Local Habitat Characteristics Research Articles

The effect of land use intensity and habitat characteristics on butterfly community composition within the Southern Great Plains of the United States

AbstractBackgroundAs grasslands decline, grassland‐dependent species such as grassland butterflies have experienced widespread population losses. To manage remaining grasslands, prescribed fire, grazing, and haying are common management practices across the Southern Great Plains of the United States. However, the impacts of management and land use intensity (LUI) on butterfly community composition and butterfly community traits are not well understood. Additionally, local habitat characteristics such as vegetation height and cover, as well as broader landscape categorization, including how much agriculture or urbanization is occurring around the habitat, can alter butterfly communities.MethodsWe conducted standardized butterfly and flowering forb surveys at grassland sites across north‐central Oklahoma.ResultsLUI influenced overall butterfly community composition with sites managed only with fire having the most dissimilar butterfly community compared to three other management regimens. The amount of agriculture, urbanization, and wetlands surrounding study sites also influenced butterfly community composition. Flowering forb community measures differed by site with sites managed by fire alone having lower blooming forbs species richness, diversity, and abundance than sites with other management regimens.ConclusionsSites managed with only prescribed fire had the most disparate butterfly community in comparison to other management methods, suggesting that specialist butterfly species may be sensitive to increasing disturbance.

Landscape diversity, habitat connectivity, age and size determine the conservation value of limestone quarries for diverse wild bee communities

Abstract Abandoned and even active limestone quarries (excavation sites) can represent important secondary habitats for many species, including wild bees, associated with dry grasslands, which are threatened biodiversity hotspots in Europe. However, is not well understood how interactions between local habitat and landscape characteristics influence the value of limestone quarries for wild bees and how this could guide conservation schemes. We studied how wild bee communities in limestone quarries are affected by landscape variables (connectivity to neighbouring dry grasslands, landscape diversity), local quarry characteristics (area, age, woody vegetation cover, flowering plant species) and their interactions. We surveyed bee communities during 208 transects in 19 quarries in southern Lower Saxony, Germany. In total, we recorded 114 bee species (2360 individuals), including 35 endangered species. High flowering plant species richness positively affected bee abundance and richness. Large quarry area was important for determining the presence of endangered bee species. High levels of woody vegetation cover had a negative effect on bee abundance and richness. Bee abundance and richness can increase with quarry age, but only at sites with moderate woody vegetation cover. We found potentially positive interactions between quarry age and landscape diversity and/or habitat connectivity to neighbouring dry grasslands. In particular, high habitat connectivity ensured stable richness of endangered species in old quarries. Synthesis and applications. Observed negative effects of high woody vegetation cover on bee communities highlight the importance of local management to reduce shrub encroachment and reset successional processes in limestone quarries. Local management is particularly important in old quarries of great ecological value, where the adverse impact of high woody vegetation cover on wild bees appears to be most severe. Large and old quarries with high connectivity to neighbouring dry grasslands are especially valuable for endangered bee species. Therefore, landscape‐scale restoration and conservation of dry grasslands is the most promising approach to promote endangered bee species through enhanced habitat connectivity.

Limited evidence for the influence of the physical structure and floristics of habitat on a boreal forest bird community

Studies conducted at regional and continental scales show that avian richness, community composition, and abundance are associated with variation in the vegetation physical structure and community composition (floristics) within broad habitat types. The relative contributions of physical structure and floristics are contested, and relationships are often taxon-specific. We used 110 microphone arrays deployed across 90 sampling locations and two breeding seasons to survey an avian community in the boreal forest in Labrador, Canada. Our objectives were (1) to describe the avian community of an underrepresented portion of the boreal forest, (2) to estimate the relationships between avian species richness and habitat characteristics, (3) to estimate if species detection at a given location was related to local habitat characteristics, and (4) to investigate the spatial and temporal patterns of the avian community composition. We detected 32 species at our sampling locations; physical structure and floristics were not related to avian species richness, although estimates of richness were higher on warmer days and lower on windier days. Habitat characteristics were associated with the detection of Boreal Chickadee (Poecile hudsonicus), Yellow-rumped Warbler (Setophaga coronata), American Robin (Turdus migratorius), and Black-throated Green Warbler (Setophaga virens). Finally, avian community composition was only moderately consistent among three categorical forest types and between audio sampling periods in two consecutive breeding seasons. Overall, we show that the structural and floristic traits measured at our study site are not related to the detection of most avian species or to species richness.

