Avian Community Composition Research Articles

Retrofitting streetlights with LEDs has limited impacts on urban wildlife

Artificial light at night (ALAN) causes a wide range of ecological impacts across diverse ecosystems. Most concentrated in urban areas, ALAN poses a particular risk to associated wildlife by disrupting physiology, behaviour and ultimately survival. This risk is predicted to shift as nighttime lightscapes in many cities undergo change. Globally, streetlights are currently being retrofitted with newer technologies that differ in the spectrum and intensity of their emissions, but there is a dearth of in situ urban experiments on the ecological impacts of this change. We monitored timing of dawn and dusk bird song; frequency of owl vocalisations; avian diversity, relative abundance and community composition; small invasive mammal and ground insect activity; and invertebrate relative abundance at 26 residential properties over an 18-month period that coincided with a retrofit from high-pressure sodium (HPS) to white light-emitting diode (LED) streetlights. Initiation time of dawn song was advanced or delayed for two bird species following the retrofit and backyard avian community composition was altered. Avian species richness, relative abundances of three bird species and ground insect activity increased in the presence of LED streetlights. No other retrofit effects were found. Our study suggests that retrofitting streetlights with white LEDs may lead to both positive and negative conservation outcomes for urban wildlife, but direct impacts are relatively small and may be mitigated by changes in lighting characteristics, such as dimming. Streetlight retrofits could provide an opportunity to reduce the impacts of ALAN on urban wildlife if intentionally designed with conservation benefits in mind.

A summer and winter’s tale: factors influencing avian community composition and species abundances in lowland subtropical floodplain forests in central eastern Australia

The ecology of avian community assembly in subtropical climate areas with seasonal and year-to-year variability is complex and poorly understood. To test for variation in year–year and seasonal (summer–winter) avian community composition and species abundances, we established 10 transects (200 m long) and sampled twice yearly for 7 years. To differentiate year–year and seasonal (summer–winter) patterns from the potential disturbance effects caused by human activities associated with music festivals (events), we monitored community composition and species abundances on sites close to disturbance areas (impact) and sites distant from disturbances (control). Impacts from large scale music events included loud noise, and thousands of vehicle and people movements on a daily basis. Raw count, abundance-weighted, and feeding guild data were analysed using multivariate and univariate methods. Seasonal (summer–winter) patterns of food resource availability in dominant forest trees (fruit and nectar resources) were identified. We found strong signals for the influence of seasonality and seasonal resource availability on community composition and feeding guild representation (nectivores and frugivores). We detected somewhat weaker effects for location relative to disturbance (control vs impact) and weak effects for sample timing associated with disturbance from the events. Avian community composition showed high similarity between control and impact sites, was dynamic in space and time (year to year) and showed strong local and regional trends in response to seasonality. Avian species abundances were greater in less disturbed (control) forest habitats, highlighting the fundamental value of conservation reserves in protecting higher quality avian habitats.

Avian Community Composition and Spatio-Temporal Patterns at Deva Vatala National Park, Azad Jammu and Kashmir, Pakistan

Avian Community Composition and Spatio-Temporal Patterns at Deva Vatala National Park, Azad Jammu and Kashmir, Pakistan

Avian community response to landscape-scale habitat reclamation

Reclamation projects encompassing more than several square kilometers (hereafter; landscape-scale) are a recommended strategy to mitigate the impacts of energy development on wildlife. However, the response of wildlife to landscape-scale reclamation remains largely undocumented. Oil and gas developments have contributed substantially to the loss and degradation of sagebrush ecosystems in North America. Management agencies are prioritizing habitat reclamation to mitigate habitat loss with an assumed benefit to wildlife, including songbirds. To determine the influence of landscape-scale habitat reclamation on songbirds, we measured avian species abundance and community composition in sagebrush habitats across a gradient of energy development: 1) active oil and gas, 2) landscape-scale reclamation, and 3) undisturbed sagebrush, in northeastern Wyoming, USA (2016–2018). We modeled the influence of treatment (active, reclaimed, and control), and key habitat variables on songbird abundance using a Bayesian hierarchical approach. We also assessed differences in community composition across treatments using the rarity-weighted richness estimate and the Jaccard Similarity Index. Reclamation efforts had a measurable influence on some species abundance. Human-commensal species increased in abundance with increasing disturbance, which may have increased species richness and rarity in our active and reclaimed sites. The community composition in reclaimed areas more closely resembled undeveloped habitat (control), than active development areas. Terrain roughness was the most consistently influential variable on abundance, and we recommend that this often overlooked habitat variable be included in future studies. The habitat variables that represent where we can most easily target reclamation efforts (e.g., herbaceous cover) had minimal influence on abundance.

