Influence Of Habitat Characteristics Research Articles

Evaluating the influence of marine protected areas on surf zone fish.

Marine protected areas (MPAs) globally serve conservation and fisheries management goals, generating positive effects in some marine ecosystems. Surf zones and sandy beaches, critical ecotones bridging land and sea, play a pivotal role in the life cycles of numerous fish species and serve as prime areas for subsistence and recreational fishing. Despite their significance, these areas remain understudied when evaluating the effects of MPAs. We compared surf zone fish assemblages inside and outside MPAs across 3 bioregions in California (USA). Using seines and baited remote underwater videos (BRUVs), we found differences in surf zone fish inside and outside MPAs in one region. Inside south region MPAs, we observed higher abundance (Tukey's honest significant difference [HSD]=0.83, p=0.0001) and richness (HSD=0.22, p=0.0001) in BRUVs and greater biomass (HSD=0.32, p=0.0002) in seine surveys compared with reference sites. Selected live-bearing, fished taxa were positively affected by MPAs. Elasmobranchs displayed greater abundance in BRUV surveys and higher biomass in seine surveys inside south region MPAs (HSD=0.35, p=0.0003 and HSD=0.23, p=0.008, respectively). Although we observed no overall MPA signal for Embiotocidae, abundances of juvenile and large adult barred surfperch (Amphistichus argenteus), the most abundant fished species, were higher inside MPAs (K-S test D=0.19, p<0.0001). Influence of habitat characteristics on MPA performance indicated surf zone width was positively associated with fish abundance and biomass but negatively associated with richness. The south region had the largest positive effect size on all MPA performance metrics. Our findings underscored the variability in species richness and composition across regions and survey methods that significantly affected differences observed inside and outside MPAs. A comprehensive assessment of MPA performance should consider specific taxa, their distribution, and the effects of habitat factors and geography.

Influence of habitat features on the colonisation of native and non-indigenous species

Marine artificial structures provide substrates on which organisms can settle and grow. These structures facilitate establishment and spread of non-indigenous species, in part due to their distinct physical features (substrate material, movement, orientation) compared to natural habitat analogues such as rocky shores, and because following construction, they have abundant resources (space) for species to colonise. Despite the perceived importance of these habitat features, few studies have directly compared distributions of native and non-indigenous species or considered how functional identity and associated environmental preferences drive associations. We undertook a meta-analysis to investigate whether colonisation of native and non-indigenous species varies between artificial structures with features most closely resembling natural habitats (natural substrates, fixed structures, surfaces oriented upwards) and those least resembling natural habitats (artificial materials, floating structures, downfacing or vertical surfaces), or whether functional identity is the primary driver of differences. Analyses were done at global and more local (SE Australia) scales to investigate if patterns held regardless of scale. Our results suggest that functional group (i.e., algae, ascidians. barnacles, bryozoans, polychaetes) rather than species classification (i.e., native or non-indigenous) are the main drivers of differences in communities between different types of artificial structures. Specifically, there were differences in the abundance of ascidians, barnacles, and polychaetes between (1) upfacing and downfacing/vertical surfaces, and (2) floating and fixed substrates. When differences were detected, taxa were most abundant on features least resembling natural habitats. Results varied between global and SE Australian analyses, potentially due to reduced variability across studies in the SE Australian dataset. Thus, the functional group and associated preferences of the highest threat NIS in the area should be considered in design strategies (e.g., ecological engineering) to limit their establishment on newly built infrastructure.

Restored oyster reefs and living shorelines can augment predator trophic dynamics