Combined Effects of Local and Regional Drivers on Oyster Spat Density and Growth in Eastern Australia

Up to 85% of shellfish reefs have been lost worldwide, resulting in declining ecosystem services, and increasing restoration demand. However, more information regarding the conditions which maximise oyster settlement and growth is required to optimise restoration. We deployed oyster settlement tiles at 21 intertidal sites throughout Moreton Bay, Australia; a region where > 96% of rock oyster reefs are lost and demand for restoration is high. We quantified effects of variables describing the spatial (from GIS), local habitat (using quadrats and water quality measures), and oyster predator (using underwater videography) characteristics of sites on oyster density and size on tiles. Oyster density was highest at sites with intermediate predator abundance and temperature, highest nearby invertebrate cover, and low and high values of turbidity and nearby rock and algae cover. Conversely, oyster size was highest at sites with intermediate predator density, higher fish species richness and turbidity, and lowest temperatures. Together, this showed that optimal restoration requires sites with 22 to 23 °C average water temperatures, between 10 and 15 oyster predators, and either low (< 2 NTU) or high (> 6 NTU) turbidity levels. Notably, we observed multiple peaks for several variables, suggesting the potential presence of multiple cryptic oyster species on settlement tiles. We found that oysters shared preferred environmental conditions with polychaetes, coralline algae, and tunicates, and were more prevalent and abundant at sites with lower turf algae, barnacle, and mussel cover. Identifying environmental variables influencing oyster population distribution, settlement, and growth can guide the selection and approach of oyster restoration sites.

Ecological drivers of nesting behavior in a subtropical city: An observational study on spotted doves.

Due to rapid homogenization in habitat types as a result of urbanization, some urban birds adapt their nesting strategies to changes in local habitat characteristics. Bird nesting decisions might have been mainly linked to resource constraints and ensuring reproductive success. In this study, we examined patterns of nesting behavior by spotted doves (Spilopelia chinensis) in a rapidly urbanizing area of Nanchang, China using ArcGIS 10.8, satellite tracking, camera traps, and field survey. To explore the mechanisms underlying nesting behavior in urban habitats, we assessed the correlations between nest reuse and reproductive success, and between nest reuse and nest predation. From December 2018 to December 2021, a total of 302 breeding nests were surveyed. The results revealed that the nest reuse rate was 38.08% (n = 115). Nests closer to trunk, with lower nest position and higher large-scale urbanization score tended to have higher reuse rate. In addition, nests with the higher the nest height and percent of canopy cover, and the lower small-scale urbanization score were more likely to reproduce successfully, and the reused nests also reproduce more successfully. The reproductive success associated with nest reuse was significantly higher than that associated with new nests (χ 2 = 8.461, p = .004). High degree of urbanization promoted nest reuse of spotted doves (large-scale urbanization score, z = 2.094, p = .036), which apparently enhanced their reproductive success (nest reuse, z = 2.737, p = .006). In conclusion, a nest structure with good permeability is the material basis for the nest reuse in spotted dove, while the relatively low risk of predation in urban habitat and the scarcity of nest site resources due to urbanization increase the tendency of birds to reuse old nests, which is associated with their reproductive success and evolutionary fitness.

Environmentally-driven variations in reproductive traits in a sandy beach bivalve throughout its geographic range

