Response Of Bird Communities Research Articles

Restoration treatments reduce threats to oak ecosystems and provide immediate subtle benefits for oak‐associated birds

Oak ecosystems support a high amount of biodiversity and are critical for avian conservation in the Pacific Northwest, yet most of the remaining habitat is in a degraded state. A landscape‐scale restoration project in the Klamath Siskiyou Bioregion of southern Oregon and northern California reduced factors that stress oak trees while improving the function of oak‐associated plant communities on 450 ha of private lands from 2011 to 2013. We implemented a before‐after‐control‐impact study to measure changes in vegetation structure and composition, avian community composition, and individual avian species density within 23 restored and 23 control stands. Restoration resulted in reduced Douglas fir and western juniper tree cover and overall shrub cover, but generally did not cause notable shifts between vegetation types (e.g. oak‐conifer forest did not become oak woodland). Oak‐associated birds were positive indicator species following treatment at the restored sites; yet, the avian community composition shift toward an oak‐associated community observed in the NMS ordination was not statistically significant. Furthermore, we observed only negligible change in individual species density of both conifer‐ and oak‐associated birds following restoration. While restoration objectives at all sites sought to improve oak tree vigor and associated ecosystem health, the pre‐restoration stand conditions and thus the specific prescriptions varied widely. More study is needed to disentangle how overstory and understory restoration actions interact to affect bird community response.

Metrics for conservation success: Using the “Bird‐Friendliness Index” to evaluate grassland and aridland bird community resilience across the Northern Great Plains ecosystem

AbstractAimEvaluating conservation effectiveness is essential to protect at‐risk species and to maximize the limited resources available to land managers. Over 60% of North American grassland and aridlands have been lost since the 1800s. Birds in these habitats are among the most imperilled in North America, yet most remaining habitats are unprotected. Despite the need to measure impact, conservation efforts on private and working lands are rarely evaluated, due in part to limited availability of suitable methods.LocationNorthern Great Plains of North America.MethodsWe developed a novel metric to evaluate grassland and aridland bird community response to habitat management, the Bird‐Friendliness Index (BFI), consisting of density estimates of grassland and aridland birds weighted by conservation need and a functional diversity metric to incorporate resiliency. We used the BFI to identify ecologically significant areas for grassland and aridland birds and compared them with other prioritizations. Then, we used the BFI to evaluate the effects of simulated habitat management on grassland and aridland bird communities.ResultsThe most resilient bird communities were found in the Prairie Potholes region of Alberta, Saskatchewan and North Dakota and the lowest BFI values in the southern and western regions of the Northern Great Plains. BFI values were significantly greater in areas included in one or more prioritization, and increased with the number of prioritizations an area was included within. BFI values increased in response to simulated bird‐friendly habitat management.Main conclusionsOur findings suggest that practices recommended for use in bird‐friendly grassland habitat management plans will increase the abundance and resilience of the grassland and aridland bird community and that bird community responses to management will be detected using the BFI. The BFI is a tool by which conservationists and managers can carry out adaptive management and accountable conservation now and into the future.

Effects of habitat transitions on rainforest bird communities across an anthropogenic landscape mosaic

AbstractWe compared bird community responses to the habitat transitions of rainforest‐to‐pasture conversion, consequent habitat fragmentation, and post‐agricultural regeneration, across a landscape mosaic of about 600 km2 in the eastern Australian subtropics. Birds were surveyed in seven habitats: continuous mature rainforest; two size classes of mature rainforest fragment (4–21 ha and 1–3 ha); regrowth forest patches dominated by a non‐native tree (2–20 ha, 30–50 years old); two types of isolated mature trees in pasture; and treeless pasture, with six sites per habitat. We compared the avifauna among habitats and among sites, at the levels of species, functional guilds, and community‐wide. Community‐wide species richness and abundance of birds in pasture sites were about one‐fifth and one‐third, respectively, of their values in mature rainforest (irrespective of patch size). Many measured attributes changed progressively across a gradient of increased habitat simplification. Rainforest specialists became less common and less diverse with decreased habitat patch size and vegetation maturity. However, even rainforest fragments of 1–3 ha supported about half of these species. Forest generalist species were largely insensitive to patch size and successional stage. Few species reached their greatest abundance in either small rainforest fragments or regrowth. All pastures were dominated by bird species whose typical native habitats were grassland, wetland, and open eucalypt forest, while pasture trees modestly enhanced local bird communities. Overall, even small scattered patches of mature and regrowth forest contributed substantial bird diversity to local landscapes. Therefore, maximizing the aggregate rainforest area is a useful regional conservation strategy.

