Species Richness Of Breeding Birds Research Articles

The transformation of river ecosystems caused by mining affects bird breeding in indigenous riparian habitats

Our study considered the excavation of sand and gravel, which modifies the landscapes of riparian ecosystems. It promotes the creation of water bodies with surrounding vegetation, but it also results in the loss of natural habitats.We investigated the species richness, composition, and abundance of aquatic and terrestrial breeding birds and their interaction with three habitat types: managed and abandoned flooded pits, and oxbow lakes. We surveyed 117 sites in medium-sized river valleys in the foreground of the Bohemian Massif (Czech Republic), and in the Carpathian Mountains (Poland, Slovakia) in 2022.Flooded pits were suitable for open-water and colonial birds. Managed flooded pits were also suitable for early successional land birds, but they did not provide habitat for birds that use marshes and wet meadows, or riparian woodlands. The majority of species preferred to breed in oxbow lakes with riparian forests and these areas hosted the highest number of threatened species.We concluded that high levels of disturbance in riparian ecosystems promoted some birds (e.g. colonial or breeding in early-successional habitats), but it negatively affected the overall bird diversity, and it led to a species composition shift with the elimination of taxa associated with indigenous riparian habitats. The importance of flooded pits increases with subsequent plant succession. Our results indicate that gravel or sand mine pits, although beneficial for some taxa, are not substitutes for natural habitats in riparian ecosystems, as they do not support birds breeding in indigenous riparian habitats. Natural oxbow lakes with riparian forests are habitats that need to be preserved to effectively promote local biodiversity.

The occurrence of a flagship raptor species in intensive agroecosystems is associated with more diverse farmland bird communities: Opportunities for market-based conservation

Traditional livestock systems have supported farmland biodiversity for millennia. However, modern intensive husbandry is challenging wildlife persistence in agroecosystems. We assessed the multiscale determinants of the species richness of breeding bird communities, as well as the occurrence of a flagship raptor species, the lesser kestrel Falco naumanni, in an intensive agroecosystem mostly dedicated to the production of the world-renowned Parmigiano Reggiano cheese. We relied on three avian community richness metrics reflecting a gradient of increasing association with farmed landscapes, i.e. the overall breeding bird species richness, the richness of farmland species, and the richness of ground-nesters (i.e. species that mostly breed within crops) and tested their association with the landscape, agricultural, and pedological variables as well as with lesser kestrel occurrence. We showed that environmental variables determining overall richer avian assemblages did not coincide with those shaping farmland and ground-nesting species richness, thus challenging the potential effectiveness of conservation actions. However, such actions could be optimized by taking into account different spatial scales affecting different species groups. Indeed, landscape heterogeneity, semi-natural/marginal habitats, and a moderate cover of build-up areas enhanced overall species richness at a small spatial scale. At a broader scale, landscape heterogeneity enhanced farmland species richness, whereas fragmentation determined by urbanization negatively affected ground-nesters. Avian community richness metrics were maximized at an intermediate cover of three prevailing crops (winter, summer, and hay crops), increasing when they co-occurred, i.e., in the presence of crop rotation. Lesser kestrel occurrence was associated with richer assemblages of ground-nesting species because this raptor and ground-nesters showed analogous ecological requirements. These findings suggest that the lesser kestrel can be regarded as an ideal flagship for market-based conservation initiatives (e.g., tailored to the production of biodiversity-friendly agri-food products) in intensive agroecosystems since actions aimed at improving the foraging habitats of the species are likely to benefit co-occurring farmland birds of conservation interest.

Are Lay People Able to Estimate Breeding Bird Diversity?

