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At least 415 records · Page 23Linked to original sources
USGS2024

Molecular sexing of birds using quantitative PCR (qPCR) of sex-linked genes and logistic regression models

The ability to sex individuals is an important component of many behavioural and ecological investigations and provides information for demographic models used in conservation and species management. However, many birds are difficult to sex using morphological characters or traditional molecular sexing methods. In this study, we developed probabilistic models for sexing birds using quantitative PCR (qPCR) data. First, we quantified distributions of gene copy numbers at a set of six sex-linked genes, including the sex-determining gene DMRT1 , for individuals across 17 species and seven orders of birds ( n = 150). Using these data, we built predictive logistic models for sex identification and tested their performance with independent samples from 51 species and 13 orders ( n = 209). Models using the two loci most highly correlated with sex had greater accuracy than models using the full set of sex-linked loci, across all taxonomic levels of analysis. Sex identification was highly accurate when individuals to be assigned were of species used in model building. Our analytical approach was widely applicable across diverse neognath bird lineages spanning millions of years of evolutionary divergence. Unlike previous methods, our probabilistic framework incorporates uncertainty around qPCR measurements as well as biological variation within species into decision-making rules. We anticipate that this method will be useful for sexing birds, including those of high conservation concern and/or subsistence value, that have proven difficult to sex using traditional approaches. Additionally, the general analytical framework presented in this paper may also be applicable to other organisms with sex chromosomes.

Molecular Ecology Resources↗
USGS2013

Estimating true instead of apparent survival using spatial Cormack-Jolly-Seber models

Survival is often estimated from capture–recapture data using Cormack–Jolly–Seber (CJS) models, where mortality and emigration cannot be distinguished, and the estimated apparent survival probability is the product of the probabilities of true survival and of study area fidelity. Consequently, apparent survival is lower than true survival unless study area fidelity equals one. Underestimation of true survival from capture–recapture data is a main limitation of the method. We develop a spatial version of the CJS model that allows estimation of true survival. Besides the information about whether a specific individual was encountered at a given occasion, it is often recorded where the encounter occurred. Thus, information is available about the fraction of dispersal that occurs within the study area, and we use it to model dispersal and estimate true survival. Our model is formulated hierarchically and consists of survival, dispersal and observation submodels, assuming that encounters are possible anywhere within a study area. In a simulation study, our new spatial CJS model produced accurate estimates of true survival and dispersal behaviour for various sizes and shapes of the study area, even if emigration is substantial. However, when the information about dispersal is scarce due to low survival, low recapture probabilities and high emigration, the estimators are positively biased. Moreover, survival estimates are sensitive to the assumed dispersal kernel. We applied the spatial CJS model to a data set of adult red-backed shrikes ( Lanius collurio ). Apparent survival of males ( c . 0·5) estimated with the CJS model was larger than in females ( c . 0·4), but the application of the spatial CJS model revealed that both sexes had similar survival probabilities ( c . 0·6). The mean breeding dispersal distance in females was c . 700 m, while males dispersed only c . 250 m between years. Spatial CJS models enable study of dispersal and survival independent of study design constraints such as imperfect detection and size of the study area provided that some of the dispersing individuals remain in the study area. We discuss possible extensions of our model: alternative dispersal models and the inclusion of covariates and of a habitat suitability map.

Methods in Ecology and Evolution↗
USGS2018

Animal movement models for migratory individuals and groups

Animals often exhibit changes in their behaviour during migration. Telemetry data provide a way to observe geographic position of animals over time, but not necessarily changes in the dynamics of the movement process. Continuous‐time models allow for statistical predictions of the trajectory in the presence of measurement error and during periods when the telemetry device did not record the animal's position. However, continuous‐time models capable of mimicking realistic trajectories with sufficient detail are computationally challenging to fit to large datasets. Furthermore, basic continuous‐time model specifications (e.g. Brownian motion) lack realism in their ability to capture nonstationary dynamics. We present a unified class of animal movement models that are computationally efficient and provide a suite of approaches for accommodating nonstationarity in continuous trajectories due to migration and interactions among individuals. Our approach uses process convolutions to allow for flexibility in the movement process while facilitating implementation and incorporating location uncertainty. We show how to nest convolution models to incorporate interactions among migrating individuals to account for nonstationarity and provide inference about dynamic migratory networks. We demonstrate these approaches in two case studies involving migratory birds. Specifically, we used process convolution models with temporal deformation to account for heterogeneity in individual greater white‐fronted goose migrations in Europe and Iceland, and we used nested process convolutions to model dynamic migratory networks in sandhill cranes in North America. The approach we present accounts for various forms of temporal heterogeneity in animal movement and is not limited to migratory applications. Furthermore, our models rely on well‐established principles for modelling‐dependent data and leverage modern approaches for modelling dynamic networks to help explain animal movement and social interaction.

