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Article

A Beautiful Bird in the Neighborhood: Canopy Cover and Vegetation Structure Predict Avian Presence in High-Vacancy City

by
Sebastian Moreno
1,2,*,
Andrew J. Mallinak
2,3,
Charles H. Nilon
2,* and
Robert A. Pierce II
2
1
College of Natural Resources, University of Massachusetts, Amherst, MA 01003, USA
2
School of Natural Resources, University of Missouri, Columbia, MO 65211, USA
3
Florida Fish and Wildlife Conservation Commission, Tallahassee, FL 32399, USA
*
Authors to whom correspondence should be addressed.
Land 2025, 14(7), 1433; https://doi.org/10.3390/land14071433
Submission received: 22 May 2025 / Revised: 3 July 2025 / Accepted: 4 July 2025 / Published: 8 July 2025
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Abstract

Urban vacant land can provide important habitat for birds, especially in cities with high concentrations of residential vacancy. Understanding which vegetation features best support urban biodiversity can inform greening strategies that benefit both wildlife and residents. This study addressed two questions: (1) How does bird species composition reflect the potential conservation value of these neighborhoods? (2) Which vegetation structures predict bird abundance across a fine-grained urban landscape? To answer these questions, we conducted avian and vegetation surveys across 100 one-hectare plots in St. Louis, Missouri, USA. These surveys showed that species richness was positively associated with canopy cover (β = 0.32, p = 0.003). Canopy cover was also the strongest predictor of American Robin (Turdus migratorius) and Northern Cardinal (Cardinalis cardinalis) abundance (β = 1.9 for both species). In contrast, impervious surfaces and abandoned buildings were associated with generalist species. European Starling (Sturnus vulgaris) abundance was strongly and positively correlated with NMS Axis 1 (r = 0.878), while Chimney Swift (Chaetura pelagica) abundance was negatively correlated (r = −0.728). These findings underscore the significance of strategic habitat management in promoting urban biodiversity and addressing ecological challenges within urban landscapes. They also emphasize the importance of integrating biodiversity goals into urban planning policies to ensure sustainable and equitable development.