Coastal habitat loss has led to declines in many higher trophic level predators. These declines can be mitigated through habitat restoration, which putatively enhances predator populations and trophic dynamics by creating foraging opportunities in reestablished habitat, but this lacks empirical support. Here, we assess the prediction restored coastal habitat supports sportfish feeding relationships similar to natural habitat, at restored oyster reefs (Crassostrea virginica) and living shoreline habitats in Florida, U.S.A. Stable isotopes and gut contents were analyzed from young sportfish (i.e. predatory fish targeted by anglers) collected at control and restored sites for up to 3 years. The influence of habitat features, predator size, and prey availability on carbon and nitrogen isotope values were examined using a model species (mangrove/gray snapper [Lutjanus griseus]). In summary, sportfish species had distinct isotopic values, consuming similar prey but in different proportions between habitats. Prey abundance and richness, and reef height were influential predictors of L. griseus stable isotope values, with restored reefs contributing to their diet more than controls according to Bayesian mixing models. The trophic niche area of L. griseus and their predominant prey achieved trophic equivalence between restored and natural oyster reefs within 1 year following restoration. Stabilized living shorelines attained trophic equivalency to natural shorelines, but may take longer to accrue prey for some species. These findings generate fundamental ecological knowledge and actionable science, including targets, timelines, and indicator species, that natural resource managers and restoration practitioners can use to assess trophic structure and success of coastal habitat restoration.

The influence of habitat characteristics on the occupancy and dispersal of two headwater fishes in a dendritic network

AbstractThe bifurcating configuration of stream networks impacts the connectivity of patches and therefore influences the effects of habitat variables on dispersal and occupancy. In this study, we developed a comparative framework to explore the influence of environmental and anthropogenic variables on the dispersal and occupancy of two headwater darters, the Yazoo darter (Etheostoma raneyi) and goldstripe darter (Etheostoma parvipinne). We conducted our study in two subbasins that are nested within a larger Gulf Coastal Plain drainage in the southeastern United States. We examined patterns of occupancy using detection data collected within standardized stream reaches within the larger subbasin. Genotype by sequencing identified single nucleotide polymorphisms, which we then used to calculate genetic distance among samples obtained from localities distributed across both subbasins. Goldstripe darter and Yazoo darter occupancy were both best modeled by a single environmental variable (Yazoo darter: well depth; goldstripe darter: drainage area). Similarly, model rankings suggested that well depth explained a substantial amount of the variability in Yazoo darter genetic distance in this subbasin. However, we found no evidence that drainage area strongly affected goldstripe darter genetic distance within the larger subbasin. Our findings also suggested that the best predictors of Yazoo darter and goldstripe darter genetic distance differed between the two subbasins, and that variation in goldstripe darter genetic distance in the smaller subbasin was largely a consequence of anthropogenic variables. The comparative approach we used in this study suggests that the habitat variables regulating the dispersal and occupancy of some headwater fishes may differ, thus the use of site‐occupancy models to predict the dispersal habitat of these fishes may be inappropriate. Therefore, we suggest that understanding the effects of habitat variables regulating dispersal and occupancy may be crucial to understanding the metapopulation dynamics of headwater fishes.

Habitat characteristics and climatic factors influence microhabitat selection and arthropod community structure in a globally rare central Appalachian shale barren.

The central Appalachian shale barrens, a globally unique habitat type restricted to the eastern United States, presents an insular and physiologically stressful environment with sparse vegetation and extreme ground surface and air temperatures. Despite the high levels of plant species endemism within these systems, information on invertebrate communities and habitat preferences is extremely limited.Through this study, we aimed to better understand a shale barren arthropod community, microhabitat selection, and the influence of habitat characteristics and climatic factors. We employed pitfall traps to sample epigeic arthropods during the 2016 growing season in a shale barren habitat.Arthropod community composition was driven by overstory trees, mediated through accumulated leaf litter and availability of shaded microhabitats. Ambient air temperature also influenced the surface activity of various taxa with spiders decreasing at higher temperatures and ants, crickets, flies, and harvestmen all increasing in relative abundance.Habitat integrity of the central Appalachian shale barrens is threatened by forest succession and mesophication, encroaching invasive plant species, and rising ambient air temperatures, all of which can alter the extent of overstory vegetation and availability of shaded microhabitats. These biotic and physical pressures will subsequently affect epigeic arthropod community composition, depending on adaptive capacity of individual taxa.To the authors’ knowledge, these findings constitute only the second published work on arthropod communities and the first to focus on epigeic taxa in this globally rare habitat type. Continued conservation of these unique, insular habitats and their adapted inhabitants requires a multifaceted approach that considers current and future conditions.