Methods in Ecology and Evolution↗
USGS2024

Lead poisoning of raptors: State of the science and cross-discipline mitigation options for a global problem

Lead poisoning is an important global conservation problem for many species of wildlife, especially raptors. Despite the increasing number of individual studies and regional reviews of lead poisoning of raptors, it has been over a decade since this information has been compiled into a comprehensive global review. Here, we summarize the state of knowledge of lead poisoning of raptors, we review developments in manufacturing of non-lead ammunition, the use of which can reduce the most pervasive source of lead these birds encounter, and we compile data on voluntary and regulatory mitigation options and their associated sociological context. We support our literature review with case studies of mitigation actions, largely provided by the conservation practitioners who study or manage these efforts. Our review illustrates the growing awareness and understanding of lead exposure of raptors, and it shows that the science underpinning this understanding has expanded considerably in recent years. We also show that the political and social appetite for managing lead ammunition appears to vary substantially across administrative regions, countries, and continents. Improved understanding of the drivers of this variation could support more effective mitigation of lead exposure of wildlife. This review also shows that mitigation strategies are likely to be most effective when they are outcome driven, consider behavioural theory, local cultures, and environmental conditions, effectively monitor participation, compliance, and levels of raptor exposure, and support both environmental and human health.

Biological Reviews↗
USGS2015

Establishing conservation baselines with dynamic distribution models for bat populations facing imminent decline

Aim Bat mortality rates from white-nose syndrome and wind power development are unprecedented. Cryptic and wide-ranging behaviours of bats make them difficult to survey, and population estimation is often intractable. We advance a model-based framework for making spatially explicit predictions about summertime distributions of bats from capture and acoustic surveys. Motivated by species-energy and life-history theory, our models describe hypotheses about spatio-temporal variation in bat distributions along environmental gradients and life-history attributes, providing a statistical basis for conservation decision-making. Location Oregon and Washington, USA. Methods We developed Bayesian hierarchical models for 14 bat species from an 8-year monitoring dataset across a ~430,000 km 2 study area. Models accounted for imperfect detection and were temporally dynamic. We mapped predicted occurrence probabilities and prediction uncertainties as baselines for assessing future declines. Results Forest cover, snag abundance and cliffs were important predictors for most species. Species occurrence patterns varied along elevation and precipitation gradients, suggesting a potential hump-shaped diversity–productivity relationship. Annual turnover in occurrence was generally low, and occurrence probabilities were stable among most species. We found modest evidence that turnover covaried with the relative riskiness of bat roosting and migration. The fringed myotis ( Myotis thysanodes ), canyon bat ( Parastrellus hesperus ) and pallid bat ( Antrozous pallidus ) were rare; fringed myotis occurrence probabilities declined over the study period. We simulated anticipated declines to demonstrate that mapped occurrence probabilities, updated over time, provide an intuitive way to assess bat conservation status for a broad audience. Main conclusions Landscape keystone structures associated with roosting habitat emerged as regionally important predictors of bat distributions. The challenges of bat monitoring have constrained previous species distribution modelling efforts to temporally static presence-only approaches. Our approach extends to broader spatial and temporal scales than has been possible in the past for bats, making a substantial increase in capacity for bat conservation.

Oregon, Washington↗
USGS2022

Riparian buffers provide refugia during secondary forest succession

Aim Secondary forests regenerating from human disturbance are increasingly becoming a predominant forest type in many regions, and they play a significant role in forest community dynamics. Understanding the factors that underlie the variation in species responses during secondary succession is important for understanding community assembly and biodiversity monitoring and management. Because species vary in ecology and behaviour, responses to ecosystem change should vary among species. Here, we show that habitat type (riparian, upland), phylogeny, and species traits mediate anuran and lizard probability of occurrence and species richness in pasture and secondary forest. Location Sarapiquí and Osa Peninsula, Costa Rica. Methods We used phylogenetic occupancy models to estimate assemblage-level and species-specific responses to forest succession in 30 chronosequence sites that include pasture, secondary forest regenerating from pasture, and mature forest sites. Results For the majority of species, we found increasing probability of occurrence in upland habitats as forest regenerated from pasture to secondary forest and similar probability of occurrence in riparian habitats across pasture, secondary forest, and mature forest sites. Species' responses to forest stage were phylogenetically correlated, and the trend was especially strong for anuran response to pasture sites. Anurans with lentic larval habitat had a positive occupancy response to pasture upland habitat, and anurans with lotic larval habitat had a variable response to different forest stages compared to mature forest. Main Conclusions Our study, which focuses on sites that are minimally isolated from mature forest reference sites, indicated that anuran and lizard occupancy rapidly recovered to a level similar to mature forest in a relatively short time span (approximately 20 years). Riparian habitats are key ecosystem features in our system and provide refugia for organisms in early successional stages. Maintenance of vegetation along streams shows that we can mitigate forest conversion by maintaining riparian buffers.

