the European and Ural-Siberian parts of their range, and by the deterioration of the state of forage lands on the airport territory after the elimination of solid waste landfills and a decrease of farmland areas nearby.

Effects of urban demand for food and water on physicochemicals and biotic structure of riverine wetlands in the Pampean plain

ABSTRACT Riparian areas of riverine plains develop extensive floodable areas named riverine wetlands, which are essential to the water cycle balance and ecosystem dynamics. In this study, we contrasted the hydrological and physicochemical variables of riverine wetlands of both peri-urban areas impacted by intensive farming and those of rural areas with the indicators of the biotic structure (taxonomic richness, Shannon diversity and total density) of benthic diatoms, phytoplankton, zooplankton, macroinvertebrates, chironomids, fishes, turtles, and birds. The study was performed on riverine waters of the Pampean plain, Argentina, with four seasonal samplings conducted in 2017–2018. Our results showed that the significant deepening of the groundwater level caused by aquifer overexploitation in peri-urban areas, as well as the declining surface water quality with higher phosphorus and total nitrogen concentrations, affected the taxonomic richness, diversity, and total density of the biotic assemblages of riverine wetlands. The taxonomic richness of birds, turtles, phytoplankton, chironomids, and fishes was the most sensitive to land use. Phytoplankton, chironomid, and fish diversity showed the greatest differences between rural and peri-urban riverine waters, while the total density of chironomids and birds showed the greatest differences according to land use. The results suggest that the socioeconomic development in those riverine wetlands that still maintain conditions close to the natural ones needs to be subject to guidelines derived from integrated basin management and sustainable urban planning.

Identification of “Primorsk-1” wind power plant impact on the ecological situation connected with the behavior of ornithofauna on the Azov Sea coast

The results of ornithocomplexes monitoring in the territory of the wind power plant (WPP) “Primorsk-1” in 2017 and 2018 are presented. The research was conducted by two methods: observations made according to the recommendations of the Scottish Natural Heritage Fund (SNH) and route accounting method (RAM). The distribution of birds by seasons, direction of migration and flight altitudes has been identified. The number of birds, registered in 2017 by the SNH method, was 5923 specimens of 45 species: 3795 specimens of 33 species were flying in transit, 2,113 specimens of 40 species belonged to the forage group, 15 birds of four species belonged to the demonstration type. Most of the birds (64.2%) were flying in transit. The greatest activity of birds was observed in spring (36.3%) and autumn (35.0%) seasons of migration, when the share of the transit group accounted for 75.5% of all annual transit flights. At an altitude of up to 10 m 5086 (86.2%) birds were registered, in the range of altitudes (11÷25) m – 697 (11.8%), in the range of altitudes (26÷50) m – 53 (0.7%). No birds were found at an altitude above 180 m. In the risk zone of interaction with turbines, there were 72 birds of four species: Larus ridibundus, Merops apiaster, Circus aeruginosus, Buteo buteo. The total number of birds, registered by the RAM method in 2018, was 8927 specimens of 72 species: 802 specimens of 11 species were flying in transit, 2511 specimens of 32 species belonged to the forage group, 5614 specimens of 60 species belonged to the terrestrial group. The greatest activity of birds was registered in autumn (70.0%) and spring (15.2%) seasons of migration, and the share of the transit group in these seasons accounted for 93.4% of all annual transit flights. The predominant directions of migration were western, north-eastern and south-western. At an altitude of up to 10 m – 2369 (71.5%) birds were registered, in the range of altitudes (11÷25) m – 371 (11.2%), in the range of altitudes (26÷50) m – 367 (11.2%). At an altitude above 51 m – 202 birds (6.1%) were registered. Comparison of the results, obtained by different monitoring methods, was carried out by bringing the number of birds to 1 hour of observation in an area of 1 km2. The total bird density in the case of the RAM method was 3.3 times higher. The density of transit type birds according to different methods was within the admissible statistical dispersion of 10.2÷12.7 specimens/hour·km2. However, the density of forage type birds, registered by the RAM method, was 7.1 times higher than the density, identified by the SNH method. The average number of all the birds flying over the wind park territory at each moment of time according to various counting methods was within the statistical scatter (1.15÷1.28) specimen/(hour·km2). The size of the transit group in the case of the SNH method use was 3 times larger than that calculated by the RAM method, while the size of the forage group, on the contrary, was 2.5 times less. The anticipated number of collisions during one year of the wind power plant functioning, calculated by the SNH and RAM methods, was in the range of 5.6÷6.7 (about 0.6 specimens per turbine for one year of its functioning, or 0.2 specimen/1 MW/year). The number of collisions was about 6.9 −4 % of the total number of transit and forage type birds in the wind park territory, 3.3-3% of the number of the considered species specimens present at all altitudes, and 0.25% of all birds in a risk zone. The data obtained indicate an insignificant impact of the “Primorsk-1” wind power plant on the ornithofauna of the Azov sea coast.