Sagebrush Bird Communities Differ with Varying Levels of Crested Wheatgrass Invasion

AbstractSagebrush communities, covering millions of hectares in the western United States, are among our most imperiled ecosystems. They are challenged by various anthropogenic stressors, including invasion by nonnative grasses that degrade habitat quality and alter ecosystem function. Sagebrush restoration efforts are underway to improve habitat conditions to benefit a wide range of sagebrush-dependent species. Because birds are good indicators of habitat quality, monitoring avian metrics is an effective way to measure progress of sagebrush restoration. We compared avian community composition and individual species abundance among three sagebrush–steppe habitat types with varying degrees of invasion by nonnative crested wheatgrass Agropyron cristatum at the Camas National Wildlife Refuge in southeastern Idaho, USA. Sagebrush-obligate birds, such as sage thrasher Oreoscoptes montanus and sagebrush sparrow Artemisiospiza nevadensis, were most abundant in sagebrush habitats with an understory of native grass. Community composition was similar between sagebrush habitats with native and nonnative grasses, but quite different from bird communities occupying crested wheatgrass. The Habitats and Populations Strategies database, a conservation planning tool, predicts that restoration of crested wheatgrass sites to sagebrush in poor or fair condition will increase the density of sagebrush-obligate bird species. Taken together, these results suggest that restoration of crested wheatgrass near-monocultures back to sagebrush will improve habitat value for much of the bird community whether or not the understory can be converted to primarily native grasses, or a mix of natives and nonnatives. Of the sagebrush bird species of concern, Brewer's sparrow Spizella breweri occupied sagebrush habitats with native vs. nonnative understory at similar abundances, and this species could serve as a metric of intermediate restoration success. However, sagebrush sparrow and sage thrasher, which were significant indicators of sagebrush with native grasses, will likely benefit most from full restoration of a native herbaceous understory. Grassland-obligate birds such as horned lark Eremophila alpestris and grasshopper sparrow Ammodramus savannarum were most abundant at crested wheatgrass–dominated sites and may not benefit from restoration back to shrubland; managers should understand potential trade-offs.

Treeline ecotones shape the distribution of avian species richness and functional diversity in south temperate mountains

Mountains produce distinct environmental gradients that may constrain or facilitate both the presence of avian species and/or specific combinations of functional traits. We addressed species richness and functional diversity to understand the relative importance of habitat structure and elevation in shaping avian diversity patterns in the south temperate Andes, Chile. During 2010–2018, we conducted 2202 point-counts in four mountain habitats (successional montane forest, old-growth montane forest, subalpine, and alpine) from 211 to 1,768 m in elevation and assembled trait data associated with resource use for each species to estimate species richness and functional diversity and turnover. We detected 74 species. Alpine specialists included 16 species (22%) occurring only above treeline with a mean elevational range of 298 m, while bird communities below treeline (78%) occupied a mean elevational range of 1,081 m. Treeline was an inflection line, above which species composition changed by 91% and there was a greater turnover in functional traits (2–3 times greater than communities below treeline). Alpine birds were almost exclusively migratory, inhabiting a restricted elevational range, and breeding in rock cavities. We conclude that elevation and habitat heterogeneity structure avian trait distributions and community composition, with a diverse ecotonal sub-alpine and a distinct alpine community.

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.

Urban divide: predictors of bird communities in forest fragments and the surrounding urban matrix

ABSTRACT Over 50% of the world’s human population lives in cities, and the rate of urbanisation continues to increase globally. Consequences of urbanisation, such as noise pollution and land use change, impact bird communities and movement dynamics. Furthermore, cities are fragmented and heterogeneous, so it is pertinent to assess how birds respond to urbanisation at different scales. We quantified avian community composition in relation to environmental variables at 1) a city scale across an urbanisation gradient, and 2) a smaller spatial scale, within urban forest fragments. In the gradient study, species richness was highest in the peri-urban zone and declined with urbanisation. Bird density peaked at a moderate level of urbanisation, with medium housing density. Native species were more likely to be recorded where there were more shrubs and trees, less noise pollution and fewer impermeable surfaces. Within urban forest fragments, bird communities were less likely to be dominated by a few introduced species, and had high native species richness relative to counts in the urban matrix. Increased native bird richness and abundance within fragments were primarily associated with less noise and lower neighbouring human density. Differences in bird composition between the urban matrix and urban fragments suggest the matrix can be improved to facilitate the dominance of native bird species by reducing noise and adding vegetation. Understanding how birds use urban environments not only allows us to measure changes as a result of urban intensification but also allows for management of cities to improve the status of urban bird communities.

