Effects Of Habitat Fragmentation Research Articles

How does landscape permeability affect the movement of eastern red‐backed salamanders?

AbstractDemographic and genetic connectivity have important implications for population dynamics of wildlife and their ability to adapt to changing environments. Landscape features such as roads and streams can inhibit movement of species with poor dispersal capabilities and exacerbate the effects of habitat fragmentation. Terrestrial plethodontid salamanders are generally thought of as incapable of long‐distance movement and may vary in their motivation to move across a landscape by sex and size classes. To examine landscape permeability to movement, we assessed how distance and natural or man‐made landscape features affect recapture rates after displacement in red‐backed salamanders (Plethodon cinereus). We randomly assigned marked salamanders from 6 plots at Camp Karoondinha in Millmont, Pennsylvania, USA, to a control (placed under the same cover board) or a treatment (displaced 25 m or 50 m through the forest or across a stream or road). Of 290 marked individuals, we recaptured 29.8%. We recaptured more individuals in the control treatment compared to displaced individuals, with recapture rates decreasing with the presence of a road or stream. Landscape feature type and sex did not affect the probability of recapture, but developmental stage did, with adult salamanders more likely to be recaptured than juvenile salamanders. Our results suggest that landscape permeability is reduced for terrestrial salamanders when a landscape feature is present compared to open forest. Narrow, dirt roads present a similar challenge to a natural stream for red‐backed salamanders. Our study should be of value to land managers who are concerned about the negative effects of landscape permeability on terrestrial salamander populations.

The effects of human‐altered habitat spatial pattern on frugivory and seed dispersal: a global meta‐analysis

Seed dispersal by frugivorous animals is important for plant mobility, regeneration and persistence. Human‐caused landscape change is thought to disrupt seed dispersal, but evidence is scarce. We performed a comprehensive meta‐analysis on the effects of habitat spatial pattern on frugivory and seed dispersal. We found 233 effects from 71 studies. At a patch or local scale, altered habitat spatial pattern was measured as declining patch size, increasing patch isolation or habitat edge (versus interior). At a landscape scale it was measured as declining amount of habitat, increasing mean patch isolation, increasing number of patches or increasing habitat edge in the landscape. We found overall negative effects of altered habitat spatial pattern on: 1) the quantity of frugivory or seed dispersal, 2) the number of species involved in a plant–frugivore interaction and 3) seed dispersal distance. Moderator variable analysis was only possible for the first of these. It revealed negative responses of the quantity of frugivory or seed dispersal to habitat loss at both the local scale (declining patch size), and the landscape scale (declining habitat amount), but little evidence for a response to habitat edge at either scale. In addition, altered habitat spatial pattern reduced the quantity of frugivory or seed dispersal more strongly in temperate than tropical areas. Finally, the few‐recorded effects of landscape‐scale fragmentation per se (increasing patch density or edge density) on the quantity of frugivory or seed dispersal were mixed and weak. Our meta‐analysis reinforces the notion that habitat loss is a major threat to frugivory and seed dispersal by animals, and reveals an insufficiency of studies of the effects of habitat fragmentation per se. Thus, based on the current literature, we conclude that maintaining and increasing habitat amount is vital for maintaining seed dispersal by frugivorous animals.

No Evidence of Low Genetic Diversity Despite High Levels of Inbreeding and Poor Genetic Connectivity AmongTetrastigma loheri(Vitaceae) Populations in Remaining Forest Areas in Cebu, Philippines

Abstract—Little is known about the effects of habitat fragmentation on the patterns of genetic diversity and genetic connectivity of species in the remaining tropical forests of Southeast Asia. This is particularly evident in Cebu, a Philippine island that has a long history of deforestation and has lost nearly all of its forest cover. To begin filling this gap, data from 13 microsatellite loci developed forTetrastigma loheri(Vitaceae), a common vine species in Philippine forests, were used to study patterns of genetic diversity and genetic connectivity for the four largest of the remaining forest areas in Cebu. Evidence of relatively high levels of inbreeding was found in all four areas, despite no evidence of low genetic diversity. The four areas are genetically differentiated, suggesting low genetic connectivity. The presence of inbreeding and low genetic connectivity in a commonly encountered species such asT. loheriin Cebu suggests that the impact of habitat fragmentation is likely greater on rare plant species with more restricted distributions in Cebu. Conservation recommendations for the remaining forest areas in Cebu include the establishment of steppingstone corridors between nearby areas to improve the movement of pollinators and seed dispersers among them.