1. Introduction

Neighborhoods with high vacancy rates, resulting from socioeconomic and demographic shifts, are characterized by a mix of residential properties, planned greenspaces, and vacant lots [1,2]. Such neighborhoods, shaped by persistent structural inequalities, offer unique urban habitats that influence biodiversity and ecosystem dynamics [3]. Although vacancy is often framed as a symptom of urban decline, it also creates novel configurations of greenspace that can affect species distributions and habitat availability. Greenspaces in these neighborhoods vary regarding adjacent land cover, native species richness, management intensity, and landowner management capacity and investment, resulting in significant consequences for wildlife species in cities, including birds [4,5,6,7,8,9].
Birds are valuable indicators for assessing ecological changes in cities [10,11,12]. Avian species respond to habitat alterations at multiple spatial scales, making them well suited for studying ecological responses across urban landscapes, including those shaped by high vacancy [2,13]. Despite increasing interest in urban bird ecology, few studies have evaluated bird–habitat relationships across the fine-grained mosaic of vegetated spaces that characterize disinvested neighborhoods. By identifying habitat features that support sustainable bird populations within residential areas with significant concentrations of vacant land, informed management decisions can be formulated to enhance avian biodiversity while addressing social concerns [10,11,12]. The importance of urban greenspaces in providing suitable habitats for urban bird populations is well documented [14,15,16,17,18,19,20]. Vacant lots may serve as refuges for urban bird populations by supporting generalist and specialist species, offering food resources, nesting opportunities, and connectivity between fragmented habitats [12,13]. Although formal urban greenspaces, such as residential yards and parks, constitute substantial portions of urban land, they offer limited diversity for plant and bird species [14,15,16,17,18,19,20]. Conversely, informal urban greenspaces, such as vacant lots, may foster greater plant and bird diversity due to their heightened vegetation structural complexity and prevalence of native species [1,21,22]. However, their inclusion in ecological studies remains limited [13].
Greenberg et al. [23] define vacant lots as “parcels of land that are temporarily obsolete, abandoned, or derelict”. Vacant lots, especially in urban environments, are closely tied to social, economic, and ecological issues [24,25,26]. Research on neighborhoods with many vacant lots has connected vacancy to patterns of historical disinvestment, discriminatory policies, and systemic injustices, particularly the uneven allocation of resources and wealth, which is predominantly rooted in structural racism and classism [27,28,29]. These disparities affect urban infrastructure, governance, and landscape management, ultimately shaping neighborhood conditions that influence ecological processes and evolutionary pathways for urban organisms [3,30]. Like other urban greenspaces, vacant lots harbor substantial ecological potential, offering alternative habitats that support avian biodiversity [12,31,32]. Unlike managed parks and gardens, which often feature simplified plantings and structured landscapes, vacant lots can develop into diverse, structurally complex habitats [2]. This complexity, including early successional vegetation and reduced human disturbances, can enhance habitat stability for various bird species [33]. However, vacant lots are often embedded in a matrix of residential and commercial areas, featuring a variety of built and greenspaces, and different management regimes. Their condition is shaped by a mix of resident-initiated stewardship, municipal maintenance, and neglect, highlighting the human dimension of urban ecological patterns even in studies focused primarily on habitat and wildlife.
Despite growing interest in urban greening, most ecological research in cities has focused on parks, gardens, and other formally managed greenspaces [7,8,34]. Far less attention has been given to residential neighborhoods characterized by a heterogeneous mix of greenspace types, including private yards, street trees, and vacant lots, particularly in areas affected by long-term disinvestments and high vacancy rates [13,35]. Within these complex urban landscapes, vacant lots—often viewed as degraded or ecologically marginal—may nonetheless contribute meaningful conservation value [2,36]. We extend this work by evaluating bird–habitat relationships at a fine spatial scale across distinct vegetation types in high-vacancy neighborhoods, moving beyond aggregated land cover metrics or studies restricted to final greenspaces. Evaluating how birds respond to this diversity of habitat types across neighborhoods with differing management histories can inform more inclusive and ecologically grounded urban land-use planning [37,38].
High-vacancy neighborhoods can focus urban greening efforts that combine community-led initiatives with citywide programs to enhance their revitalization. One such initiative, the Green City Coalition (GCC) in St. Louis, Missouri, USA, exemplifies a greening effort that illustrates the type of collaborative urban land management central to this study and serves as a model for multi-scalar, community-oriented restoration of vacant lands [29]. The GCC aims to transform vacant lots into vibrant greenspaces that enhance the urban environment and promote biodiversity and sustainability [29]. GCC collaborates with residents, organizations, and government agencies to establish community gardens, urban orchards, and other greenspaces [39]. These initiatives enhance biodiversity, mitigate environmental concerns, and serve as a model for integrating community engagement into urban land management [37,40].
This work contributes to growing interest in urban socio-ecological dynamics by integrating habitat heterogeneity, vacancy history, and community stewardship into fine-scale biodiversity analysis. Rather than treating vacant lots as isolated ecological units, these spaces can be understood as part of a dynamic social–ecological system within neighborhoods experiencing high vacancy levels [29]. This study draws on that perspective to explore how fine-scale vegetation structure, land-use history, and stewardship practices affect the habitat of birds within this urban matrix. Schell et al. [3] highlight how poverty, segregation, gentrification, and social dynamics contribute to variations in ecological conditions across neighborhoods. We also recognize that both resident stewardship and top–down planning decisions by city officials, coalitions like GCC, and other stakeholders play a role in shaping habitat management. Building on this foundation, we assess habitat features relevant to both ecological function and urban land management, with an emphasis on vegetation complexity, maintenance patterns, and spatial arrangement. In doing so, our study examines the intersection of socio-economic disparities, community-level greening, and avian communities in high-vacancy urban neighborhoods.
Recent studies have underscored the importance of examining bird diversity in historically redlined neighborhoods to gain a deeper understanding of urban biodiversity. Ellis-Soto et al. [41] emphasized the importance of studying bird populations in these areas, arguing that they provide key insights into broader ecological patterns and environmental justice concerns. Similarly, Wood et al. [42] document lower bird diversity in redlined neighborhoods, underscoring the lasting impacts of historical racial segregation on urban ecosystems. Although the GCC neighborhoods do not fall within redlined boundaries, they have experienced similar legacies of disinvestment, segregation, and demographic change that contributed to elevated vacancy rates and altered urban form [43]. By examining bird diversity in neighborhoods shaped by these dynamics, this study expands on prior research from historically redlined areas and highlights how ecological value can emerge in spaces undergoing active land transformation.
To better understand how habitat variation influences bird communities in neighborhoods with high vacancy, we asked two research questions: (1) How does bird species composition reflect the potential conservation value of these neighborhoods? (2) Which vegetation structures predict bird abundance across a fine-grained urban landscape? Our study focuses on two neighborhoods in North St. Louis undergoing active greening interventions in partnership with the Green City Coalition. By examining bird–habitat relationships across a heterogeneous mix of vacant lots and residential greenspaces, we contribute new insights into how fine-scale vegetation patterns shape urban biodiversity in historically disinvested areas.

2. Materials and Methods

2.1. Study Area

St. Louis, Missouri, USA, has experienced a dramatic 60% reduction in population since its peak in the 1950s, primarily driven by systemic racism, deindustrialization, suburbanization, and deteriorating living conditions [27,44,45]. This complex interplay has contributed to the rise in vacant lots, with the city’s total vacancy rate reaching 19.3% [39]. St. Louis is in the Ozark Border Natural Division of Missouri, situated along the transition between grasslands and deciduous forests [46]. The North City neighborhoods of St. Louis encompass approximately 3000 ha and are located adjacent to the Mississippi River [47]. These neighborhoods are situated within the River Hills Ecoregion of Missouri and exhibit a range of lot conditions influenced by past land-use and maintenance practices [48]. They are commonly vegetated with a mix of herbaceous plants, scattered shrubs, and mature trees. Among the most affected areas are the Baden and Wells-Goodfellow neighborhoods in North St. Louis, designated pilot sites for GCC due to their high vacancy rates and proximity to existing public greenspace projects [29,39].
Vacant lots in these neighborhoods reflect a range of vegetation conditions and land-uses, including mowed lawns, grassy meadows, densely vegetated areas with shrub and tree growth, and surfaces dominated by impervious cover. Residents or city management programs actively manage some lots as areas of mown lawn or green infrastructure, such as fenced and grassy water drainage basins. While other vacant lots lie overgrown, sometimes containing abandoned buildings. Inhabited residential properties, with yards primarily composed of mowed lawn, an occasional tree and shrubs around the house’s foundation, surround or weave in between vacant lots. This heterogeneity creates diverse habitat types embedded within a matrix of residential, commercial, and green infrastructure features.
To investigate how bird communities respond to fine-scale habitat variation within high-vacancy areas, we selected 1 ha plots that encompass different configurations of vacant lots, residential yards, and green infrastructure features. This scale of analysis allowed us to capture localized habitat conditions while accounting for the broader urban patchwork typical of shrinking cities [12,26]. By working in neighborhoods undergoing transformation through GCC, we explored the ecological dimensions of vacant land management relevant to cities with legacies of disinvestment [2,13].