Studies about biodiversity and well-being used different approaches to assess biodiversity, e.g., scientific counts and censuses or perceived biodiversity estimated by the respondents. Here, we assessed whether laypeople could estimate the breeding bird diversity or species richness at specific places. For comparison, we carried out bird censuses with standard methods of professional ornithologists and used citizen science data from the internet platform Ornitho (Germany). Lay people from the public (1184 respondents) were surveyed between May and July 2022 at 40 different places in southwest Germany between Rottenburg/Tübingen and Stuttgart following the catchment of the river Neckar (30 people surveyed per place). People were asked to estimate the bird species richness/diversity at this current place. Here, we show that the data from the citizen science platform does not correlate with the professional census counts nor with the perceived species richness of laypeople. Laypeople have a generally good assessment of the bird species richness, correlating with the data of professionals (r = 0.325, p = 0.041). On average, the number of species assessed by laypeople lies in between the values of the professional morning and afternoon census. People were most often surveyed in the afternoon; therefore, their assessment must be done on other factors than actual birds present. This result is valuable for future studies on the connection between biodiversity and well-being.

Habitat Area, Not Fragmentation, Associated with Breeding Bird Species Richness

Habitat Area, Not Fragmentation, Associated with Breeding Bird Species Richness

Mapping breeding bird species richness at management‐relevant resolutions across the United States

Human activities alter ecosystems everywhere, causing rapid biodiversity loss and biotic homogenization. These losses necessitate coordinated conservation actions guided by biodiversity and species distribution spatial data that cover large areas yet have fine-enough resolution to be management-relevant (i.e., ≤5km). However, most biodiversity products are too coarse for management or are only available for small areas. Furthermore, many maps generated for biodiversity assessment and conservation do not explicitly quantify the inherent tradeoff between resolution and accuracy when predicting biodiversity patterns. Our goals were to generate predictive models of overall breeding bird species richness and species richness of different guilds based on nine functional or life-history-based traits across the conterminous United States at three resolutions (0.5, 2.5, and 5km) and quantify the tradeoff between resolution and accuracy and, hence, relevance for management of the resulting biodiversity maps. We summarized 18 years of North American Breeding Bird Survey data (1992-2019) and modeled species richness using random forests, including 66 predictor variables (describing climate, vegetation, geomorphology, and anthropogenic conditions), 20 of which we newly derived. Among the three spatial resolutions, the percentage variance explained ranged from 27% to 60% (median=54%; mean=57%) for overall species richness and 12% to 87% (median=61%; mean=58%) for our different guilds. Overall species richness and guild-specific species richness were best explained at 5-km resolution using ~24 predictor variables based on percentage variance explained, symmetric mean absolute percentage error, and root mean square error values. However, our 2.5-km-resolution maps were almost as accurate and provided more spatially detailed information, which is why we recommend them for most management applications. Our results represent the first consistent, occurrence-based, and nationwide maps of breeding bird richness with a thorough accuracy assessment that are also spatially detailed enough to inform local management decisions. More broadly, our findings highlight the importance of explicitly considering tradeoffs between resolution and accuracy to create management-relevant biodiversity products for large areas.

Influence of grazing and fire on breeding birds and perennial plants in Cyprus scrub and forest systems

Grazing and browsing by sheep and goats has been an important anthropogenic influence on ecosystems in the Mediterranean region for centuries. This influence has changed significantly in recent decades, with a general shift from range grazing to the penning of animals. The intermediate disturbance hypothesis (IDH) proposes that perturbation - including anthropogenic disturbance - is the norm for Mediterranean ecosystems, and that higher species diversity is found under conditions of continuous, moderate disturbance. Here we test the IDH as it relates to grazing of scrub and open forest habitats in Cyprus, while also testing for the effects of fire. We carried out surveys of breeding birds and vegetation at 48 study sites in scrub and open woodland across Cyprus. We estimated relative grazing pressure (past and present) and fire history at these sites, and tested for associations between these factors, breeding bird species richness and perennial vegetation diversity. We found moderate current grazing reduces density of lower and middle level scrub, and a higher level of diversity of perennial vegetation at moderately over intensively grazed sites. We found that moderate historical grazing pressure had a positive influence on richness of breeding bird species in lower scrub habitat such as phrygana, but that this effect was weaker the taller and denser the habitat. By contrast, current grazing pressure had a negative effect on species richness in lower scrub, but species richness in grazed habitats was higher in denser, taller scrub habitat such as garrigue and maquis. Our study suggests grazing plays an important role in maintaining habitat heterogeneity but the impact on avian species richness depends on the density and height of the vegetation.