The effects of habitat loss and fragmentation on updated estimates of the population of the Agulhas Long-billed Lark Certhilauda brevirostris, a South African endemic

The Agulhas Long-billed Lark Certhilauda brevirostris is a South African endemic and is restricted to the fynbos habitat of the Agulhas Plain in the southwestern corner of South Africa. The 1990, 2014, and 2018 land use land cover (LULC) databases prepared for South Africa were used to determine the LULC categories that best describe suitable habitat for this bird using beta regressions. Previously published densities of Agulhas Long-billed Lark and the surface area of the LULC categories considered suitable habitat for the birds were used to estimate their historical and current population sizes, and the rates of change in the bird’s population. Beta regression models were compiled from the bird’s adjusted reporting rate and the total surface area, and three other landscape metrics, of the per pentad LULC categories considered suitable habitat for them. These models revealed that although the Agulhas Long-billed Lark is adversely affected by the loss of its natural fynbos habitat these adverse effects have been offset by an increase in the availability of fallow fields in summer. This confirms previous observations that agriculture may have allowed the Agulhas Long-billed Lark to increase in numbers. The Agulhas Long-billed Lark’s extent of occurrence (EOO) was estimated at 1 322 509 ha (n = 197 pentads) with an area of occupancy (AOO) estimated to be 1 076 854 ha in 2020. The decline in habitat available to the birds was estimated to be 3.5% over three generations (10.5 years). The present study provides improved estimates of the population of the Agulhas Long-billed Lark of between 146 344 and 264 691 individuals, with between 60 753 and 109 883 individuals in natural habitat, and between 85 591 and 154 808 individuals in transformed habitat. The results of the present study indicate that the Agulhas Long-billed Lark’s Near Threatened status should be reviewed.

Occasional long-distance dispersal may not prevent inbreeding in a threatened butterfly

BackgroundTo set up successful conservation measures, detailed knowledge on the dispersal and colonization capacities of the focal species and connectivity between populations is of high relevance. We developed species-specific nuclear microsatellite molecular markers for the grayling (Hipparchia semele), a butterfly endemic to Europe and of growing conservation concern in North-West Europe, and report on its population genetics, in a fragmented, anthropogenic landscape in Belgium. Our study included samples from 23 different locations nested in two regions and additional historical samples from two locations. We assessed contemporary, long-distance dispersal based on genetic assignment tests and investigated the effect of habitat loss and fragmentation on the population genetic structure and genetic variation using data of nine microsatellite loci.ResultsDetected dispersal events covered remarkably long distances, which were up to ten times larger than previously reported colonisation distances, with the longest movement recorded in this study even exceeding 100 km. However, observed frequencies of long-distance dispersal were low. Our results point to the consequences of the strong population decline of the last decades, with evidence of inbreeding for several of the recently sampled populations and low estimates of effective population sizes (Ne) (ranging from 20 to 54 individuals).ConclusionsOur study shows low frequencies of long-distance dispersal, which is unable to prevent inbreeding in most of the local populations. We discuss the significance for species conservation including future translocation events and discuss appropriate conservation strategies to maintain viable grayling (meta) populations in highly fragmented, anthropogenic landscapes.

The effects of habitat fragmentation on the genetic structure of wild boar (Sus scrofa) population in Lithuania

BackgroundWild boar (Sus scrofa) is a widely distributed ungulate whose success can be attributed to a variety of ecological features. The genetic variation and population structure of Lithuania’s wild boar population have not yet been thoroughly studied. The purposes of this study were to investigate the genetic diversity of S. scrofa and assess the effects of habitat fragmentation on the population structure of wild boar in Lithuania. A total of 96 S. scrofa individuals collected from different regions of Lithuania were genotyped using fifteen microsatellite loci.ResultsThe microsatellite analysis of the wild boars indicated high levels of genetic diversity within the population. Microsatellite markers showed evidence of a single panmictic wild boar population in Lithuania according to STRUCTURE’s highest average likelihood, which was K = 1. This was supported by pairwise Fst values and AMOVA, which indicated no differentiation between the four sampling areas. The results of the Mantel test revealed a weak isolation by distance and geographic diversity gradients that persisted between locations. Motorway fencing and heavy traffic were not an effective barrier to wild boar movement.ConclusionsThere was limited evidence of population genetic structure among the wild boar, supporting the presence of a single population across the study area and indicating that there may be no barriers hindering wild boar dispersal across the landscape. The widespread wild boar population in Lithuania, the high level of genetic variation observed within subpopulations, and the low level of variation identified between subpopulations suggest migration and gene flow between locations. The results of this study should provide valuable information in future for understanding and comparing the detailed structure of wild boar population in Lithuania following the outbreak of African swine fever.