Pollination, Crop Productivity, and Arthropod and Bird Communities Are Marginally Impacted by Border Vegetation in Highbush Blueberry Production

Herbaceous flowering or woody plant borders adjacent to highbush blueberry (Vaccinium corymbosum) fields have the potential to benefit both native pollinators and species of predatory and parasitic arthropods and birds that feed on key highbush blueberry pests, such as spotted wing drosophila [SWD (Drosophila suzukii)]. However, they may also draw pollinators away from the crop, serve as overwintering and/or refugia sites for SWD, and increase the abundance of wild birds that feed on fruit and harbor foodborne pathogens. The objective of this 1-year, observational study was to explore the potential impacts of border vegetation adjacent to commercial highbush blueberry fields on pollination, crop productivity, and arthropod and bird communities within the Pacific Northwest region in the United States. The study included three highbush blueberry cultivars (Duke, Draper, and Liberty), and three field border vegetation treatments: 1) woody perennial vegetation; 2) herbaceous vegetation; and 3) medium-height grasses (control). There was one border treatment per cultivar for a total of nine sites. No cultivar effects nor interactions for any of the variables were detected, so results were combined across cultivars. No differences in pollinator abundance, pollinator visitation rates, estimated yield, berry weight, and seed number were observed across the treatments. Herbaceous borders had more natural enemies than the woody perennial borders, but both were similar to the control. This trend is attributed to higher abundances of parasitic wasps (suborder Apocrita) in the herbaceous and control borders compared with the woody perennial borders. Increased abundances of aphids (family Aphididae), a host for parasitic wasps, likely influenced these results. Differences in predatory arthropods were not observed. Insect abundances were overall low in all field sites measured in this study, likely influenced by SWD insecticide applications. There were no differences in total wild bird density by treatment except for barn swallows (Hirundo rustica), which were greatest in the control treatment. Overall, the border treatments evaluated in this study had small-to-negligible impacts on the measured variables, and there was no clear crop production benefit. Additionally, none of the investigated border treatments negatively impacted highbush blueberry production. Taken together, border vegetation treatments can provide benefits such as reducing pesticide drift, deterring trespassers, and serving as a windbreak; but any potential benefits from a pollination or biocontrol aspect are likely diminished due to current SWD management practices.

Breeding bird response to season of burn in an upland hardwood forest

Upland hardwood forest managers are increasingly burning during the growing-season in hopes of improving wildlife habitat and attaining or accelerating other restoration goals, highlighting the need for research addressing how season of burning affects wildlife, including breeding birds. We used 1-ha strip transects in nine units before (2011) and after (2013–2016) treatments to experimentally assess how breeding birds respond to early growing-season (26 April 2013; GSB) and dormant-season (5 March 2014; DSB) burns, and controls (C). Burn effects on forest structure were minor and transitory, regardless of burn season. Burns did not affect overstory or midstory tree basal area or density; shrub cover did not significantly differ among treatments, but within GSB and DSB it decreased for 1–2 years post-burn. A trend of reduced leaf litter depth immediately following both burn treatments was apparent, and recovery was rapid. Percent canopy cover decreased slightly in GSB within four years post-burn. Total bird species richness and density did not differ among treatments or years, and no treatment × year interaction effects were detected. A treatment effect was detected for one of the 10 species tested; Red-bellied woodpecker density was greater in GSB than C in 2013 and 2015. No treatment × year interaction effect was detected for any tested species. Density of birds within the tree-, cavity-, and shrub and midstory-nesting guilds were not detectably affected by either burn treatment, but ground-nester density was lower in GSB and DSB than C in 2014. Our results indicate that single, low-intensity burns, regardless of burn season, are not an effective tool in creating suitable forest structure for disturbance-dependent breeding bird species, or changing breeding bird community composition. In the short-term, substantial forest overstory reduction by timber harvests or high-severity burns will likely be required to improve forest conditions for disturbance-dependent species, and to increase species richness and abundance of breeding birds.