2.2. Vacant Lot Classification

We classified vacant lots based on the type of ground cover and the dominant vegetation under 5 m in height, following the entitation method described by Rogers and Rowntree [49]. This involved classifying distinct vegetation parcels within lots into distinct cover types, physiognomic and ecological assessment (Figure 1; Table 1). This approach allowed us to capture the variety of vacant lot vegetation types in the neighborhoods in a way that may be relevant to birds. We used aerial imagery from the 2014 National Agriculture Imagery Program (NAIP) and parcel data from the St. Louis City Assessor’s Office to identify vacant properties in the Wells-Goodfellow and Baden neighborhoods. We then conducted on-the-ground surveys in August and September 2017 to confirm and refine our classification of vegetation structure and land cover on each lot.
We used 1 ha plots as study sites to investigate how bird communities respond to land-use/land-cover configurations that influence bird habitat. This scale of analysis allowed us to capture the broader urban patchwork of residential, cultural, managed, and vacant greenspaces typical of shrinking cities [12,26]. By working in neighborhoods undergoing transformation through GCC management efforts, our research may address some of the ecological and conservation dimensions of vacant land management relevant to cities with legacies of disinvestment [2,13]. We employed a stratified random sampling technique that considered the proportion of vacant land within a 1 ha plot to select 50 plots per neighborhood, totaling 100 plots. This approach ensured adequate representation of different vegetation and land cover types of high-vacancy neighborhoods [12]. Bird and vegetation surveys were conducted during the 2018 breeding bird season, which spanned from May to July.

2.3. Vegetation Structure of 1 Ha Plots

We used a visual line-intercept survey to assess vegetation structure within each 1 ha plot [50,51,52]. We established a 100 m transect in each plot and made visual cover estimates at 5 m intervals along the transect. At each interval, we alternated sides of the transect to estimate the percent cover for distinct vegetation height classes: ground (0–0.5 m), shrub (0.5–5 m), and canopy (>5 m). Percent cover for each category was visually estimated based on the proportion of each cover type relative to the total visible area at each interval (Table 2).

2.4. Bird Counts

We conducted bird counts between June and July 2018 using the strip transect method within each plot. A pilot study conducted in 2017 informed the timing and scope of data collection, indicating that summer surveys provided consistent detection of resident species while minimizing variability introduced by seasonal migration. Because data were collected during a single season, migratory bird species that utilize these habitats in spring or fall were not captured. To minimize urban noise interference and address limited visibility caused by structures and vegetation, we recorded birds within a 50 m strip on each side of the transect. This configuration provided reliable estimates of avian densities [53,54]. To ensure robust data, each site was randomly sampled three times throughout the 2018 field season.
Each bird count session lasted five minutes, occurring between local sunrise and four hours post-sunrise. During these sessions, we recorded the observed species along with their distance and mode of detection (e.g., seen, heard, or in flight). Additionally, we collected supplementary environmental variables, including wind speed and direction, temperature, observation time, observer identity, and the date, to assess their potential impact on species detectability.

2.5. Data Analysis: Vegetation

We conducted a Principal Component Analysis (PCA) of the 100 × 1 ha plots, using all vacant lot cover and vegetation structure variables recorded in each plot. The PCA helped us to reduce the dimensionality of the dataset and identify the habitat variables that best explained variation among the 1 ha plots [55]. We examined the eigenvectors (variable loadings) associated with the principal components to identify combinations of plot characteristics, such as shrub cover, impervious surfaces, and woodland-type vacant lots, that most strongly separated plots in ordination space. These variable combinations were used to interpret how local habitat structure varied across the urban landscape. We used the percentage of variance explained by each principal component to assess how much of the total variability in plot-level habitat conditions was captured by the first four components. We retained components that explained at least 40% of the variance for inclusion in subsequent modeling of bird communities.

2.6. Data Analysis: Birds

We recorded the total number of birds detected, by species, in each 1 ha plot and used total detections to identify the five most abundant species in the neighborhoods. We used non-metric multidimensional scaling (NMS) as an ordination technique to assess differences in bird species composition and abundance among plots. This approach enabled us to evaluate how bird communities respond to the ecological gradient associated with urban vegetation and land cover [56]. The NMS ordination was based on the Bray–Curtis similarity index. We examined correlations (r > 0.5 or r < −0.5) between bird species abundance values and bird species scores on the first two ordination axes to identify species with life histories or habitat requirements that may be useful in understanding how environmental variables are shaping bird communities in the two neighborhoods.

