Habitat Variables Research Articles

Urban gradient resolution matters! Avian diversity patterns in a boreal green city

Urbanization is a prominent driver of environmental change worldwide, profoundly impacting biodiversity dynamics. While much research has originated from large urban areas in temperate regions, medium-sized boreal cities remain relatively understudied. By following a citywide survey approach, we studied the impact of urbanization intensity gradient resolution on bird diversity in Lahti, Finland, a green boreal city. While one of the urbanization intensity gradients (four-category gradient) showed no significant differences in species richness, the more detailed resolution (ten-category gradient) revealed a decline in species richness within the most urbanized categories, albeit such decline was not pronounced, probably due to the extensive green cover of the city. Species identity analyses confirmed distinct bird community compositions at 50% built cover threshold for both gradient resolutions. Our analyses identified key variables related to bird species richness on the site level, highlighting the positive correlation with tree cover and negative correlations between built cover and noise level with recorded bird species richness. These findings expose the intricate interplay of habitat variables in shaping bird diversity in urban environments. Moreover, the results of this study emphasize the importance of detailed resolutions when assessing urbanization gradients, particularly in less biodiverse regions. Finally, we show the pivotal role of citywide surveys in providing a comprehensive understanding of urban biodiversity, allowing for precise categorization and comparison of conditions within the city. This approach provides valuable insights for urban planning and conservation efforts in boreal climatic regions.

The population structure and habitat use of resident of Mandarin Duck (Aix galericulata) in Wu River (Southwest China)

BackgroundThe Mandarin Duck (Aix galericulata) has recently been recognized as a partial migrant in China. The resident population of this species is primarily recorded in southern China, which is not only the traditional wintering range, but also the southernmost breeding sites. However, little information is known about their abundance and habitat requirements during breeding periods. This study provided the first report on the structure of the resident population and the habitat used during the post-breeding period at a tributary of the Wu River in Guizhou Province, Southwest China, which was one of the recently identified breeding sites within the traditional wintering range.ResultsA total of 36 Mandarin ducks were recorded among 15 sites, and the mean population density was estimated to be 3.51 ± 3.06 ind./km. The observed adults sex ratio of males to females was 0.44:1. At the microhabitat scale, the results of logistic regression models indicated that the key habitat variables included the distance to the nearest forest edge (dist.forest), opening extent of valley (deg.valley) and distance to the nearest human settlement (dist.settlement). The Mandarin Duck preferred to use foraging sites near forest edges, where dense marginal growth of woodland and shrubs was present.ConclusionThese findings suggested that dense vegetation along rivers could play a positive, important role in habitat use by the resident population of Mandarin ducks. Compared to traditional breeding ranges, both adults and ducklings of this species were more likely to experience human-related disturbances due to the limited availability of ancient trees outside villages. This information will contribute to provide baseline knowledge on the resident population of Mandarin ducks, and enhance understanding of the causes and consequences of breeding partial migration.

Factors Affecting Bird Diversity in the Wetlands of Muara Gembong, Indonesia

Marshlands and backswamps are among the threatened habitats in Indonesia, along with mangroves, particularly in Java due to area development and land conversion. Muara Gembong is one of the remaining wetlands in Java and serves as one of the last refuges for the bird community in wetlands, particularly mangrove and marsh-associated birds. We observed bird communities and collected eleven habitat variables in three habitats, namely mangrove, marsh, and fishpond, to see which variable affects bird abundance and diversity most. We found out that the total number of plant species, along with the number of tree, understory, and shrub species, were the strongest factors affecting bird diversity in Muara Gembong. Separate analysis in each habitat, however, reveals that different abiotic factors also strongly correlate with bird diversity. Vegetation correlates strongly with bird diversity in mangroves and marshes, while pH and turbidity play a strong role in bird diversity in fishponds.

