Avian Community Structure and Spatial Distribution in Anthropogenic Landscapes in Central Mexico

Simple Summary

Monitoring bird populations can provide crucial information about the health of ecosystems and alerts regarding emerging environmental problems. Bird species responses to habitat change differ depending on species-specific ecological traits and differences in modifications. The aim of this study was to evaluate the impacts of habitat conversion on bird species diversity and richness in the peri-urban landscape of the Mexico City Metropolitan Area in central Mexico. A total of 290 bird species belonging to 19 orders and 55 families were identified. The effect of distance to the nearest greenspace differed significantly among the three seasons. The results of this study show the importance of habitat heterogeneity and how bird richness and abundance vary in a highly urbanized environment. It found the highest diversity in waterbodies with heterogeneous environments, and significant decreases in avian diversity were recorded in the semi-urban and urban habitats. Conserving sites in peri-urban landscapes may be a viable conservation strategy for bird communities. To do this, emphasis must be placed on identifying and reducing anthropogenic stressors to protect and conserve bird diversity in the study area.

Abstract

Habitat loss, pollution, and climate change have a global impact on bird diversity, particularly in central Mexico, where human disturbances and unplanned urbanization can lead to the decline of this faunal group. In this study, the effects of season (rainy, warm–dry, or cool–dry) and environmental variables (size, perimeter, vegetation cover, built cover, distance to nearby greenspaces and distance to the closet natural vegetation patch) on the avian diversity at different sites located in a peri-urban landscape in the Metropolitan Area of Mexico City were determined. The study was conducted using the linear transect method to assess the diversity and composition of bird communities from November 2019 to March 2022, recording 290 total bird species. Zumpango Lagoon was the study site with the highest diversity (N = 209, H′  =  3.22) and evenness index (J′  =  0.76). Linear mixed models were used to determine the effects of season and environmental variables of the study sites on the avian diversity. The effect of distance to the nearest greenspace was significantly more positive during the rainy season than the two dry seasons. An ANOSIM test also showed that the avian community associated with water bodies differed significantly from the other communities (R = 0.16, p < 0.001). Despite some anthropogenic activities and human intrusion, sites with water bodies retain a high diversity of birds. This finding indicates the need for immediate conservation efforts to protect many resident breeding species and wintering migratory birds in the study area.

1. Introduction

Urbanization has numerous negative impacts on biodiversity, primarily through habitat loss and fragmentation, pollution, introduction of invasive species, alteration of natural cycles, resource availability, and distribution of different species [1,2]. These changes can lead to declining populations of native species, loss of genetic diversity, and alteration of ecological communities, underscoring the importance of incorporating conservation practices into urban development [1,2]. The accelerated urbanization process is one of the main threats to biodiversity and a major conservation challenge [3,4].

Urbanization has transformed landscapes worldwide, creating environments that significantly impact on the wildlife that inhabits them [1,2]. Among the species affected, birds have had to adapt to drastic changes in their ecosystems due to increasing urban expansion [5,6]. Birds are valuable bioindicators due to their diversity, sensitivity to environmental changes, ease of monitoring, and their role in various parts of the food chain [7,8]. Monitoring bird populations can provide crucial information about the health of ecosystems and an alert of emerging environmental problems [9,10]. Avian diversity and abundance vary, and both are influenced by the climate, and another environmental factors such as vegetation cover, and habitat heterogeneity [11,12] and thus serve as prominent indicators of ecosystem health. Environmental changes can have profound and varied impacts on birds, including altered behavior and migratory patterns to decrease long-term health and survival, often resulting in shifts in species composition and diversity in avian communities [13,14]. Therefore, understanding how birds respond to habitat loss can provide insights into the maintenance of ecosystem resilience [15]. While some bird species thrive in cities, many faces serious challenges that threaten their survival. The main consequences for birds that inhabit urban areas include habitat loss, exposure to pollution, changes in food availability, increased predation, and behavioral adaptations [16,17]. One of the most significant consequences of urbanization for birds is habitat loss and fragmentation. As cities expand, natural habitats such as forests, wetlands, and grasslands are replaced by buildings, roads, and infrastructure. This reduces the availability of suitable nesting sites and feeding areas, forcing birds to adapt to artificial structures like rooftops and bridges [5,17,18]. Additionally, habitat fragmentation isolates bird populations, making it harder for them to find mates and reducing genetic diversity, which can weaken species over time [16,17,18]. In this sense, bird species responses to habitat change differ depending on species-specific ecological traits and differences in modifications [19,20]. However, bird diversity can be affected by modifying the structure and function of urban space due to the continuous growth of the urban landscape [21,22]. Greenspaces and wetlands within the urban area or in the peri-urban area in a city are essential to maintain and promote urban biodiversity. They provide shelter and vital resources for wildlife, connect fragmented ecosystems, regulate climate and air quality, and provide numerous ecological and social benefits [23,24,25]. The conservation and creation of these spaces are crucial for the ecological balance and well-being of urban communities [26,27]. Within the urban ecosystem, wetlands serve as a critical link between natural resources management and agricultural practices [28]. Recent studies have found that the presence of wetlands in peri-urban areas helps mitigate urbanization effects on bird diversity by providing enhanced habitat and increased resource availability [29,30]. For this reason, identifying bird diversity between different habitats helps assess community structure and niche relationships, which are important for bird conservation. This is because different bird species have specific habitat preferences and ecological needs [29,30].

Urban habitats are refuges for many bird populations in cities and their surroundings; however, the urbanization process, like landscape changes, is a great threat to the bird population [31,32]. The aim of this study was to evaluate the effects of season (rainy, warm–dry, or cool–dry) and environmental variables (size, perimeter, vegetation cover, built cover, distance to nearby greenspaces and distance to the closet natural vegetation patch) on bird diversity in the peri-urban landscape of the Metropolitan Area of Mexico City. The study also examined, quantified and compared the avian diversity in a mosaic of different land cover types (e.g., urban, semi-urban, and rural areas). We hypothesized that the presence of more microhabitats (e.g., native vegetation remnants, wetlands and other habitats) and longer distance from the urban center would promote a higher species diversity and richness of bird assemblages than other habitats.

2. Materials and Methods

2.1. Study Area

The Mexico City Metropolitan Area (MCMA) is one of the largest megalopolises in the world [33]. This region contains 412 bird species [34] out of a total of 1151 species found in Mexico [35]. According to recent studies [23,25,36], the number of bird species in the MCMA has declined due to different factors, including global climate change, habitat loss, rapid urbanization, industrialization, and deforestation, which pose serious threats to avifauna globally, including within the MCMA [23,25,37]. There are many remaining greenspaces with native or non-native vegetation in the MCMA which are small and isolated remnants that vary widely in their habitat quality [19,20,24,25], depending largely on the degree of urbanization [38]. For most species, the destruction of habitats and the deterioration of habitat quality result in decreased population size, population fluctuations, reduced population viability, and low individual fitness [38,39,40].

