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Landscape capability models as a tool to predict fine-scale forest bird occupancy and abundance

Authors:
Zachary Loman at University of Maine
Zachary Loman
William V. Deluca at National Audubon Society
William V. Deluca
Daniel J. Harrison at University of Maine
Daniel J. Harrison
Cynthia Loftin at United States Geological Survey
Cynthia Loftin
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Abstract and Figures

Context Species-specific models of landscape capability (LC) can inform landscape conservation design. Landscape capability is “the ability of the landscape to provide the environment […] and the local resources […] needed for survival and reproduction […] in sufficient quantity, quality and accessibility to meet the life history requirements of individuals and local populations.” Landscape capability incorporates species’ life histories, ecologies, and distributions to model habitat for current and future landscapes and climates as a proactive strategy for conservation planning. Objectives We tested the ability of a set of LC models to explain variation in point occupancy and abundance for seven bird species representative of spruce-fir, mixed conifer-hardwood, and riparian and wooded wetland macrohabitats. Methods We compiled point count data sets used for biological inventory, species monitoring, and field studies across the northeastern United States to create an independent validation data set. Our validation explicitly accounted for underestimation in validation data using joint distance and time removal sampling. Results Blackpoll warbler (Setophaga striata), wood thrush (Hylocichla mustelina), and Louisiana (Parkesia motacilla) and northern waterthrush (P. noveboracensis) models were validated as predicting variation in abundance, although this varied from not biologically meaningful (1%) to strongly meaningful (59%). We verified all seven species models [including ovenbird (Seiurus aurocapilla), blackburnian (Setophaga fusca) and cerulean warbler (Setophaga cerulea)], as all were positively related to occupancy data. Conclusions LC models represent a useful tool for conservation planning owing to their predictive ability over a regional extent. As improved remote-sensed data become available, LC layers are updated, which will improve predictions.
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RESEARCH ARTICLE
Landscape capability models as a tool to predict fine-scale
forest bird occupancy and abundance
Zachary G. Loman .William V. Deluca .Daniel J. Harrison .
Cynthia S. Loftin .Brian W. Rolek .Petra B. Wood
Received: 25 April 2017 / Accepted: 6 October 2017 / Published online: 16 October 2017
Springer Science+Business Media B.V. 2017
Abstract
Context Species-specific models of landscape capa-
bility (LC) can inform landscape conservation design.
Landscape capability is ‘‘the ability of the landscape to
provide the environment […] and the local resources
[…] needed for survival and reproduction […]in
sufficient quantity, quality and accessibility to meet
the life history requirements of individuals and local
populations.’’ Landscape capability incorporates spe-
cies’ life histories, ecologies, and distributions to
model habitat for current and future landscapes and
climates as a proactive strategy for conservation
planning.
Objectives We tested the ability of a set of LC
models to explain variation in point occupancy and
abundance for seven bird species representative of
spruce-fir, mixed conifer-hardwood, and riparian and
wooded wetland macrohabitats.
Methods We compiled point count data sets used for
biological inventory, species monitoring, and field
studies across the northeastern United States to create
an independent validation data set. Our validation
explicitly accounted for underestimation in validation
data using joint distance and time removal sampling.
Results Blackpoll warbler (Setophaga striata), wood
thrush (Hylocichla mustelina), and Louisiana (Parke-
sia motacilla) and northern waterthrush (P. novebo-
racensis) models were validated as predicting
variation in abundance, although this varied from not
biologically meaningful (1%) to strongly meaningful
Electronic supplementary material The online version of
this article (doi:10.1007/s10980-017-0582-z) contains supple-
mentary material, which is available to authorized users.
Z. G. Loman (&)D. J. Harrison B. W. Rolek
Department of Wildlife Fisheries and Conservation
Biology, University of Maine, 5755 Nutting Hall, Room
210, Orono, ME 04469, USA
e-mail: zachary.loman@maine.edu
W. V. Deluca
Department of Environmental Conservation, University of
Massachusetts, 160 Holdsworth Way, Amherst,
MA 01003, USA
C. S. Loftin
Maine Cooperative Fish and Wildlife Research Unit, U.S.