2.7. Data Analysis: Predicting Species Abundance

To estimate true species abundance and account for imperfect detection, we fit N-mixture models for the five most frequently observed species and those correlated with the NMS axes. We conducted these analyses using the Vegan and Unmarked packages in R [57,58]. We used the observation date, time, temperature, cloud cover, wind speed, and direction as detection probability covariates (p); abundance covariates included 1 ha plot vacant lot cover types (mowed lawn, woodland), and vegetation structure from line-intercept surveys (canopy and shrub cover, ground cover by grass, ground cover by impervious surface) as abundance covariates (λ).

3. Results

3.1. Vacant Lot Characteristics

Across Baden and Wells-Goodfellow, we classified the vegetation cover types within vacant lots to characterize the structure of the available habitat. Mowed lawn was the most prevalent cover type, comprising an average of 18.1% of the vacant lot area. The second most common types included artificial surfaces (e.g., pavement, building remnants), which accounted for 3.2% on average, and woodland vegetation, which comprised 4.6% (Table 3; Figure 1). Other vacant lot covers included shrub-dominated areas, meadows, and rock or bare soil, although these were less widespread. These patterns reflect a landscape in which most vacant land is managed turfgrass or impervious cover, with fewer lots supporting structurally complex vegetation such as shrubs or trees.

3.2. One-Ha Study Plots

The average vacant lot cover across the 100 one-hectare study plots was 33.5%, indicating that approximately one-third of each plot’s area was vacant lots. The predominant types of vacant land cover within these plots were mowed lawn (16.5% of the total area) and woodland vegetation (4.9%). The line-intercept sampling of bird habitat characteristics found that artificial surfaces, such as pavement, buildings, and other impervious features, were the most extensive ground cover type, occupying an average of 39.2% of the plot area. This was followed by grassy cover, which averaged 33.8%. Shrub and tree canopy cover were generally less common but contributed to vegetation structure, with shrub cover averaging 7.2% and tree canopy averaging 7.9% across all plots (Table 2). These vegetation characteristics provided the foundation for identifying habitat gradients in subsequent analyses, including principal components analysis (PCA) and ordination of bird community composition.

3.3. Birds

In 2018, 53 bird species were detected among the 100 × 1-hectare plots, with an average of 8.3 ± 1.8 (SD) bird species detected per site. The five most abundant species were the European Starling (Sturnus vulgaris), American Robin (Turdus migratorius), Common Grackle (Quiscalus quiscula), Northern Cardinal (Cardinalis cardinalis), and Chimney Swift (Chaetura pelagica) (Table 4).
NMS was used to identify patterns in bird community composition across the 1 ha study plots. The final ordination had a stress value of 24.09, indicating a satisfactory fit of the data to the NMS ordination (stress < 30). Plots that were more similar in bird species composition were located closer together in ordination space, while those differing in species composition were farther apart.
Two of the 53 species were correlated (r > 0.5 or r < −0.5) with at least one of the ordination axes, indicating that there were differences in their abundance among the 1 ha plots that might be associated with differences in vegetation cover or bird habitat characteristics that are driving the ordination.
Chimney Swift abundance was negatively correlated with Axis 1 (r = −0.841), suggesting a possible relationship with vacant lots and abandoned buildings. American Robin abundance was positively correlated with Axis 2 (r = 0.742). These axes represent a gradient from impervious cover and abandoned structures (Axis 1) to increasing vegetation structure, including tree and shrub cover (Axis 2) (Figure 2).
Chimney Swifts were primarily found in plots containing vacant lots with abandoned buildings, which provided important roosting and nesting structures. American Robins were strongly associated with plots featuring moderate to high canopy cover and residential greenspace, consistent with their preference for structured habitats that offer both foraging and nesting opportunities. Chimney Swifts were primarily found in plots containing vacant lots with abandoned buildings, which provided important roosting and nesting structures.
Although not among the most abundant species, several birds were associated with specific vacant lot features along the strip transects. In Baden, emergent wetlands within vacant lots supported nesting Red-winged Blackbirds (Agelaius phoeniceus). At the same time, a detention basin with meadow habitat in Wells-Goodfellow provided breeding habitat for Dickcissels (Spiza americana) and Red-winged Blackbirds. Vacant lots with large trees served as stopover sites for Cedar Waxwings (Bombycilla cedrorum). In contrast, sites with standing dead trees offered nesting cavities for woodpeckers such as the Northern Flicker (Colaptes auratus).

3.4. Principal Components Analysis (PCA) of Vacant Lot Characteristics

The first four principal components accounted for 42% of the total variation in plot characteristics. The first component (PC1) explained 14.2% of the variance and described a gradient from impervious surfaces (e.g., pavement, buildings) to more vegetated plots, with high negative loadings for artificial surfaces. PC2 accounted for 12.1% of the variance and captured the extent of maintained open greenspace, with positive associations for mowed lawns, grassy cover, and vacant lot area, indicative of regularly managed but ecologically simple lots. PC3 explained 8.0% of the variance and distinguished plots with mature tree canopy from those dominated by bare soil or rock, suggesting a contrast between shaded, established greenspaces and sparsely vegetated areas. PC4 accounted for 7.5% of the variance and reflected unmanaged or transitional spaces, with positive loadings for meadow vegetation, woody litter, and canopy layering, features of minimally maintained lots (Table 5).
These variables, associated with the four principal components, were used as covariates in the detection and abundance models developed for the five most frequently observed bird species. Principal components representing gradients of impervious surface, mowed lawn, canopy cover, and meadow vegetation structure were incorporated to assess how fine-scale habitat variation influenced species-specific abundance patterns across the study area. The results of these models are presented in the following section.