The MCMA is located in the south-central region of Mexico (19°25′ N, 99°07′ W) (Figure 1), it is located in the Trans-Mexican Volcanic Belt physiographic province. Currently, it is one of the largest megalopolises in the world [33], covering more than 7954 km². The rapid growth of the human population in the MCMA, which currently numbers over 22 million (>2559.8 hab/km²) [41], has led to the conversion of original habitats. The MCMA has a semi-humid temperate climate with a warm–dry season from March to May, cold–dry season from October to February and a rainy season from June to September [42] with a relatively narrow annual temperature range between 5 and 25 °C and precipitation between 600 and 1500 mm/year. The topography includes an extensive high plateau in the northern half of the city, where the urban area sits, surrounded by mountains and volcanoes that reach >3900 m of elevation, especially on the southern and western sides [43]. The urban area covers almost the whole northern half of Mexico City and is rapidly expanding, including through illegal, unplanned urban development. The southern half is occupied by mountains and ravines covered by extensive forests and grasslands, some of them highly fragmented by dwellings and agricultural areas. The intense loss of the original habitats in the area currently occupied by the MCMA has created a highly heterogeneous system with different land cover types, where only 34% of these remain [43].

This study was conducted in contrasting habitats within the Valley of Mexico, with the specific purpose of generating quantitative information on bird diversity. The present study was conducted from November 2019 to March 2022 covering different seasons of the year (rainy, warm–dry and cold–dry seasons) in five study sites (

Table 1. Summary data of the study sites in Mexico City Metropolitan Area, Mexico.

Site	Coordinates	Elevation (m)	Land Use Coverage	Microhabitat Structure
Guadalupe Lake	19°37′ N, 99°15′ W	2305	Urban and semi-urban	Wetland, native and non-native vegetation, agricultural areas, urban areas
Zumpango Lagoon	19°46′ N, 99°08′ W	2250	Urban, semi-urban and rural	Wetland, native and non-native vegetation, induced grasslands, agricultural areas, urban areas
Nabor Carrillo Lake	19°28′ N, 98°58′ W	2235	Semi-urban and rural	Wetland, native and non-native vegetation, agricultural areas, natural grasslands, and xeric scrub
Sierra Hermosa Ecological, Tourist and Recreational State Park	19°42′ N, 98°59′ W	2245	Urban, semi-urban, and rural	Wetland, urban areas, native and non-native vegetation, native and induced grasslands, agricultural areas
Cerro de Paula and surrounding areas	19°47′ N, 98°55′ W	2495	Semi-urban and rural	Agricultural areas, native and non-native vegetation, natural grasslands, xeric scrub

, Figure 1) based on the anthropogenic landscape and habitat structures: (a) Nabor Carrillo Lake is a semi-urban and rural habitat with wetland surrounded by aquatic or hydrophilic vegetation, native and non-native trees (Eucalyptus sp., Schinus molle, Casuarina equisetifolia), halophytic grasslands and xeric scrub; (b) Zumpango Lagoon includes urban, semi-urban and rural habitats, with a wetland that is surrounded by urban areas, roads, industrial areas, scattered native and non-native woodland (Eucalyptus sp., Schinus molle, Casuarina equisetifolia, Salix sp.), xeric scrub (Prosopis juliflora, Opuntia sp., Mimosa biuncifera), induced grasslands for grazing and agricultural areas; (c) Guadalupe Lake is an urban and semi-urban habitat with wetland surrounded by urban areas (residential areas, residential houses, roads), remnants of native and non-native wooded vegetation (Eucalyptus sp., Schinus molle, Casuarina equisetifolia, Salix sp., Quercus sp., Juniperus sp., Pinus sp., Taxodium sp., Fraxinus sp.), agricultural areas and a golf course; (d) Sierra Hermosa Ecological, Tourist and Recreational State Park is an urban, semi-urban and rural habitat made up of two permanent and two semi-permanent water bodies surrounded by spars halophytic and reedy vegetation (tular), recreational areas, abandoned buildings, induced grasslands and induced wooded areas, and the vegetation is composed of a scarce presence of trees (Schinus molle, Eucalyptus sp., Cinnamomum canphora, Casuarina equisetifolia, Ficus sp., Castilla elastica, Jacaranda mimosifolia); the valley area is represented by induced grasslands in addition to being surrounded by urban areas (residential houses, roads, schools, international airport) and agricultural areas cultivating corn, barley, wheat and beans; and (e) Cerro de Paula (and surrounding areas) is a semi-urban and rural habitat with natural grasslands, scattered trees and live fences (Schinus molle, Eucalyptus sp.), with remnants of natural scrub and agricultural areas of corn, barley, Agave sp. and Opuntia sp.

For study sites, we analyzed various spatial features that could influence bird species richness within them: size, perimeter, urbanization degree (constructed and paved surfaces within the study site), built cover in the surroundings, vegetation cover (natural and non-native vegetation coverage within the study site), distance to nearest greenspace (i.e., distance from sampled study site to the nearest greenspace), and distance to the closet natural vegetation patch (i.e., distance from the sampled study site to the nearest protected area or to an area with natural vegetation greater than 1 km²) (see Supplementary Materials Table S1). These spatial features were estimated using digital maps from Google Earth Pro (© 2021), Google Earth Engine [44], and complemented with field work information. In each of these study sites, microhabitats were characterized by direct observation and divided into the following categories: agricultural land (Al) consisting of active or semi-abandoned corn, bean, barley, wheat, Agave sp. and Opuntia sp. crops; wetlands (W) defined by natural or artificial waterbodies with halophyte and tular vegetation; urban area (Ur), including residential houses surrounded by large and small trees, roads (streets and avenues), factories, and other urban infrastructure; grassland (Gl), characterized by natural or induced, short, small grassy and bushy vegetation with a maximum height ≤ 2 m; semi-desert xeric scrubs (Sm), consisting of native vegetation with trees ≤ 2 m (Prosopis juliflora, Opuntia sp., Mimosa biuncifera); and native and non-native vegetation remnants (Nr) defined by small patches of native (e.g., Pinus sp., Quercus sp., Juniperus sp.) or non-native trees (e.g., Schinus molle, Salyx babylonica, Eucalyptus sp., Casuarina equisetifolia).

2.2. Data Collection

Bird data were collected using the transect line method following Emlen [45,46], and surveys were conducted from 06:00 to 13:00 h. One day per month was spent at each site, and three linear transects were surveyed measuring ~4 km in length. Upon spotting any bird species, the number of individuals (abundance) of each bird species was counted and the microhabitat they were using during each survey was noted. Birds were observed using binoculars (Bushnell 10 × 45 m), and photographs were taken using digital cameras (Nikon D3500) for further identification. Taxonomic identification of observed birds was followed by Peterson and Chalif [47], Kaufmann [48], Dunn and Alderfer [49], and Sibley [50]. The bird taxonomy and nomenclature followed Chesser et al. [51].

The residency status of the enlisted birds was determined based on Howell and Webb [52] and personal observations. The residential status of the birds was categorized into resident breeders (the species can be found throughout the year in the area) and migratory (the species can be found throughout certain times of year in the area, including winter visitors, transient migrants, summer residents, non-breeding visitors, and vagrants). The vulnerability status of birds was classified based on Mexican national legislation NOM-059-Semarnat-2010 [53] and at the global level with the IUCN Red List of Species [54]. Bird species were grouped based on the major feeding guilds and complemented with González-Salazar et al. [55] into the following groups: carnivores, scavengers, insectivores, nectarivores, granivores, frugivores, and omnivores.

2.3. Statistical Analysis

Bird diversity was assessed in terms of species richness (overall, resident, and migrant species richness) and abundance, considering the total number of species and the number of individuals per species at each site. The species accumulation curve was plotted to evaluate whether the number of bird species sampled was representative in the study area. The total number of species in the study area was estimated using Jackknife first-order and Chao second-order estimators [56], since they are two of the estimators with the least bias. This was done using the ‘specpool’ function of the Vegan Package [57] in RStudio 2023.09.0 [58]. Species richness represents a measure of the variety of species, and this was calculated based on the number of different species present in a study site. Bird species diversity was calculated using the Shannon diversity index (H’) and evenness index (J’) at each site. Relative abundance (the abundance of a given bird species divided by the total number of individuals present at the study site) was also presented as a stacked bar diagram divided by habitat type for each study site.