Species Richness, Abundance, and Productivity of Birds Along a Powerline Right-of-way within a Forested Landscape, Northeastern United States

Utility rights-of-way (ROW) serve as nesting areas and maintain a high diversity of early successional birds. ROW incorporating wire zone–border zone and integrated vegetation management can be used as examples of early successional habitat management for bird conservation more generally in the Northeastern United States, given artificial disturbances not created solely for natural resource conservation comprise approximately 80% of early successional habitats. The objective of our study was to determine the effect of herbicide and mechanical vegetation management approaches on the abundance, species richness, and reproductive success of breeding bird species occupying an electric transmission line ROW in central Pennsylvania. The overall abundance of birds was significantly lower within the wire and border management zones, following initiation of a new vegetation management cycle at State Game Lands (SGL 33) than in the years prior to management. Sections of ROW with no border zones contained the lowest abundance and species richness of breeding birds compared to sections with borders prior to the initiation of a new management cycle. Sections of ROW with no border zones and mowing sections had the lowest bird abundance and species richness of all ROW sections at the onset of a new management cycle, and contained the lowest number of bird species displaying evidence of breeding, both prior to and at the beginning of management cycles. Sections of ROW managed using herbicides were comparable or more beneficial to bird communities in terms of abundance, species richness, indices of productivity, and nesting success than sections maintained via mechanical treatments (mowing and hand cutting), both at the end and beginning of management cycles within a forested landscape in the central Appalachian Mountains and surrounding forested regions in the northeastern United States.

Features of formation bird population structure in Minsk in the time aspect

The structure of bird population of urbanized areas is determined by the diversity of habitats within the city, the diversity of bird species in suburban biotopes, and regional processes of dispersal of birds closely associated with human settlements. The analysis of the dynamics of the breeding bird species richness in Minsk showed that its formation progressed in different ways. All in all, since 1946, 141 bird species have been recorded nesting (including allegedly) in the territory of Minsk.The breeding bird assemblages is dominated by dendrophilous (45.0 % of all species) as well as wetland and semi-aquatic (29,3 %) bird species, with more than half of all the breeding bird species (50.3 %) associated with trees and shrubs. In different periods, the breeding bird species richness varied, by now, it has noticeably increased (from 77 to 132 species). This happened due to the expansion of the administrative boundaries of the city with the inclusion of bird species of suburban habitats, an increase in the diversity of habitats suitable for bird nesting (for example, the formation of large water bodies) as well as due to active colonization of urban ecosystems by various bird species. At the same time, after 2000, 9 bird species stopped nesting and 17 bird species started nesting. Active processes of synurbization of some bird species on the European continent observed in recent decades have become the reason for the addition of new species to the avifauna in Minsk, although the basis of the current structure of bird population was formed back in 1986–1999. At the same time, the synurbized groups of various bird species may be of autochthonous, allochthonous, or mixed origin.

Wetland birds of middle Vistula River during breeding season: the impact of human activities on the distribution, abundance and richness of species

Wetland birds of middle Vistula River during breeding season: the impact of human activities on the distribution, abundance and richness of species

Livestock grazing impacts components of the breeding productivity of a common upland insectivorous passerine: Results from a long‐term experiment