The yellow clam Amarilladesma mactroides (Reeve, 1854) inhabits the intertidal zone of sandy beaches along the temperate Atlantic coast from Brazil to Argentina (24°-41°S). Over the past decades, there has been a noticeable decline in its abundance, underscoring the importance of understanding their reproductive strategies and phenotypic plasticity for conservation efforts. This study explored large-scale variations in the size at first sexual maturity (SL50), the age at maturity (A50), the vitellogenic oocyte area (VOA), and a reproductive age index (RAI) that combines A50 and the lifespan of each clam population, in relation to local habitat characteristics (e.g., beach morphodynamics) and large-scale environmental variables, such as salinity, sea surface temperature (SST) and chlorophyll-a. Four sandy beach clam populations from Uruguay and Argentina (latitudinal range: 33°45′S - 38°56′S) were sampled monthly between June and August during the reproductive season. SL50 increased linearly with the mean and maximum SST (SSTmean, SSTmax), while VOA and RAI decreased with tidal range and width of intertidal zone, respectively. In beaches that had higher SSTmean and SSTmax, yellow clams reached maturity earlier and spent more than 70% of their lifespan in reproduction. The yellow clam population at the lowest latitude showed the largest oocyte sizes and a shorter lifespan of 3.5 years, while the population at the highest latitude had a longer lifespan (7 years) and the smallest VOA values. Populations at intermediate latitudes showed delayed sexual maturity, a 50–60% investment of their lifespan in reproduction, the longest lifespan (up to 9 years) and intermediate VOA values. The influence of the Rio de la Plata and Bahia Blanca estuaries modified the expected latitudinal gradient in reproductive traits, but local habitat conditions prevailed over large-scale environmental variables as explanatory factors of the reproductive strategy of the yellow clam. Therefore, the species displays phenotypic plasticity in its reproductive aspects to ensure population success.

Anthropogenic material in pied flycatcher (Ficedula hypoleuca) nests varies with local habitat features and between nest sections

Anthropogenic materials are often incorporated into bird's nests in marine and terrestrial habitats globally, although we understand very little about the non-random abundance, and variation in the abundance, of anthropogenic materials in the wider environment and in different sections of bird's nests. Here, we address these oversights by examining if the abundance of anthropogenic material in the environment is influenced by local habitat features and if their abundance varies between the outer and inner sections of pied flycatcher (Ficedula hypoleuca) nests in rural woodlands. Locations in the wider environment with farms, houses and barns contained more anthropogenic material than locations without them, whilst the presence of roads, footpaths and hedges was not associated with the abundance of anthropogenic material in the environment. Nestboxes occupied by pied flycatchers had a greater mass of anthropogenic material in the environment surrounding nestboxes than unoccupied nestboxes. Meanwhile, pied flycatchers incorporated more white and to a lesser extent orange anthropogenic material into the inner and outer sections of their nests, whilst not including significant amounts of red, blue and yellow anthropogenic material. Our results suggest that local habitat features influence the abundance of anthropogenic material in the wider environment, which is presumably because such material is more abundant in modified habitats and that anthropogenic materials are non-randomly incorporated into birds’ nests in relation to their colour and also the nest section. Our study therefore increases our understanding of the incorporation of anthropogenic material into birds’ nests.

Response of grassland birds to management in national battlefield parks

AbstractGrassland birds are in steep decline, with population declines reported in 74% of North American grassland species in the past 50 years. Declines are particularly severe in the eastern United States where they are influenced by habitat loss and alteration due to urbanization, forest regrowth, and agricultural intensification. The United States National Park Service maintains civil war battlefields in the eastern United States as historical and cultural parks that may also provide habitat refuge for grassland birds within an increasingly urbanized matrix. To assess the conservation importance of battlefield parks and the role of park management in sustaining grassland birds, we surveyed for 2 declining grassland‐breeding species, eastern meadowlark (Sturnella magna) and grasshopper sparrow (Ammodramus savannarum), at 242 points across 4 battlefield parks in Maryland, Virginia, and West Virginia, USA, from 2014–2019 and in 2021. We modeled the effects of park management activities (prescribed fire, agricultural leases, and delayed harvest) and habitat and landscape characteristics on breeding‐season occupancy. There was support for the influence of local habitat features, landscape, and management. Breeding‐season occupancy of both species was consistently higher in hayfields and pasture than in row crops, and both species responded positively to hay and crop harvest delays intended for grassland bird conservation. Prescribed fire within the past 2 years had a positive effect on occupancy of grasshopper sparrows but did not influence eastern meadowlarks. Eastern meadowlarks responded to land cover at multiple spatial scales that are influenced by land use within and outside the parks. Management activities that maintain the parks' cultural goals, including partnerships between national parks and private agricultural operators, are likely to provide valuable habitat for these 2 obligate grassland birds.