Osa Peninsula, Sarapiquí↗
USGS2023

Limited hybridisation and introgression despite stocking among endemic Interior Highlands black basses (Centrarchidae: Micropterus)

Aim: Smallmouth Bass ( Micropterus dolomieu ; SMB) are globally popular among anglers and have been widely introduced (i.e. stocked) for population management and sportfishing. Importantly, stocking was prevalent before cryptic diversity within the SMB complex was known, which now includes three newly elevated species: Neosho Bass ( M. velox ; NB), Little River Bass ( M. sp. cf. dolomieu Little River; LRB) and Ouachita Bass ( M. sp. cf. dolomieu Ouachita River; OB). We sought to quantify population structure and hybridisation and introgression in these three recently described species. Location: Species-level diversity, particularly in the basin-restricted LRB and OB in the Ouachita Mountains within the Central Interior Highlands (CIH), North America, suggests the presence of distinct genetic variation that could be eroded by introgression. Methods: We estimated interspecific introgression and intraspecific population differentiation in the Smallmouth Bass species complex (SMB-C) using 472 specimens comprising SMB, NB, LRB and OB, including the naturally sympatric Spotted Bass ( M. punctulatus ; SPB). Genomic samples were genotyped on a SNP panel of 192 loci designed to detect allele-sharing on multiple hierarchical levels. Results: We found low range-wide hybridisation between species in the SMB-C and SPB (mostly SMB-C backcrosses), and interspecific heterozygosity varied, indicating differential introgression. Range-wide hybridisation between species in the CIH and SMB was similar overall (but mostly F 2 and CIH backcrosses) and was observed in streams with known SMB stocking in connected reservoirs. Interspecific heterozygosity in SMB hybrids was also generally lower, indicating later-generation backcrosses. We found strong population structure in the Ouachita Mountains (LRB and OB). Main conclusions: Despite isolated incidences of natural (SPB) and human-mediated (SMB) introgression, genomic identity appears intact in endemic LRB and OB, suggesting potential ecological or behavioural isolating mechanisms preventing cross-species reproduction. Our findings reveal that genetic variation remains in cryptic, basin-restricted species in the Ouachita Mountains ecoregion that may be managed for long-term conservation.

Arkansas, Missouri, Oklahoma↗
USGS2016

Household evacuation characteristics in American Samoa during the 2009 Samoa Islands tsunami

Tsunamis represent significant threats to human life and development in coastal communities. This quantitative study examines the influence of household characteristics on evacuation actions taken by 211 respondents in American Samoa who were at their homes during the 29 September 2009 M w 8.1 Samoa Islands earthquake and tsunami disaster. Multiple logistic regression analysis of survey data was used to examine the association between evacuation and various household factors. Findings show that increases in distance to shoreline were associated with a slightly decreased likelihood of evacuation, whereas households reporting higher income had an increased probability of evacuation. The response in American Samoa was an effective one, with only 34 fatalities in a tsunami that reached shore in as little as 15 minutes. Consequently, future research should implement more qualitative study designs to identify event and cultural specific determinants of household evacuation behaviour to local tsunamis.

Disasters↗
USGS2018

Phylogeny and species traits predict bird detectability

Avian acoustic communication has resulted from evolutionary pressures and ecological constraints. We therefore expect that auditory detectability in birds might be predictable by species traits and phylogenetic relatedness. We evaluated the relationship between phylogeny, species traits, and field‐based estimates of the two processes that determine species detectability (singing rate and detection distance) for 141 bird species breeding in boreal North America. We used phylogenetic mixed models and cross‐validation to compare the relative merits of using trait data only, phylogeny only, or the combination of both to predict detectability. We found a strong phylogenetic signal in both singing rates and detection distances; however the strength of phylogenetic effects was less than expected under Brownian motion evolution. The evolution of behavioural traits that determine singing rates was found to be more labile, leaving more room for species to evolve independently, whereas detection distance was mostly determined by anatomy (i.e. body size) and thus the laws of physics. Our findings can help in disentangling how complex ecological and evolutionary mechanisms have shaped different aspects of detectability in boreal birds. Such information can greatly inform single‐ and multi‐species models but more work is required to better understand how to best correct possible biases in phylogenetic diversity and other community metrics.