Arthropod abundance modulates bird community responses to urbanization

AbstractAimWe analysed the role of species interactions in wildlife community responses to urbanization. Specifically, we investigated non‐trophic associations within a bird community and the role of trophic interactions in the responses of bird species to the urbanization gradient.LocationCity‐state of Berlin, Central Europe.MethodsArthropod and bird abundances were sampled across the study area and analysed using hierarchical joint species distribution models (JSDMs). Urbanization gradient was defined by environmental predictors reflecting anthropogenic disturbances, for example noise level and human population density, as well as nature‐like features, for example tree cover and open green area. Relevant environmental predictors for each group and relevant spatial resolution were selected a priori using AICc. Arthropod abundances were modelled for the bird sampling transects and included as additional predictor variable in the bird community model. In this model, we used abundances and traits of 66 breeding bird species as response variables.ResultsBird species responses to urbanization were captured by the interaction between invertebrate abundance and environmental predictors. We identified three groups of birds: the urban group (12 species) showed no decrease in abundance along the urbanization gradient and were not related to arthropods abundance; the woodland group (18 species) were positively related to tree cover and arthropod abundance, also in areas with high anthropogenic disturbance; and the nature group (36 species) were positively related to arthropod abundance, but the species abundance decreased sharply with increasing anthropogenic disturbance. All the non‐trophic associations found within the bird community were positive.Main conclusionsArthropod abundance clearly modulated birds’ responses to the urbanization gradient for most species. Especially at moderate levels of anthropogenic disturbance, the abundance of arthropods is key for the occurrence and abundance of bird species in urban areas. To maintain bird diversity in urban green areas, management measures should focus on maintaining and increasing invertebrate abundance.

BIRD COMMUNITY STRUCTURE IN MACROHABITATS OF THE AQUATICTERRESTRIAL TRANSITION ZONE IN THE PANTANAL WETLAND, BRAZIL

Ecological responses of bird communities in aquatic-terrestrial transition zones (ATTZs) are only partially understood. The aim of this study was to evaluate community structure of birds in different macrohabitats of ATTZs from a protected area in the Pantanal wetland, Brazil. The survey of birds was carried out in three types of macrohabitats: Erythrina fusca Lour. monospecific forest, shrubland and pioneer polyespecific forest, and flooded grassland. The bird community living within the ATTZ varied according to macrohabitat type and period of the wetland landscape. We emphasise the need to expand this protected area, and exert greater environmental control, since the region is not exempt from direct and indirect impacts derived from the Upper Paraguay River Basin.

Impacts of an invasive plant on bird communities differ along a habitat gradient

Plants invasions may have important impacts on populations of the native species including birds. We can expect that these impacts will vary in respect to the ecological context where the species live. Consequences of such a variation are, however, still poorly understood. For this purpose, we studied the responses of bird communities to the invasion of Sosnowsky’s hogweed (Heracleum sosnowskyi) along a gradient from open to forest habitats in relation to the ecological traits of bird species. The research was conducted in southern Poland in spring 2019. Birds were counted twice on 52 site pairs (control and Heracleum). As expected, the invader had generally negative impact on the total number of birds, their species richness and abundance of all bird guilds except the birds living in the ecotone zone. However, the magnitude of these impacts significantly differed along the habitat gradient: the response of ground dwellers and farmland birds to the invasion was more negative towards open habitats, while the opposite pattern, i.e. a more negative response towards forest habitats, was observed in birds associated with bushes. Individual bird species, however, sometimes differed in the direction and severity of the response to the invasion from the guild to which they belonged. Taken together, our results indicate that the impact of Sosnowsky’s hogweed depended on habitats preferred by individual species and whether this alien changed their habitat. This finding should be taken into account when designing management plans for the affected species.