Abstract The intensity of pastoral management in areas of High Nature Value farming is declining in some regions of Europe but increasing in others. This affects open habitats of conservation concern, such as the British uplands, where bird species that benefit from low‐intensity grazing may be most sensitive to such polarization. While experimental manipulations of livestock grazing intensities have improved our understanding of upland breeding bird responses in the short term, none have examined the long‐term impacts of altered management on reproductive success. Using a replicated landscape‐scale experiment that started in 2003, we investigated the effects of four grazing treatments (intensive sheep; low‐intensity sheep; low‐intensity mixed sheep and cattle; and no grazing) on the breeding productivity of meadow pipits Anthus pratensis, the most common upland passerine. Surveys were carried out systematically during early (2003 and 2004) and late (2015 and 2016) sampling periods of the experiment to compare the short‐ and long‐term effects of grazing treatments on breeding density and productivity of pipits specifically, but also on the overall bird community. Pipit breeding density was lowest under low‐intensity sheep grazing while the highest egg‐stage nest survival was observed in the same treatment, although no significant treatment effects were detected on overall nest survival or fledgling output. There were no significant differences in treatment effects between the sampling periods on any breeding variable, but overall nest survival was lower in the later sampling period across all treatments. Breeding bird species richness differed between treatments in the later sampling period, with highest species richness in the ungrazed treatment. Synthesis and applications. Livestock grazing management can have different outcomes for different upland birds. Our results showed that, with time, meadow pipit breeding productivity tended to be higher when sheep grazing intensity was reduced and/or mixed with cattle, and lower when livestock were removed, but not significantly so. Removal of grazing, however, can significantly increase bird species richness. The long‐term experiment showed an overall decline in fledglings regardless of grazing treatments, potentially a result of increased predator numbers harboured by nearby developing woodland, highlighting the importance of considering wider landscape processes in grazing management decisions.

Benefits and costs of native reforestation for breeding songbirds in temperate uplands

Global tree planting initiatives may benefit biodiversity depending on woodland type, but ecological effects must be understood when woodland replaces open habitats supporting characteristic wildlife. In the UK's temperate uplands, large-scale reforestation is replacing long-established open ‘moorland’ (heath, bog and grassland) supporting breeding bird communities of conservation importance. We quantified breeding bird species richness and abundance in 8–24 year-old native woodland plantations in Scotland and adjacent moorland and used bird densities to predict potential future abundance changes in woodland and moorland avian indicator species from recent national-level woodland creation policies. Bird species richness at point counts increased with increasing woodland cover, height and age and declined with increasing elevation. Differing abundances of bird species of conservation concern between woodland and moorland were related to their associations with vegetation measures, especially woodland cover and tree species composition. The creation of 54.9 km2 of native woodland in Scotland across 2017 and 2018 predicts reduced Meadow Pipit Anthus pratensis (moorland indicator) abundance of 6214 individuals or 0.13% of current UK population, and increased Willow Warbler Phylloscopus trochilus (indicator of young woodland) abundance of 6040 individuals or 0.13% of current UK population. Native woodland plantations comprised c34% of new woodland creation and the projections should be extended to other woodland types in particular non-native commercial conifer forestry. Native reforestation of open ground offers net gains in bird species richness but could disbenefit open-ground birds including those of conservation concern. Where retention of open-ground species is desired, landscape-scale reforestation should consider both woodland and open-ground wildlife.

The effectiveness of area protection to capture coastal bird richness and occurrence in the Swedish archipelago

Protected areas are a key component in biodiversity conservation strategies, but evaluations of how effective they are in capturing species diversity is lacking for many ecosystems. We compared different protection types (animal sanctuaries, nature reserves and unprotected areas) using data on species richness and occurrence of coastal breeding bird species in a large archipelago in the Baltic Sea. Data were from extensive inventories based on a grid with 1 × 1 km resolution covering 4646 km2 on the East coast of Sweden. We focused on specialist species breeding exclusively in coastal habitats since these species are of specific conservation concern, but considered generalists, which also breeds in inland wetlands, as well. Animal sanctuaries had significantly higher species richness of specialist species than unprotected areas and nature reserves. Nature reserves had even lower richness of specialist species than unprotected areas. Further, a rarity-weighted diversity index showed that animal sanctuaries were better in capturing hotspots of bird diversity compared to nature reserves and unprotected areas. Hotspots, both protected and unprotected, were scattered throughout the entire archipelago. The rarity-weighted richness is therefore useful to identify gaps in the protected area network. Overall, we conclude that the establishment of animal sanctuaries has been a successful conservation measure for protecting specialist species in several aspects. Ongoing human exploitation of the Baltic archipelagos prompt further consideration of protecting still unprotected but species rich shorelines for the benefit of many coastal breeding birds.