To determine the effects of season (rainy, warm–dry, or cool–dry) and environmental variables of the study sites on the avian diversity variables (species richness, abundance, diversity index, and evenness index), a set of linear mixed models was constructed with each aspect of diversity as the response variable and the site as the random intercept. The perimeter, vegetation cover, and building cover were divided by the size (area) of each study site to make them independent of area size. Since there was multicollinearity among several of the environmental variables, these could not include them as explanatory variables in a single model; rather, there was a single environmental variable included in each model, then Akaike’s Information Criterion, adjusted for small sample size, was used (AICc) to determine which variable (if any) best explained each aspect of diversity. The explanatory variables were centered and scaled to a standard deviation of 0.5 to improve model convergence and interpretation using the arm package for R [59]. To minimize the total number of models generated, we first determined whether season had an important effect (95% confidence interval excluding zero), and if so, included it in the competing models. We also included a set of models with the interaction between season and the environmental variable (regardless of whether the main effect of season was important) to account for the possibility that the effect of the environmental variables differed among seasons. All model sets included the null model (random effect only). This resulted in a set of 16 competing models for each response variable (see Supplementary Materials Table S2). It was interpreted that the most supported model was the one with the lowest AICc score, or the simplest model was the one with equivalent support (within 2 AICc points) to avoid including uninformative parameters [60,61]. All models met the assumptions of normality and homoscedasticity of the residuals, except for those evaluating Abundance, which met the assumptions after log-transforming the response variable. Analyses were performed in R version 4.4.3 [62] using the RStudio interface [58]. Models were constructed using the lme4 [63] and lmerTest [64] packages; model assumptions were verified graphically for all models using the performance package [65]; pairwise comparisons among seasons were performed using the emmeans package [66]; and figures were produced using the ggeffects [67] and ggplot2 [68] packages.

The Bray–Curtis index was used to assess the similarity of the bird community among study sites. We also performed a cluster analysis with the Bray–Curtis index to observe the similarities among the different habitats [69], and this analysis was represented with a heatmap. Analysis of Similarities (ANOSIM) and a Similarity Percentages test (SIMPER) were performed to test significant differences between groups, and to identify which taxa are responsible for those differences amongst study sites, respectively. The ‘adonis’ and ‘simper’ functions were used from the vegan package of RStudio [58] for the ANOSIM analysis [57]. The non-parametric multidimensional scale (nMDS) test was performed to determine whether bird communities differed significantly among habitats using the permutation test. All statistical analyses were carried out using relevant statistical packages in PAST [70], Biodiversity Pro [71], JMP, v. 17 (available at https://www.jmp.com/), and JASP v.0.19 (available at https://jasp-stats.org/, accessed 14 September 2024). The ggplot2 package was used for plotting [72] in RStudio [58].

3. Results

During the study, 290 bird species belonging to 19 orders and 55 families were identified (

Table A1. Checklist of bird species of study sites in central Mexico.