Can’t see the Woodlark for the trees? Commercial forests as a habitat for a bird of conservation concern

This study investigated the extent to which intensive forest management practices influence a widespread bird of conservation concern, the Woodlark Lullula arborea. We compared trends of the studied population in Notec Forest, Poland during 2010–2014 against country-wide monitoring data, and populations of the forest interior versus forest edge dominated landscapes (forest-agricultural area mosaic). We also studied the influences of forest management practice (clearing size, stand structure, forestry activities on restock sites, harvesting in the neighboring habitat, and retaining tree aggregates) on the population of this species. Changes in woodlark numbers, habitat availability, and quality differences among studied sites and years were assessed using ANOVA. The influence of habitat characteristics on woodlark occupancy and abundances were tested by Generalized Estimation Equations, while the magnitude of influences in the study years was compared by Random Forest algorithm (as were population trends). Over the four study years, 419 woodlark pairs occupied 336 patches, with a maximum of 127 pairs. The number of woodlark pairs fell by 40% on the studied areas over the period, in line with declines across Poland as a whole. In our study system, population trends did not differ between forest and forest- agro mosaic landscapes. Size, age and number of available habitats did not differ either temporally or spatially during the study. Retention of unfelled trees in clearfell areas and forest works in the nearby sites, however, showed slight differences among the sampling polygons. Larger habitat patch size and restock areas under five years favored woodlarks. Less important but still significant positive influences were a higher proportion of retained trees and elongated shape of the habitat patches. Forestry activities on the neighbor stands were correlated with increased woodlark abundances, which is an unexpected result. Moreover, forestry provides suitable habitats for woodlarks in a dynamically changing arrangement. The magnitude of the studied factors’ influences on woodlarks showed a very high difference between study years, with the highest values in the years where woodlarks are the most numerous. In conclusion, we found no evidence that contemporary forestry adversely affects Woodlark habitat occupancy. Our study suggests that while managing land for one ecosystem service (timber), an apparent dis-benefit (loss of recreational attractiveness) might benefit some semi-open habitat species.

Influence of habitat characteristics on the assemblage and distribution of Ephemeroptera, Plecoptera and Trichoptera (EPT) at selected recreational rivers in Kelantan, Malaysia

This study was carried out to identify the habitat factors that contribute to the variation of EPT at three recreational rivers in Kelantan, Malaysia. Therefore, the further implementation of EPT index as bio-indicator can be standardized and efficient. The results showed that, EPT assemblage and distribution at these rivers varies even though there is no significant difference in the water quality. Water quality of all the rivers are in the range of ‘good’ level. Therefore, regression analysis was made to confirm the main factors influencing the variation of EPT assemblage within selected recreational rivers in Kelantan, Malaysia. The substrate composition appeared as the main factor influencing the variation in distribution and composition of EPT in good water quality from the analysis. Thus, it is concluded that the substrate composition is the major factor influencing the composition and distribution of EPT in recreational river (good water quality).

Influence of landscape, habitat, and species co-occurrence on occupancy dynamics of Canada Warblers

ABSTRACT The Canada Warbler (Cardellina canadensis) is a species of high conservation importance because of its low overall density and long-term widespread population declines on the breeding grounds. Results of previous research on the species suggest that its breeding habitat preferences vary across its range. However, the underlying processes associated with habitat use are unknown. Using a 20 yr dataset, we developed occupancy models for Canada Warblers to determine the influence of habitat characteristics (e.g., understory vegetation, canopy cover), landscape context (e.g., edge, forest patch size), and species co-occurrence on occupancy, colonization, and local extinction parameters. Our results show that multiple habitats are used by Canada Warblers on the breeding grounds; common variables associated with large-scale, long-term occupancy dynamics are forest age, landscape composition at the 100 m and 500 m scales, and mean patch size. Overall, Canada Warblers were nearly twice as persistent in ma...