Ecosystem engineers enter the city: Habitat characteristics influencing the distribution of Eurasian beavers Castor fiber in a human-transformed landscape

In recent decades, the population of the Eurasian beaver Castor fiber has increased significantly, and from near extinction the species has become widespread again over large part of its former range. However, the recovery of the beaver population is giving rise to increasing numbers of human-beaver conflicts in areas inhabited by humans. The key challenge of beaver population management is, therefore, to identify habitat characteristics that determine the presence of the species in the human-dominated landscape, including urban areas. Based on a large-scale inventory of beavers conducted in one of the most densely populated regions of Europe, we show that the factors enhancing habitat suitability for beavers at the landscape scale are the increasing cover of meadows and surface waters, and the total length of watercourses. Although beavers avoid built-up areas, 13% of all recorded sites were located in the most densely populated regions, and the local habitat features that favour the presence of beavers in an urban landscape are the increasing cover of forests, meadows and surface waters, the total length of watercourses and the total length of roads. This indicates that patches of natural or semi-natural vegetation persisting along watercourses located in the vicinity of communication routes constitute a habitat for beavers entering the most urbanized areas. The beaver is currently expanding into western and southern Europe, but the species’ future distribution will include highly transformed urban areas. To limit human-beaver conflicts, predictions of beaver distributions in human-dominated landscapes should be used in urban and landscape planning.

Fine-Scale Species Distribution Modeling of Abies koreana across a Subalpine Zone in South Korea for In Situ Species Conservation

Severe declines in the population of Abies koreana, a conifer native to the subalpine regions of South Korea, are likely a consequence of climate change. However, local-scale modeling of the species’ spatial distribution has seen limited application to in situ conservation policies. Therefore, we intended for this study to examine the applicability of fine-scale species distribution modeling of A. koreana in the Mt. Jiri National Park area in S. Korea in order to explore candidate areas for its in situ conservation. We simulated the potential habitat of the species in the area with four separate models using different dominance patterns, then created an index based on habitability probabilities and residual durations to determine priority conservation areas. Under the highest sensitivity of potential habitats to temperature (spatially downscaled based on geomorphological characteristics), rapid habitat reduction occurred under climate warming in all experiments. At the regional scale, hydrological characteristics such as precipitation and slope characterized different secondary habitat distributional patterns among the experiments. Final conservation priority sites were identified based on specified criteria for the designed index. Our results suggest that a fine-scale modeling system with adequate spatial resolution of environmental inputs is advantageous in representing local habitat characteristics of A. koreana and can be applied to in situ conservation strategies.

Alien vs. Predator: Impacts of Invasive Species and Native Predators on Urban Nest Box Use by Native Birds.

Many bird species in Australia require tree hollows for breeding. However, assessing the benefits of urban nest boxes to native birds requires frequent monitoring that allows to assess nesting success. To better understand the benefits of nest boxes for native birds, we examined the impact of local habitat characteristics, invasive species (common myna, Acridotheres tristis), and native mammalian predators on urban nest box use and nesting success of native birds. We installed 216 nest boxes across nine locations in southeastern Australia (S.E. Queensland and northern New South Wales) in both long-invaded sites (invaded before 1970) and more recently invaded sites (after 1990). We monitored all boxes weekly over two breeding seasons. We recorded seven bird species and three mammal species using the nest boxes. Weekly box occupancy by all species averaged 8% of all boxes, with the species most frequently recorded in the nest boxes being the common brushtail possum (Trichosurus vulpecula), a native cavity user and nest predator. We recorded 137 nesting attempts in the boxes across all bird species. The most frequent nesting species were the invasive alien common mynas (72 nesting attempts). We recorded an average nesting failure rate of 53.3% for all bird species. We did not record any common mynas evicting other nesting birds, and found that several native species used the same box after the common myna completed its nesting. We recorded native possums in 92% of the boxes, and possum occupancy of boxes per site was negatively correlated with bird nesting success (p = 0.021). These results suggest that when boxes are accessible to invasive species and native predators, they are unlikely to significantly improve nesting opportunities for native birds. To ensure efficient use of limited conservation resources, nest boxes should be designed to target species of high conservation importance and limit other species of both predators and competitors.