Fall Migration of the Northern Shoveler at Hypersaline Mono Lake, California

From 2002 to 2022, waterfowl were surveyed at Mono Lake to evaluate the their response to lake-level changes under the State Water Resources Control Board’s landmark Decision 1631, in which the public trust doctrine was first applied to water rights. From September through mid-November, the total numbers of Mono Lake’s most numerous dabbling duck, the Northern Shoveler (Spatula clypeata), averaged 13,018 ± 1571 (standard error), ranging from a high of 27,400 in 2008 to a low of 2719 in 2018. Annual peak counts averaged 5562 ± 709, ranging from a low of 768 in 2018 to the highest single-day count of 13,793 in 2012. Annual totals were higher under conditions of monomixis than under the stratified condition of meromixis. In a generalized linear model, the combined effects of survey period, biomass of Mono Lake brine shrimp (Artemia monica), and regional drought explained 67.8% of the variation in Northern Shoveler numbers at Mono Lake, i.e., higher Artemia biomass and more severe drought in northeast California resulted in higher shoveler counts. Lake level, a key component of waterfowl-habitat restoration, showed no effect within the range of lake levels observed. These results suggest that food resources and regional drought have been the most important factors influencing Northern Shoveler use of Mono Lake, so far overriding any small-scale influences of habitat variation due to lake-level changes.

How do red foxes (Vulpes vulpes) explore their environment? Characteristics of movement patterns in time and space

BackgroundMany animals must adapt their movements to different conditions encountered during different life phases, such as when exploring extraterritorial areas for dispersal, foraging or breeding. To better understand how animals move in different movement phases, we asked whether movement patterns differ between one way directed movements, such as during the transient phase of dispersal or two way exploratory-like movements such as during extraterritorial excursions or stationary movements.MethodsWe GPS collared red foxes in a rural area in southern Germany between 2020 and 2023. Using a random forest model, we analyzed different movement parameters, habitat features—for example landclasses and distances to linear structures—and time variables (season and time of day) within red fox exploratory, transient and stationary movement phases to characterize phase specific movement patterns and to investigate the influence of different variables on classifying the movement phases.ResultsAccording to the classification model, the movement patterns in the different phases were characterized most strongly by the variables persistence velocity, season, step length and distance to linear structures. In extraterritorial areas, red foxes either moved straight with high persistence velocity, close to anthropogenic linear structures during transient movements, or more tortuously containing a higher variance in turning angles and a decrease in persistence velocity during exploratory-like movements. Transient movements mainly took place during autumn, whereas exploratory-like movements were mainly conducted during winter and spring.ConclusionMovement patterns of red foxes differ between transient, exploratory and stationary phases, reflecting displacement, searching and resident movement strategies. Our results signify the importance of the combined effect of using movement, habitat and time variables together in analyzing movement phases. High movement variability may allow red foxes to navigate in extraterritorial areas efficiently and to adapt to different environmental and behavioral conditions.

Age and reproductive status determine spatial niche utilization in Vipera ammodytes (Linnaeus, 1758)

While data on habitat use of Vipera ammodytes are abundant, most studies are purely descriptive and only list the typical habitats in which the species is found. The intraspecific variations (i.e., ontogenetic and intersexual) in habitat and microhabitat utilization remain very poorly studied. In order to assess those intraspecific variations, we studied five different populations in western Bulgaria between 2014–2017, searching for vipers from early spring to late autumn in 24 different habitat types. The ontogenetic and intersexual variations in spatial niche breadth were analysed using several ecological diversity indices, and microhabitat characteristics were estimated by the presence of trees/shrubs, grasses and stones/rocks within a 5 m diameter of each viper’s location. Vipers were found in 17 habitat types. Habitat and microhabitat selection of Vipera ammodytes were age-dependent, with juveniles having the narrowest spatial niche and preferring more open microhabitats. The breadth of the spatial niche gradually increased with age, along with the tendency to inhabit microhabitats with more shrubs. During gestation, female’s spatial niche narrowed significantly and pregnant vipers again tended to use more open microhabitats, known as rookery. The observed results could be explained by a combination of factors, such as 1) the ontogenetic differences in the trophic niche and feeding patterns, 2) different prey type abundance in distinct habitats and microhabitats, 3) the size differences between age groups with all benefits and limitations that come with them, 4) distinct behavioural patterns differing between sex/age groups or 5) a size-related bias in detection probabilities.