First assessment of ectoparasite prevalence in Apennine populations of Eurasian red squirrel: does habitat fragmentation affect parasite presence?

Although habitat fragmentation is widely reported to affect species survival and distribution, its effect in terms of host-parasite interactions in small mammal communities is poorly studied yet. Using information collected from carcasses of 34 road-kill and two preyed-upon individuals, we present the first comprehensive study dealing with the relationship between habitat fragmentation and the presence of different ectoparasite species infecting a small Sciurus vulgaris population inhabiting the Apennine ridge. We predicted that the probability to find individuals infested by parasites would be lower in highly fragmented areas because of the trade-off effects over both mammal and ectoparasite communities. Our findings showed that the most frequent ectoparasites were the squirrel fleas Ceratophyllus sciurorum and hard ticks Ixodes ricinus. Males showed higher presence of ectoparasites than females, probably because of different behaviour in space use and higher hormone levels, which may compromise host’s resistance to infection. As to the relationship with habitat fragmentation, we did not find support that individuals in highly fragmented areas would be less susceptible to C. sciurorum infestation because of lower red squirrel relative density. The presence of highly suitable habitat patches in fragmented habitats may have favoured the presence of squirrels, hence promoting C. sciurorum transmission among specimens. Similarly, we did not find support that habitat fragmentation would have reduced the likelihood of generalist ectoparasites transmission among squirrels. This finding may be explained by the increasing tolerance of generalist ectoparasites towards habitat fragmentation because of the presence of species (e.g., roe deer Capreolus capreolus) able to better exploit ecotonal areas. We believe that our research provides interesting preliminary results on ectoparasites infesting red squirrels in the Apennine area, and of the potential impact which habitat fragmentation may have on them. Nevertheless, the effect of habitat fragmentation over parasite communities is still poorly considered, and further researches are needed.

Delayed effects of climate on vital rates lead to demographic divergence in Amazonian forest fragments.

Deforestation often results in landscapes where remaining forest habitat is highly fragmented, with remnants of different sizes embedded in an often highly contrasting matrix. Local extinction of species from individual fragments is common, but the demographic mechanisms underlying these extinctions are poorly understood. It is often hypothesized that altered environmental conditions in fragments drive declines in reproduction, recruitment, or survivorship. The Amazon basin, in addition to experiencing continuing fragmentation, is experiencing climate change-related increases in the frequency and intensity of droughts and unusually wet periods. Whether plant populations in tropical forest fragments are particularly susceptible to extremes in precipitation remains unclear. Most studies of plants in fragments are relatively short (1-6years), focus on a single life-history stage, and often do not compare to populations in continuous forest. Even fewer studies consider delayed effects of climate on demographic vital rates despite the importance of delayed effects in studies that consider them. Using a decade of demographic and climate data from an experimentally fragmented landscape in the Central Amazon, we assess the effects of climate on populations of an understory herb (Heliconia acuminata, Heliconiaceae). We used distributed lag nonlinear models to understand the delayed effects of climate (measured as standardized precipitation evapotranspiration index, SPEI) on survival, growth, and flowering. We detected delayed effects of climate up to 36months. Extremes in SPEI in the previous year reduced survival, drought in the wet season 8-11months prior to the February census increased growth, and drought two dry seasons prior increased flowering probability. Effects of extremes in precipitation on survival and growth were more pronounced in forest fragments compared to continuous forest. The complex delayed effects of climate and habitat fragmentation in our study point to the importance of long-term demography experiments in understanding the effects of anthropogenic change on plant populations.

Effect of disturbances and habitat fragmentation on an arboreal habitat specialist mammal using GPS telemetry: a case of the red panda.