Fine‐scale variation in soil and topography influences herbaceous vegetation and the distribution of large mammalian herbivores

AbstractCurrent understanding of the distribution of vegetation and large mammalian herbivores (LMH) is based on a combination of biogeographic studies and highly controlled field experiments, but a more complete understanding of these patterns requires study of their natural co‐occurrence patterns at intermediate spatial scales. The study was conducted in the 120‐ha Mpala Forest Global Earth Observatory (ForestGEO) plot, Kenya. We examined differences in herbaceous plant communities and habitat use by LMH among three topographic habitats with distinct soil types, namely steep slopes, valley and plateau. Each pair of habitats differed in plant and animal composition. The steep slopes and plateau respectively had ≥1‐fold higher percentage herbaceous cover than the valley, whereas the steep slopes and valley had &gt;1.5‐fold greater grass species richness and diversity than the plateau. The activity of LMH was ≥1.7‐fold higher in the valley than the steep slopes and plateau, reflecting a positive relationship between LMH activity index and richness and diversity of grass species. Results indicate that fine‐scale variation in topography and soil are associated with both the distribution of herbaceous vegetation and LMH, suggesting a need to account for local habitat characteristics when examining the distributions of plants, animals, and plant‐herbivore interactions in natural systems.

Spatial patterns of seedlings dominated by proximity to deadwood and adult trees for Pinus flexilis and Pinus longaeva

The spatial patterns of trees are a defining feature of forests, yet because of the long lifespan of trees, the full origins of these spatial patterns remain unclear. We used 15.6 ha of a mapped forest plot to assess the local habitat characteristics and spatial structure of 1,550 naturally established seedlings and 1,955 adults of Pinus flexilis (limber pine) and Pinus longaeva (Great Basin bristlecone pine) in southern Utah, USA. For both species, proximity to deadwood (large end diameter ≥ 10 cm) and mature trees were key parameters of habitat, likely indicating abiotic or biotic facilitation. Both seedlings and mature trees were highly aggregated 0.0–2.5 m around large pieces of deadwood, which can persist in this ecosystem for centuries or millennia. Seedlings were most often located around deadwood 15–22 cm in diameter, though deadwood size had little influence on the distance at which seedlings established. Seedlings of both P. flexilis and P. longaeva were abundant near heterospecific adult Pinus. The elevational distribution of seedlings and adults of both species were not different, indicating a regeneration niche similar to the niche of mature trees and also that changing climate at this site has not yet affected species distributions. Low amounts of manganese and higher levels of pH and potassium in the mineral soil were associated with P. longaeva seedlings but were less important for P. flexilis. Edaphic patterns combined with the presence of deadwood define the overlap between seedling and mature species habitat and identify the key drivers influencing the spatial structure in this high-elevation, old-growth forest. Likely, persistence of these two Pinus species as well as regeneration or site colonization is more favorable in the presence of large deadwood.

Terrain Ruggedness and Canopy Height Predict Short-Range Dispersal in the Critically Endangered Black-and-White Ruffed Lemur.

Dispersal is a fundamental aspect of primates' lives and influences both population and community structuring, as well as species evolution. Primates disperse within an environmental context, where both local and intervening environmental factors affect all phases of dispersal. To date, research has primarily focused on how the intervening landscape influences primate dispersal, with few assessing the effects of local habitat characteristics. Here, we use a landscape genetics approach to examine between- and within-site environmental drivers of short-range black-and-white ruffed lemur (Varecia variegata) dispersal in the Ranomafana region of southeastern Madagascar. We identified the most influential drivers of short-range ruffed lemur dispersal as being between-site terrain ruggedness and canopy height, more so than any within-site habitat characteristic evaluated. Our results suggest that ruffed lemurs disperse through the least rugged terrain that enables them to remain within their preferred tall-canopied forest habitat. Furthermore, we noted a scale-dependent environmental effect when comparing our results to earlier landscape characteristics identified as driving long-range ruffed lemur dispersal. We found that forest structure drives short-range dispersal events, whereas forest presence facilitates long-range dispersal and multigenerational gene flow. Together, our findings highlight the importance of retaining high-quality forests and forest continuity to facilitate dispersal and maintain functional connectivity in ruffed lemurs.