3.5. Detection and Abundance Models for the Five Most Abundant Species

Canopy cover emerged as the most influential factor, positively associated with American Robin and Northern Cardinal abundance (β = 1.9 for both species; Table 4) and overall species richness (β = 0.61). This suggests that tree-dominated plots in residential or more established vacant lots support a higher diversity of urban-adapted songbirds. European Starling abundance was negatively associated with the proportion of closed forest cover within plots (β = −3.2), indicating a preference for open canopy areas. However, starlings were positively associated with shrub cover (β = 5.8), aligning with their frequent occurrence in mowed residential lawns with scattered woody vegetation. In contrast, Chimney Swifts and Common Grackles showed opposite patterns. Both species were less abundant in plots with dense thicket cover (Chimney Swift: β = −5.9; Grackle: β = −6.3) but were more frequently detected in areas with greater forest canopy (β = 2.8 for both). Chimney Swifts were associated with plots containing abandoned buildings and tall structures, which likely serve as roosting or nesting sites.

4. Discussion

This study found that vacant lots and residential greenspaces in high-vacancy neighborhoods support bird communities with measurable conservation value, particularly when vegetation structure includes mature canopy and shrub layers. Species richness and the abundance of native birds, including Northern Cardinal and American Robin, were strongly associated with increased canopy cover. In contrast, impervious surfaces and abandoned buildings were more closely linked to generalist species such as European Starling. These findings suggest that fine-scale vegetation structure is a key predictor of bird abundance and that targeted greening efforts can enhance biodiversity in historically disinvested urban areas.
The 53 bird species documented across our plots suggest that high-vacancy residential neighborhoods retain substantial avian biodiversity despite widespread disinvestment and habitat modification. Compared to previous studies conducted in more formal urban greenspaces, such as Azerrad and Nilon [31], who reported 67 species in St. Louis parks, cemeteries, and greenspaces along the Mississippi River, our results reinforce the potential conservation value of fragmented greenspaces in historically underserved neighborhoods. Similarly, research in cities such as Baltimore [12] and Vancouver [4] has shown that residential yards and neighborhood greenspaces make a significant contribution to urban bird diversity, particularly when vegetation structure is complex. These findings show that bird diversity can persist in shrinking cities when structurally complex vegetation is present across a mosaic of land-uses, including both formal and informal greenspaces. The 1 ha plots included combinations of residential yards, vacant lots, and other neighborhood features, and our models showed that canopy cover, regardless of its location, was the strongest predictor of bird abundance. This suggests that habitat quality, rather than land-use designation alone, is key to supporting avian communities in high-vacancy neighborhoods [12,22].
We examined abundance and detection models for the five most frequently observed species—American Robin, Northern Cardinal, European Starling, Common Grackle, and Chimney Swift—to evaluate which vegetation structures best predicted bird abundance. These findings align with previous studies in urban settings, emphasizing the importance of vegetation height, canopy cover, and shrub density in shaping urban bird communities [31,59]. Species richness and the occurrence of individual species varied based on the structural characteristics of 1 ha plots. Canopy cover strongly predicted the presence of species such as American Robins and Northern Cardinals. This reinforces the ecological value of tree-dominated patches within residential neighborhoods, including both mature trees in yards and naturally regenerating trees in vacant lots [60]. Conversely, we observed that impervious surfaces and abandoned buildings were frequently present in plots where species like Chimney Swifts and European Starlings were detected. While our final abundance models did not support these associations, they reflect known habitat preferences of these species [60,61,62]. European Starlings were commonly found in residential areas with mowed lawns and impervious surfaces, consistent with their generalist, human-adapted behavior. Chimney Swifts were often associated with vacant lots containing abandoned structures, which may provide important nesting or roosting sites, as previously reported in urban studies [61,62]. While models were generated for all five species, only American Robin and Northern Cardinal models showed strong support and consistent ecological interpretation. The remaining species’ models included multiple covariates or global structures, making them less interpretable. This finding is consistent with previous studies that suggest abundance models with multiple covariates or complex global structures may compromise interpretability in ecological contexts [56].
These modeling results directly address the second research question, which is to identify the vegetation structures that predict bird abundance. Among all structural characteristics, tree canopy cover emerged as the most important predictor across species. While other vegetation types, such as shrub patches and unmowed herbaceous areas, provided value for certain birds, canopy cover best explained abundance patterns for the most frequently observed species. This reinforces the importance of tree cover in supporting urban biodiversity [6,12,22] and highlights it as a top priority for vacant lot restoration and habitat management.
Vacant lots significantly contributed to urban habitat heterogeneity, with some serving as stopover sites for migratory species [63,64]. Red-winged Blackbirds were observed nesting in emergent wetlands, while Dickcissels were found in detention basins with meadow vegetation. Cedar Waxwings utilized large trees in vacant lots, and woodpeckers, including Northern Flickers, nested in standing dead trees. Importantly, these examples demonstrate how informal and underutilized spaces can serve ecologically valuable functions, particularly in neighborhoods where formal greenspaces are limited [6,65].
Although mowed lawns and impervious surfaces were common in our study plots, we observed fewer bird species in plots dominated by these low-complexity cover types. Increasing vegetation complexity, particularly through the addition of tree and shrub cover, was consistently linked to higher species richness and abundance of native birds. Previous studies have demonstrated that tree cover is a primary driver of native bird abundance in urban areas [22,60]. Similarly, dense shrubs provide essential nesting and foraging resources for many species [66]. These findings suggest that vacant lots with unmowed herbaceous growth, natural litter, and canopy layers support higher-quality bird habitat than lots dominated by lawns or impervious surfaces. This supports growing interest in rewildling or naturalistic management approaches to vacant land [1,2] as cost-effective strategies to enhance ecological value in shrinking cities.
Management strategies should prioritize increasing tree and diverse vegetation structures to improve habitat quality for urban birds. GCC aims to repurpose vacant lots for stormwater management, pollinator gardens, and community greenspaces. This study reinforces the importance of increasing canopy cover, such as strategic tree planting in vacant lots and alongside residential corridors, as a means of supporting higher bird species richness and promoting the presence of native, forest-associated species [12]. Incorporating multi-layered vegetation, such as mixed-age tree plantings and native shrub restoration, would enhance avian biodiversity while aligning with broader sustainability goals. These recommendations are particularly relevant for urban greening programs that aim to strike a balance between ecological restoration and stormwater mitigation, achieving heat reduction, and promoting community co-benefits. Given the strong positive association between canopy cover and native species, planting efforts should emphasize locally adapted, structurally complex species that provide foraging and nesting resources [34].
The spatial distribution of vacant lots presents an opportunity to create interconnected habitat corridors, particularly in neighborhoods with high vacancy rates. In neighborhoods such as Wells-Goodfellow, where lot consolidation and greening projects are underway, these spaces can be integrated into broader ecological networks [9]. Furthermore, promoting resident-led stewardship initiatives, such as tree-planting programs and small-scale habitat enhancements, can strengthen community engagement while fostering biodiversity in conservation [34,40]. This study identifies specific habitat features, particularly tree canopy, that most strongly influence bird diversity and abundance. This thereby informs the design of greener, more connected neighborhoods. These findings support citywide greening efforts that prioritize long-term habitat development in conjunction with social and environmental objectives.
Although this study focused on key habitat features such as canopy and shrub cover, further research is needed to examine additional structural elements, like foliage height diversity, understory density, and seasonal dynamics, that may influence bird use of vacant lots. Longitudinal studies of vegetation management practices such as mowing frequency, native plantings, and successional changes could yield important insights into how habitat quality evolves and supports bird communities over time. Moreover, integrating social science approaches, such as resident perception of vacant lots and their role in urban greening, could enhance efforts to align biodiversity conservation with community priorities [29]. Understanding the socio-ecological dynamics of vacant lot management is essential for developing sustainable and equitable urban habitat interventions [27,28,67,68,69].