Body Condition and Blood Biochemistry of Free-Range Caiman latirostris in Northeast Brazilian Atlantic Forest.

The Atlantic Forest broad-snouted caiman (Caiman latirostris) inhabits regions within one of the world's most ecologically diverse ecosystems, yet few studies have explored the relationship between body condition, blood biochemistry, and environmental factors in the wild. Our study investigated the effects of sex, ontogeny, habitat, and environmental variables on the body condition and blood biochemistry of free-ranging caimans from the state of Alagoas, Northeast Brazil. From 2020 to 2022, we captured 75 caimans across three sites in different seasons. Results revealed sex-specific responses to seasonal and Interannual weather changes, with females showing higher body condition in the wet season, while males peaked in the dry season. Elevated glucose, total protein, albumin, triglycerides, and fructosamine were linked to higher body condition and larger individuals, while elevated aspartate aminotransferase to low body condition. Seasonal rainfall influenced blood parameters, with the dry season associated with higher creatinine, calcium, and alanine aminotransferase levels, and the wet season with higher total protein, sodium, and potassium. Differences in glucose, alkaline phosphatase, and gamma-glutamyl transferase across sites pointed to physiological effects of human activities. Blood biochemical values varied widely, with some exceeding reported species ranges. These findings highlight the need to interpret physiological data within the context of local habitat and environmental conditions. Conservation strategies should go beyond species presence and habitat preservation, incorporating pollution control. Our study advances understanding of Caiman latirostris ecophysiology, offering valuable insights for the conservation and management of crocodilian populations in both wild and captive environments.

Coastal eutrophication transforms shallow micro-benthic reef communities.

Coral reefs are impacted worldwide by coastal eutrophication, which is often translated by a decrease in coral cover and an increase in potentially harmful invertebrates and algal blooms. Additionally to corals and other macro-benthos, micro-benthic communities are affected tremendously, however few studies reported the specific effect of eutrophication on those communities. This study addresses how micro-benthic communities are impacted by turbidity and associated eutrophication. To answer this question, we compared three groups that have been previously suggested as bioindicators of reef environmental conditions: foraminifera, diatoms and bacteria, from 12 islands (and 600 samples) in the Spermonde Archipelago (Indonesia) along a near- to offshore turbidity gradient. Insights from environmental DNA metabarcoding and satellite images highlighted differences between the reef slope (deep) and the reef flat (shallow) communities, a distinction that has been omitted in most previous studies. The reef flat communities were 1.5- to 2-fold more affected by turbidity parameters compared to the reef slope, which we argue is related to eutrophication. Based on previous work, we expected that prokaryotes would be the most impacted group by water quality. However, we found that large benthic foraminifera and diatom communities were highly impacted by turbidity, whereas the reef flat prokaryotic communities were primarily shaped by the substrate type. Additionally, a total of 112 exact sequence variants (ESVs) were identified as indicators of different turbidity levels, of which 87 foraminifera and diatom ESVs were associated with high-moderate turbid waters. Our study revealed fundamental knowledge and provides key information of the specific effect of turbidity and associated eutrophication and habitat variables (substrate type and reef area) on foraminifera, diatoms and prokaryotic communities. We argue that local and regional eutrophication participates in shaping reef flat micro-benthic communities, which may therefore play an important role as early warning signals for local degradation in coral reefs.