Amphibian decline in a Central European forest and the importance of woody debris for population persistence

Achieving an understanding of species’ temporal and spatial abundance patterns is a prerequisite for proper conservation and management decisions. Little is known of the ecological indicators of census size or biomass of terrestrial amphibian communities and historical estimates of population size are rare. Here we took advantage of abundance and biomass data collected in 1967/1968 for a leaf-litter amphibian community in Niepołomice Forest (NF) in south-central Poland. Using the same technique (removal sampling), we censused the amphibian community of this forest 50 years later (2016/2017), spatially matching a subset of current plots with the historical sampling sites. Averaged over all plots, we revealed at least a fourfold decline in amphibian abundance from 2817 ± 776 individuals/ha in 1967 to 674 ± 508 individuals/ha currently, paralleled by a decline in biomass from roughly 15.5 ± 1.7 to 3.8 ± 3.1 kg/ha. The decline was more striking (over 15-fold) for current plots placed in the same forest division as the historical plots (mean counts of 157 ± 103 individuals/ha corresponding in biomass to 1.0 ± 0.5 kg/ha). We also recorded a change in species composition between surveys, and propose that conversion of aquatic habitat and forest succession have decreased amphibian diversity and abundance in NF. Further, we estimated densities of anuran amphibians in forest plots differing in management regime and local habitat characteristics for contemporary plots (all historical plots were placed in managed forest). We found that unmanaged, old growth forest plots with coarse woody debris on the forest floor held on average twice as many anurans compared to plots in managed stands. Average body condition of the most common species, Rana temporaria, measured as a scaled mass index, was enhanced in plots situated in old growth forest. Our findings suggest that the preservation of old growth forests containing coarse woody debris may boost anuran abundance, biomass and body condition, and has the potential to buffer against long-term demographic decline. Moreover, the retention of deadwood could be a means of increasing the conservation potential of managed forests for terrestrial amphibian communities.

Hedgerows have contrasting effects on pollinators and natural enemies and limited spillover effects on apple production

Agricultural intensification has resulted in a decline in insect biodiversity and threatens the provision of valuable ecosystem services. Agri-environment schemes (AESs) have been implemented in an effort to conserve biodiversity on farmland and increase agricultural sustainability, but their effectiveness can vary widely. To better determine which factors influence AES effectiveness, the relative roles of local habitat features, habitat quality, and landscape context need to be further explored. The aim of this study was to determine the most important factors influencing field margin AES effectiveness in commercial apple orchards, in terms of arthropod biodiversity conservation and ecosystem service provision. We surveyed wild bees and aphid natural enemies in field margins and apple trees in 20 orchards, ten bordered by hedgerow field margins (an AES) and ten with herbaceous field margins (no hedgerows present, not an AES). We considered field margin floral resources and the cover of semi-natural habitat in the surrounding landscape as indicators of local habitat quality and landscape context, respectively. We furthermore quantified pollination and pest control as measures of ecosystem service delivery and the relationship between arthropod communities and apple yield (initial and final fruit set) and quality. We found that hedgerow presence strongly predicted both pollinator and natural enemy communities and that these relationships were more pronounced than those with local habitat quality and landscape context. Hedgerows were negatively related to wild bee richness and abundance within the orchard, and positively related to natural enemy richness and abundance at the field margin but not within the orchard. We found no relationships between local and landscape factors and ecosystem service delivery, and no relationship between wild bee communities and apple yield, suggesting that apple is not pollen limited in our study system. There was, however, a negative relationship between natural enemy richness and initial fruit set. We conclude that annually cut hedgerows can benefit the conservation of natural enemies, but have limited arthropod-mediated private benefits for apple production, and likely need to be supplemented with additional local habitat resources for the conservation of wild bees. Our findings indicate that local habitat factors can strongly influence biodiversity regardless of landscape context, but that AESs likely need to be designed with separate biodiversity and ecosystem service targets, and specific taxonomic groups, in mind.

Testing macroecological hypotheses in sandy beach populations: the wedge clam Donax hanleyanus in South America

Large-scale spatial and temporal variability in environmental conditions may result in differences in life-history traits, population demography, and abundance of sandy-beach species. We analyzed the effects of salinity, chlorophyll a (chl a), and sea surface temperature (SST) on population parameters of the wedge clam Donax hanleyanus from 75 South American sandy beaches covering a 15° latitudinal range. Generalized modeling results showed that between-beach differences in abundance, population structure, growth performance, productivity, mortality, and individual shell mass were mainly explained by salinity fluctuations, with chl a and SST as secondary contributors, overriding, in most cases, local habitat features (Dean’s parameter, grain size, slope). Our results provide valuable insights into macroscale ecological processes, setting a basis to delineate conservation guidelines at large spatial scales that respond to the potential effects of climate variability and change on sandy beach populations.