Regional variability in landscape effects on forest bird communities

ContextFunctional responses to landscape heterogeneity are context-dependent, hampering the transferability of landscape-scale conservation initiatives. Japan provides a unique opportunity to test for regional modification of landscape effects due to its broad temperature gradient, coincident with a gradient of historical disturbance intensity.ObjectivesTo quantify and understand how regional contexts modify forest bird community responses to landscape heterogeneity across Japan.MethodsWe characterised the functional trait composition and diversity of breeding bird communities from 297 forest sites, and applied a cross-scale analytical framework to explain regional variation in community responses.ResultsThe effects of landscape diversity, coincident with forest loss, varied in strength and even direction across the temperature gradient. Cool regions of Japan with highly forested, homogeneous landscapes supported bird communities dominated by forest specialists: those with narrow habitat breadths and insectivorous diets. Warmer regions comprised communities dominated by generalists with wider habitat breadths, even in contiguous, highly forested landscapes. Heterogeneous landscapes selected for generalists, and only promoted functional trait diversity in cool regions where both specialists and generalists can be supplied by a diverse regional pool.ConclusionsOur results provide evidence that regional variation in trait responses to landscape heterogeneity—driven by past environmental filtering and broad-scale climates—leads to differential community responses across Japan. Future research that seeks a nuanced understanding of the regional modification of landscape variables will better serve to inform and target real-world conservation efforts.

Long-term response of forest bird communities to retention forestry in northern temperate coniferous forests

Retention forestry aims to maintain structural and functional continuity in managed stands. While short-term benefits to forest dwellers are well documented, few studies have followed patterns over decades to assess whether benefits continue. Initiated in 1992, the Date Creek Research Forest in northwest BC includes four replicates of four retention levels: 0% (clearcut), 40%, 70% and 100% (unharvested control). These ~20-hectare stands, with retention designed to mimic typical insect and wind disturbance, are now entering the canopy closure seral stage. We followed breeding bird community dynamics over 25 years (pre-harvest and 24 years post-harvest). Given relatively consistent landscape conditions over time, we focused on stand-level changes in bird community composition and species abundance. Community similarity to controls decreased as retention decreased; communities changed over time, with those in clearcuts changing most. Patterns in species abundance varied with habitat preference. Conifer-forest species declined immediately after harvest, with some responding linearly to retention level while others responded similarly to 40%, 70% and 100% treatments; Pacific Slope Flycatcher, Pacific Wren and Brown Creeper remained significantly less abundant in some treatments by year 24. Open-habitat and generalist species increased most in clearcut and somewhat in 40% retention stands, with generalists taking advantage of the increased heterogeneity immediately and open-habitat species colonizing by year 10; some of these species, particularly shrub specialists, remained at high abundance in harvested stands in year 24. Mixed-forest species reached their highest abundance at 40% retention in year 2 and 10, and dropped to control levels by year 24. Although conifer-forest, open-habitat and generalist species treated retention stands as intermediate between clearcuts and controls, mixed-forest species perceived them as a different, preferred habitat for the first decade. We conclude first that most forest birds do not discriminate between 70% retention stands and unharvested forest, confirming strategies in the region to maintain biodiversity in landscape corridors, second that aggregated 40% patch retention partially or fully mitigates impacts for conifer-forest birds, and provides new habitat for mixed-forest and open-habitat species, and third that bird communities are still changing after 24 years as these stands enter canopy closure.

Bird Communities in Urban Riparian Areas: Response to the Local- and Landscape-Scale Environmental Variables

Understanding how environmental changes driven by urbanization impact the biodiversity in urban riparian areas has great importance for landscape planning and river ecosystem conservation. There have been many studies on the response of bird communities to different environmental variables in urban parks; however, although supporting some of the highest bird diversities, case studies in urban riparian areas remain limited. In existing research, few studies have considered the impact of both local waterfront characteristics and surrounding environmental variables at a larger scale. In this study, we selected birds as the indicator to clarify their response to both local- and landscape-scale environmental variables in riparian areas of Tsing river, Beijing, in terms of (a) vegetation composition, (b) human disturbance, (c) land cover, and (d) landscape connectivity. We hypothesized that birds with different biological characteristics may respond differently to environmental variables. Birds were then further grouped according to the habitat type, residential type, and feeding type. It turned out that the coverage of grass and the disturbance of pedestrians are the most influential variables. Besides, compared with the land cover and landscape connectivity, the total contribution of vegetation characteristics and human disturbance accounts for the main proportion of explained variance. Information pertaining to these environmental variables can provide evidence to support bird conservation efforts in urban areas, and the identified distance threshold provides a basis for future landscape connectivity assessments.