A comparison of Dynamic Habitat Indices derived from different MODIS products as predictors of avian species richness

Understanding past and current patterns of species richness is essential for predicting how these patterns may be affected by future global change. The species energy hypothesis predicts that higher abundance and richness of animal species occur where available energy is higher and more consistently available. There is a wide range of remote sensing proxies for available energy, such as vegetation productivity, but it is not clear which best predict species richness. Our goal here was to evaluate different proxies for annual plant productivity from Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) as input for the Dynamic Habitat Indices (DHIs), and to determine how well they predict the richness of breeding bird species in six functional guilds across the conterminous United States. The DHIs are measures of vegetation productivity over the course of a year and consist of three components: (1) cumulative productivity (DHI Cum), (2) minimum productivity (DHI Min), and (3) intra-annual variation of productivity (DHI Var). We hypothesized that increases in cumulative and minimum productivity and reductions in intra-annual variation will be associated with higher species richness. We calculated the DHIs from a range of MODIS 1000-m vegetation productivity data sets for 2003–2014, i.e., the Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Fraction of absorbed Photosynthetically Active Radiation (FPAR), Leaf Area Index (LAI), and Gross Primary Productivity (GPP). We summarized bird species richness of different guilds within ecoregions (n=85) based on abundance maps derived from the >3000 routes of the North American Breeding Bird Survey for 2006 to 2012. Generally, we found all the DHIs had high explanatory power for predicting breeding bird species richness. However, the strength of the associations between the DHIs and bird species richness depended on habitat, nest placement, and migratory behavior. We found highest correlations for habitat-based guilds, such as grassland breeding species (R2adj 0.66–0.73 for the multiple DHI regression model; R2adj 0.41–0.61 for minimum DHI) and woodland breeding species (R2adj 0.34–0.60 for the multiple DHI regression model; R2adj 0.26–0.51 for cumulative DHI). The strong relationship between the DHIs and bird species richness reinforces the importance of vegetation productivity as a determinant of species diversity patterns, and the usefulness of satellite data for applying the species energy hypothesis to predictions in service to conservation.

Breeding, Early-Successional Bird Response to Forest Harvests for Bioenergy.

Forest regeneration following timber harvest is a principal source of habitat for early-successional birds and characterized by influxes of early-successional vegetation and residual downed woody material. Early-successional birds may use harvest residues for communication, cover, foraging, and nesting. Yet, increased market viability of woody biomass as bioenergy feedstock may intensify harvest residue removal. Our objectives were to: 1) evaluate effects of varying intensities of woody biomass harvest on the early-successional bird community; and (2) document early-successional bird use of harvest residues in regenerating stands. We spot-mapped birds from 15 April– 15 July, 2012–2014, in six woody biomass removal treatments within regenerating stands in North Carolina (n = 4) and Georgia (n = 4), USA. Treatments included clearcut harvest followed by: (1) traditional woody biomass harvest with no specific retention target; (2) 15% retention with harvest residues dispersed; (3) 15% retention with harvest residues clustered; (4) 30% retention with harvest residues dispersed; (5) 30% retention with harvest residues clustered; and (6) no woody biomass harvest (i.e., reference site). We tested for treatment-level effects on breeding bird species diversity and richness, early-successional focal species territory density (combined and individual species), counts of breeding birds detected near, in, or on branches of harvest piles/windrows, counts of breeding bird behaviors, and vegetation composition and structure. Pooled across three breeding seasons, we delineated 536 and 654 territories and detected 2,489 and 4,204 birds in the North Carolina and Georgia treatments, respectively. Woody biomass harvest had limited or short-lived effects on the early-successional, breeding bird community. The successional trajectory of vegetation structure, rather than availability of harvest residues, primarily drove avian use of regenerating stands. However, many breeding bird species used downed wood in addition to vegetation, indicating that harvest residues initially may provide food and cover resources for early-successional birds in regenerating stands prior to vegetation regrowth.