Assessing avian diversity and community composition along a successional gradient in traditional Lacandon Maya agroforests

AbstractEvidence regarding the ability of agroforests to conserve biological diversity has been mixed; they tend to maintain avian communities with species richness similar to that of undisturbed forest ecosystems but generally do not completely preserve community composition. Using a combination of occupancy modeling and non‐metric multidimensional scaling on point‐count data, we assessed changes in avian community diversity and composition along a successional gradient in traditional Lacandon Maya agroforests and compared them to protected areas in the region. Bird species richness and diversity in Lacandon agroforests peaked in early secondary forest stages. These agroforests' mean Shannon–Weiner diversity was 5% higher than that of nearby protected areas, but their species richness was similar. Community composition in Lacandon agroforests changed throughout succession, with earlier stages supporting communities distinctly characterized by generalist species, while subsequent, less‐intensively managed stages tended to support more forest‐dwellers. The bird community observed in even the most mature secondary forest stages in Lacandon agroforests differed from that of undisturbed rain forest ecosystems. These results demonstrate the potential of traditional Lacandon agroforestry management to conserve avian biodiversity while ensuring food sovereignty for farmers. However, because the community composition of early‐successional stages was different than later stages, shortening fallow cycles and reducing forest cover to increase agricultural production will limit the species this system can support. This study illustrates the value of incorporating traditional agroecosystems into conservation planning as well as maintaining protected areas, because the latter serve as refugia for species that require undisturbed forest habitat in an agroecological matrix.Abstract in Spanish is available with online material.

Bird species richness in High-Andean forest fragments: habitat quality and topography matter

Montane forests worldwide are known centers of endemism and biodiversity but are highly threatened by fragmentation processes. Using data collected in 15 Polylepis forest remnants covering 2000 hectares, we investigated how bird species richness and bird community composition, particularly for species of conservation concern, are influenced by habitat quality and topography in the Tunari National Park in the High Andes of Bolivia. Bird species richness was highest in topographically complex, low-elevation Polylepis patches located in areas with a high potential to retain rainwater. Bird communities differed strongly between Polylepis lanata and P. subtusalbida remnants, each supporting different threatened and endemic species. Within the P. subtusalbida forest, high-elevation fragments characterized by high amounts of sunlight and low anthropogenic disturbance were more likely to contain threatened species. Surprisingly, we found no effect of fragment size on the diversity or composition of bird communities or the presence of bird species of conservation concern. The presence of exotic plantations (Pinus and/or Eucalyptus spp.) in or outside forest remnants was negatively associated with the number of bird species as well as with occurrence of the endangered Cochabamba-mountain finch (Compsospiza garleppi). To support the different communities found in Polylepis forests, these results suggest that conservation efforts should be directed towards both forest types (P. subtusalbida and P. lanata) present in the area. For an efficient management of avian diversity, exotic plantations should be established away from native remnants while existing patches should be managed to maintain or increase habitat quality. Finally, the importance of local topography in determining avian species richness and community composition in forest fragments, mainly through topographic controls on moisture distribution and the amount of sunlight received by the fragments, should be considered when planning conservation and reforestation schemes.

Tropical forest fragmentation and isolation: Is community decay a random process?

Habitat destruction and degradation are the leading causes of species declines and extinctions in the world. Human altered landscapes often leave fragments of previously continuous habitat, which may be of significant conservation value. We assessed the effects of habitat fragmentation on the taxonomic diversity, community composition, and nestedness of avian communities before and after fragment isolation at the Biological Dynamics of Forest Fragments Project research site in the Amazon rainforest. Species loss in 10ha and 100ha fragments was significantly different from random taxonomic loss. In addition, after fragment isolation, but not prior to fragmentation, the species in the 10ha fragments were a nested subset of the species in the 100ha fragments. Finally, within the fragments two distinct communities formed, those on the edge of the fragments and those at the interior of the fragments, indicating that edge species did not penetrate the interior portion of the fragments. The controlled isolation of fragments from continuous forest resulted in rapid changes in the taxonomic diversity and species composition where fragment size served as a driver of species assemblages across the landscape. We suggest that future research continue to assess community level adjustments to habitat fragmentation and investigate the drivers behind the non-random loss of taxonomic groups and the nested structure of species composition of smaller fragments into larger ones after habitat fragmentation.