Effects of development of wind energy and associated changes in land use on bird densities in upland areas.

Wind energy development is the most recent of many pressures on upland bird communities and their habitats. Studies of birds in relation to wind energy development have focused on effects of direct mortality, but the importance of indirect effects (e.g., displacement, habitat loss) on avian community diversity and stability is increasingly being recognized. We used a control-impact study in combination with a gradient design to assess the effects of wind farms on upland bird densities and on bird species grouped by habitat association (forest and open-habitat species). We conducted 506 point count surveys at 12 wind-farm and 12 control sites in Ireland during 2 breeding seasons (2012 and 2013). Total bird densities were lower at wind farms than at control sites, and the greatest differences occurred close to turbines. Densities of forest species were significantly lower within 100 m of turbines than at greater distances, and this difference was mediated by habitat modifications associated with wind-farm development. In particular, reductions in forest cover adjacent to turbines was linked to the observed decrease in densities of forest species. Open-habitat species' densities were lower at wind farms but were not related to distance from turbines and were negatively related to size of the wind farm. This suggests that, for these species, wind-farm effects may occur at a landscape scale. Our findings indicate that the scale and intensity of the displacement effects of wind farms on upland birds depends on bird species' habitat associations and that the observed effects are mediated by changes in land use associated with wind-farm construction. This highlights the importance of construction effects and siting of turbines, tracks, and other infrastructure in understanding the impacts of wind farms on biodiversity.

Bird diversity and dissimilarity show contrasting patterns along heavy metal pollution gradients in the Urals, Russia.

The effects of industrial pollution on bird diversity have been widely studied using traditional diversity measures, which assume all species to be equivalent. We compared species richness and Shannon index with distance-based measures of taxonomic, functional, and phylogenetic diversity (the abundance-weighted mean nearest taxon distances), which describe within-community dissimilarity at terminal branches. Analysis of dissimilarity can shed light on the processes underlying community assembly, i.e., environmental filtering decreases dissimilarity whereas competitive exclusion increases it. In the 2-year study near Karabash and Revda copper smelters in Russia, point counts of nesting birds and habitat descriptions were taken at 10 sites (40 plots) along each pollution gradient. The abundance and diversity of birds showed good repeatability in both regions. The total density of birds, number of species per plot, and Shannon diversity decreased at high toxic load in both regions. The taxonomic, functional, and phylogenetic nearest taxon distances showed the same pattern within regions. Species dissimilarity within communities increased with pollution in Karabash (due to loss of functionally similar species), but did not change in Revda (due to mass replacement of forest species by species of open habitats). Pollution-induced changes in bird communities near Karabash were greater due to the stronger deterioration of the forest ecosystems and less favorable natural conditions (more arid climate, lower diversity and vitality of the tree stand and understorey) compared to Revda. This study emphasizes the need for a multi-level approach to the analysis of bird communities using traditional indices of diversity, functional, taxonomic, or phylogenetic distances between species and environmental variables.

The dynamics of fauna and population of birds in agricultural landscapes on the border of Kazan International Airport

The dynamics of fauna and population of birds from agricultural lands near Kazan International Airport has been studied for one year. A total of 60 bird species have been registered, of which 26 species must be considered as highly dangerous to flying aircraft. With regard to seasonal activity, the nesting period (April – June) is the most hazardous, since it is characterized by maximum species richness and total population density of birds, as well as their high species diversity. Furthermore, a serious danger is posed by the period of postnesting nomadic movements and the onset of migrations (July – September) when the species diversity turns out to be the highest and the total population density begins to decrease. It has been recommended based on the obtained results that the current crops should be replaced by cultivars that will be less attractive to birds. In spring and autumn, certain bird hazing and frightening measures must be taken on a more regular basis.

Alternative scenarios of bioenergy crop production in an agricultural landscape and implications for bird communities.