Geological Survey, 5755 Nutting Hall, Room 210, Orono,
ME 04469, USA
P. B. Wood
U.S. Geological Survey, West Virginia Cooperative Fish
and Wildlife Research Unit, West Virginia University,
P. O. Box 6125, 322 Percival Hall, Morgantown,
WV 26506, USA
123
Landscape Ecol (2018) 33:77–91
https://doi.org/10.1007/s10980-017-0582-z
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... To test these questions, we used the representative (i.e., proxy) species framework informing conservation at broad spatial scales devised by the North Atlantic Landscape Conservation Cooperative (NALCC). We sought to understand how models of proxy species' landscape capability (LC;McGarigal et al. 2016;Loman et al. 2017a) could best be used as proxies for represented species. LC models were created to predict the spatially-explicit capability of the landscape to support focal species (McGarigal et al. 2016), and they were designed to be useful at local scales (tens of meters to thousands of hectares; Poiani et al. 2000). ...
... We excluded detections at distances greater than 100 m when determining point occurrence. We used 30,065 point counts at 10,122 discrete spatially referenced locations that met our criteria (Loman et al. 2017a) to evaluate the following objectives. The first objective is the primary goal, with the subsequent objectives intended to provide additional clarity, or to answer additional questions that arose during analyses (Fig. 3). ...
... It should be considered that we tested the relationships at the finest scales possible given the survey methods (100 m survey radius) and that covariance in occurrence is scale-dependent with correlations that often are weaker at finer rather than broader scales (Weaver 1995;Prendergast and Eversham 1997). Predictive ability of even the best proxy LC model used to predict a represented species (67% accurate) typically was less than a LC model at predicting its own species' occurrence (i.e., not used as a proxy; range 62-90%; Loman et al. 2017a). Thus, while improving the proxyrepresented species pair is likely useful, it is not surprising that development of a larger suite of proxy models and reducing the number of proxy-represented species pairs will provide more accurate and precise predictions. ...
How well do proxy species models inform conservation of surrogate species?
Article
Full-text available
  • Oct 2021
  • LANDSCAPE ECOL
Context Proxy species, which represent suites of organisms with similar habitat requirements, are common in conservation. Landscape Capability (LC) models aim to quantify the spatially-explicit capability of landscapes to support proxy species that represent suites of forest birds. Objectives We evaluated the North Atlantic Landscape Conservation Cooperative (NALCC) proxy models of LC and represented species framework across 13 states in the northeastern United States from Virginia to Maine. We validated a suite of questions related to co-occurrence of proxy and represented species with a compilation of independent datasets. Methods We tested proxy species LC models ability to explain represented species’ occurrences, including using multiple proxies together, and benchmarked against empirical data and land cover type classifications. We tested effect of several factors on predictive ability including relative range overlap and ecological and taxonomic dissimilarity between proxy and represented species. Results LC models performed variably, but represented species occurrences were rarely predicted as accurately as proxy species. Models improved predictions over macrohabitat classifications. Using multiple proxies together occasionally improved predictions of represented species. Considerable range overlap was needed for models to be predictive of represented species. Ecological and taxonomic similarity had no effect on predictive ability. LC models worked similarly to using empirical observations, suggesting shortcomings were because of imperfect surrogacy. Conclusions Conservation proxies as representatives of species groups that are associated with macrohabitats are useful, but empirical data are necessary to evaluate proxy species’ effectiveness. Habitat-based models can provide similar predictive ability as empirical observations of proxies and represent a useful tool in conservation planning.
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... Detection probabilities ≥0.9 have been reported for ACFL in harvested and unharvested forests (Farnsworth et al. 2002;Twedt and Wilson 2017). In unharvested forests, reported detection probabilities for LOWA ranged from 0.7 to ≥0.9 (Loman et al. 2018;Reidy, Thompson, and Bailey 2011). Estimates of BHVI detection probability are sparse in the literature, and only one estimate for the species' detection probability near streams in Appalachian-hardwood forests has been reported (0.25-0.5; ...