Conservation and Production Responses Vary by Disturbance Intensity in a Long‐Term Forest Management Experiment

Reductions in management intensity are often proposed to support a broader range of beneficial ecosystem responses than traditional management approaches. However, few studies evaluate responses across approaches. We used data collected over eight years from a manipulative experiment in the Coast Range, Oregon, USA, to test how four strategies influenced avian community composition and wood production. Our results suggested that the least intensive prescription will cause substantial reductions in wood biomass while providing modest, temporary gains for avian species richness and diversity. Current operational practices provided more balance between these two responses. Photo credit: Jake Verschuyl. Photo credit: Jake Verschuyl. These photographs illustrate the article “Conservation and production responses vary by disturbance intensity in a long-term forest management experiment” by Andrew J. Kroll, Aaron Springford, and Jake Verschuyl published in Ecological Applications. https://doi.org/10.1002/eap.2148

Conservation and production responses vary by disturbance intensity in a long-term forest management experiment.

Reductions in management intensity are often proposed to support a broader range of beneficial ecosystem responses than traditional management approaches. However, few studies evaluate ecosystem responses across approaches. Also, managers lack information about how species traits mediate responses across management approaches, a potentially substantial source of spatial and temporal variation in population and community responses that if ignored may hinder effectiveness of management programs. We used data collected over eight years from a manipulative experiment to test how four forest management strategies influenced avian community composition and wood production. After harvesting, we evaluated responses to three levels of plant cover suppression (Light, Moderate, and Intensive herbicide applications) in relation to a control without herbicide. We predicted the Moderate and Intensive treatments would exert strong negative effects on leaf-gleaning insectivores, including species of conservation concern due to long-term population declines. However, given high forest productivity, we expected temporal duration of effects to be short. Richness of leaf-gleaning bird species was reduced by 20-50% during the first four years post-harvest (when herbicide treatments were on-going), but the effect size declined over the next four years once treatments were completed (13-20% reduction). Effect sizes were substantially smaller for the non-leaf-gleaner group during years 1-4 (19-27%) and disappeared during years 5-8 (2-3%). However, in our final year of observation, we did find an average of five fewer non-leaf-gleaner species on Light vs. Control units. In the last two years of observation, turnover probabilities for the leaf-gleaner species remained higher on all treatments compared to the Control (0.11-0.21), indicating that new species continued to colonize treatments. Planted conifers were 40-44% taller and 74-81% larger in diameter in the Moderate and Intensive treatments compared to the Control, leading to substantial gains in wood biomass. Current practices provided more balance between two ecosystem responses, avian diversity and wood production, compared to less intensive alternatives. When short-term negative effects occur, the spatial distribution of harvesting and regeneration regionally indicates that habitat is often available locally to support leaf-gleaning and non-leaf-gleaning bird populations while releasing other portions of the region for high priority conservation objectives including late-successional forest reserves.

The role of native and introduced birds in transmission of avian malaria in Hawaii.

The introduction of nonnative species and reductions in native biodiversity have resulted in substantial changes in vector and host communities globally, but the consequences for pathogen transmission are poorly understood. In lowland Hawaii, bird communities are composed of primarily introduced species, with scattered populations of abundant native species. We examined the influence of avian host community composition, specifically the role of native and introduced species, as well as host diversity, on the prevalence of avian malaria (Plasmodium relictum) in the southern house mosquito (Culex quinquefasciatus). We also explored the reciprocal effect of malaria transmission on native host populationsand demography. Avian malaria infection prevalence in mosquitoes increased with the density and relative abundance of native birds, as well as host community competence, but was uncorrelated with host diversity. Avian malaria transmission was estimated to reduce population growth rates of Hawai'i 'amakihi (Chlorodrepanis virens) by 7-14%, but mortality from malaria could not explain gaps in this species' distribution at our sites. Our results suggest that, in Hawaii, native host species increase pathogen transmission to mosquitoes, but introduced species can also support malaria transmission alone. The increase in pathogen transmission with native bird abundance leads to additional disease mortality in native birds, further increasing disease impacts in an ecological feedback cycle. In addition, vector abundance was higher at sites without native birds and this overwhelmed the effects of host community composition on transmission such that infected mosquito abundance was highest at sites without native birds. Higher disease risk at these sites due to higher vector abundance could inhibit recolonization and recovery of native species to these areas. More broadly, this work shows how differences in host competence for a pathogen among native and introduced taxa can influence transmission and highlights the need to examine this question in other systems to determine the generality of this result.