ContextHabitat specialists residing in human-modified landscapes are likely to be more vulnerable to disturbance because of a functional reliance on very particular habitat features. However, there have been few studies designed to specifically address that issue.ObjectivesThis study aimed to explore how the red panda, an iconic endangered habitat specialist, behaves when faced with disturbances and habitat fragmentation. In particular, we attempted to examine the effect of anthropogenic disturbances and fragmentation on home-range size, activity patterns, and recursion.MethodsUsing GPS telemetry we monitored 10 red pandas and documented disturbances using camera trapping for one year in eastern Nepal. We performed spatial analysis, analysed activity patterns and evaluated the effect of habitat fragmentation and disturbances on home-range size and residence time using Linear Mixed Models.ResultsHome-range size increased in areas with low availability of forest cover whilst home ranges were smaller in areas with a high road density. Red pandas spent more time in large habitat patches away from roads and cattle stations. Crossing rates suggested that roads acted as a barrier for movement across their habitat. Red pandas also partitioned their activity to minimize interactions with disturbances.ConclusionsRed pandas seem to make a trade-off to co-exist in human-dominated landscapes which may have adverse long-term effects on their survival. This indicates that current patterns of habitat fragmentation and forest exploitation may be adversely affecting red panda conservation efforts and that landscape-scale effects should be considered when planning conservation actions.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10980-021-01357-w.

Mixed effect of habitat fragmentation on pollinator visitation rates but not on seed production in renosterveld of South Africa

Habitat fragmentation – in terms of a combination of habitat loss and separation – is a major threat to the renosterveld of the Cape Floristic Region (CFR) of which 85% has been transformed, mostly for agriculture. The effects thereof has not been well studied, in particular in the Eastern inland areas. In this study we seek to understand how habitat patch size influence visitation rate of pollinators of winter flowering plants in the Eastern-Rûens Shale Renosterveld of the Overberg region. We compared pollinator visitation rates to flowers of Relhania garnotii, Clutia sp. nov and Oxalis purpurea between small (0–4.9 ha) and medium (5–15 ha) sized fragments, and compared these to the last large intact protected area, the Haarwegskloof Renosterveld Reserve (>500 ha), termed mainland. We classified degree of isolation among fragments into high (>100 m) and low (<100 m) based on the distance between the outer edge of a fragment to its surrounding fragments and compared pollinator visitation rates between the two levels of isolation. Furthermore, we compared seed set of Bobartia longicyma and Trichodiadema strumosum between fragments and the mainland. We recorded 442 plant-pollinator interactions over a total of 75 h of observation. Pollination rate was significantly higher in fragments compared to the mainland. Within fragments, pollination rate and species richness were significantly higher in medium-sized fragments compared to small fragments. The degree of isolation had a negative effect on pollinator visitation rates among habitat patches, with lower visitation rates and pollinator species richness recorded in fragments with higher degree of isolation, supporting the Habitat Amount Hypothesis (HAH). Plant species exhibited a strong reliance on pollinators for reproduction but were not pollen-limited in either the fragments or mainland. These results indicate that the effect of fragmented habitats do not necessarily affect pollination rates of a certain size of habitat patches, but beyond an undefined threshold, pollinator rates decrease significantly. While in very small fragments ecosystem functions might be declining, in this study insect species have been observed in the smaller fragments that only occurred there, which indicates that heterogeneity of habitat fragments could offer ecological benefits. This highlights the importance of preserving fragments, as an important part of maintaining the remaining renosterveld. Therefore, conservation efforts should be enhanced to also preserve the small fragments that may serve as stepping stones for pollinators in the fragmented renosterveld.

Microbiome-mediated effects of habitat fragmentation on native plant performance.

Habitat fragmentation is a leading cause of biodiversity and ecosystem function loss in the Anthropocene. Despite the importance of plant-microbiome interactions to ecosystem productivity, we have limited knowledge of how fragmentation affects microbiomes and even less knowledge of its consequences for microbial interactions with plants. Combining field surveys, microbiome sequencing, manipulative experiments, and random forest models, we investigated fragmentation legacy effects on soil microbiomes in imperiled pine rocklands, tested how compositional shifts across 14 fragmentation-altered soil microbiomes affected performance and resource allocation of three native plant species, and identified fragmentation-responding microbial families underpinning plant performance. Legacies of habitat fragmentation were associated with significant changes in microbial diversity and composition (across three of four community axes). Experiments showed plants often strongly benefited from the microbiome's presence, but fragmentation-associated changes in microbiome composition also significantly affected plant performance and resource allocation across all seven metrics examined. Finally, random forest models identified ten fungal and six bacterial families important for plant performance that changed significantly with fragmentation. Our findings not only support the existence of significant fragmentation effects on natural microbiomes, but also demonstrate for the first time that fragmentation-associated changes in microbiomes can have meaningful consequences for native plant performance and investment.