The effect of human population size on the breeding bird diversity of urban regions

Most studies of the effects of urbanization on avian diversity are carried out in a single urban area. However, urban areas vary in characteristics, such as human population size and biophysical context, that likely influence within-urban area ecological structure and functioning. In this paper, we describe the first direct test of the effect of urban area human population size on bird diversity. We applied simultaneous autoregressive modeling and multi-model inference to North American Breeding Bird Survey and US Census data from 48 urban areas in the conterminous United States to determine the effect of urban area human population size on total breeding bird species richness and abundance in surrounding urban regions, controlling for variation in elevation, air temperature, precipitation, urban area age, human population density, and original habitat type. We hypothesized that increasing urban area human population size is a driver of increasing regional habitat loss and fragmentation and disturbance and therefore would have a negative effect on breeding bird species richness and abundance in regions. We found strong evidence for a negative effect of urban area human population size on species richness and show that urban area human population size is positively correlated with impervious surface cover and air pollutant emissions in urban regions, lending provisional support to our hypothesis. Our results imply that we prioritize urban regions surrounding urban areas with large human population sizes for conservation activities that will benefit birds, such as preserving green spaces. In future, greater emphasis should be placed on the acquisition of high-quality ecological data in multiple urban areas in order to increase our understanding of the structure and functioning of complex urban systems, a frontier in urban ecology.

Avian Community Composition in Response to High Explosive Testing Operations at Los Alamos National Laboratory in Northern New Mexico

Breeding bird abundance, species richness, evenness, diversity, composition, productivity, and survivorship were determined near a high-explosive detonation site at Los Alamos National Laboratory, New Mexico, USA, during pre-operation (1997-1999) and operation (2000-2014) periods. The operation periods consisted of detonations ( 0.05) in mean avian abundance and species evenness in any of the operation periods as compared with the pre-operation period. Species richness and diversity were significantly higher (p < 0.05) during the vessel containment period (2007-2014) than the pre-operation period. The time period of this study coincided with a wildfire (2000), a bark beetle infestation (2002), and two periods of drought (Nov 1999-Mar 2004 and Dec 2005-Dec 2014) that affected the study area. Analysis of aerial photos determined that the average percent canopy cover of mature ponderosa pines (Pinus ponderosa) within 100 feet of mist net sites declined from 12% to 3% between 1991 and 2014 and the percent cover of shrubs slightly increased. The percent similarity in presence/abundance between the pre-operation avian community and avian community during the open air, foam containment, and vessel containment periods were 59%, 63% and 68% respectively. Two bird species associated with large trees became less common over the study period (capture rate dropped below 2.0 adults per 600 net-hours relative to the pre-operations period), and four bird species associated

Bird community characteristics as indicators of sustainable management in olive grove ecosystems of Central Greece

The role of breeding birds as indicators of sustainable management in olive groves was investigated. The data revealed significantly higher alpha diversity in organic and abandoned olive groves and maquis than in conventional ones. The highest beta diversity was found between the following pairs: organic olive groves–maquis, and abandoned olive groves–maquis. Breeding bird diversity, Heteroptera, Hymenoptera, Hemiptera and Coleoptera densities positively influenced bird species richness in organic olive groves and maquis, and additionally, manure application positively influenced bird species richness in organic ones. Bird species richness was negatively influenced by pesticide and inorganic fertilizer application in conventional ones. Moreover, isopod density was unimportant in explaining breeding bird richness in organic olive groves. Finally, our study suggests a difference in bird communities of various olive groves as a result of different management and practices, and concludes that birds might serve as indicators of overall olive grove health. Furthermore, these findings could be used as a tool for prediction of breeding bird species richness probability in different olive grove management systems and maquis. Finally, the results of the present study may contribute to highlighting some aspects of the effect of different farming practices on the dynamics of Mediterranean bird communities.