Intensive farming drives long-term shifts in avian community composition.

Agricultural practices constitute both the greatest cause of biodiversity loss and the greatest opportunity for conservation1,2, given the shrinking scope of protected areas in many regions. Recent studies have documented the high levels of biodiversity-across many taxa and biomes-that agricultural landscapes can support over the short term1,3,4. However, little is known about the long-term effects of alternative agricultural practices on ecological communities4,5 Here we document changes in bird communities in intensive-agriculture, diversified-agriculture and natural-forest habitats in 4 regions of Costa Rica over a period of 18 years. Long-term directional shifts in bird communities were evident in intensive- and diversified-agricultural habitats, but were strongest in intensive-agricultural habitats, where the number of endemic and International Union for Conservation of Nature (IUCN) Red List species fell over time. All major guilds, including those involved in pest control, pollination and seed dispersal, were affected. Bird communities in intensive-agricultural habitats proved more susceptible to changes in climate, with hotter and drier periods associated with greater changes in community composition in these settings. These findings demonstrate that diversified agriculture can help to alleviate the long-term loss of biodiversity outside natural protected areas1.

Avian community composition, but not richness, differs between urban and exurban parks

Abstract Urban development alters landscape structure and available resources, potentially threatening avian diversity worldwide. However, it is unclear how bird communities respond in areas currently undergoing urban development, particularly in the non-breeding season. We examined avian communities at 8 parks in urban (within established urban matrix; >50% built cover) and 9 parks in exurban (within adjacent grassland; 5–20% built cover) areas in Sacramento County, CA. We measured bird species and abundance, conducting five line-transect surveys per park (85 total). We investigated factors influencing avian assemblage, including local habitat features (land cover, number of trees, fruiting trees and tree species, tree height and diameter at breast height, park size, park age), and landscape features (land cover within 500 m and distance to riparian habitat). Fifty bird species, including 15 migrants, were observed. Total species richness and abundance at urban and exurban parks was not significantly different, but community assemblages differed significantly. Park area positively predicted species richness. Abundance was negatively associated with in-park percent built cover, average number of fruiting trees and landscape-scale percent water cover. Species composition changes were associated with distance to riparian habitat and landscape percent grass cover for all but one exurban park; and with tree height, DBH and park and landscape percent tree cover for urban parks. The expansion of exurban areas in many parts of the world poses a significant risk for natural habitat loss. Parks in such areas should be planned to harbor some of the displaced biodiversity.

Bird communities across varying landcover types in a Neotropical city

AbstractUrbanization poses a serious threat to local biodiversity, yet towns and cities with abundant natural features may harbor important species populations and communities. While the contribution of urban greenspaces to conservation has been demonstrated by numerous studies within temperate regions, few consider the bird communities associated with different landcovers in Neotropical cities. To begin to fill this knowledge gap, we examined how the avifauna of a wetland city in northern Amazonia varied across six urban landcover types (coastal bluespace; urban bluespace; managed greenspace; unmanaged greenspace; dense urban; and sparse urban). We measured detections, species richness, and a series of ground cover variables that characterized the heterogeneity of each landcover, at 114 locations across the city. We recorded >10% (98) of Guyana's bird species in Georgetown, including taxa of conservation interest. Avian detections, richness, and community composition differed with landcover type. Indicator species analysis identified 29 species from across dietary guilds, which could be driving community composition. Comparing landcovers, species richness was highest in managed greenspaces and lowest in dense urban areas. The canal network had comparable levels of species richness to greenspaces. The waterways are likely to play a key role in enhancing habitat connectivity as they traverse densely urbanized areas. Both species and landcover information should be integrated into urban land‐use planning in the rapidly urbanizing Neotropics to maximize the conservation value of cities. This is imperative in the tropics, where anthropogenic pressures on species are growing significantly, and action needs to be taken to prevent biodiversity collapse.