Using a species-centered approach to predict bird community responses to habitat fragmentation

The relative importance of habitat fragmentation versus loss on species richness has been much debated. However, recent findings that fragmentation effects are relatively weak may be an artifact of using human-classified vegetation rather than adopting a species-eye view to measure landscape structure. We present the first example of a species-centered approach for examining fragmentation effects on ecological communities. We tested hypotheses relating to the relative influence of habitat amount, configuration, and focal patch size on southwest Oregon bird communities. We used boosted regression trees based on unclassified Landsat TM to create ‘stacked’ species distribution models (S-SDMs) for a large pool of avian species and nested subset of habitat specialists. We tested the relative importance of S-SDM-derived habitat amount, patch number, mean patch size, and focal patch size in explaining species richness. We compared this approach to metrics based on generic land-cover classifications. Species-centered models had greater statistical support than land-cover models. In species-centered models, species richness increased as a function of focal patch size and decreased with patch number, supporting the hypothesis of negative effects of fragmentation per se. Land-cover based models indicated inconsistent support for habitat amount but a positive effect of fragmentation. The species-centered approach identified habitat configuration relationships obscured by land-cover based approaches. While positive land-cover based fragmentation effects were consistent with recent synthesis work, the species-centered approach consistently revealed strong negative effects of fragmentation matching traditional theoretical expectations. S-SDMs may offer promise for generalizing ecological theory to real species distributions.

Functional shifts in bird communities from semi-natural oak forests to conifer plantations are not consistent across Europe.

While the area of plantation forest increased globally between 2010 and 2015, more than twice the area of natural forests was lost over the same period (6.5 million ha natural forest lost per year versus 3.2 million ha plantation gained per year). Consequently, there is an increasing need to understand how plantation land use affects biodiversity. The relative conservation value of plantation forests is context dependent, being influenced by previous land use, management regimes and landscape composition. What is less well understood, and of importance to conservation management, is the consistency of diversity patterns across regions, and the degree to which useful generalisations can be provided within and among bioregions. Here, we analyse forest birds in Ireland, France and Portugal, representing distinct regions across the Atlantic biogeographic area of Europe. We compared taxonomic, functional and phylogenetic diversity of bird communities among conifer plantations and semi-natural oak forests, and assessed correlations between species traits and forest type across these regions. Although bird composition (assessed with NMDS ordination) differed consistently between plantation and oak forests across all three regions, species richness and Shannon diversity did not show a consistent pattern. In Ireland and France, metrics of taxonomic diversity (richness and Shannon diversity), functional diversity, functional dispersion and phylogenetic diversity were greater in oak forests than plantations. However, in Portugal taxonomic and phylogenetic diversity did not differ significantly between forest types, while functional diversity and dispersion were statistically significantly greater in plantations. No single bird trait-forest type association correlated in a consistent direction across the three study regions. Trait associations for the French bird communities appeared intermediate between those in Ireland and Portugal, and when trait correlations were significant in both Ireland and Portugal, the direction of the correlation was always opposite. The variation in response of bird communities to conifer plantations indicates that care is needed when generalising patterns of community diversity and assembly mechanisms across regions.