Macrozoobenthos of the rivers of North-Eastern Azerbaijan

Between 2020 and 2023, an in-depth analysis was conducted on the species composition of the macrozoobenthos in the Yalama River, including its tributaries Telchay, Mukhtadyrchay, Velmirchay, and Khuraychay, as well as other significant rivers in northeastern Azerbaijan. During this period, a total of 53 species of benthic organisms, representing 14 different taxonomic groups, were identified across the rivers studied. These findings provide important insights into the biodiversity and ecological health of the region's freshwater ecosystems. Among the various groups recorded, mollusks, dragonflies, crustaceans, and chironomid larvae were particularly prominent, both in terms of species richness and their ecological significance within the aquatic habitats. These groups are crucial for understanding the dynamics of the river systems, as they play key roles in nutrient cycling, sediment stability, and the food web. The diversity of these species also reflects the environmental conditions and the unique characteristics of the rivers in this region, which may be influenced by factors such as water quality, habitat variation, and seasonal changes.

Amphipod size variation and substrate color preferences in coastal habitats: An experimental study in Ujung Genteng, West Java

Amphipod size variation and substrate color preferences in coastal habitats: An experimental study in Ujung Genteng, West Java

Using predictive models to identify kelp refuges in marine protected areas for management prioritization.

Kelp forests serve as the foundation for shallow marine ecosystems in many temperate areas of the world but are under threat from various stressors, including climate change. To better manage these ecosystems now and into the future, understanding the impacts of climate change and identifying potential refuges will help to prioritize management actions. In this study, we use a long-term dataset of observations of kelp percentage cover for two dominant canopy-forming species off the coast of Victoria, Australia: Ecklonia radiata and Phyllospora comosa. These observations were collected across three scuba sampling programs that extend from 1998 to 2019. We then associated those observations with habitat and environmental variables including depth, seafloor structure, wave climate, currents, temperature, and population connectivity in generalized additive mixed-effects models and used these models to develop predictive maps of kelp cover across the Victorian marine protected areas (MPAs). These models were also used to project kelp coverage into the future by replacing wave climate and temperature with future projections (2090, Representative Concentration Pathways [RCPs] 4.5 and 8.5). Once the spatial predictions were compiled, we calculated percent cover change from 1998 to 2019, stability over the same period, and future predicted change in percent cover (2019-2090) to understand the dynamics for each species across the MPAs. We also used the current percentage cover, stability, and future percentage cover to develop a ranking system for classifying the maps into very unlikely refugia, unlikely refugia, neutral, potential refugia, and likely refugia. A management framework was then developed to use those refugia ranking values to inform management actions, and we applied this framework across three case studies: one at the scale of the MPA network and two at the scale of individual MPAs, one where management decisions were the same for both species, and one where the actions were species-specific. This study shows how species distribution models, both contemporary and with future projections, can help to identify potential refugia areas that can be used to prioritize management decisions and future-proof restoration actions.

Environmental DNA Reveals Habitat Variables Driving Platypus (Ornithorhynchus anatinus) Distribution Across an Urbanised Landscape.

Freshwater waterways, and species that depend on them, are threatened by urbanisation and the consequences of the urban stream syndrome. In south-east Queensland, Australia, little is known about the impacts of the urban stream syndrome on the platypus (Ornithorhynchus anatinus), meaning that populations cannot be adequately managed by conservation practitioners. The aim of this study was to determine how habitat and environmental variables, related to the urban stream syndrome, influenced platypus distribution across this region. We used environmental DNA sampling over a 5-year period (2016-2020) to determine how platypus occurrence (presence or absence) was affected by habitat and the environment. Five scenarios based on key characteristics of the urban stream syndrome were modelled using binomial generalised linear models. The highest-ranked model of platypus occurrence included positive effects of topographic wetness index and coarse organic matter. These findings reflect important waterway connectivity and food resources for platypus, highlighting relationships between platypus, their environment and their tolerance to urban stream threats. For example, platypuses are unlikely to occur in streams where water availability is reduced, and movement will be limited in shallow, dry streams. Therefore, waterway management should focus on water availability and connectivity, especially during drought. Our study can be used to guide management plans for the persistence of platypus and other freshwater species.