Species	Residency Status *	Habits †	Feeding Guilds ‡	Habitats •	NOM-059 ◊	IUCN ∆
Accipiter cooperi	RES	TER	Ca	Gl, Al, Nr, W, Sm	Sp	LC
Accipiter striatus	RES	TER	Ca	Gl, Al, Nr, W, Sm	Sp	LC
Actitis macularia	MIG	AQ	In	W		LC
Aechmophorus clarkii	RES	AQ	Ca	W		LC
Aechmophorus occidentalis	RES	AQ	Ca	W		LC
Aeronautes saxatalis	RES	TER	In	Gl, Sm, Nr		LC
Agelaius phoeniceus	RES	TER	In, Gr	Gl, Al, W		LC
Aimophila rufescens	RES	TER	Gr	Gl, Sm		LC
Aimophila ruficeps	RES	TER	Gr	Gl, Sm		LC
Amazona albifrons	EXO	TER	Fr	Gl, Ur, Nr		LC
Amazona autumnalis	EXO	TER	Fr	Gl, Ur, Nr		LC
Ammodramus savannarum	MIG	TER	Gr	Gl, Sm		LC
Anas acuta	MIG	AQ	Om	W		LC
Anas crecca	MIG	AQ	Om	W		LC
Anas diazi	RES	AQ	Om	W	T	LC
Anas platyrhynchos (domestic)	EXO	AQ	Om	W		LC
Anser albifrons (domestic)	EXO	AQ	Om	W		LC
Anser anser (domestic)	EXO	AQ	Om	W		LC
Anser cygnoides (domestic)	EXO	AQ	Om	W		LC
Anthus rubescens	MIG	TER	In	Gl, Al		LC
Aphelocoma ultramarina	RES	TER	Om	Nr		LC
Archilochus alexandri	MIG	TER	Ne	Nr		LC
Archilochus colubris	MIG	TER	Ne	Nr		LC
Ardea alba	MIG	AQ	Ca, In	W		LC
Ardea herodias	MIG	AQ	Ca, In	W		LC
Ardea ibis	EXO	TER	In	Gl, Al, W		LC
Asio flammeus	MIG	TER	Ca	Gl, Al	Sp	LC
Athene cunicularia	RES	TER	In	Gl, Al		LC
Atthis heloisa	RES	TER	Ne	Nr		LC
Aythya affinis	MIG	AQ	Om	W		LC
Aythya americana	MIG	AQ	Om	W		LC
Aythya collaris	MIG	AQ	Om	W		LC
Aythya valisineria	MIG	AQ	Om	W		LC
Bartramia longicauda	MIG	AQ	In	W		LC
Basileuterus rufifrons	MIG	TER	In	Nr		LC
Basilinna leucotis	RES	TER	Ne	Nr		LC
Bombycilla cedrorum	MIG	TER	In, Fr	Nr		LC
Botaurus lentiginosus	RES	AQ	In	W	T	LC
Bubo virginianus	RES	TER	Ca	Gl, Al, Nr		LC
Buteo brachyurus	RES	TER	Ca	Gl, Al, Nr		LC
Buteo jamaicensis	RES	TER	Ca	Gl, Al, Nr, Sm, Ur		LC
Buteo lineatus	MIG	TER	Ca	Gl, Al, Nr, Sm		LC
Buteo plagiatus	RES	TER	Ca	Gl, Al, Ur, Nr		LC
Buteo platypterus	MIG	TER	Ca	Gl, Al, Ur, Nr	Sp	LC
Buteo swainsoni	MIG	TER	Ca	Gl, Al, Ur, Nr, Sm	Sp	LC
Butorides virescens	MIG	AQ	Ca, In	W		LC
Cairina moschata (domestic)	EXO	AQ	Om	W		LC
Calidris alba	MIG	AQ	In	W		LC
Calidris alpina	MIG	AQ	In	W		LC
Calidris bairdii	MIG	AQ	In	W		LC
Calidris himantopus	MIG	AQ	In	W		LC
Calidris mauri	MIG	AQ	In	W		LC
Calidris melanotus	MIG	AQ	In	W		LC
Calidris minutilla	MIG	AQ	In	W		LC
Calidris pusilla	MIG	AQ	In	W		LC
Calothorax lucifer	RES	TER	Ne	Nr		LC
Camptostoma imberbe	RES	TER	In	Nr		LC
Campylorhynchus brunneicapillus	RES	TER	In	Sm		LC
Caracara cheriway	RES	TER	Ca, Sc	Gl, Al, Sm		LC
Cardellina pusilla	MIG	TER	In	Nr		LC
Cardinalis cardinalis	EXO	TER	Gr, Fr	Nr, Sm		LC
Cathartes aura	RES	TER	Sc	Gl, Al, Nr, Ur, Sm		LC
Catharus guttatus	MIG	TER	In	Nr		LC
Catherpes mexicanus	RES	TER	In	Nr, Sm		LC
Chaetura vauxi	RES	TER	In	Gl, Al, Sm		LC
Anarhynchus nivosus	MIG	AQ	In	W	T	NT
Charadrius semipalmatus	MIG	AQ	In	W		LC
Charadrius vociferus	RES	AQ	In	W, Al, Gl		LC
Chlidonias niger	MIG	AQ	In	W		LC
Chondestes grammacus	MIG	TER	Gr	Gl, Sm, Nr		LC
Chordeiles acutipennis	RES	TER	In	Gl, Sm		LC
Circus hudsonius	MIG	TER	Ca	Gl, Al, Sm, Nr		LC
Cistothorus palustris	RES	TER	In	W		LC
Cistothorus platensis	RES	TER	In	W		LC
Coccyzus americanus	MIG	TER	In	Nr, Sm		LC
Colaptes auratus	RES	TER	In	Nr		LC
Colibri thalassinus	RES	TER	Ne	Nr		LC
Colinus virginianus	RES	TER	Gr	Al, Sm		LC
Columba livia	EXO	TER	Om	Ur, Al		LC
Columbina inca	RES	TER	Gr	Ur, Gl, Al, Nr, Sm		LC
Columbina passerina	RES	TER	Gr	Gl		LC
Columbina tapalcoti	EXO	TER	Gr	Gl		LC
Contopus cooperii	MIG	TER	In	Gl, Nr		LC
Contopus pertinax	RES	TER	In	Gl, Nr		LC
Contopus sordidulus	MIG	TER	In	Gl, Nr		LC
Coragyps atratus	MIG	TER	Sc	Gl, Al		LC
Corthylio calendula	MIG	TER	In	Nr		LC
Corvus corax	RES	TER	Om	Gl, Al, Sm		LC
Crotophaga sulcirostris	RES	TER	Gr, Fr	Gl, Al		LC
Cyanocorax yncas	EXO	TER	Om	Nr, Sm		LC
Cynanthus latirostris	RES	TER	Ne	Nr		LC
Cyrtonyx montezumae	RES	TER	Gr	Sm, Al	Sp	LC
Dendrocygna autumnalis	RES	AQ	Om	W		LC
Dendrocygna bicolor	RES	AQ	Om	W		LC
Diglossa baritula	RES	TER	Ne	Nr		LC
Dryobates scalaris	RES	TER	In	Nr, Sm, Al		LC
Egretta caerulea	MIG	AQ	Ca, In	W		LC
Egretta thula	MIG	AQ	Ca, In	W		LC
Egretta tricolor	MIG	AQ	Ca, In	W		LC
Elanus leucurus	RES	TER	Ca	Gl, Al		LC
Empidonax fulvifrons	RES	TER	In	Nr		LC
Empidonax hammondii	MIG	TER	In	Nr		LC
Empidonax minimus	MIG	TER	In	Nr		LC
Empidonax oberholseri	MIG	TER	In	Nr		LC
Empidonax occidentalis	RES	TER	In	Nr		LC
Empidonax traillii	MIG	TER	In	Nr		LC
Empidonax wrightii	MIG	TER	In	Nr		LC
Eremophila alpestris	RES	TER	Gr	Al		LC
Eugenes fulgens	RES	TER	Ne	Nr		LC
Euphagus cyanocephalus	RES	TER	Om	W, Al		LC
Eupsittula canicularis	EXO	TER	Fr	Gl, Ur		LC
Falco columbarius	MIG	TER	Ca	Gl, Al, Sm		LC
Falco peregrinus	RES	TER	Ca	Gl, Al, Sm		LC
Falco sparverius	MIG	TER	Ca, In	Gl, Al, Sm, Nr		LC
Fulica americana	RES	AQ	Om	W		LC
Gallinago delicata	MIG	AQ	In	W		LC
Gallinula galeata	MIG	AQ	Om	W		LC
Gelochelidon nilotica	MIG	AQ	Ca, In	W		LC
Geococcyx californianus	RES	TER	Ca, In	Sm		LC
Geothlypis tolmiei	MIG	TER	In	W		LC
Geothlypis trichas	RES	TER	In	W		LC
Glaucidium gnoma	RES	TER	In	Sm		LC
Haemorhous mexicanus	RES	TER	Gr	Al, Ur, Nr, Gl, Sm		LC
Himantopus mexicanus	MIG	AQ	In	W		LC
Hirundo rustica	MIG	TER	In	Al, Sm, Gl, W, Nr, Ur		LC
Hydroprogne caspia	MIG	AQ	Ca, In	W		LC
Icteria virens	MIG	TER	In	Nr		LC
Icterus abeillei	RES	TER	In, Fr	Nr		LC
Icterus bullockii	RES	TER	In, Fr	Nr, Sm		LC
Icterus cucullatus	MIG	TER	In, Fr	Nr		LC
Icterus galbula	MIG	TER	In, Fr	Sm		LC
Icterus parisorum	RES	TER	In, Fr	Sm		LC
Icterus pustulatus	EXO	TER	In, Fr	Nr		LC
Icterus spurius	MIG	TER	In	W, Al		LC
Icterus wagleri	RES	TER	In, Fr	Nr, Sm		LC
Junco phaeonotus	RES	TER	Gr	Gl, Sm		LC
Lampornis clemenciae	RES	TER	Ne	Nr		LC
Lanius ludovicianus	RES	TER	Ca, In	Gl, Al, Nr, Sm		LC
Larus delawarensis	MIG	AQ	Ca, In	W		LC
Leiothlypis ruficapilla	MIG	TER	In	Nr		LC
Leiothlypis celata	MIG	TER	In	Nr		LC
Leiothlypis peregrina	MIG	TER	In	Nr		LC
Leiothlypis virginiae	MIG	TER	In	Nr		LC