Response of Bird Community Toward Tourism Activities in the Karst Area of Bantimurung Bulusaraung National Park

ABSTRACTCountless birds live in environments that have been modified, to some degree, by human activities. This study aims to determine the response of bird community to tourism activities in the karst area of Bantimurung Bulusaraung National Park. Bird populations were observed and compared under four different circumstances: in the center of tourist activity (A) with a crowd (on weekends) or (B) without visitors (on weekdays), (C) in rarely used sites through which only the local community passes, and (D) in sites rarely visited by tourists. These circumstances represent four different gradients of human presence disturbances. ANOVA, Kruskal–Wallis, and Mann–Whitney were used to compare the differences in the number and composition of bird families, species, individuals, and feeding guilds. Results show a low number of birds in the crowded areas, thereby confirming the impact of human presence on the bird community.

The conservation value of cacao agroforestry for bird functional diversity in tropical agricultural landscapes.

Cacao agroforestry have been considered as biodiversity‐friendly farming practices by maintaining habitats for a high diversity of species in tropical landscapes. However, little information is available to evaluate whether this agrosystem can maintain functional diversity, given that agricultural changes can affect the functional components, but not the taxonomic one (e.g., species richness). Thus, considering functional traits improve the understanding of the agricultural impacts on biodiversity. Here, we measured functional diversity (functional richness‐FD, functional evenness‐FEve, and functional divergence‐Rao) and taxonomic diversity (species richness and Simpson index) to evaluate changes of bird diversity in cacao agroforestry in comparison with nearby mature forests (old‐growth forests) in the Brazilian Atlantic Forest. We used data from two landscapes with constraining areas of mature forest (49% Una and 4.8% Ilhéus) and cacao agroforestry cover (6% and 82%, respectively). To remove any bias of species richness and to evaluate assembly processes (functional overdispersion or clustering), all functional indices were adjusted using null models. Our analyses considered the entire community, as well as separately for forest specialists, habitat generalists, and birds that contribute to seed dispersal (frugivores/granivores) or invertebrate removal (insectivores). Our findings showed that small cacao agroforestry in the forested landscape sustains functional diversity (FD and FEve) as diverse as nearby forests when considering the entire community, forest specialist, and habitat generalists. However, we observed declines for frugivores/granivores and insectivores (FD and Rao). These responses of bird communities differed from those observed by taxonomic diversity, suggesting that even species‐rich communities in agroforestry may capture lower functional diversity. Furthermore, communities in both landscapes showed either functional clustering or neutral processes as the main driver of functional assembly. Functional clustering may indicate that local conditions and resources were changed or lost, while neutral assemblies may reveal high functional redundancy at the landscape scale. In Ilhéus, the neutral assembly predominance suggests an effect of functional homogenization between habitats. Thus, the conservation value of cacao agroforestry to harbor species‐rich communities and ecosystem functions relies on smallholder production with reduced farm management in a forested landscape. Finally, we emphasize that seed dispersers and insectivores should be the priority conservation targets in cacao systems.

Regional variation in responses of wetland-associated bird communities to conversion of boreal forest to agriculture

Regional variation in responses of wetland-associated bird communities to conversion of boreal forest to agriculture

Bird community responses to changes in vegetation caused by increasing large mammal populations in the Serengeti woodlands

Context The increase in density of large tree species, Vachellia robusta and V. tortilis, in the Serengeti Ecosystem of Tanzania has resulted in a decline of small tree species Senegalia senegal, V. hockii, Commiphora spp. This change has occurred since the late 1970s, a consequence of an increase in wildebeest following the extirpation of rinderpest, which reduced the dry grass fuel for fires, resulting in low fire frequencies. Change in tree species raises the question of whether there are indirect consequences for the avifauna that depend on the large trees for food and nesting. Aims To determine how an increase in large mammals could influence diversity and distribution of avifauna communities in the Serengeti ecosystem woodlands. Methods Data used to estimate changes in density of large and small trees were measured by Point Centre Quarter (PCQ). Bird species were recorded in 19 small-tree sites and 18 large-tree sites in the Serengeti National Park. Richness of bird guilds was calculated in the two habitat complexes (small and large trees), and the ‘rarefaction’ method was used to assess the difference in richness in habitats of the study area. Mean abundance for each species was calculated over the total number of sites for each habitat and compared using the Wilcoxon Rank Sum test to examine how the abundance of avifauna changes with each habitat type. Key results There was an increase in the density of large trees in some areas in which they have replaced the original small trees. Such changes have resulted in greater richness of hole nesters and bark feeders, and a greater abundance of large-hole nesters and gleaner bird species. Conclusions Because the increase in tree density was caused by an increase in large mammals, we conclude that this increasing mammal population is indirectly increasing richness and abundance of birds using the trees. Implications Understanding the influence of large mammal populations on bird distributions has important conservation implications because the Serengeti ecosystem is classified as an important, endemic bird area.