Increased demand and government mandates for bioenergy crops in the United States could require a large allocation of agricultural land to bioenergy feedstock production and substantially alter current landscape patterns. Incorporating bioenergy landscape design into land-use decision making could help maximize benefits and minimize trade-offs among alternative land uses. We developed spatially explicit landscape scenarios of increased bioenergy crop production in an 80-km radius agricultural landscape centered on a potential biomass-processing energy facility and evaluated the consequences of each scenario for bird communities. Our scenarios included conversion of existing annual row crops to perennial bioenergy grasslands and conversion of existing grasslands to annual bioenergy row crops. The scenarios explored combinations of four biomass crop types (three potential grassland crops along a gradient of plant diversity and one annual row crop [corn]), three land conversion percentages to bioenergy crops (10%, 20%, or 30% of row crops or grasslands), and three spatial configurations of biomass crop fields (random, clustered near similar field types, or centered on the processing plant), yielding 36 scenarios. For each scenario, we predicted the impact on four bird community metrics: species richness, total bird density, species of greatest conservation need (SGCN) density, and SGCN hotspots (SGCN birds/ha ≥ 2). Bird community metrics consistently increased with conversion of row crops to bioenergy grasslands and consistently decreased with conversion of grasslands to bioenergy row crops. Spatial arrangement of bioenergy fields had strong effects on the bird community and in some cases was more influential than the amount converted to bioenergy crops. Clustering grasslands had a stronger positive influence on the bird community than locating grasslands near the central plant or at random. Expansion of bioenergy grasslands onto marginal agricultural lands will likely benefit grassland bird populations, and bioenergy landscapes could be designed to maximize biodiversity benefits while meeting targets for biomass production.

Long-term decline of southern boreal forest birds: consequence of habitat alteration or climate change?

Climate change and habitat degradation due to land use are the key factors threatening biodiversity. It is important to study both the separate and joined effects of climate warming and land use on biodiversity. In this work long-term population changes of southern boreal forest birds were studied in relation to climate change and direct habitat alteration due to forestry. The study was based on annually repeated bird censuses in 23 consecutive years (1993–2015) in a managed forest landscape. Results were compared with population changes in protected areas where logging is not allowed. During the study period, total bird density declined by 18 % with a change in the bird community composition. Out of the 12 most abundant species seven showed a significant negative trend and only one species a positive trend. Population declines could be connected with the direct alteration of habitat as a consequence of forestry or with the effect of climate change in the case of those species which declined also in protected areas. The increased species are abundant across Europe in human-modified habitats. Due to habitat alteration and climate warming, specific characteristics of southern boreal forest bird communities are changing with communities representing a pattern towards global homogenization. Thus, habitat alteration strengthens the negative effects of climate change.

Importance of Native Understory for Bird and Butterfly Communities in a Riparian and Marsh Restoration Project on the Lower Colorado River, Arizona

Heidi Kloeppel Trathnigg Corresponding author, Principal Biologist, Fred Phillips Consulting, LLC, 401 South Leroux St., Flagstaff, AZ, 86001, htrathnigg{at}fredphillipsconsulting.com.

Implications of afforestation for bird communities: the importance of preceding land-use type

Afforestation of open habitats is one of the principal land-use changes underway in Europe and elsewhere in the world at present, and it can have a considerable impact on local biodiversity. The sustainable expansion of global forest plantations requires an understanding of the factors that determine the ecological impacts of afforestation. This study set out to determine the importance of preceding land-use type in determining the outcomes of afforestation for bird communities. Paired comparisons of 5-year-old exotic conifer plantations and matching non-forested sites were studied in areas of low (peatland), intermediate (wet grassland) and high (improved grassland) management intensity. Afforestation resulted in an overall increase in total bird density in all three habitat types. The effects of forest planting on bird conservation were found to be positively related to prior management intensity at the site. The density of bird species of conservation concern increased in response to the planting of intensively managed grassland sites, but decreased in response to afforestation of peatlands and of grasslands under intermediate management intensity. This study shows that plantation forests can, in some contexts, offer opportunities for bird conservation, and the findings highlight the trade-offs that are an integral part of land-use change. Therefore, where afforestation planning includes consideration of its impact on bird communities, planting should take place predominantly on sites of low biodiversity value, such as agriculturally improved grasslands. Furthermore, the preservation of sites of high conservation value within areas of afforestation would confer advantages on bird communities.