5. Conclusions

Vacant lots in North St. Louis offer untapped potential to support urban biodiversity while creating opportunities for residents to connect with nature [2,12,66]. In neighborhoods shaped by disinvestment and high vacancy rates, these spaces can be reimagined as sites for ecological restoration and community care [26,40]. This study identified key habitat features, including tree canopy, shrub cover, and reduced impervious surfaces, that are associated with greater bird species richness and abundance. These findings can inform targeted management strategies, including transitioning some lots to meadow vegetation, increasing native tree plantings, and reducing mowing frequency [6,9,60]. When thoughtfully implemented, these changes can support a broader range of bird species, particularly those dependent on more complex vegetation structures.
Our findings are consistent with the broader literature on residential greenspace management and bird diversity. For example, Lerman et al. [35] demonstrate that residential yard composition and cover significantly shape bird communities across urban areas in the United States, emphasizing the importance of local habitat heterogeneity. Similarly, Michalczuk [70] provides specific recommendations for managing urban greenery to support cavity-nesting birds, reinforcing the role of canopy and vegetation structure in enhancing habitat suitability.
Urban greening strategies must also account for the historical, social, and spatial context of neighborhoods like Wells-Goodfellow and Baden, where vacancy is not just a land-use issue but a reflection of systemic disinvestment. These predominantly Black, low-income neighborhoods have experienced decades of housing loss, underinvestment, and shifting land tenure patterns, all of which influence ecological conditions and community engagement. As Spirn [71,72] has highlighted, the history of greenspaces and spatial arrangement fundamentally shapes ecological processes and management outcomes. In our study area, vacant lots are interspersed among residential yards and street corridors, each with unique vegetation patterns, ownership structures, and potential for ecological restoration.
Equally important is ensuring ecological management strategies align with community priorities and lived experiences. Vacant lot transformations can be most effective when paired with resident engagement, safety improvements, and long-term maintenance support [34,69]. In addition to the Green City Coalition, other programs, such as those led by the University of Missouri Extension, provide practical guidance and institutional support for greening efforts across different lot types [73,74,75]. Extension programs provide applied guidance that aligns with our findings, recommending context-specific designs for vacant lot reuse that enhance biodiversity while addressing environmental justice concerns [74,75]. These programs represent scalable and collaborative models for implementing evidence-based greening strategies across diverse land-use contexts. Our work supports these initiatives empirically by demonstrating how specific habitat elements can increase avian richness and abundance in historically underserved neighborhoods.
Future research may explore how different types of greenspace, such as vacant lots, streets, and residential yards, vary in vegetation composition and structure, and how these differences influence wildlife use and community preferences. Although our study did not assess reproductive success, it provides a foundation for future inquiries into how management strategies can be tailored to habitat function and community expectations. Vacant land, when restored with ecological and social goals in mind, can contribute to a more connected, biodiverse, and equitable urban environment. In this way, our findings contribute to a growing urban socio-ecological framework that recognizes the links between green infrastructure, biodiversity, and environmental justice.