Predation on Artificial Nests Imitating the Broods of Two Rallid Species: The Influence of Habitat Features

ABSTRACT We tested the influence of nest concealment (vegetation type, density and height), water depth and nest distance from the bank on predation rates upon simulated nests of the water rail (Rallus aquaticus) and the little crake (Porzana parva). Broods of both rallids were simulated by real and wax-filled quail (Coturnix coturnix) eggs coloured typically for each species. Three grades of nest concealment were used: uncovered nests located on wooden floating boards, nests hidden in littoral vegetation and nests hidden under a plastic mesh covered with plants, which made them invisible from the air. Concealment proved to have a stronger impact on the fate of artificial nests than water depth; 95% of the nests on boards were depredated after one week of exposure. Nests attached to a peg at water level and hidden in vegetation had survival rates of 18 and 22%, after three weeks of exposure in two experiment repetitions. In 2012, we found significant differences between survival rates of nests located in ...

Predator identity influences the effect of habitat management on nest predation.

Predation is the leading cause of nest failure for many passerines and considerable effort is devoted to identifying the habitat characteristics and management practices that influence nest loss. The habitat components associated with nest loss are strongly influenced by the ecology of nest predators and differ among predator species as a result. Nevertheless, there is a tendency to generalize about the effects of habitat features and management on nest failure without considering how resulting patterns are influenced by nest predators. We examined how predator-specific patterns of nest loss differed among predators and in response to grassland management with fire and grazing by cattle (Bos taurus). We used video cameras to monitor and identify predators at nests of the Grasshopper Sparrow (Ammodramus savannarum), a species of conservation concern throughout its range. We observed predation by 15 different species that differed in their response to management and the habitat characteristics associated with nests they preyed on. Losses to mammals and snakes were more likely at nests with greater amounts of litter cover and tall fescue (Schedonorus phoenix). Mammals were less likely to prey on nests surrounded by greater forb cover. Nest predation by snakes was lower in burned areas, whereas predation by mammals and Brown-headed Cowbirds (Molothrus ater) was unaffected by the use of fire. Neither vegetation density at the nest, nor landscape context was related to nest loss by any predator taxon. Although there were many similarities, we identified important differences in the species composing the nest predator community between our. study and other published research. These differences are likely to be responsible for geographic variation in the influence of habitat features and management actions on nest success. Our results demonstrate the need for natural resource managers to incorporate knowledge of local nest predators and their ecology when developing management prescriptions aimed at enhancing the reproductive success of songbirds.

The interaction of intraspecific competition and habitat on individual diet specialization: a near range-wide examination of sea otters.

The quantification of individuality is a common research theme in the fields of population, community, and evolutionary ecology. The potential for individuality to arise is likely context-dependent, and the influence of habitat characteristics on its prevalence has received less attention than intraspecific competition. We examined individual diet specialization in 16 sea otter (Enhydra lutris) populations from southern California to the Aleutian Islands in Alaska. Because population histories, relative densities, and habitat characteristics vary widely among sites, we could examine the effects of intraspecific competition and habitat on the prevalence of individual diet specialization. Using observed diet data, we classified half of our sites as rocky substrate habitats and the other half containing a mixture of rocky and unconsolidated (soft) sediment substrates. We used stable isotope data to quantify population- and individual-level diet variation. Among rocky substrate sites, the slope [±standard error (SE)] of the positive significant relationship between the within-individual component (WIC) and total isotopic niche width (TINW) was shallow (0.23 ± 0.07) and negatively correlated with sea otter density. In contrast, the slope of the positive WIC/TINW relationship for populations inhabiting mixed substrate habitats was much higher (0.53 ± 0.14), suggesting a low degree of individuality, irrespective of intraspecific competition. Our results show that the potential for individuality to occur as a result of increasing intraspecific competition is context-dependent and that habitat characteristics, which ultimately influence prey diversity, relative abundance, and the range of skillsets required for efficient prey procurement, are important in determining when and where individual diet specialization occurs in nature.