Leptotila verreauxi	RES	TER	Gr	Gl, Sm		LC
Leucolia violiceps	RES	TER	Ne	Nr		LC
Leucophaeus atricilla	MIG	AQ	Ca, In	W		LC
Leucophaeus pipixcan	MIG	AQ	Ca, In	W		LC
Limnodromus griseus	MIG	AQ	In	W		LC
Limnodromus scolopaceus	MIG	AQ	In	W		LC
Limosa haemastica	MIG	AQ	In	W		LC
Mareca americana	MIG	AQ	Om	W		LC
Mareca penelope	MIG	AQ	Om	W		LC
Mareca strepera	MIG	AQ	Om	W		LC
Megaceryle alcyon	MIG	TER	Ca	W		LC
Melanerpes aurifrons	RES	TER	In	Nr		LC
Melanerpes formicivorus	RES	TER	In	Nr		LC
Melanotis caerulescens	RES	TER	Om	Nr		LC
Melopsittacus undulatus	EXO	TER	Gr	Gl, Al, Ur		LC
Melospiza lincolnii	RES	TER	Gr	Gl		LC
Melospiza melodia	RES	TER	Gr	Gl, W		LC
Melozone fusca	RES	TER	Gr	Gl, Nr, Ur, Al, Sm		LC
Mimus polyglottos	RES	TER	In	Nr, Al, Ur, Sm		LC
Mitrephanes phaeocercus	RES	TER	In	Nr		LC
Mniotilta varia	MIG	TER	In	Nr		LC
Molothrus aeneus	RES	TER	Gr	Gl, Al, W		LC
Molothrus ater	RES	TER	Gr	Gl, Al, W		LC
Myiarchus cinerascens	MIG	TER	In	Gl, Nr, Sm		LC
Myiarchus crinitus	MIG	TER	In	Nr		LC
Myiarchus nuttingi	RES	TER	In	Nr		LC
Myioborus pictus	RES	TER	In	Nr		LC
Myiopsitta monachus	EXO	TER	Fr	Nr, Ur		LC
Nannopterum auritus	MIG	AQ	Ca	W		LC
Nannopterum brasilianum	MIG	AQ	Ca	W		LC
Numenius americanus	MIG	AQ	Om	W		LC
Numida meleagris	EXO	TER	Gr	Gl		LC
Nycticorax nycticorax	RES	AQ	Ca, In	W		LC
Nyctinassa violacea	MIG	AQ	Ca, In	W		LC
Oreothlypis superciliosa	MIG	TER	In	Nr		LC
Oriturus superciliosus	RES	TER	In	Nr		LC
Oxyura jamaicensis	RES	AQ	Om	W		LC
Pandion haliaetus	MIG	TER	Ca	Al, W		LC
Parabuteo unicinctus	EXO	TER	Ca	Gl, Al, Ur, Nr		LC
Parkesia noveboracensis	MIG	TER	In	Nr		LC
Passer domesticus	EXO	TER	Om	Ur, Al, Gl, Sm, W, Nr		LC
Passerculus sandwichensis	RES	TER	Gr	Gl, Sm, W, Al		LC
Passerina caerulea	RES	TER	In, Gr	Gl, Al, Nr, Sm		LC
Passerina ciris	MIG	TER	Gr	Gl	Sp	LC
Passerina cyanea	MIG	TER	Gr	Gl, Al, Nr		LC
Passerina versicolor	RES	TER	Gr	Gl, Al, Nr		LC
Pavo cristatus	EXO	TER	Gr	Gl		LC
Pelecanus erythrorynchus	MIG	AQ	Ca	W		LC
Petrochelidon pyrrhonota	RES	TER	In	Al, W		LC
Peucaea botterii	RES	TER	Gr	Gl, Sm		LC
Peucedramus taeniatus	RES	TER	In	Nr		LC
Phainopepla nitens	MIG	TER	In	Nr, Sm		LC
Phalaropus lobatus	MIG	AQ	In	W		LC
Phalaropus tricolor	MIG	AQ	In	W		LC
Phasianus colchicus	EXO	TER	Gr	Gl		LC
Pheucticus ludovicianus	RES	TER	In	Nr		LC
Pheucticus melanocephalus	RES	TER	Gr	Nr		LC
Phoenicopterus ruber	EXO	AQ	Om	W		LC
Pipilo chlorurus	RES	TER	Gr	Sm		LC
Pipilo maculatus	RES	TER	Gr	Sm		LC
Piranga flava	RES	TER	In	Nr		LC
Piranga ludoviciana	MIG	TER	In	Nr		LC
Piranga rubra	MIG	TER	In	Nr		LC
Plegadis chihi	RES	AQ	In	W		LC
Pluvialis dominica	MIG	AQ	In	W		LC
Pluvialis squatorola	MIG	AQ	In	W		LC
Podiceps nigricollis	RES	AQ	In	W		LC
Podylimbus podiceps	RES	AQ	In	W		LC
Polioptila caerulea	MIG	TER	In	Nr, Gl, Sm		LC
Pooecetes gramineus	MIG	TER	Gr	Gl, Al, Sm		LC
Porphyrio martinicus	MIG	AQ	In	W		LC
Porzana carolina	MIG	AQ	In	W		LC
Progne chalybea	MIG	TER	In	Sm		LC
Psaltriparus minimus	RES	TER	In	Nr		LC
Ptiliogonys cinereus	RES	TER	In	Nr		LC
Pyrocephalus rubinus	RES	TER	In	Gl, Al, W, Ur, Nr, Sm		LC
Quiscalus mexicanus	EXO	TER	Om	Ur, Al, W, Nr, Sm, Gl		LC
Rallus limicola	RES	AQ	In	W		LC
Rallus tenuirostris	RES	AQ	In	W		NT
Recurvirostra americana	RES	AQ	In	W		LC
Riparia riparia	MIG	TER	In	W		LC
Salpinctes obsoletus	RES	TER	In	Nr, Sm		LC
Saucerottia beryllina	RES	TER	Ne	Nr		LC
Sayornis nigricans	RES	TER	In	W		LC
Sayornis phoebe	MIG	TER	In	Nr		LC
Sayornis saya	MIG	TER	In	Gl, Sm, Al		LC
Selasphorus platycercus	RES	TER	Ne	Nr		LC
Selasphorus rufus	MIG	TER	Ne	Nr		LC
Setophaga coronata	MIG	TER	In	Nr, Ur		LC
Setophaga nigrescens	MIG	TER	In	Nr		LC
Setophaga occidentalis	MIG	TER	In	Nr		LC
Setophaga palmarum	MIG	TER	In	Nr		LC
Setophaga petechia	MIG	TER	In	Nr		LC
Setophaga pitiayumi	MIG	TER	In	Nr		LC
Setophaga ruticilla	MIG	TER	In	Nr		LC
Setophaga townsendi	MIG	TER	In	Nr		LC
Setophaga virens	MIG	TER	In	Nr		LC
Sicalis luteola	MIG	TER	Gr	Gl		LC
Sitta canadensis	MIG	TER	In	Nr		LC
Spatula clypeata	MIG	AQ	Om	W		LC
Spatula cyanoptera	RES	AQ	Om	W		LC
Spatula discors	MIG	AQ	Om	W		LC
Sphyrapicus varius	RES	TER	In	Nr		LC
Spinus pinus	MIG	TER	Gr	Nr, Sm		LC
Spinus psaltria	RES	TER	Gr	Al, Nr, Gl, Ur, Sm		LC
Spiza americana	MIG	TER	Gr	Gl		LC
Spizella atrogularis	RES	TER	Gr	Gl, Sm		LC
Spizella pallida	MIG	TER	Gr	Gl, Sm		LC
Spizella passerina	RES	TER	Gr	Gl, Sm		LC
Sporophila torqueola	RES	TER	Gr	W		LC
Stelgidopteryx serripennis	RES	TER	In	Al, W, Ur, Sm, Gl, Nr		LC
Sterna forsteri	MIG	AQ	Ca, In	W		LC
Sterna hirundo	MIG	AQ	Ca, In	W		LC
Streptopelia decaocto	EXO	TER	Om	Ur, Nr, Al		LC
Sturnella magna	RES	TER	In	Al, Gl, Sm		LC
Sturnus vulgaris	EXO	TER	Om	Ur, Al, Nr		LC
Tachybaptus dominicus	MIG	AQ	Ca, In	W	Sp	LC
Tachycineta bicolor	MIG	TER	In	Al, W		LC
Tachycineta thalassina	RES	TER	In	Al, W		LC
Thryomanes bewickii	RES	TER	In	Nr, W, Sm, Ur		LC
Toxostoma curvirostre	RES	TER	In	Nr, Al, Ur, Sm		LC
Tringa flavipes	MIG	AQ	In	W		LC
Tringa melanoleuca	MIG	AQ	In	W		LC
Tringa semipalmata	MIG	AQ	In	W		LC
Tringa solitaria	MIG	AQ	In	W		LC
Troglodytes aedon	RES	TER	In	Nr, Sm		LC
Turdus migratorius	RES	TER	In	Nr		LC
Turdus rufopalliatus	RES	TER	In	Nr, Ur		LC
Tyrannus forficatus	MIG	TER	In	Gl, Nr		LC
Tyrannus melancholicus	RES	TER	In	Gl, Nr		LC
Tyrannus tyrannus	MIG	TER	In	Gl		LC
Tyrannus verticalis	MIG	TER	In	Gl, Nr, Sm		LC
Tyrannus vociferans	RES	TER	In	Gl, Nr, Sm, Ur		LC
Tyto furcata	RES	TER	Ca	Gl, Al, Nr, Ur		LC
Vermivora chrysoptera	MIG	TER	In	Nr		LC
Vireo bellii	MIG	TER	In	Nr		LC
Vireo cassini	MIG	TER	In	Nr		LC
Vireo gilvus	MIG	TER	In	Nr		LC
Vireo griseus	MIG	TER	In	Nr		LC
Vireo huttoni	RES	TER	In	Nr		LC
Vireo plumbeus	MIG	TER	In	Nr		LC
Vireo solitarius	MIG	TER	In	Nr		LC
Volatinia jacarina	RES	TER	Gr	Gl		LC
Xanthocephalus xanthocephalus	MIG	TER	Gr	Al, Gl, W		LC
Zenaida asiatica	RES	TER	Gr, Fr	Gl, Ur, Al, Nr, Sm		LC
Zenaida macroura	RES	TER	Gr, Fr	Gl, Al, Sm		LC
Zonotrichia leucophrys	RES	TER	Gr	Gl		LC