The relative importance of climate and vegetation properties on patterns of North American breeding bird species richness

Recent advances in remote sensing and ecological modeling warrant a timely and robust investigation of the ecological variables that underlie large-scale patterns of breeding bird species richness, particularly in the context of intensifying land use and climate change. Our objective was to address this need using an array of bioclimatic and remotely sensed data sets representing vegetation properties and structure, and other aspects of the physical environment. We first build models of bird species richness across breeding bird survey (BBS) routes, and then spatially predict richness across the coterminous US at moderately high spatial resolution (1 km). Predictor variables were derived from various sources and maps of species richness were generated for four groups (guilds) of birds with different breeding habitat affiliation (forest, grassland, open woodland, scrub/shrub), as well as all guilds combined. Predictions of forest bird distributions were strong (R2 = 0.85), followed by grassland (0.76), scrub/shrub (0.63) and open woodland (0.60) species. Vegetation properties were generally the strongest determinants of species richness, whereas bioclimatic and lidar-derived vertical structure metrics were of variable importance and dependent upon the guild type. Environmental variables (climate and the physical environment) were also frequently selected predictors, but canopy structure variables were not as important as expected based on more local to regional scale studies. Relatively sparse sampling of canopy structure metrics from the satellite lidar sensor may have reduced their importance relative to other predictor variables across the study domain. We discuss these results in the context of the ecological drivers of species richness patterns, the spatial scale of bird diversity analyses, and the potential of next generation space-borne lidar systems relevant to vegetation and ecosystem studies. This study strengthens current understanding of bird species–climate–vegetation relationships, which could be further advanced with improved canopy structure information across spatial scales.

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.

Exploring the ecological processes driving geographical patterns of breeding bird richness in British Columbia, Canada

British Columbia (BC), Canada, has a diverse landscape that provides breeding habitat for > 300 avian species, and the recent development of the BC Breeding Bird Atlas data set presents key information for exploring the landscape conditions which lead to biological richness. We used the volunteer-collected raw breeding bird evidence data set to analyze the effects of sampling biases on spatial distribution of observed breeding bird species and implemented regression tree analysis (Random Forests) to examine the influence of productivity, ambient energy, and habitat heterogeneity on independently measured breeding bird richness. Results indicated that total breeding species richness is correlated with total survey effort (alpha < 0.001). By stratifying species richness by survey effort, we observed that ambient energy is the top-ranked environmental predictor of breeding bird richness across BC, which, when used in combination with a number of other environmental variables, explains -40% of the variation in richness. Using our modeled relationships, we predicted breeding bird species richness in the areas of BC not presently surveyed between three and six hours. The majority of the productive Boreal Plains, the southern portion of the Taiga Plains region, the lowlands of the Southern and Central Interior, along the Rocky Mountain Trench, and the coastal areas of the Georgia Depression are predicted to have the highest categories of breeding richness (35-57 unique species). Our results support ongoing species diversity gradient research, which identifies ambient energy as an important factor influencing species diversity distributions in the Northern Hemisphere. By linking breeding bird richness to environmental data derived from remotely sensed data and systematically collected climate data, we demonstrate the potential to monitor shifts in ambient energy as a surrogate for vertebrate habitat condition affecting population levels. By analyzing the influence of survey effort on species richness metrics, we also highlight the need to consider adding attributes to the raw breeding bird data set to describe observer experience, such as hours or seasons spent surveying, and provide survey dates to allow greater flexibility for removing survey bias. These additions can increase the utility of atlas data for species richness studies useful for conservation planning.