Ten-Year Response of Riparian-Associated Songbirds to Implementation of Streamside Management Zones in Watershed-Scale Harvests in the Appalachian Mountains
Article
  • May 2024
Streamside management zones (SMZs) are regulated components of actively managed forests in the eastern United States, but width and overstory retention requirements vary widely among states. Within watershed-scale harvests, we evaluated the relative abundances of three riparian-associated songbirds (Acadian flycatcher, Empidonax virescens; blue-headed vireo, Vireo solitarius; and Louisiana waterthrush, Parkesia motacilla) near Appalachian headwater streams receiving three SMZ treatments representative of a range of current state SMZ regulations in the eastern United States. Prior to harvest, all species were relatively abundant near all stream types, including ephemerals. Abundances of all species were largely similar among SMZ treatments at 3 years and 10 years postharvest and were higher along streams with greater residual canopy cover within 100 m. Forested SMZs as prescribed by current regulations can sustain these species in managed forests up to 10 years postharvest, but abundance appears to be driven largely by canopy cover retention in adjacent stands. Managing habitat for riparian-associated songbirds in harvested watersheds will require expanding the extent of focus beyond the local stream corridor to include consideration of silvicultural systems that retain greater canopy cover in surrounding forests. Where conservation of riparian-associated songbirds is a management objective, SMZ protection should be extended to all streams. Study Implications. The results of this study suggest that forested streamside management zones (SMZs) mandated by contemporary best management practices (BMPs) in Kentucky and other eastern US states can sustain similar abundances of three riparian-associated songbirds in managed watersheds up to 10 years after harvest. Overstory retention in SMZs along perennial and intermittent streams is common across the eastern United States, but state BMPs rarely require retention along ephemeral streams. Target songbird species occupied forests along all stream types prior to harvest, and their postharvest abundances were positively associated with canopy retention within 100 m of streams. If long-term occupancy of managed stands by riparian-associated songbirds is an objective, we recommend using SMZs around all streams, including ephemerals, and implementing at least moderate-retention silvicultural systems in areas within 100 m of streams.
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... However, due to the lack of spatially explicit report data on the oak decline sites and associated environmental characteristics, risk assessment and mapping at landscape and regional scales are challenging, as researchers in other systems have also noted [22,23]. Other studies have successfully combined remote sensing and ground truthing to strengthen resulting models in a variety of systems and for different purposes, from mapping land cover [24] to testing models of habitat suitability [25]. Risk maps for tree health issues that use GIS and satellite information have been developed in a number of contexts, such as forest fire and disease spread [26,27]. ...
Integrating GIS, Remote Sensing, and Citizen Science to Map Oak Decline Risk across the Daniel Boone National Forest
Article
Full-text available
  • Apr 2023
Oak decline is a general term used for the progressive dieback and eventual mortality of oak trees due to many compounding stressors, typically a combination of predisposing, inciting, and contributing factors. While pinpointing individual causes of decline in oak trees is a challenge, past studies have identified site and stand characteristics associated with oak decline. In this study, we developed a risk map of oak decline for the Daniel Boone National Forest (DBNF), combining GIS, remote sensing (RS), and public reporting (citizen science, CS). Starting with ground reports of decline (CS), we developed a site-scale model (GIS and RS) for oak decline based on four previously identified predisposing factors: elevation, slope, solar radiation, and topographic wetness. We found that areas identified in the model as having a high oak decline risk also reflected areas of observed oak decline (CS). We then optimized and expanded this risk model to the entire range of the DBNF, based on both site characteristics (as piloted for the case study site) and stand inventory data. The stand inventory data (including species composition and age) further improved the model, resulting in a risk map at the landscape level. This case study can serve as a planning tool and highlights the potential usefulness of integrating GIS, remote sensing, and citizen science.