Multidecadal trends in brown trout populations in France reveal a decline in adult abundance concomitant with environmental changes

Most studies of brown trout ( Salmo trutta) populations in headwater streams have focused on the year-to-year variability in recruitment and survival, but only few analyzed long-term trends in trout densities, under both control and regulated flow conditions. Here, we conducted trend analyses of brown trout age class densities on 36 stream reaches over the 1990–2020 period, including reaches located in a bypassed section. We also investigated long-term trends in a panel of key environmental variables (water temperature, stream flow, current velocity, and habitat suitability). We found that annual water temperatures significantly increased by a median of +0.21 °C per decade. Analyses of stream flow revealed only a few significant trends, including a general increase in median values in spring and a general decrease in fall. A significant general decline in adult trout densities was observed, although disparities between geographic areas were highlighted. This decline is likely due to multifactorial effects, including possible interacting factors. Our results highlight the need to maintain and extend long-term monitoring of trout populations, which should be combined with extensive environmental monitoring.

Avian communities show distinct responses to forest-to-bog restoration.

Since the 1990's, attempted restoration of blanket bogs which have been previously afforested with non-native conifers has taken place in Ireland and Britain, with the aim of reinstating hydrological functioning and hence, peatland biodiversity. Here, we assess the conservation benefit of these restoration measures at sites in the west of Ireland, 16-20 years post works, by comparing avian communities between trios of restored (n=6), near-natural (n=6), and afforested (n=6) lowland blanket bogs. We assessed avian community response in terms of differences in the richness and density of all bird species and of Birds of Conservation Concern in Ireland (BoCCI), as well as community composition. We also investigated which structural habitat variables were responsible for variation in community composition among site types. Restoration resulted in no changes in overall species richness and lower overall bird density but importantly, increased BoCCI richness in comparison to afforested sites. In particular, restoration benefited red-listed species, with richness and density of these species being similar to that of near-natural sites. Avian communities of restored sites were variable but more similar overall to those of near-natural than afforested sites, indicating partial restoration success. Changes in conifer cover, dwarf shrub height, deadwood cover, and broadleaf cover explained the majority of variation occurring across site types. These results indicate that the response of avian communities following forest-to-bog restoration is a prolonged process influenced by the evolving habitat structure, which, in turn, is contingent on the effectiveness of hydrological restoration measures, local conditions and ongoing management.

Bioacoustic Assessment of Mangrove Health: Influence of Habitat Characteristics on Bird Richness

ABSTRACTMangroves play a vital role in coastal ecosystems, providing numerous ecosystem functions and services as well as supporting high levels of biodiversity. Using a bioacoustic approach, we assessed the influence of mangrove habitat variables on birds in four sites in Peninsular Malaysia. We set up 20 bioacoustic audio recorders across Telok Gong, Kapar Tambahan, Banjar Utara Forest Reserves, and Kuala Selangor Nature Park. The recorders operated for 30 min every hour over a period of 24 h for seven consecutive days. We assessed the habitat characteristics at each site by establishing one 20 m × 20 m quadrat at each of the recording points. Generalized linear mixed models indicated that the percentage of canopy cover, average tree height, forest age, number of saplings, forest size, and ground cover positively influenced bird richness. Our findings highlight the importance of maintaining these habitat features to support higher bird species richness in mangroves. This study demonstrated the possible use of bioacoustics to assess mangrove restoration recovery progress via birds as bioindicators.Abstract in Malay is available with online material.

A Complete Assembly and Annotation of the American Shad Genome Yields Insights into the Origins of Diadromy.