Forest structure determines spatial changes in avian communities along an elevational gradient in tropical Africa

AbstractAimTo test if tree species richness and forest structure drive spatial variation in avian communities along a tropical elevation gradient and to present information about the role of detailed forest parameters.LocationA 2,000‐m long elevational gradient of tropical forest on Mt. Cameroon, west‐central Africa.TaxonBirds and trees.MethodsWe performed bird censuses and vegetation mapping at the same plots across six forested sites at elevations of 350, 650, 1,100, 1,500, 1,850, and 2,200 m a.s.l., with 16 plots per elevation. We tested the effects of elevation, forest structure and tree diversity on the species richness, functional diversity and β‐diversity of birds (Bray–Curtis dissimilarity). We used conditional inference trees based on random forests (RF) to investigate these relationships across all elevation sites as well as within elevations.ResultsBoth tree and bird species richness declined monotonically with elevation. Vegetation structure correlated with elevation, and all vegetation attributes significantly differed among elevations. The RF explained 70% of the variance in avian species richness, with the most important predictors being elevation, proportion of dead trees, tree species richness and herb layer coverage. We found that elevation (and shrub layer) was a particularly important predictor of avian functional diversity. We identified no important predictor of bird species richness after standardization within elevations, and the proportion of dead trees was the sole important predictor of functional diversity. Within‐elevation β‐diversity in avian community composition was determined by the dissimilarity of the tree community and differences in leaf area index, solar radiation and spatial distance. The functional dissimilarity was best explained by leaf area index.Main conclusionsApart from elevation itself, spatial distance even within elevations correlated with compositional and functional variation among avian assemblages. Forest structural traits can have a significant influence on distribution of birds. Thus, gaps in the spatial distribution of species such as along elevations might be caused by fine‐scale recognition of suitable habitats.

Differences exist in bird communities using restored and natural wetlands in the Parkland region, Alberta, Canada

Wetland restoration is used to compensate for historic and ongoing wetland losses. We compared bird community composition in 24 restored wetlands and 36 natural wetlands in the Parkland region of Alberta. Natural wetlands ranged in exposure to agricultural activity and were binned into three classes (low, medium, and high disturbance). Although the abundance and average species richness of birds were similar between restored and natural wetlands (analysis of variance: p > 0.22), the avian community composition differed significantly among wetland types (multiresponse permutation procedure [MRPP]: A = 0.05, p < 0.001). The avifauna using restored wetlands was distinct from the avifauna using natural wetlands spanning a range of disturbance levels (A = 0.02–0.06; p ≤ 0.006). Notably, restored wetlands were surrounded by less shrub/forest cover and more open water than low‐disturbance, natural wetlands. The majority (58%) of species using the surveyed wetlands were not classified as wetland‐dependent. Interestingly, if only wetland‐dependent species are considered, the avifauna using restored wetlands is no longer distinctive (MRPP: A < 0.01, p = 0.187), although the abundance of wetland‐dependent birds was marginally higher in restored wetlands (n = 24) than in low‐disturbance, natural wetlands (n = 10; Tukey's honestly significant difference test: p = 0.041). Overall, restored wetlands had reduced beta diversity compared to natural wetlands, regardless of whether the avifauna were restricted to wetland‐dependent species or considered comprehensively. This draws into question the legitimacy of the assumption that restoration can fully offset continued losses of natural wetlands.

Temporal changes in avian community composition in lowland conifer habitats at the southern edge of the boreal zone in the Adirondack Park, NY

Climate change represents one of the most significant threats to human and wildlife communities on the planet. Populations at range margins or transitions between biomes can be particularly instructive for observing changes in biological communities that may be driven by climate change. Avian communities in lowland boreal habitats in the Adirondack Park, located at the North American boreal-temperate ecotone, have been the focus of long-term monitoring efforts since 2007. By documenting long-term changes in community structure and composition, such datasets provide an opportunity to understand how boreal species are responding differently to climate change, and which habitat characteristics may be best able to retain boreal avian communities. We examined three specific questions in order to address how well current biological communities in Adirondack boreal wetland habitats are being maintained in a changing climate: (1) how do trends in occupancy vary across species, and what guilds or characteristics are associated with increasing or decreasing occupancy? (2) how is avian community composition changing differently across sites, and (3) what distinguishes sites which are retaining boreal birds to a higher degree than other sites? Our analysis revealed that (1) boreal species appear to exhibit the largest changes in occupancy among our study locations as compared to the larger avian community, (2) dynamics of community change are not uniform across sites and habitat structure may play an important role in driving observed changes, and (3) the particular characteristics of large open peatlands may allow them to serve as refugia for boreal species in the context of climate change.