Bird Communities and Biomass Yields in Potential Bioenergy Grasslands

Demand for bioenergy is increasing, but the ecological consequences of bioenergy crop production on working lands remain unresolved. Corn is currently a dominant bioenergy crop, but perennial grasslands could produce renewable bioenergy resources and enhance biodiversity. Grassland bird populations have declined in recent decades and may particularly benefit from perennial grasslands grown for bioenergy. We asked how breeding bird community assemblages, vegetation characteristics, and biomass yields varied among three types of potential bioenergy grassland fields (grass monocultures, grass-dominated fields, and forb-dominated fields), and assessed tradeoffs between grassland biomass production and bird habitat. We also compared the bird communities in grassland fields to nearby cornfields. Cornfields had few birds compared to perennial grassland fields. Ten bird Species of Greatest Conservation Need (SGCN) were observed in perennial grassland fields. Bird species richness and total bird density increased with forb cover and were greater in forb-dominated fields than grass monocultures. SGCN density declined with increasing vertical vegetation density, indicating that tall, dense grassland fields managed for maximum biomass yield would be of lesser value to imperiled grassland bird species. The proportion of grassland habitat within 1 km of study sites was positively associated with bird species richness and the density of total birds and SGCNs, suggesting that grassland bioenergy fields may be more beneficial for grassland birds if they are established near other grassland parcels. Predicted total bird density peaked below maximum biomass yields and predicted SGCN density was negatively related to biomass yields. Our results indicate that perennial grassland fields could produce bioenergy feedstocks while providing bird habitat. Bioenergy grasslands promote agricultural multifunctionality and conservation of biodiversity in working landscapes.

Isolation, patch size and matrix effects on bird assemblages in forest reserves

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.

Factors affecting the bird diversity of planted and semi-natural oak forests in Ireland

Capsule In Ireland, which has relatively low diversity of bird species, commercially mature plantation oak forests (aged 72–151 years old) have similar bird diversity to typical semi-natural oak woodlands, and higher bird diversity than over-browsed semi-natural oak woodland, with bird diversity related to habitat complexity.Aims To investigate whether oak plantations can support comparable bird assemblages to semi-natural oak woodlands, and to assess if high levels of ungulate browsing and grazing impact on the quality of semi-natural oak woodland habitat for birds.Methods Bird and vegetation surveys were conducted in commercially mature oak plantations (n = 4), semi-natural oak woodlands (n = 10) and intensively browsed semi-natural oak woodland (n = 4). Species richness, total bird density, warbler density and density of parids were compared between oak forest types. Variation in bird communities between sites was investigated using ordination, and relationships between bird and vegetation metrics were assessed using general linear models.Results Bird diversity in plantation oak and the semi-natural forests subject to low levels of ungulate browsing, was similar, with no difference in species richness, total bird density or density of warbler and density of parids. However, browsed semi-natural oak woods had lower species richness than either of the other two study site types, and lower density of warblers than oak plantations. These observed differences in bird communities appear to be a result of browsing mediated differences in habitat complexity between the forest types.Conclusions Plantation forests of native tree species may support comparable bird communities to semi-natural woodlands in areas that lack forest specialists. Bird diversity in woodlands subject to high levels of browsing and grazing is likely to be limited, unless ungulate populations and their access to these woodlands are managed to promote the development of a more complex understorey.