Transitions across ecological boundaries, such as those separating freshwater from the sea, are major drivers of phenotypic innovation and biodiversity. Despite their importance to evolutionary history, we know little about the mechanisms by which such transitions are accomplished. To help shed light on these mechanisms, we generated the first high-quality, near-complete assembly and annotation of the genome of the American shad (Alosa sapidissima), an ancestrally diadromous (migratory between salinities) fish in the order Clupeiformes of major cultural and historical significance. Among the Clupeiformes, there is a large amount of variation in salinity habitat and many independent instances of salinity boundary crossing, making this taxon well-suited for studies of mechanisms underlying ecological transitions. Our initial analysis of the American shad genome reveals several unique insights for future study including: (i) that genomic repeat content is among the highest of any fish studied to date; (ii) that genome-wide heterozygosity is low and may be associated with range-wide population collapses since the 19th century; and (iii) that natural selection has acted on the branch leading to the diadromous genus Alosa. Our analysis suggests that functional targets of natural selection may include diet, particularly lipid metabolism, as well as cytoskeletal remodeling and sensing of salinity changes. Natural selection on these functions is expected in the transition from a marine to diadromous life history, particularly in the tolerance of nutrient- and ion-devoid freshwater. We anticipate that our assembly of the American shad genome will be used to test future hypotheses on adaptation to novel environments, the origins of diadromy, and adaptive variation in life history strategies, among others.

Canada goose fecal microbiota correlate with geography more than host‐associated factors

Gut microbiota interact with host biology in numerous important ways. The forces shaping the composition, diversity, and function of the microbiota vary within and between species. Avian microbiota often correlate more strongly with sampling location specific environmental variables than with host‐associated factors such as age, but robust, range‐wide sampling is rare. To better understand the connection between geographic distance and the microbiota, fecal samples were collected from non‐migratory Canada goose populations across the United States. We expected that geographically closer populations would be exposed to more similar environmental microbes and would therefore have more similar gut microbiota. We hypothesized that intrinsic host‐associated factors would have a weak correlation to gut microbial composition and geographic distance would have a stronger correlation. We found that some components of Canada goose microbiota are present in a majority of the geese, including four bacterial phyla, five families, and three genera. However, there were significant differences in microbial alpha diversity based on state of origin as well as significant positive correlations between geography and beta diversity. Supervised machine learning models were able to predict the state and flyway of origin of a fecal sample based on bacterial composition alone. Distance−decay analysis showed a significant positive relationship between geographic distance and beta diversity. Our work provides novel insights into the microbiota of the Canada goose and supports the hypothesis that avian microbiota are influenced by the host's environment. This work also suggests that there is a minimum geographic distance, likely associated with sufficient variation in habitat, climate, and local food sources, that must be reached before significant differences in the microbiota between two populations can be detected.

Exploring latitudinal gradients and environmental drivers of amphipod biodiversity patterns regarding depth and habitat variations

Amphipods are known as umbrella species in conservation biology that their protection indirectly protects other species. Recent hypotheses suggest a bimodal latitudinal global species richness pattern for amphipods, irrespective of species’ depth or habitat type. Phylogeographic hypotheses suggested two distinct procedures for amphipod diversification: ecological radiation and Pangea fragmentation. This study aimed to revisit the bimodal latitudinal pattern of species richness for amphipods, investigate similarities in species composition and main environmental amphipod distribution drivers regarding their depth and habitat variations. The comprehensive database was collected from open-access data and a personal sampling database from the Persian Gulf and the Gulf of Oman. After rigorous data quality controls, the final dataset comprised 1,142,416 distribution records of 6,424 accepted marine amphipod species distributed from 0 to 10,900 m depth. All the species were grouped into pelagic and benthic, shallow-water (> 200 m), and deep-sea (< 200 m). Alpha and gamma species richness and the expected number of species per 50 random samples (ES50) were calculated. Our findings showed that species richness patterns in amphipods are shaped not only by habitat types but also by depth, and they are not significantly bimodal in all groups. Also, the Beta diversity of benthic species revealed distinct diversification patterns between benthic and pelagic species. The species similarity clusters revealed a fragmentation between Gondwana and Laurasia for shallow benthic species. However, the similarity between pelagic amphipod communities is more compatible with ecological parameters. Generalized Additive Models (GAMs) highlighted that environmental variables play a significant role in species distributions, for example, temperature and chlorophyll levels were the main predictors of species richness in shallow waters. However, a complete effect of multiple environmental variables is responsible for deep-sea species gradients. These findings are crucial information to be considered when managing the species richness and establishing conservation priorities for their habitats.