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... While these simple correlative models used only climatic variables, further analysis with more sophisticated models has similarly projected declines in the suitability of boreal birds in northeastern United States in the coming decades. McGarigal et al. [34] used climate, habitat, and land use variables to calculate and project changes in Landscape Capability, an index reflecting the ability of the landscape to meet species' breeding season natural history requirements [35]. There was a projected 64% decline in Landscape Capability for Blackpoll Warbler across northeastern United States by 2080, along with a predicted upslope shift in distribution greater than 100 m. ...
Conservation Lessons from the Study of North American Boreal Birds at Their Southern Periphery
Article
Full-text available
Many North American boreal forest birds reach the southern periphery of their distribution in the montane spruce–fir forests of northeastern United States and the barren coastal forests of Maritime Canada. Because the southern periphery may be the first to be impacted by warming climates, these populations provide a unique opportunity to examine several factors that will influence the conservation of this threatened group under climate change. We discuss recent research on boreal birds in Northeastern US and in Maritime Canada related to genetic diversity, population trends in abundance, distributional shifts in response to climate change, community composition, and threats from shifting nest predators. We discuss how results from these studies may inform the conservation of boreal birds in a warming world as well as open questions that need addressing.
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... It is often selected as an efficient metric for modeling ecological networks and maintaining biodiversity by using focal species, although usually empirical evidence is insufficient to verify the focal species [44,45]. However, studies considering the dispersal ability of the whole bird communities are still lacking, because information about their dispersal ability based on empirical evidence is limited in existing research [41,46]. ...
Bird Communities in Urban Riparian Areas: Response to the Local- and Landscape-Scale Environmental Variables
Article
Full-text available
  • Aug 2019
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.
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... Due to the strong relationship between elevation and precipitation in our study region (as noted above), we tested the relationship that the downscaled and interpolated precipitation values increase with elevation across our bird sampling locations with a linear regression model. These precipitation data are incorporated in fine-scale wildlife species distribution models and have been evaluated and used by the US Fish and Wildlife Service to inform landscape conservation design (Loman et al., 2017(Loman et al., , 2018. ...
Direct and indirect effects of climate on bird abundance along elevation gradients in the Northern Appalachian mountains
Article
Full-text available
Aim The stratification of organisms along elevational gradients is widely reported, with montane communities characterized by species occurring in relatively small and isolated populations; these species are of considerable interest to ecologists and conservationists. This stratification is generally attributed to climatic zonation. Evidence that species are shifting upward in elevation has fuelled speculation that species are tracking their climatic niches in response to climate change. Uncertainty regarding the degree to which climate directly influences species abundance versus the degree to which climate has an indirect influence via vegetation represents a key impediment to understanding the ecology of montane species; here, we evaluate these direct and indirect effects. Location White Mountains, New Hampshire, USA. Methods We used N‐mixture models to correct for imperfect detection of species, principal component analysis to represent gradients in vegetation structure and composition and structural equation models to assign variation to the direct and indirect effects of climate upon birds. Results Analysis of 13 species revealed that climate exerts direct influences on bird abundance and indirect influences mediated by vegetation composition and structure. All species exhibited indirect effects of climate via forest habitat, with 77% exhibiting both direct and indirect effects and 53% exhibiting stronger indirect effects. Main conclusions We provide insight into the mechanistic pathways of how climate influences the distribution of species along elevational gradients, underscoring the complex vulnerability of species to climate change. Our results reveal that the majority of species experience both direct and indirect effects of climate, implying that forests play a key role in mediating climate effects. For species that are primarily influenced by climate directly, typical climate envelope models may continue to be informative, but for the majority of the species included in this study, we show that distribution models should also include measures of habitat.