Urbanization as a driver of taxonomic, functional, and phylogenetic diversity losses in bird communities

Urbanization is one of the most important threats to biodiversity worldwide, as it drives declines in species diversity, functional diversity, and phylogenetic diversity and increases functional redundancy among species. We estimated taxonomic, functional, and phylogenetic diversities, as well as the abundance of several functional groups, in bird communities from a town in east-central Argentina in 1985–1986 and 30 years after (2015–2016). In 1985–1986, we found that taxonomic diversity (abundance, species richness, and alpha diversity), functional richness, and basal phylogenetic diversity were negatively related to building cover, whereas terminal phylogenetic diversity showed a positive relationship with building cover. Moreover, the abundance of specialized functional groups (ground, aerial, and foliage insectivores; nectarivores/insectivores; ground/canopy and ground granivores) decreased with increased building cover, whereas the reverse pattern for the abundance of generalists (medium-sized/large and small omnivores) was found. In 2015–2016, by contrast, taxonomic, functional, and phylogenetic diversities were not related to building cover. Our results not only support the hypothesis that urbanization affects the potential number of ecosystem functions, but also that this relationship may change through time. Given the accelerated rate of urbanization worldwide, an integrative approach between different facets of biodiversity is promoted to gain insight into the response of bird communities in urban environments.

Disturbance shapes avian communities on a grassland–sagebrush ecotone

AbstractEcotones, or transitional zones between ecosystems, are often hotspots for biodiversity and targets for conservation. Where the Great Plains meet the sagebrush (Artemisia spp.) steppe, an opportunity exists to conserve habitat for the two most imperiled avian guilds in North America, grassland and shrub‐steppe birds. This ecotone creates a unique challenge with respect to the management of disturbance processes, such as fire and grazing, because grassland and sagebrush‐shrubland birds respond quite dissimilarly to disturbance. To address this management challenge and maximize conservation opportunities, we examined the responses of grassland and sagebrush bird communities to disturbance at a grassland–sagebrush ecotone in northeast Wyoming, USA. Specifically, we surveyed bird communities on active black‐tailed prairie dog (Cynomys ludovicianus) colonies and burned areas, as well as on paired undisturbed points in 2016 and 2017. Bird community structure varied in response to both the presence and type of disturbance. Although alpha diversity of avian species was highest on undisturbed sites and burned areas, only prairie dog colonies provided breeding habitat for the imperiled shortgrass‐obligate mountain plover (Charadrius montanus), and species turnover (beta diversity) was greatest between on‐colony and off‐colony points. Furthermore, bird communities were shaped by both disturbance‐dependent (e.g., disturbance age) and disturbance‐independent (e.g., topography and soils) landscape features. Managers must balance the benefits of high species diversity in undisturbed sagebrush with habitat requirements of other imperiled species like the mountain plover. This may entail prioritizing the amount and distribution of disturbances in relation to population goals for species of conservation concern while simultaneously maintaining a mosaic of all three patch types in this landscape.

The impact of cattle grazing regimes on tropical savanna bird assemblages

AbstractGlobally, agricultural land use is implicated in the decline of avifauna. In rangelands (areas used for livestock grazing), bird community responses to grazing can be complex, species‐specific and scale dependent. A greater understanding of bird responses to grazing will lead to more meaningful management recommendations. We tested the hypothesis that foraging height predicts bird species’ responses to grazing, such that species using lower vegetation strata are most likely to respond to the impacts of livestock grazing. We examined the response of a tropical savanna bird community to four grazing strategies at a long‐term grazing trial in northern Australia. We predicted that ground‐foraging guilds would be more responsive to grazing treatment than foliage‐ or aerial‐foraging guilds. We analysed the bird community assemblage using generalised linear mixed models and examined individual species’ abundance in relation to microhabitat variables. We found that while ground‐foraging guilds were more responsive to grazing treatment, individual species dynamics within a foraging guild could be contradictory. For example, the red‐backed fairy‐wren decreased in abundance with increased grazing and was positively associated with grass and shrub (Carissa ovata) cover, whereas Australian magpies increased in abundance in the most heavily grazed paddocks. In general, the responses of bird species to grazing were more pronounced in guilds that forage closer to the ground, but whether the responses were positive or negative was driven by bird species ecology. Measures examining the responses of individual species are more useful than assemblage measures (such as richness) to describe the impacts of anthropogenic disturbance such as grazing.