Multi‐scale habitat selection and nest survival of whinchats and stonechats: implications for grassland conservation management

Effective management for endangered grassland birds requires a sound understanding of habitat requirements and factors shaping reproductive success. We studied multi‐level habitat selection of endangered whinchats Saxicola rubetra and locally increasing stonechats Saxicola rubicola in a nature reserve using Sentinel‐2 images, LiDAR data, and habitat variables measured onsite. We monitored nest fates, and estimated how the causes of nest mortality varied with nest initiation date. Further, we analyzed how nest‐site selection, precipitation, nest initiation date, and nest age influenced daily nest survival.At the landscape‐ and site‐level, both species primarily selected for territories in lightly farmed meadows. However, stonechats appeared to be less specialized and used most available habitat types. Within home‐ranges, both species selected for nest‐sites in fallow patches, but in contrast to stonechats, whinchats also selected for large viewsheds.In both species, the main causes of nest failure were predation by red foxes Vulpes vulpes, weather‐related factors, and nest desertion. In whinchats, the probability of nest desertion increased and predation risk decreased with nest initiation date, possibly due to better nest concealment in the later season. Daily nest survival decreased with nest age and precipitation in both species, and increased with nest initiation date in whinchats. None of the habitat variables examined were positively linked to daily nest survival, and viewshed was negatively related to whinchat daily nest survival.Our study suggests that extending core habitat may help to promote settlement and potentially reproductive success of whinchats. However, as habitat selection was not positively associated with daily nest survival, land management measures alone might not be sufficient to halt rapid population declines. To effectively conserve whinchats and other grassland bird populations, the causes of nest failures must be identified and addressed. Within the examined reserve and similar habitats, flood management and predator control may yield the biggest short‐term conservation gains.

Comparing perch availability and perch use between African dwarf chameleon (Bradypodion) ectomorphs

Abstract Adaptation to different environments can lead to local adaptations that facilitate morphological divergence between closely related taxa, potentially leading to speciation. Quantifying habitat variation can thus provide valuable insights into evolutionary processes. Arboreal dwarf chameleons of the genus Bradypodion exhibit three distinct ecomorphological forms: forest, shrub, and “little brown chameleons” (LBCs). It is assumed these ecomorphs are the result of convergence among species that are in similar habitats regardless of ancestry, or in some cases, morphological conservatism and retention of an ancestral form that is adapted to a shared habitat type. If so, then the habitat of different ecomorphs would differ in vegetation structure. Our results show that vegetation structure in fynbos/grassy habitats is characterised by significantly narrower perches than shrubby habitats, but both have a largely vertical perch orientation. In contrast, forests have significantly fewer vertical perches than fynbos/grassy habitats with significantly thicker diameter perches. Accordingly, LBC and shrub species used more vertically oriented perches than forest species, suggesting that perch use corresponds with the most widely available perch angles. Although LBC chameleons used the smallest diameter perches, when corrected for body size there was no difference in perch diameter among ecomorphs. These results suggest that body size of LBC chameleons is constrained by the prevalence of small diameter perches in their habitat. Species in habitats with wider perches attain larger body size. These findings support the notion that variation in perch structure is critical for phenotypic convergence that has resulted in the three Bradypodion ecomorphs.