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... To be most effective, conservation network planning would include: 1) a good understanding of habitat requirements for the species of interest, including how variation in habitat types, amounts, and juxtapositions influence population growth [14]; 2) a method for translating knowledge of habitat requirements into a spatially-explicit map representing variation in habitat suitability at a scale relevant to the species [15,16]; 3) an understanding of each species' adaptive demographic response to multiple networks under both current and future conditions; and 4) performance metrics that can be used to rank networks in terms of their relative risk to species persistence or likelihood of achieving desired conservation outcomes. Conservation network planning typically uses a variety of modeling tools to determine species' habitat and resource requirements [17,18]. For evaluating potential critical habitat for the spotted owl, we chose this approach to provide decision makers with a set of scientifically defensible outputs from a series of plausible scenarios (viz., changes in habitat suitability and barred owl [S. ...
Conservation planning for species recovery under the Endangered Species Act: A case study with the Northern Spotted Owl
Article
Full-text available
The northern spotted owl (Strix occidentalis caurina) was listed as threatened under the U.S. Endangered Species Act (ESA) in 1990. We applied modern spatial conservation theory and models to evaluate several candidate critical habitat networks, and sought an efficient conservation solution that encompassed the highest value lands for spotted owl recovery rather than maximizing the total area of potential critical habitat. We created a map of relative habitat suitability, which served as input to the spatial conservation prioritization program Zonation. We used the spatially-explicit individual-based population model HexSim to estimate and compare simulated spotted owl population outcomes among a suite of candidate critical habitat networks that varied in size and spatial arrangement under alternative scenarios of future habitat suitability and barred owl (S. varia) effects. We evaluated simulated spotted owl population outcomes, including total population size, and extinction and quasi-extinction likelihoods for 108 combinations of candidate critical habitat networks by habitat change by barred owl scenarios, both range-wide and within 11 distinct portions of the owl’s range. Barred owl encounter rates and the amount and suitability of habitat had substantial effects on simulated spotted owl populations. When barred owl encounter rates were high, changes in the amount and suitability of habitat had minimal impacts on population performance. Under lowered barred owl encounter rates, candidate critical habitat networks that included most existing high suitability habitat supported a high likelihood of long-term population persistence. Barred owls are currently the primary driving force behind poor population performance of NSOs; however, our models demonstrated that a sufficient area of high suitability habitat remains essential for recovery when effects of barred owls can be reduced. The modeling approach we employed is sufficiently flexible to incorporate new information about spotted owls as it becomes available and could likely be applied to conservation planning for other species.
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... To be most effective, conservation network planning would include: 1) a good understand- ing of habitat requirements for the species of interest, including how variation in habitat types, amounts, and juxtapositions influence population growth [14]; 2) a method for translating knowledge of habitat requirements into a spatially-explicit map representing variation in habi- tat suitability at a scale relevant to the species [15,16]; 3) an understanding of each species' adaptive demographic response to multiple networks under both current and future condi- tions; and 4) performance metrics that can be used to rank networks in terms of their relative risk to species persistence or likelihood of achieving desired conservation outcomes. Conserva- tion network planning typically uses a variety of modeling tools to determine species' habitat and resource requirements [17,18]. For evaluating potential critical habitat for the spotted owl, we chose this approach to provide decision makers with a set of scientifically defensible outputs from a series of plausible scenarios (viz., changes in habitat suitability and barred owl [S. ...
Integrating species distributional, conservation planning, and individual based population models: A case study in conservation network evaluation for the northern spotted owl
Conference Paper
Full-text available
  • Aug 2012
Background/Question/Methods As part of the ongoing northern spotted owl recovery planning effort, we evaluated a series of alternative potential critical habitat scenarios using a species-distribution model (MaxEnt), a conservation-planning model (Zonation), and an individual-based population model (HexSim). Our approach was designed to permit a comparison of estimated owl population responses to multiple hypothetical habitat conservation scenarios. Each scenario represented a different set of assumptions regarding critical habitat size/spatial arrangement, trends in relative habitat suitability, and barred owl impacts. A total of 98 “what if” scenarios were evaluated using HexSim, and the results were used to forecast relative spotted owl population responses to the candidate conservation strategies. Results/Conclusions Based on our HexSim model results, we were able to identify conservation network scenarios that, in our estimation, would allow spotted owl populations to become stable (rather than the currently-estimated decrease), remain well-distributed throughout the majority of their current range, and would allow for a stable population despite future uncertainty regarding habitat trends and barred owl impacts. The modeling framework we developed and used, in particular our methods for the application of HexSim, should be readily transferrable to other reserve planning studies. Finally, our study illustrates a method for quantifying the relative risk of alternative conservation scenario design decisions while there is still flexibility in the planning process.