* Residency status: resident (RES), migrant (MIG). ^† Habits: terrestrial (TER), aquatic or semiaquatic (AQ). ^‡ Feeding guilds: carnivore (Ca), insectivore (In), granivore (Gr), omnivore (Om), frugivore (Fr), nectarivore (Ne), scavenger (Sc). • Habitats: agricultural lands (Al), wetlands (W), urban areas (Ur), remnants of native and non-native vegetation (Nr), grasslands (Gr), semi-desert xeric scrubs (Sm). ^◊ Vulnerability status in Mexican national legislation NOM-059-Semarnat-2010: special protection (Sp), threatened (T). ^∆ Vulnerability status at global level (IUCN Red List): least concern (LC), near threatened (NT).

in Appendix A). The species accumulation curves illustrate the completeness of the survey conducted and the sufficiency of sampling efforts in study sites (Figure 2). The richness estimators predicted 300 to 305 species, which is very close to our observed species richness (N = 290).

In total, 809,337 individuals were recorded during the study period (

Table 2. Bird diversity values of the study sites in the Mexico City Metropolitan Area, Mexico.

	Total	Guadalupe Lake	Zumpango Lagoon	Nabor Carrillo Lake	Sierra Hermosa Ecological, Tourist and Recreational State Park	Cerro de Paula
Species richness	290	197	209	193	199	146
Species richness (monthly average)	138.8	73.6	87.2	74.3	77.7	50.9
Chao 2	300 (96.6%)	200 (98.5%)	217 (96.3%)	201 (96.0%)	219 (90.4%)	166 (87.9%)
Jakk 1	305 (95.0%)	205 (96.1%)	229 (91.2%)	209 (92.3%)	228 (87.8%)	170 (85.9%)
Abundance (monthly average)	5686.5	4760.1	11,408.1	8263.9	2669.0	806.4
H’	3.12	3.07	3.22	3.04	3.19	2.99
H’ max	5.67	5.28	5.34	5.26	5.29	4.98
J’	0.79	0.76	0.76	0.75	0.78	0.82

). Species richness and abundance were both highest in Zumpango Lagoon (209 species, 11,408.1 ind/month) followed by Sierra Hermosa (199 species, 2669 ind/month), and the lowest in Cerro de Paula (146 species, 806.4 ind/month) (Figure 3). The Shannon diversity index (Hʹ) value was highest for Zumpango Lagoon (H′ = 3.22) and lowest for Cerro de Paula (H′ = 2.99) (Figure 3). Contrary to what was expected, the evenness of the species distribution was highest in Cerro de Paula (J′ = 0.82) and lowest in Zumpango Lagoon (J′ = 0.76), Guadalupe Lake (J′ = 0.76), and Nabor Carrillo Lake (J′ = 0.75) (Figure 3). The species’ richness differed significantly among sites (F_4,139 = 35.18, p <0.001), as did abundance (F_4,139 = 19.46, p < 0.001); as well as the Shannon diversity index (F_4,139 = 3.01, p = 0.02) and evenness (F_4,139 = 4.45, p =0.002) among sites, respectively. The residency status of the study sites revealed that 125 species (43.1% of the total birds) were residents and 140 were migrants (48.2%), and the remaining 25 were introduced species (8.6%); 209 species were terrestrial and 82 were aquatic. These proportions were similar across all the study sites. In terms of habitat, the native and non-native remnants had the highest species richness (n = 134 species), followed by wetlands (n = 110); both species richness and abundance varied among habitats. Regarding the feeding guild of bird species, it was found that insectivores dominated all study sites (n = 166 species) and all habitats. Granivores were the second most represented (n = 48), followed by carnivores (n = 43), except in the wetlands, where there were more omnivores (n = 28) than carnivores (n = 25). In all habitat types, frugivores, scavengers, and nectarivorous bird species were documented in comparatively lesser numbers.

Model selection tables are provided in Supplementary Materials Table S2, as well as full results of the most supported model. For the models examining total richness, the most supported model contained the interaction of season and distance to the nearest greenspace, which outperformed the second-best model by >11 AICc points. Although the interaction showed that the effect of distance on richness was significantly more positive during the rainy season than during the two dry seasons (Figure 3A,

Table A2. Results of most supported mixed models (CI = Confidence Interval, Dgs = Distance to nearest greenspace).

Predictors	Estimates	95% CI	p
Overall species richness
Intercept)	74.81	48.88–100.75	<0.001
Dgs	1.01	−2.18–4.21	0.533
Season [warm–dry]	−1.55	−11.74–8.64	0.763
Season [rainy]	−34.97	−44.73–−25.22	<0.001
Dgs × Season [warm–dry]	−0.76	−2.02–0.49	0.232
Dgs × Season [rainy]	2.39	1.19–3.59	<0.001
Random effects: Σ2Site = 167.3, Σ2Residual = 127.08
Resident species richness
(Intercept)	40.11	26.96–53.27	<0.001
Dgs	1.25	−0.37–2.87	0.130
Season [warm–dry]	3.56	−4.30–11.42	0.372
Season [rainy]	−13.07	−20.59–−5.54	0.001
Dgs × season [warm–dry]	−0.69	−1.66–0.28	0.162
Dgs × season [rainy]	2.12	1.20–3.05	<0.001
Random effects: Σ2Site = 39.99, Σ2Residual = 75.57
Migrant species richness
(Intercept)	32.99	26.12–39.85	<0.001
Season [warm–dry]	−5.64	−8.87–−2.42	0.001
Season [rainy]	−19.96	−23.05–−16.87	<0.001
Random effects: Σ2Site = 55.77, Σ2Residual = 62.17
Shannon diversity index
(Intercept)	3.19	3.09–3.29	<0.001
Season [warm–dry]	0.06	−0.07–0.19	0.378
Season [rainy]	−0.33	−0.45–−0.20	<0.001
Random effects: Σ2Site = 0.01, Σ2Residual = 0.10
Log (Abundance)
(Intercept)	7.96	7.22–8.71	<0.001
Random effects: Σ2Site = 0.68, Σ2Residual = 0.77
Evenness
(Intercept)	0.78	0.76–0.80	<0.001
Random effects: Σ2Site = 0.0004732, Σ2Residual = 0.0048856