Camera Trapping: A Contemporary Approach to Monitoring Invasive Rodents in High Conservation Priority Ecosystems

Invasive rodent species have established on 80% of the world's islands causing significant damage to island environments. Insular ecosystems support proportionally more biodiversity than comparative mainland areas, highlighting them as critical for global biodiversity conservation. Few techniques currently exist to adequately detect, with high confidence, species that are trap-adverse such as the black rat, Rattus rattus, in high conservation priority areas where multiple non-target species persist. This study investigates the effectiveness of camera trapping for monitoring invasive rodents in high conservation areas, and the influence of habitat features and density of colonial-nesting seabirds on rodent relative activity levels to provide insights into their potential impacts. A total of 276 camera sites were established and left in situ for 8 days. Identified species were recorded in discrete 15 min intervals, referred to as ‘events’. In total, 19 804 events were recorded. From these, 31 species were identified comprising 25 native species and six introduced. Two introduced rodent species were detected: the black rat (90% of sites), and house mouse Mus musculus (56% of sites). Rodent activity of both black rats and house mice were positively associated with the structural density of habitats. Density of seabird burrows was not strongly associated with relative activity levels of rodents, yet rodents were still present in these areas. Camera trapping enabled a large number of rodents to be detected with confidence in site-specific absences and high resolution to quantify relative activity levels. This method enables detection of multiple species simultaneously with low impact (for both target and non-target individuals); an ideal strategy for monitoring trap-adverse invasive rodents in high conservation areas.

The influence of habitat features on amphibian distribution in Northeastern Greece

Environmental and isolation variables relating to abundance of breeding amphibians, species richness and community structure at different spatial scales were examined in the Dadia-Lefkimi-Soufli Forest National Park, Evros, Greece. Logistic regression and a generalized linear model were used to relate several habitat characteristics to species occurrence and species richness. The community structure responses to breeding-pond features were examined at four spatial scales using canonical correspondence analysis (CCA). The richest communities live in low-altitude ponds, with stony or clay bottoms, high solar exposure and abundant submerged and floating vegetation. The CCA models were significant (p < 0.005) and revealed the influence of altitude, percentage of field and broadleaf forest coverage, and number of water bodies on amphibian species assemblages at all four spatial scales. There is a specific need for holistic management of amphibians that will consider habitat connectivity, particularly between aquatic and terrestrial habitats, at a larger, more interconnected scale.

Influence of habitat features and hunter behavior on white‐tailed deer harvest

AbstractSport hunting may help in controlling cervid populations over large areas. As with natural predators, several environmental factors can influence sport harvest. A better understanding of the environmental variables that limit the efficiency of sport hunting could provide guidelines for more efficient wildlife management using hunting. We studied white‐tailed deer (Odocoileus virginianus) hunting on a high deer density island where hunting was the sole form of predation. Our objective was to study the behavior of sport hunters and determine the habitat characteristics (e.g., abundance of deer forage, visibility of the deer from the hunter's point of view, and accessibility of the territory to hunters) that are associated with a successful harvest. We collected movements and harvest site location data from 477 hunters equipped with handheld Global Positioning System (GPS) units. Harvest sites were visited and characterized, along with a paired random site, to determine the environmental conditions associated with a successful hunt. We also developed a model to predict the daily number of deer seen by hunters considering weather conditions, hunter characteristics (e.g., age, experience), and date of hunting. We used the mean number of deer seen per hunter per day as a relative index of local density in each hunted territory. At both the site and landscape scales, the combination of visibility and access had a positive effect on the distribution of harvested deer. Habitat types with less visual obstruction from vegetation enabled hunters to see more deer in a given day. At the site scale, harvested deer were located in areas with a lower density of access routes compared to areas where hunters travelled throughout the day. Using an innovative approach of studying hunter behavior with GPS technology, digital maps, and questionnaires, we highlighted the factors associated with hunter success. Our study suggests that habitat characteristics could be modified to increase harvest by improving accessibility and visibility near roads. Creating openings in mature and regenerating forest near access roads could make sport hunting a more efficient management tool, but the potential impact of increased forage availability in forest openings should not be overlooked. © 2012 The Wildlife Society.