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Landscape capability predicts upland game bird abundance and occurrence: Landscape Capability
Article
Full-text available
  • Apr 2017
  • J WILDLIFE MANAGE
Landscape capability (LC) models are a spatial tool with potential applications in conservation planning. We used survey data to validate LC models as predictors of occurrence and abundance at broad and fine scales for American woodcock (Scolopax minor) and ruffed grouse (Bonasa umbellus). Landscape capability models were reliable predictors of occurrence but were less indicative of relative abundance at route (11.5–14.6 km) and point scales (0.5–1 km). As predictors of occurrence, LC models had high sensitivity (0.71–0.93) and were accurate (0.71–0.88) and precise (0.88 and 0.92 for woodcock and grouse, respectively). Models did not predict point-scale abundance independent of the ability to predict occurrence of either species. The LC models are useful predictors of patterns of occurrences in the northeastern United States, but they have limited utility as predictors of fine-scale or route-specific abundances.
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Shale gas development effects on the songbird community in a central Appalachian forest
Article
Full-text available
  • Sep 2016
  • BIOL CONSERV
In the last decade, unconventional drilling for natural gas from the Marcellus-Utica shale has increased exponentially in the central Appalachians. This heavily forested region contains important breeding habitat for many neo-tropical migratory songbirds, including several species of conservation concern. Our goal was to examine effects of unconventional gas development on forest habitat and breeding songbirds at a predominantly forested site from 2008 to 2015. Construction of gas well pads and infrastructure (e.g., roads, pipelines) contributed to an overall 4.5% loss in forest cover at the site, a 12.4% loss in core forest, and a 51.7% increase in forest edge density. We evaluated the relationship between land-cover metrics and species richness within three avian guilds: forest-interior, early-successional, and synanthropic, in addition to abundances of 21 focal species. Land-cover impacts were evaluated at two spatial extents: a point-level within 100-m and 500-m buffers of each avian survey station, and a landscape-level across the study area (4326 ha). Although we observed variability in species-specific responses , we found distinct trends in long-term response among the three avian guilds. Forest-interior guild richness declined at all points across the site and at points impacted within 100 m by shale gas but did not change at unimpacted points. Early-successional and synanthropic guild richness increased at all points and at impacted points. Our results suggest that shale gas development has the potential to fragment regional forests and alter avian communities, and that efforts to minimize new development in core forests will reduce negative impacts to forest dependent species.
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Ecological Monitoring Through Harmonizing Existing Data: Lessons from the Boreal Avian Modelling Project
Article
Full-text available
  • Aug 2015
To accomplish the objectives of a long-term ecological monitoring program (LTEM), repurposing research data collected by other researchers is an alternative to original data collection. The Boreal Avian Modelling (BAM) Project is a 10-year-old project that has integrated the data from >100 avian point-count studies encompassing thousands of point-count surveys, and harmonized across data sets to account for heterogeneity induced by methodological and other differences. The BAM project faced the classic data-management challenges any LTEM must deal with, as well as special challenges involved with harmonizing so many disparate data sources. We created a data system consisting of 4 components: Archive (to preserve each contributor's data), Avian Database (harmonized point-count data), Biophysical Database (spatially explicit environmental covariates), and Software Tools library (linking the other components and providing analysis capability). This system has allowed the project to answer many questions about boreal birds; we believe it to be successful enough to merit consideration for use in monitoring other taxa. We have learned a number of lessons that will guide the project as it moves forward. These include the importance of creating a data protocol, the critical importance of high-quality metadata, and the need for a flexible design that accommodates changes in field techniques. One of the challenges the BAM team faced—gaining access to relevant data sets—may become easier with the increased expectation by journals and funding agencies that documenting and preserving research data be a standard part of scientific research. © 2015 The Wildlife Society.