Hindcasting the impacts of land-use changes on bird communities with species distribution models of Bird Atlas data.

Habitat loss and degradation induced by human development are among the major threats to biodiversity worldwide. In this study, we tested our ability to predict the response of bird communities (128 species) to land-use changes in southern Quebec (~483,100km2 ) over the last 30yr (between 1984-1989 and 2010-2014) by using species distribution models (299,302 occurrences in 30,408 locations) from a hindcasting perspective. Results were grouped by functional guilds to infer potential impacts on ecosystem services, and to relate model transferability (i.e., ability of our models to be generalized to other times and scales) to specific functional and life-history traits. Overall, our models were able to accurately predict, both in space and time, habitat suitability for 69% of species, especially for granivorous, nonmigrant, tree-nesting species, and species that are tied to agricultural areas under intensive use. These findings indicate that model transferability depends upon specific functional and life-history traits, providing further evidence that species' ecologies affect the ability of models to accurately predict bird distributions. Declining bird species were mostly short-distance migrants that were associated with open habitats (agricultural and nonproductive forest) with aerial insectivorous or granivorous diets, which may be related to agricultural intensification and land abandonment. Land-use changes were positive for some forest bird species that were mainly associated with mixed and deciduous forests, generalist diets and tree-nesting strategies. Yet cavity-nesting birds have suffered substantial reductions in their distributions, suggesting that cumulative effects of intensive logging and wildfires on mature forests pose a threat for forest-specialist species. Habitat suitability changes predicted by our coarse-scale species distribution models partially agreed with the long-term trends reported by the North American Breeding Bird Survey. Our findings confirm land-use change as a key driving force for shaping bird communities in southern Quebec, together with the need to explicitly incorporate it into global change scenarios that better inform decision-makers on conservation and management.

Shifts in vegetation and avian community structure following the decline of a foundational forest species, the eastern hemlock

Eastern hemlock (Tsuga canadensis) is undergoing widespread decline throughout the eastern United States due to the introduction of the nonnative hemlock woolly adelgid (Adelges tsugae). In light of hemlock's unique significance for avian communities, we examined the long-term response of the breeding bird community to the decline and die-off of this foundational forest species. We conducted variable-radius point counts to survey bird communities in both hemlock and hardwood stands in 2000, during the early stages of adelgid infestation, and again in 2015 and 2016, following significant hemlock decline. We also measured the severity of hemlock decline and associated vegetation variables in the same hemlock stands in which avian surveys were completed. We used multispecies occupancy models to examine species-specific and species group responses to hemlock decline. Results showed that, across hemlock stands, hemlock basal area declined from a mean of 56% of the total basal area to 46%, and that hemlock decline was correlated with current vegetation structure, including an increased deciduous understory. Species richness of hemlock-associated birds declined by an average of ∼1 species per survey location. The Black-throated Green Warbler (Setophaga virens) was the most strongly affected, declining in occupancy by 30%. All other species groups responded positively, with the strongest responses by species associated with the shrub layer, forest edge, and mature deciduous habitat. The species composition in hemlock and hardwood stands became more similar over time as the unique species assemblages in hemlock stands gave way to the avian community of the surrounding hardwood landscape, highlighting a trend toward homogenization of the avian community. Where hemlock-associated bird species persisted, their presence was correlated with a combined effect of greater hemlock basal area and better hemlock condition. Our results demonstrate that the decline of hemlocks has restructured vegetation communities and their associated avian communities over time, with strong implications for forest-specialist birds.