Interplay between local and landscape-scale effects on the taxonomic, functional and phylogenetic diversity of aerial insectivorous neotropical bats

ContextHuman-modified landscapes are globally ubiquitous. It is critical to understand how habitat loss and fragmentation impact biodiversity from both a local habitat context and landscape-scale perspective to inform land management and conservation strategies.ObjectivesWe used an experimentally fragmented landscape in the Brazilian Amazon to investigate variation in aerial insectivorous bat diversity in response to local habitat and wider landscape characteristics, applying a multiscale approach.MethodsWe conducted bat acoustic surveys at 33 sites, comprising old secondary forests and fragments of primary forest. Taxonomic, functional and phylogenetic diversity facets were calculated within a Hill numbers framework. We analysed responses to fragment size, interior-edge-matrix gradients, as well as local vegetation structure, continuous forest cover, edge density and patch density across five spatial scales (0.5−3 km) surrounding detector locations.ResultsCompared with continuous forest, secondary forest matrix around the smallest fragments harboured lower diversity. The overall negative effect of the matrix became less pronounced with increasing fragment size. In contrast, forest edges generally contained higher taxonomic, functional and phylogenetic diversity. We found subtle scale-sensitive associations for functional diversity, responding positively to forest cover (at the 1 km scale) and negatively to edge (1 km scale) and patch density (2.5 km scale).ConclusionsDespite a low-contrast matrix of tall secondary forest surrounding fragments after ~ 30 years of forest recovery, aerial insectivorous bat diversity is not comparable to continuous primary forest. Assemblage functional diversity responds to compositional and configurational landscape characteristics at scales deserving further evaluation at guild and species level.

Abundance and Growth of the European Eels (Anguilla anguilla Linnaeus, 1758) in Small Estuarine Habitats from the Eastern English Channel

Abundance and growth of the European eel from six small northern French estuaries during their growth phase were examined to explore variations according to the local habitat characteristics. The length–weight relationships and growth models fitted to length-at-age back-calculated otolith growth increments were used to compare the growth. Higher abundances were observed in the smaller estuaries (2.4 to 10.5 ind. fyke nets 24 h−1). The eel length ranged from 215–924 mm with an age range of 4–21 years. There was no significant difference in fish eel lengths or age except in the Liane estuary where the individuals were larger. The length–weight relationships showed an isometric or positive allometric growth in most estuaries. The Gompertz growth models, which best fits the growth, showed no significant differences between estuaries except for female eels from the Liane and the Somme estuaries where the growth performance index was higher. The estimated annual growth rate varied from 2.7 to 115.0 mm·yr−1 for female and from 4.4 to 90.5 mm·yr−1 for male. The present study shows that eels in the six estuaries had CPUE and growth rates similar to those previously reported in larger habitats. These results reinforce the idea that small estuaries are important habitats that contribute significantly to the eel population and, therefore, play an essential role in conservation strategies for European eel.

Rock Refuges Are Strongly Associated with Increased Urban Occupancy in the Western Fence Lizard, Sceloporus occidentalis

Urbanization has dramatically altered habitats for local species worldwide. While some species are unable to meet the challenges that these alterations bring, others are able to persist as long as a threshold for suitable habitat is met. For reptiles, a key feature for persistence in urban areas can be access to suitable refuges from predation, high temperatures, and/or other environmental challenges. We tested for effects of local and landscape variables affecting urban occupancy in the Western Fence Lizard, Sceloporus occidentalis, in transects across an urban–rural gradient, with a specific focus on the presence of rock, tree, and shrub refuges. We found that fence lizards were much more likely to be present in areas with more rock cover, and in parks or low-density residential areas. Occupancy was also positively related to canopy cover in the general vicinity, though negatively related to number of trees along the transects. Our results highlight the importance of assessing local habitat features to successfully predict the occupancy of reptile species in urban habitats, and present directions for future research with concrete conservation and management applications.