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Bird community response to Marcellus shale gas development: Shale Gas Development and Forest Birds
Article
  • Jul 2016
  • J WILDLIFE MANAGE
The Appalachian shale play, which includes the Marcellus shale formation, is an important source of natural gas and underlies much of the remaining large areas of extensive contiguous forest within the eastern United States, areas that are important breeding sites for forest songbirds. Shale gas development in contiguous forest creates large disturbances and causes habitat fragmentation; the landscape matrix remains characterized by stands of mature forest. We assessed the effects of shale gas development on counts of passerines and near- passerine birds within an extensively forested landscape. We surveyed birds within 2 broad forest types (northern hardwood and mixed oak) at increasing distances from 49 shale gas pads established within contiguous forest habitat. We compared counts of individual species and 3 vegetation-association groups (forest interior, synanthropic, and early successional) in relation to distance from a pad edge, and we compared community composition with distance from a pad edge. Counts of individuals and species within the forest interior group increased with increasing distance from a pad edge; counts of individuals were approximately 4 times greater at 250 m than at 0 m and 3 times greater than at 50 m. Twelve of 15 species in the forest interior group increased with increasing distance from a pad edge with no species showing a declining trend. In contrast, counts of synanthropic (i.e., human-associated) individuals and species were greatest at the pad edge and declined with distance to a pad edge. Counts of individuals at 250 m were 92% lower than at 0 m, and counts for 4 of the 5 individual species declined with increasing distance from a pad edge. Counts of individuals and species within the early successional habitat group were greater in oak (Quercus spp.) than in northern hardwood forests, and the response to a pad edge differed among species and between the 2 forest types. In northern hardwood stands, counts were greatest near the pad edge, whereas counts in oak stands showed no trend with distance to a pad edge. Overall, the combined avian community differed with distance from a pad edge. Our results suggest that synanthropic species, which are rare in core forest, are able to rapidly exploit new development-associated habitat. Counts of forest interior specialists declined, suggesting the habitat is becoming less suitable for this group. Our results are an early indication that shale gas development in core forest can have negative consequences for forest songbird communities as synanthropic species, which tend to be habitat generalists with wide geographic ranges, replace forest specialists. Long-term effects will depend on the scale and extent of shale gas development, emphasizing the need for proactive planning to minimize negative effects.
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Modeling the occurrence of bird species: Are the errors predictable?
Article
  • Aug 1999
Typical assessments of models where many species occurrences are predicted (e.g., from species-habitat matrices or Gap Analyses) report overall omission and commission errors. Yet species' attributes suggest that we may predict a priori that some species are more likely to be modeled correctly than others. Because the likelihood of modeling species correctly is related to species incidences in surveys, a method was created that ranked the 183 avian species known to be breeding in Maine as to how likely they would be to occur in surveys. Attributes (e.g., population level, niche width, aggregation) were used to model 79% of the variation in incidence within the Maine Breeding Bird Atlas. Likelihood of Occurrence Ranks (LOORs) were assigned to each species based upon the modeled incidences to reflect how likely the species are to be observed in future surveys. The occurrence of birds on areas with species checklists were then modeled and compared to the LOORs. For five of six areas, the number of species correctly modeled using species-habitat associations was highly correlated with LOORs: species judged a priori to be likely to be modeled correctly actually were. For one large area (9172 ha) with a checklist covering 52 years, the number of species correctly modeled was not correlated with LOORs, evidence that the checklist is essentially complete. In general, sites with checklists from many years (e.g., > 10 yr) and from large areas (e.g., > 1000 ha) yielded the lowest commission error. These results demonstrate that the confidence assigned to results where the occurrences of species are modeled (e.g., Gap Analysis) is highly dependent on the test sets and the species modeled.
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