Author Contributions

Conceptualization, S.M., C.H.N. and R.A.P.II; methodology, S.M. and C.H.N.; formal analysis, S.M.; writing—original draft preparation, S.M.; writing—review and editing, C.H.N., A.J.M. and R.A.P.II; visualization, S.M.; supervision, C.H.N. and R.A.P.II; project administration, C.H.N. and R.A.P.II; funding acquisition, C.H.N. and R.A.P.II. All authors have read and agreed to the published version of the manuscript.

Funding

This material is based upon work supported by the National Science Foundation under Award Numbers 1355406 and 1430427. Any opinions, findings, conclusions, or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.

Data Availability Statement

The data presented in this study are available on request from the corresponding authors.

Conflicts of Interest

The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

Abbreviations

The following abbreviations are used in this manuscript:
GCCGreen City Coalition
NAIPNational Agriculture Imagery Program
PCAPrincipal component analysis

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Land 14 01433 g001
Figure 1. Entitation-based vegetation cover classification of vacant lots in Baden (a) and Wells-Goodfellow (b) neighborhoods, St. Louis, Missouri. Maps show all vacant lots categorized by dominant vegetation type. Photo (c) is an example of a vacant lot classified as vegetation type VA2a (meadow) during ground-truthing.
Figure 1. Entitation-based vegetation cover classification of vacant lots in Baden (a) and Wells-Goodfellow (b) neighborhoods, St. Louis, Missouri. Maps show all vacant lots categorized by dominant vegetation type. Photo (c) is an example of a vacant lot classified as vegetation type VA2a (meadow) during ground-truthing.
Land 14 01433 g001
Land 14 01433 g002
Figure 2. Non-metric multidimensional scaling (NMS) ordination of bird communities across 1 ha study plots in Baden (b) and Wells-Goodfellow (w). Plots with similar bird species composition are located closer together in ordination space. Axes reflect ecological gradients identified through species correlations: Axis 1 represents a gradient from low to high Chimney Swift (Chaetura pelagica) abundance, associated with vacant lots and impervious surfaces; Axis 2 represents a gradient from low to high American Robin (Turdus migratorius) abundance, associated with increasing tree and shrub cover.
Figure 2. Non-metric multidimensional scaling (NMS) ordination of bird communities across 1 ha study plots in Baden (b) and Wells-Goodfellow (w). Plots with similar bird species composition are located closer together in ordination space. Axes reflect ecological gradients identified through species correlations: Axis 1 represents a gradient from low to high Chimney Swift (Chaetura pelagica) abundance, associated with vacant lots and impervious surfaces; Axis 2 represents a gradient from low to high American Robin (Turdus migratorius) abundance, associated with increasing tree and shrub cover.
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Table 1. Vegetation classification categories used to describe vacant lots in Baden and Wells-Goodfellow. Cover types were identified via aerial imagery and verified during ground-truthing surveys in 2017.
Table 1. Vegetation classification categories used to describe vacant lots in Baden and Wells-Goodfellow. Cover types were identified via aerial imagery and verified during ground-truthing surveys in 2017.
CodeForm ClassForm SubclassForm GroupForm Subgroup
VA2bHerbaceous vegetationTerrestrial herbaceous vegetationMeadow and lawnLawn
VA2aHerbaceous vegetationTerrestrial herbaceous vegetationMeadow and lawnMeadow
VIDBeaches/scarcely vegetatedScarcely vegetated artificial----------Artificial surface
IB2aClosed forestTemperate deciduous forestCold deciduous forest and pinesCold deciduous forest with evergreen
IIB2aWoodlandDeciduous woodlandCold deciduous woodlandBroad-leaved deciduous woodland
IIIA1ScrubThicketMainly deciduous----------
IIIB1aScrubShrublandMainly deciduousTemperate upland deciduous shrubland
VB1aHerbaceous vegetationSemi-aquatic herbaceous vegetationFreshwater vegetationEmergent wetland
Table 2. Mean (±std dev) percent ground, shrub, canopy, and vacant lot vegetation structure across 1 ha study plots in Baden and Wells-Goodfellow neighborhoods, St. Louis, Missouri. Values represent mean percentage cover and standard deviation across all plots.
Table 2. Mean (±std dev) percent ground, shrub, canopy, and vacant lot vegetation structure across 1 ha study plots in Baden and Wells-Goodfellow neighborhoods, St. Louis, Missouri. Values represent mean percentage cover and standard deviation across all plots.
Vegetation LayerStructure TypeMean Cover (%)Standard Deviation (%)