Complex effects of habitat amount and fragmentation on functional connectivity and inbreeding in a giant panda population

AbstractThe relationships between habitat amount and fragmentation level and functional connectivity and inbreeding remain unclear. Thus, we used genetic algorithms to optimize the transformation of habitat area and fragmentation variables into resistance surfaces to predict genetic structure and examined habitat area and fragmentation effects on inbreeding through a moving window and spatial autoregressive modeling approach. We applied these approaches to a wild giant panda population. The amount of habitat and its level of fragmentation had nonlinear effects on functional connectivity (gene flow) and inbreeding. Functional connectivity was highest when approximately 80% of the surrounding landscape was habitat. Although the relationship between habitat amount and inbreeding was also nonlinear, inbreeding increased as habitat increased until about 20% of the local landscape contained habitat, after which inbreeding decreased as habitat increased. Because habitat fragmentation also had nonlinear relationships with functional connectivity and inbreeding, we suggest these important responses cannot be effectively managed by minimizing or maximizing habitat or fragmentation. Our work offers insights for prioritization of protected areas.

Local ecological knowledge reveals combined landscape effects of light pollution, habitat loss, and fragmentation on insect populations

Recent reports of drastic declines in insect populations have raised global concerns about their conservation. Light pollution is a near inseparable feature of human-altered landscapes and is a potential contributing factor to insect declines. However, despite the wide recognition of the deleterious effects of lights on insects, whether these effects scale up to impact insect populations remains unclear. Here, we relied on a combination of ecological niche modeling, geographical information systems, and interviews on local ecological knowledge to assess the synergistic effects of landscape light pollution and habitat loss and fragmentation on populations of the Chocó golden scarab Chrysina argenteola. Sightings of C. argenteola by locals revealed individuals are scarcer in areas with reduced forest cover and rely on inter-patch dispersal to cope with habitat fragmentation, where they were constantly attracted to urban lights. Increasingly lit landscapes had more individuals attracted to lights, but the opposite was true in areas with less than 4 km2 of remaining forest cover. We suggest this pattern arises as landscape light pollution intercepts individuals during inter-patch dispersal. This hinders habitat connectivity, potentially disrupting metapopulation dynamics, being populations inhabiting areas with scarce fragmented habitat more vulnerable to this process. We show light pollution acts in combination with habitat loss and fragmentation in detriment of insect populations at the landscape scale.

Passive acoustic monitoring reveals the role of habitat affinity in sensitivity of sub‐tropical East Asian bats to fragmentation

AbstractHydropower infrastructure represents a major driver of habitat loss and insular fragmentation worldwide, mostly across the tropics and sub‐tropics. Despite growing evidence of dam‐induced impacts on biodiversity, the effects of insular habitat fragmentation on species assemblages remain poorly understood, particularly for East Asian vertebrates. Here, we assess how insectivorous bats respond to forest fragmentation in Thousand Island Lake, a mega‐hydroelectric dam in East China. Bat assemblages were surveyed across 36 land‐bridge islands of different sizes and degrees of isolation, using AudioMoth recorders. Echolocation calls were classified into sonotypes, each corresponding to either single or multiple species, which were further classified according to their habitat affinities into forest or open‐space foragers. Based on 22 875 five‐min recordings from 108 detector‐nights, we recorded 15 bat sonotypes, eight of which we classified as forest sonotypes (2329 bat passes) and seven as open‐space sonotypes (52 277 bat passes). Overall, sonotype richness increased with island area, but only above a certain threshold (34 ha). Habitat affinity played an important role in ensemble‐level responses to fragmentation; forest sonotype richness increased with island area, whereas open‐space sonotype activity was higher in more isolated islands. Our results highlight the relevance of particularly large fragments (&gt;1000 ha) to maintain area‐sensitive forest bat species. However, islands below 34 ha in size and those more isolated from the mainland are also of conservation value as they, correspondingly, harbour a variable (but substantial) number of species and concentrate higher activity of open‐space foragers. These findings further demonstrate that acoustic sampling methods, as the one presented here, are able to provide key information for evidence‐based policies aimed at halting the ongoing wave of dam‐induced biodiversity loss.