Soil disturbances increase songbird use of monotypic re-established Grasslands

Extensive conversion of natural areas for agricultural production has had many consequences, including reduced habitat for nesting birds. Increasing focus on habitat re-establishment has led to the establishment of patches of perennial herbaceous vegetation in these agricultural landscapes, although these often consist of monotypic grass fields with little vegetation diversity. In 2001 and 2002, we assessed songbird responses to mowing followed by a soil disturbance (disking) meant to increase vegetation diversity and abundance of arthropod food resources in conservation easements in East-central Iowa, USA. We randomly assigned fields to disking and control treatments and collected data on breeding bird density and species richness in these habitats before and after treatments were applied. Disking increased density of all species combined, several individual species including dickcissel (Spiza americana; a declining species of concern), and overall conservation value of bird communities in treated fields. Total bird density increased with disking when the size of disked area was relatively small, and dickcissels and American goldfinches (Spinus tristis) responded positively and negatively to block-shaped treatments, respectively. Most species either showed no response or increased in density with disking. Changes associated with disking treatments were likely related to changes in both vegetation structure and increased abundance and biomass of arthropod food resources. Disking appears to be an effective management practice for maintaining herbaceous habitats, increasing vegetation diversity and food availability for insectivorous birds, and increasing habitat quality for priority bird species. Given the increasing availability of monotypic grasslands in agricultural landscapes, this practice may provide a relatively inexpensive way to improve re-established habitats. © 2013 The Wildlife Society.

Multi-scale associations of grassland birds in response to cost-share management of conservation reserve program fields in Illinois

The Illinois State Wildlife Action Plan targeted the Conservation Reserve Program (CRP) as important improvable acres for grassland and grassland-successional bird species of greatest need for conservation. A large portion of CRP grasslands in Illinois and elsewhere lack floristic and structural diversity because of the absence of management and the extensive planting of monotypic grasses such as tall fescue (Schedonorus phoenix). The 2006 Farm Bill included the mid-contract management (MCM) provision requiring landowners with new CRP enrollments to provide habitat improvement midway through the 10–15-year contract duration. We compared the effects of 3 approved MCM regimes (i.e., fall strip disking, fall glyphosate spraying, fall glyphosate spraying followed by spring legume drill-seeding) on grassland bird communities in 60 tall fescue-dominated CRP fields in south-central Illinois during 2006–2008. We modeled relative density of dickcissels (Spiza americana), Henslow's sparrows (Ammodramus henslowii), and eastern meadowlarks (Sturnella magna) as a function of microhabitat, patch-level patterns, and landscape composition using a multi-scale assessment approach. We detected 10 grassland-associated bird species (e.g., Henslow's sparrow, northern bobwhite [Colinus virginianus], sedge wren [Cistothrus platensis], Savannah sparrow [Passerculus sandwichensis], grasshopper sparrow [Ammodramus savannarum]) that are recognized as species of greatest need for conservation under the Illinois State Wildlife Action Plan. Mean total bird densities and species richness were greater in glyphosate-sprayed fields (5.0 birds/ha; 11.5 species) and glyphosate drill-seeded fields (4.4 bird/ha; 12.4 species) than in disked (3.4 birds/ha; 8.7 species) and reference (3.1 birds/ha; 7.5 species) fields. The avian conservation value of glyphosate sprayed and glyphosate drill-seeded fields increased 34.2% and 32.6% post-management, respectively, but we did not detect change in disked and reference fields. Our models indicate that density of each of the focal species is likely associated with changes in plant species diversity and habitat structure resulting from management actions but is also influenced by landscape composition. Despite an overall positive response of the grassland bird communities to glyphosate-based treatment regimes in tall fescue CRP fields in south-central Illinois, the response of Henslow's sparrow density to glyphosate was not consistently positive. © 2013 The Wildlife Society.

The effect of patch area on birds in central Australian mulga (Acacia aneura) woodland of different times-since-fire.

It is often assumed that a fine-scaled mosaic of different times-since-fire supports greater biodiversity than a coarsescaled mosaic — the fire mosaic hypothesis. A potential mechanism of the fire mosaic hypothesis is the effect of area on species diversity. We investigated the effect of patch area on bird communities in mulga (Acacia aneura) woodland in central Australia. The study was conducted at Uluru Kata-Tjuta National Park using 55 fixed-area sites classified to the time since last fire: burnt 2002; burnt 1976 and long unburnt. Birds were surveyed in the winter and spring of 2005 and 2006. Of 20 key species, two showed a positive density-area effect (i.e. higher density in larger patches). Patch area did not affect total bird density or species richness. However, species turnover (ß-diversity) was greater in large patches in the burnt 2002 treatment than it was in small patches. There was no effect of patch area on the composition of the bird communities in any of the time-since-fire classes. We concluded that patch area did affect the distribution of some birds in mulga woodland. However, patch area was not a mechanism of the fire mosaic hypothesis because the effects of patch size tended to increase avian diversity in larger patches rather than small.