GroundArtificial surface3919.3
Bare soil4.54.3
Forb8.77.8
Grass33.815.7
Leaf litter5.14.6
Woody litter1.61.9
Vine0.81.2
Rock3.29.1
Water0.010.09
ShrubShrub cover7.17.5
CanopyCanopy cover7.87.6
Vacant LotTotal vacant lot cover33.620.7
Lawn (VA2b)16.520.9
Meadow (VA2a)4.310.9
Artificial surface (VID)3.48.4
Deciduous forest with evergreens (IB2a)1.85.4
Table 3. Percent vacant lot cover types for 847 vacant lots in Baden and Wells-Goodfellow neighborhood. Cover types were classified using vegetation formation subclasses and subgroups during ground-truthing surveys.
Table 3. Percent vacant lot cover types for 847 vacant lots in Baden and Wells-Goodfellow neighborhood. Cover types were classified using vegetation formation subclasses and subgroups during ground-truthing surveys.
Vacant Lot Type% Cover
Lawn (VA2b)49.1
Meadow (VA2a)12.8
Artificial surface (VID)10.6
Deciduous forest with evergreens (IB2a)5.5
Deciduous woodland (IIB2a)15.5
Thicket (IIIA1)3.7
Shrubland (IIIB1a)2.9
Emergent wetland (VB1a)0.8
Table 4. Principal component loadings of vegetation structure and vacant lot cover variables on the first four components. Eigenvalues and percentage of variance explained are shown. Higher loadings (≥|0.4|) indicate stronger associations between variables and principal components.
Table 4. Principal component loadings of vegetation structure and vacant lot cover variables on the first four components. Eigenvalues and percentage of variance explained are shown. Higher loadings (≥|0.4|) indicate stronger associations between variables and principal components.
VariablePC1PC2PC3PC4
Artificial surface−0.4000.3060.1200.080
Bare soil0.2510.054−0.337−0.126
Forb0.3140.054−0.337−0.126
Grass0.314−0.034−0.067−0.034
Leaf litter0.320−0.0800.123−0.215
Woody litter0.3130.052−0.032−0.105
Canopy layer0.2710.1130.0960.360
Shrub layer0.2580.182−0.0440.386
Vine0.1230.1630.279−0.214
Gravel0.0800.137−0.532−0.245
Water−0.0970.0900.020−0.213
Shrub cover0.3480.2590.033−0.084
Canopy cover0.2970.1630.368−0.0091
Vacant percentage0.083−0.459−0.1390.052
Lawn (VA2b)0.088−0.477−0.050−0.140
Artificial surface (VID)−0.2190.118−0.047−0.125
Deciduous forest with evergreens (IB2a)0.0870.018−0.163−0.125
Deciduous woodland (IIB2a)0.088−0.0530.3510.071
Thicket (IIIA1)0.0880.024−0.153−0.076
Emergent wetland (VB1a)0.0440.042−0.0910.340
Meadow (VA2a)−0.045−0.066−0.2500.353
Shrubland (IIIB1a)0.0870.108−0.1510.360
Eigenvalue3.1252.6681.7431.667
Percent variance explained14.2%12.1%7.9%7.6%
Table 5. Summary of top detection and abundance models for the five most common bird species observed across 1 ha study plots (ΔAIC ≤ 2). Only the models for American Robin and Northern Cardinal provided strong support and consistent ecological interpretation. Models for Chimney Swift, Common Grackle, and European Starling included multiple covariates with weaker or mixed effects.
Table 5. Summary of top detection and abundance models for the five most common bird species observed across 1 ha study plots (ΔAIC ≤ 2). Only the models for American Robin and Northern Cardinal provided strong support and consistent ecological interpretation. Models for Chimney Swift, Common Grackle, and European Starling included multiple covariates with weaker or mixed effects.
SpeciesTop Model CovariatesEffect Size (β)
American Robin% Canopy Cover1.9
Northern Cardinal% Canopy Cover1.9
Common Grackle% Closed Forest (+),
% Thicket (−)		2.8,
−6.3
European Starling% Shrub Cover (+),
% Forest Cover (−)		5.8,
−3.2
Chimney SwiftGlobal model with % Forest,
% Thicket		2.8 (forest),
−5.9 (thicket)
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Moreno, S.; Mallinak, A.J.; Nilon, C.H.; Pierce, R.A., II. A Beautiful Bird in the Neighborhood: Canopy Cover and Vegetation Structure Predict Avian Presence in High-Vacancy City. Land 2025, 14, 1433. https://doi.org/10.3390/land14071433

AMA Style

Moreno S, Mallinak AJ, Nilon CH, Pierce RA II. A Beautiful Bird in the Neighborhood: Canopy Cover and Vegetation Structure Predict Avian Presence in High-Vacancy City. Land. 2025; 14(7):1433. https://doi.org/10.3390/land14071433

Chicago/Turabian Style

Moreno, Sebastian, Andrew J. Mallinak, Charles H. Nilon, and Robert A. Pierce, II. 2025. "A Beautiful Bird in the Neighborhood: Canopy Cover and Vegetation Structure Predict Avian Presence in High-Vacancy City" Land 14, no. 7: 1433. https://doi.org/10.3390/land14071433

APA Style

Moreno, S., Mallinak, A. J., Nilon, C. H., & Pierce, R. A., II. (2025). A Beautiful Bird in the Neighborhood: Canopy Cover and Vegetation Structure Predict Avian Presence in High-Vacancy City. Land, 14(7), 1433. https://doi.org/10.3390/land14071433

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