Multi-taxa ecological responses to habitat loss and fragmentation in western Amazonia as revealed by RAPELD biodiversity surveys

ABSTRACT Habitat loss and fragmentation caused by deforestation are important anthropogenic drivers of changes in biodiversity in the Amazon rainforest, and has reached its highest rate in recent decades. However, the magnitude and direction of the effects on species composition and distribution have yet to be fully understood. We evaluated the responses of four taxonomic groups − birds, amphibians, orchid bees, and dung beetles - to habitat loss and fragmentation at both species and assemblage level in the northern Ecuadorian Amazon. We sampled fifteen 250-m long plots in terra-firme forest remnants. We calculated one landscape fragmentation index (fragindex), which considers the proportion of continuous forest cover, edge density and isolation in the landscape, and nine landscape configuration metrics. Logistic regression models and multivariate regression trees were used to analyze species and assemblage responses. Our results revealed that over 80% of birds, amphibians or orchid-bee species, and 60% of dung beetles were negatively affected by habitat loss and fragmentation. Species composition of all taxonomic groups was significantly affected by differences in forest cover and connectivity. Less than 5% of all species were restricted to landscapes with fragindex values higher than 40%. Landscape metrics related to the shape and area of forest patches determined the magnitude and direction of the effect on species responses. Therefore, changes in the landscape configuration of Ecuadorian Amazonia should be minimized to diminish the effects of habitat loss and fragmentation on species occurrence and assemblage composition.

Considering habitat conversion and fragmentation in characterisation factors for land-use impacts on vertebrate species richness

Human land use is one of the primary threats to terrestrial species richness and is considered a priority for meeting global sustainability and biodiversity targets. Decision-support tools, such as life cycle assessment (LCA), are widely used for developing strategies to achieve such objectives. Currently available life cycle impact assessment (LCIA) methods apply the countryside species-area relationship (c-SAR) to quantify habitat conversion impacts on species richness. However, additional effects of habitat fragmentation are yet ignored in these assessments. We use the species-habitat relationship (SHR), an adaptation of the c-SAR that considers both habitat conversion and fragmentation effects, to develop a new set of land-use characterisation factors for 702 terrestrial ecoregions (in 238 countries), four land-use types (urban, cropland, pasture, and forestry), and four taxonomic groups (amphibians, birds, mammals, and reptiles; plus the aggregate of these vertebrate groups). The SHR generally predicts higher per-area impacts of land-use than the impacts estimated by the c-SAR (a median relative difference of +9%), indicating that land-use impacts may be systematically underestimated when ignoring fragmentation effects. Whereas per-area impacts of land-use on regional species richness are highest in temperate regions, reflecting the diminished extent of natural habitat, per-area impacts of land-use on global species richness are highest in the subtropics, reflecting the importance of tropical regions and islands to global vertebrate species diversity. The large variety in magnitude of land-use impacts across the world's regions emphasizes the importance of regionalised assessments. The set of characterisation factors proposed here can be readily used in environmental decision-making.

Impact of weather conditions, seasonality and moonlight on the use of artificial canopy bridges by nocturnal arboreal mammals

Natural and artificial canopy bridges can be used to mitigate the effects of habitat fragmentation. Understanding the ecological factors that influence bridge use is imperative to the effective design and placement of this potential conservation intervention. Moonlight, seasonality and weather may influence the cost and risk of using bridges, potentially reducing their effectiveness. We installed five artificial waterline bridges and, between 2017 and 2019, monitored via camera trapping their use by Javan palm civets Paradoxurus musanga javanicus and Javan slow lorises Nycticebus javanicus. We used a weather station to record microclimate data (temperature and relative humidity) and calculated the illumination percentage of the moon. We tested the influence of moon luminosity, relative humidity, seasonality (Julian day) and temperature on the frequency of bridge use via Generalised Additive Models. Camera traps captured 938 instances of bridge use by civets, which was significantly lower than the reference value at moon luminosity > 90%, temperatures > 20 °C, humidity > 90%, and during the drier period (May–July). Camera traps captured 1036 instances of bridge use by lorises, which was significantly lower than the reference value during the drier period and higher than the reference value at temperatures > 20 °C. Lorises showed peaks in bridge use close to sunset and sunrise whereas civets showed peaks around 2 h after sunset and 2 h before sunrise. Our study illustrates the utility of simple-to-construct bridges by two sympatric nocturnal mammals facing severe habitat loss, with bridge use differing between those species according to abiotic factors. In particular, less use by both taxa during the drier season could suggest modifying placement of bridges or providing another intervention during that time. Camera traps were an excellent mechanism to record these differences and to validate the importance of the bridges, including during inclement weather and dark nights, when observations would be more difficult for human observers. By understanding the influence that abiotic factors have on the use of artificial bridges, we can improve bridge placement and construction to encourage use by a variety of species, particularly those threatened by habitat fragmentation.