The importance of habitat-type for defining the reference conditions and the ecological quality status based on benthic invertebrates: The Ria Formosa coastal lagoon (Southern Portugal) case study

Coastal lagoons are complex systems, with considerable habitat heterogeneity and often subject to high temporal dynamics, which constitutes a great challenge for ecological assessment programs. For defining reference conditions for benthic invertebrates, under the EU Water Framework Directive objectives, historical data from the Ria Formosa leaky lagoon (wet surface area of about 105km2) located in Southern Portugal was used. The influence of habitat features, such as channel depth, sediment type and seagrass cover, on the expression of these biological communities, was inferred by analyzing subtidal data collected at stations with different environmental characteristics. Such heterogeneity effect was analyzed at the community compositional and structural levels, and also for three indices in the multimetric Benthic Assessment Tool (BAT). This tool for the assessment of ecological status includes the Margalef index, Shannon–Wiener diversity index, and AZTI's Marine Biotic Index (AMBI). Significant variations associated with environmental features were reflected on specific reference conditions at four habitats in the lagoon. After habitat calibration, the Benthic Assessment Tool (BAT) revealed that, in general and for the period of time covered by this historical data set, the status of the lagoon corresponded to a good ecological condition, which is mainly due to its high water renewal rate. Such classification is in accordance with the majority of studies at the lagoon. However, at punctual sites with human induced high water residence times, significantly lower BAT values were registered. Such community degradation can be associated with physical stress due to salinity increase and to a degradation of water quality, with occurrence of occasional dystrophic crisis, triggered by low water renewal. Habitat differentiation was a crucial step for a correct evaluation of the ecological condition of invertebrate communities across the lagoonal system.

Birds like it Corky: the influence of habitat features and management of ‘montados’ in breeding bird communities

In the southwest part of the Iberian Peninsula the dominant land-use are the Portuguese montados and Spanish dehesas, parkland forested areas of anthropogenic origin dominated by cork oak. They form a wooded matrix with open areas, scattered woodlands and undisturbed patches of Mediterranean forest and scrublands. The montados are characterized by a rich bird community. We have focus our study in a multidisciplinary approach, evaluating how management and landscape patterns influence the bird community in order to identify potential threats to its conservation. The study was conducted in the Site of Community Importance of Serra de Monfurado were 70% of the area is cork and holm oaks. We used data from 120 10-min point counts. Using variation partitioning, we determined the independent and joint effects of Forest, Management and Habitat variables. The variation captured in bird assemblage was 65.06%. Most of the explained variation was related to the Habitat and Management variables. The explanatory variables that were high-lighted as important predictors were variables that reflected tree and shrub density and cork removal. Modelling for forest species through generalized linear models (GLM) emphasize that the management plays an important role in the species distribution. The most important variables selected in models reflected cattle grazing and cork removal. Our results point out that the type of management is crucial to maintain the equilibrium in bird community associated to montados. Farmland and forest species will benefit from areas with different tree densities, small patches of Mediterranean scrubs in the understory and correct livestock numbers.

Efeito da estrutura de habitat sobre a abundância de parasitóides Pseudacteon Coquillett (Diptera, Phoridae) em ninhos de Solenopsis invicta Buren (Hymenoptera, Formicidae)

The influence of habitat characteristics on the abundance of the parasitoids Pseudacteon Coquillett (Diptera, Phoridae) of Solenopsis invicta Buren (Hymenoptera, Formicidae) was studied in organic polyculture agroecosystem in southeastern of Brazil. Parasitoids were collected during 30 minutes after fire ant colonies perturbation in plots with annual or perennial crops. A total of 228 parasitoids belonging to four species were obtained in 61.90% of the 84 fire ant colonies disturbed. Pseudacteon obtusus Borgmeier was the most abundant species (70 females), followed by Pseudacteon litoralis Borgmeier (37 females), Pseudacteon tricuspis Borgmeier (23 females) and Pseudacteon solenopsidis Schmitz (1 female). Pseudacteon litoralis was more frequent on fire ant mounds in plots with perennial crops than annual crops whereas P. obtusus and P. tricuspis had an opposed pattern. Negative significant correlation was found between air temperature and P. litoralis and P. obtusus abundances. Fire ant mound size and parasitoid abundance were positively correlated. Considering that phorids are important natural enemies of S. invicta, this study provides information for the management of fire ants in tropical polyculture agroecosystem.