in Appendix A), none of these effects differed significantly from zero (cold–dry: β = 1.011, 95% CI= −3.70–5.72; warm–dry β = 0.248, 95% CI = −4.47–4.96; rainy: β = 3.404, 95% CI = −1.31–8.12). This trend was strengthened when considering only resident species richness; the most supported model (by >21 AICc points) contained the interaction of season and distance to the nearest greenspace, with a significantly stronger positive effect of distance during the rainy season than either of the two dry seasons (Table A2 in Appendix A). Here, there was a significant positive effect of distance during the rainy season (β = 3.372, 95% CI = 1.01–5.73), but no significant effect during the two dry seasons (cold–dry: β = 1.248, 95% CI = −1.10–3.60; warm–dry: β = 0.559, 95% CI = −1.81–2.92; Figure 3B). Considering only migrant species richness, there were four models within 2 AICc points; the simplest, and therefore best supported, was the model that included only the season. Migrant species richness was highest during the cold–dry season (estimated marginal mean [emm] = 33.0, 95% CI = 23.78–42.2), intermediate during the warm–dry season (emm = 27.3, 95% CI = 18.12–36.6), and lowest during the rainy season (emm = 13.0, 95% CI = 3.81–22.2; all pairwise comparisons were significant at p < 0.001; Figure 4A). For the Shannon diversity index, the most supported model contained the season with a similar trend; the two dry seasons had higher Shannon diversity index values than the rainy season (p < 0.0001 for rainy versus cold–dry and warm–dry; cold–dry versus warm–dry, p = 0.38; cold–dry: emm = 3.19, 95% CI = 3.07–3.31; warm–dry: emm = 3.25, 95% CI = 3.11–3.39; rainy: emm = 2.86, 95% CI = 2.73–3.00; Figure 4B). Finally, for both abundance and evenness, the most supported model was the null model (Table A2 in Appendix A).

According to the heatmap, the most similar sites in species composition were Zumpango Lagoon–Sierra Hermosa (0.82) and Zumpango Lagoon–Nabor Carrillo Lake (0.82), while the least similar sites to these were Nabor Carrillo Lake–Cerro de Paula (0.61) and Guadalupe Lake–Cerro de Paula (0.63) (Figure 5). The beta diversity pattern was assessed by the ANOSIM test, which indicated a significant difference in the avian communities (R = 0.1603; p = 0.0001) (Figure 6). Pairwise comparison showed significant differences between Zumpango Lagoon, Nabor Carrillo Lake, Sierra Hermosa, and Guadalupe Lake with Cerro de Paula (p = 0.0002), but no difference between Zumpango Lagoon, Nabor Carrillo Lake and Sierra Hermosa (p = 0.222). The nMDS results showed that bird communities were significantly different among study sites (stress = 1.1886, <0.3), indicating a good fit of the model (Figure 6).

With respect to species composition among habitats, grasslands–agricultural lands (0.66) and grasslands–semi-desert xeric scrubs (0.58) clearly form a cluster, while the least similar sites were wetlands–native and non-native vegetation (0.06), wetlands–semi-desert xeric scrubs (0.09) and wetlands–urban areas (0.08), which formed different clusters (Figure 7).

Only one of the bird species was in a threat category of the IUCN Red List: Snowy Plover (Anarhynchus nivosus) is near threatened. The rest of all bird species were in the least concern category. However, 11 species were listed in the NOM-059 with regional level protected status: eight in special protection: Cooper’s Hawk (Accipiter cooperi), Sharp-shinned Hawk (A. striatus), Short-eared Owl (Asio flammeus), Broad-winged Hawk (Buteo platypterus), Swainson’s Hawk (B. swainsoni), Montezuma Quail (Cyrtonyx montezumae), Painted Bunting (Passerina ciris) and Least Grebe (Tachybaptus dominicus); and three as threatened: Mexican Duck (Anas diazi), American Bittern (Botaurus lentiginosus) and Snowy Plover (Anarhynchus nivosus).

4. Discussion

The results of this study showed no clear relationship between bird diversity and environmental variables of the study sites analyzed. The results found agree that sites located in the peri-urban landscape are more diverse than sites within the urban area [23,72,73]. Similarly, a study by Charre et al. [24] examined comparable variables and additional indices related to vegetation cover in the same region. Their findings indicated that bird species richness increased with greenspace size only during the breeding season, whereas during the migratory season, the richness of migratory birds was instead linked to the distance from natural vegetation. Similar, these results do not align with previous research, which typically associate bird species richness with greenspace size and vegetation cover in urban areas [74,75,76]. It is unsurprising that previous studies have consistently found greater biodiversity in larger greenspaces, as they typically provide a broader range of food resources, micro-habitats, and favorable conditions for reproduction, dispersion, and survival [77,78,79].

Of the environmental variables used in this study, only distance to the nearest greenspace differed significantly between the three seasons. The effect of distance to the nearest greenspace was significantly more positive during the rainy season than the two dry seasons and was significantly greater than zero only during the rainy season. However, previous studies reported weak relationships with spatial variables, suggesting that greenspace characteristics may not be the primary factors influencing species composition, as observed in other studies [80,81]. Instead, tree density may play a more influential role [21], and most studies have observed a significant relationship between size and bird diversity [74,82,83]. This discrepancy may be partly explained by greater habitat heterogeneity and the availability of water resources in larger landscapes [81,83,84]. An unexpected finding concerns dispersal—specifically, the distance to the nearest natural vegetation patch (or protected area)—which showed no significant effects. This suggests that the distance of greenspaces from natural vegetation does not limit bird dispersal and colonization [23,79]. Therefore, nearby greenspaces or vegetation patches offer shelter and food and may also serve as habitat corridors [76,85]. Other studies have indicated that bird species richness within a site study decline when surrounded by densely urbanized areas, leading to more uniform communities [85,86]. This highlights the ecological importance of peri-urban areas as shelters for maintaining bird diversity, even in an expanding city [23,72,73].

In Mexico, 1151 bird species have been described [35], while 412 species have been documented for the Valle of Mexico region according to Peterson and Navarro-Sigüenza [34]. Thus, in this study, we recorded 27.2% of the birds distributed in Mexico and around 70.3% of those described for the Valley of Mexico region. The sampling completeness was ~97%, highlighting that the bird species sampling was very adequate and efficient in the study area. Only migratory species richness differed significantly in pairwise comparisons across seasons (p < 0.01 in all cases), and the Shannon diversity index during the cold–dry and warm–dry season were similar to each other (p = 0.38) and were each significantly higher than the rainy season (p < 0.0001) based on estimated marginal means contrasts from a linear mixed model. Bird species richness, abundance and diversity were greater in heterogeneous environments [11,12] than in homogeneous environments [87] throughout the study period. This species richness pattern is consistent not only with our expectations, but also with the findings from previous studies in other areas close to the study area [88,89,90]. Spatial distribution of bird diversity is influenced by multiple environmental factors, including food resource diversity and availability [91,92]. Previous studies have confirmed that the presence of heterogeneous environments supports a high bird diversity, due exists higher food availability [12,59]. Similar patterns were observed in all study sites which mainly included native or non-native vegetation that supported a substantial abundance of birds [93]. In a heterogeneous landscape, the scattered anthropogenic habitats can provide additional food for birds that have higher environmental plasticity that can find food in both natural and human-dominated habitats [91].