Effect of habitat fragmentation on rural house invasion by sylvatic triatomines: A multiple landscape-scale approach.

After the decrease of the relative importance of Triatoma infestans, a number of studies reported the occurrence of sylvatic triatomines dispersing actively to domestic environments in the dry western Chaco Region of Argentina. Anthropic modification of the landscape is mentioned as one of the main causes of the increase in domicile invasion. The aim of this study was to describe the occurrence and frequency of sylvatic triatomines invading rural houses, and to evaluate the effect of habitat fragmentation and other ecological factors on the invasion of rural houses in central Argentina. We hypothesized that the decrease in food sources and the loss of wild ecotopes, as a consequence of habitat fragmentation, increase the chances of invasion by triatomines. The entomological data was collected by community-based vector surveillance during fieldwork carried out between 2017-2020, over 131 houses located in fourteen rural communities in the northwest of Córdoba Province (central Argentina). We used generalized linear models to evaluate the effect of (i) the environmental anthropic disturbance in the study area, (ii) the composition and configuration of the landscape surrounding the house, (iii) the spatial arrangement of houses, (iv) and the availability of artificial refuges and domestic animals in the peridomicile, on house invasion by triatomines. We report the occurrence of seven species of triatomines invading rural houses in the study area -T. infestans, T. guasayana, T. garciabesi, T. platensis, T. delpontei, T. breyeri and P. guentheri-. Study data suggest that invasion by triatomines occurs with higher frequency in disturbed landscapes, with houses spatially isolated and in proximity to subdivided fragments of forest. The availability of domestic refuges in the peridomestic structures as well as the presence of a higher number of domestic animals increase the chances of invasion by triatomines.

Sensitivity to habitat fragmentation across European landscapes in three temperate forest herbs

ContextEvidence for effects of habitat loss and fragmentation on the viability of temperate forest herb populations in agricultural landscapes is so far based on population genetic studies of single species in single landscapes. However, forest herbs differ in their life histories, and landscapes have different environments, structures and histories, making generalizations difficult.ObjectivesWe compare the response of three slow-colonizing forest herbs to habitat loss and fragmentation and set this in relation to differences in life-history traits, in particular their mating system and associated pollinators.MethodsWe analysed the herbs’ landscape-scale population genetic structure based on microsatellite markers from replicate forest fragments across seven European agricultural landscapes.ResultsAll species responded to reductions in population size with a decrease in allelic richness and an increase in genetic differentiation among populations. Genetic differentiation also increased with enhanced spatial isolation. In addition, each species showed unique responses. Heterozygosity in the self-compatible Oxalis acetosella was reduced in smaller populations. The genetic diversity of Anemone nemorosa, whose main pollinators are less mobile, decreased with increasing spatial isolation, but not that of the bumblebee-pollinated Polygonatum multiflorum.ConclusionsOur study indicates that habitat loss and fragmentation compromise the long-term viability of slow-colonizing forest herbs despite their ability to persist for many decades by clonal propagation. The distinct responses of the three species studied within the same landscapes confirm the need of multi-species approaches. The mobility of associated pollinators should be considered an important determinant of forest herbs’ sensitivity to habitat loss and fragmentation.

Conservation and Restoration of Coastal Reed Beds in the Context of Global Change: Potential Effects of Habitat Fragmentation for Specialist Marshland Passerines

In the context of coastal marshland reduction due to sea level rise, we evaluated the value of fragmented reed beds located within agricultural polders for the conservation of habitats exploited by marshland passerines characterized by different ecological requirements. Although our study was carried out within sites sampled over different years, analyses of body condition and diet of birds during the breeding period, as well as the local daily survival rate and the body mass evolution of birds during the post-breeding period, reveal trends illustrating that fragmented reed beds within inland meadows can: (i) generate habitats that may be significantly exploited by species with a large ecological plasticity, such as the Reed Warbler that could benefit from edge effects of habitat fragmentation; (ii) offer low attractiveness for specialised species such as the Aquatic Warbler, a migratory species apparently very sensitive to the effects of reed bed fragmentation. These results underline the reed beds fragmentation effects that may impact specialised marshland passerines and which should be taken into account in wetland conservation and restoration plans.