Dynamics in a butterfly–plant–ant system: influence of habitat characteristics on turnover rates of the endangered lycaenidMaculinea alcon

Abstract1. Maculinea alcon, a myrmecophilic, stenotopic lycaenid butterfly is restricted to wet heathlands, bogs, and nutrient‐poor hay meadows. Due to intensification of agriculture and decrease of extensively grazed meadows, many suitable habitats have disappeared and the remaining ones are highly fragmented and deteriorated.2. Historical distribution data and a comparison with the present occupation of patches show the decline of this critically endangered butterfly in north‐west Germany. Most of the populations in north‐west Germany are small and often geographically isolated.3. In summer 2002, two‐thirds of 77 investigated potential patches were unoccupied as a result of unsuitable habitat structure and habitat fragmentation.4. Several habitat parameters were highly significantly correlated with the presence ofM. alcon, in particular the distribution pattern of the host plantGentiana pneumonanthe.Furthermore, butterflies were absent from many patches with an incidence probability below 50% with respect to patch size and isolation.5. In the nature reserve Lüneburger Heide, part of the study area,M. alconpopulations have been observed since 1995. Typical turnover of local populations could be detected during these years. Extinctions and re‐colonisations have stabilised the presence of this species in a metapopulation in this nature reserve.6. These data show the importance of different factors on different spatial levels influencing the presence of this endangered butterfly.

Influence of Habitat Characteristics on Detected Site Occupancy of the New Mexico Endemic Sacramento Mountains Salamander, Aneides Hardii

The Sacramento Mountains Salamander (Aneides hardii) is a state-listed threatened species endemic to three mountain ranges in south-central New Mexico. Information about the ecological requirements of this species is inadequate for managers to make informed conservation decisions, yet changes in management practices are needed throughout the species range because of poor forest health. During summer 2004, we examined patterns of A. hardii distribution in relation to several abiotic and biotic parameters on 36 plots, each of which was 9.6-ha in area and located in mixed conifer forest. We evaluated 18 a priori logistic regression models using Akaike's Information Criterion corrected for small-sample bias (AICc). The model with the highest ranking (lowest AICc value) included soil moisture and soil temperature, and the second highest ranked model (DAICc 5 0.05) included only soil temperature. Soil temperature was lower, and soil moisture was higher on plots where salamanders were detected. The relative importance of canopy cover and log volume was low in this study likely because the study plots, all of which had sufficient canopy cover and log volume, had similar disturbance history. We recommend managers focus on practices that ensure salamander microhabitats remain cool and moist in conservation areas. Resource managers are challenged with bal- ancing human interests and the conservation of threatened and endangered species. This is a current issue in the western United States because of the need to manage forests for catastrophic fire prevention while considering the response of sensitive forest species to silvicultural practices. Fire suppression has

The influence of habitat characteristics and conspecifics on attraction and survival of coral reef fish juveniles

In marine species with a pelagic larval stage, search behavior and selection of a suitable reef habitat can maximize the settlement success of recently settled juveniles and their subsequent performance (growth and survival of juveniles). Our objective was to test this hypothesis for a single target coral reef fish species ( Chromis viridis) at Moorea Island. C. viridis settle on living coral colonies of Porites rus already populated with conspecifics. In the present study (conducted in experimental cages), we found that: 1) mortality rate of recently settled juveniles of C. viridis was lower in the settlement habitat (living coral colonies of P. rus) than in other habitats having physical structure different from those of P. rus colonies; 2) C. viridis juveniles preferentially colonized coral heads of P. rus with conspecifics present rather than uninhabited coral heads and they also preferentially colonized uninhabited coral heads rather than coral heads with heterospecifics; 3) mortality rate of C. viridis juveniles did not vary with the presence or absence of conspecifics or heterospecifics on P. rus colonies. Overall, the study allows us to highlight that site selection by juveniles for habitat containing conspecifics does not benefit their short term mortality rates, suggesting that in the short term at least, site selection has little importance.