Tu et al. [94] reported that species richness and evenness were different between natural and human-dominated habitats. Though a significant difference was observed in species richness among study sites, no observation of any difference in evenness was found. This may be because these study sites are rural settlements surrounded by agricultural areas, as with native and non-native trees and remnants of scrubland, and even minimal human disturbance significantly affected bird evenness in this site [95]. The sites with the greatest habitat heterogeneity had the maximum species richness throughout the year, although in general all sites had lower species richness and abundance during May and August. This could be related to the migratory period, and in the case of residents, the abundance and availability of food, increased anthropogenic activities (e.g., corn and prickly pear harvesting), which contribute to a lower diversity of species [11,12,92]. Bird diversity declines during the warmer month and is reduced to May to August, and this starts to increase from the beginning of September, with the arrival of migratory species, through March. This seasonal variation is similar to that reported in other studies [88,89,96]. Likewise, wetlands adjacent to peri-urban areas provided shelter and food for many migratory birds during colder months [23,88,89].

Migrant birds need to feed both during migration and on their wintering grounds; they therefore stop feeding at several sites along their migration route. For example, aquatic migrants move between different waterbodies until they reach a large one. Therefore, the conditions of these stopovers are critical for their survival during their stay, and this migratory species influx contributed to the increasing bird diversity during winter. It has been reported that water bodies with adjacent vegetation had greater species richness than water bodies with sparse vegetation [97] and that remnants of native and non-native vegetation are important bird habitats [93]. Water bodies contained the highest number of birds and abundance, and this revealed that this habitat significantly differed from other habitats in this study area. Bird diversity was higher in water bodies because of the large number of gathering colonial water birds, many of which were breeding, such as the American Coot (Fulica americana), Black-necked Still (Himantopus mexicanus), American avocet (Recurvirostra americana), Killdeer (Charadrius vociferus), Mexican Duck (Anas diazi), Ruddy Duck (Oxyura jamaicensis), Common Gallinule (Gallinula galeata), Pied-billed Grebe (Podilymbus podiceps), Eared Grebe (Podiceps nigricollis), Clarkʼs Grebe (Aechmophorus clarkii), Black-crowned Night Heron (Nycticorax nycticorax), Northern Shoveler (Spatula clypeata) and Blue-winged Teal (S. discors). Birds are abundant in these habitats because of some environmental characteristics of wetlands or waterbodies, like size, depth, water level, and plant species [73,98]. Several studies have shown that waterbird diversity is greatly influenced by the composition and structure of vegetation and microclimatic variables [73,99].

In many cases, overall bird richness and abundance have not been affected by land-use change (i.e., natural vegetation loss) on the landscape scale. This is because bird assemblages are composed of species that have different responses to environmental variables and anthropogenic impact [100,101]. Bird species from sensitive habitats may be replaced by those favored by human activity and habitat modification [32], resulting in the same overall richness and abundance. The results of this study argue against richness as the sole measure of diversity, as anthropized sites showed a relatively high species richness but more uneven distribution of abundance of individuals. In anthropized habitats there is stronger dominance of a smaller set of species that probably consume a larger proportion of available resources. These likely include generalist and non-native species like House Sparrow (Passer domesticus), Cattle Egret (Ardea ibis), House Finch (Haemorhous mexicanus), Great-tailed Grackle (Quiscalus mexicanus), among others. Meanwhile, low evenness and less dominance of certain species (those species associated with forests or endemic) were observed inside the urban avian community in comparison to the semi-urban and rural avian communities, where they were most frequently observed. Other studies have found similar results [31,102], in which the presence of some dominant (more relatively abundant) species is responsible for an uneven ecological community. Specifically, insectivore and granivore birds were more abundant in open areas with crops and grassland areas, due to the high availability of invertebrates and seeds. In addition to supporting more species, the remnants of natural habitat within peri-urban areas deserve better planning due to many species using them as shelter, feeding sites and breeding, as higher ecological diversity benefits species survival and human well-being [103,104]. Species can use transformed habitats to survive as ecosystems are destroyed and converted into human-dominated landscapes. However, these habitats may not be as valuable as the original ecosystems [31,91,95,102]. Bird diversity is influenced by habitat type and size around the world, but especially in countries with emerging economies, which tend to have rapid population growth and unplanned urban, agricultural, and industrial development.

Bird diversity can vary based on size [74,105], vegetation cover percentage, or overall habitat heterogeneity [21,23,24], suggesting that larger areas may attract a greater number of species. This aligns with previous studies showing that certain urban infrastructure components can have positive effects on bird species associated with highly urbanized areas [106,107], while species more sensitive to urbanization tend to seek refuge in peri-urban landscapes [25,108]. Alternatively, the lack of association between bird richness and local variables may also indicate the influence of other factors that were not considered, and that can be determining bird diversity in neotropical cities [18,109,110,111].

The peri-urban landscape also plays an important role for many species, especially migratory species [31,32] and could play an important role in improving connectivity in the urban landscape and with surrounding areas with natural vegetation [23,31,87]. Therefore, it is important to investigate the key factors affecting bird diversity in human-dominated areas, to propose actions to improve these environments, to maintain and conserve bird diversity. Accordingly, the preservation of pristine and restoration of degraded habitats and sustaining habitat heterogeneity and connectivity should be central to land use planning and management to reduce the impact of human disturbances on bird diversity.

5. Conclusions

Bird diversity is influenced by vegetation heterogeneity and structural complexity [21,112]; however, vegetation also plays a key role, as native vegetation can support more diverse bird communities [113]. Therefore, studying not only the size of urban greenspaces but also their configuration, vegetation structure, and management is essential for understanding their impact on urban bird diversity and populations [113,114].

For the long-term protection of bird communities, appropriate management programs must be designed and implemented. The results of this study reveal that cities can support a certain degree of avian diversity, but that diversity is far from that of non-urban sites. Therefore, measures are required to improve the urban landscape. The high diversity and species richness of birds in the study sites in MCMA emphasizes the importance of implementing conservation measures and that limiting human activity is important for bird conservation in order to help reduce threats to bird habitats and populations. The results showed that the highest diversity was recorded in water bodies with heterogeneous environments, while a significant decrease in avian diversity was observed in semi-urban and urban habitats. In addition, most bird species were found to have clustered dispersal patterns, especially aquatic migrants, suggesting the presence of threats and limited resources in some specific areas. Further quantification is needed to assess how anthropogenic stressors, and human intrusions impact the bird community throughout the study area. Conservation of wetlands close to the peri-urban area could be a viable strategy to preserve bird communities, as these ecosystems support and offer a variety of resources crucial for bird diversity.

Efforts are needed to mitigate the potential adverse effects of the various human interferences present in anthropogenic landscapes. Despite the great importance of conserving these habitats dominated by humans, efforts aimed at preserving native vegetation (scrublands, grasslands and native trees) should not be relaxed, because there were still many species that showed a higher specificity for these natural habitats, and some of them only persisted in these environments, being rarely found in habitats modified by humans. Furthermore, due to man-made landscape alterations and increasingly intense global changes, we recommend continuous monitoring of bird communities and their responses to ongoing environmental changes; to optimize management and conservation plans for these bird communities in central Mexico.