Ecography↗
USGS2014

Physiological indices of seawater readiness in postspawning steelhead kelts

Management goals to improve the recovery of steelhead (Oncorhynchus mykiss) stocks at risk of extinction include increasing the proportion of postspawning fish that survive and spawn again. To be successful, postspawning steelhead (kelts) migrating downstream to the ocean must prepare physiologically and physically for a seawater transition. We sampled blood, gill filaments, and evaluated the external condition of migrating kelts from an ESA-listed population in the Snake/Columbia River system over two consecutive years to evaluate their physiological readiness for transition to seawater. We chose attributes often considered as measures of preparation for seawater in juveniles, including gill Na + ,K + ATPase activity, plasma electrolytes and hormones to consider factors related to external condition, size and sex. We found kelts in good external condition had plasma profiles similar to downstream-migrating smolts. In addition, we found more than 80% of kelts ranked in good external condition had smolt-like body silvering. We compared measures from migrating kelts with samples obtained from hatchery fish at the time of spawning to confirm that Na + , K + ATPase activity in kelts was significantly elevated over spawning fish. We found significant differences in gill Na + , K + ATPase activity in migrating kelts between the years of sampling, but little indication of influence of fish condition. We conclude that the postspawning steelhead sampled exhibited a suite of behaviours, condition and physiology characteristic of fish prepared for successful transition to a seawater environment.

Idaho;Washington↗
USGS2014

Polymorphic mountain whitefish ( Prosopium williamsoni ) in a coastal riverscape: size class assemblages, distribution, and habitat associations

We compared the assemblage structure, spatial distributions, and habitat associations of mountain whitefish (Prosopium williamsoni) morphotypes and size classes. We hypothesised that morphotypes would have different spatial distributions and would be associated with different habitat features based on feeding behaviour and diet. Spatially continuous sampling was conducted over a broad extent (29 km) in the Calawah River, WA (USA). Whitefish were enumerated via snorkelling in three size classes: small (10–29 cm), medium (30–49 cm), and large (≥50 cm). We identified morphotypes based on head and snout morphology: a pinocchio form that had an elongated snout and a normal form with a blunted snout. Large size classes of both morphotypes were distributed downstream of small and medium size classes, and normal whitefish were distributed downstream of pinocchio whitefish. Ordination of whitefish assemblages with nonmetric multidimensional scaling revealed that normal whitefish size classes were associated with higher gradient and depth, whereas pinocchio whitefish size classes were positively associated with pool area, distance upstream, and depth. Reach-scale generalised additive models indicated that normal whitefish relative density was associated with larger substrate size in downstream reaches (R 2 = 0.64), and pinocchio whitefish were associated with greater stream depth in the reaches farther upstream (R 2 = 0.87). These results suggest broad-scale spatial segregation (1–10 km), particularly between larger and more phenotypically extreme individuals. These results provide the first perspective on spatial distributions and habitat relationships of polymorphic mountain whitefish.

Washington↗
USGS2017

Fine-scale acoustic telemetry reveals unexpected lake trout, Salvelinus namaycush, spawning habitats in northern Lake Huron, North America

Previous studies of lake trout, Salvelinus namaycush , spawning habitat in the Laurentian Great Lakes have used time- and labour-intensive survey methods and have focused on areas with historic observations of spawning aggregations and on habitats prejudged by researchers to be suitable for spawning. As an alternative, we used fine-scale acoustic telemetry to locate, describe and compare lake trout spawning habitats. Adult lake trout were implanted with acoustic transmitters and tracked during five consecutive spawning seasons in a 19–27 km 2 region of the Drummond Island Refuge, Lake Huron, using the VEMCO Positioning System. Acoustic telemetry revealed discrete areas of aggregation on at least five reefs in the study area, subsequently confirmed by divers to contain deposited eggs. Notably, several identified spawning sites would likely not have been discovered using traditional methods because either they were too small and obscure to stand out on a bathymetric map or because they did not conform to the conceptual model of spawning habitat held by many biologists. Our most unique observation was egg deposition in gravel and rubble substrates located at the base of and beneath overhanging edges of large boulders. Spawning sites typically comprised <10% of the reef area and were used consistently over the 5-year study. Evaluation of habitat selection from the perspective of fish behaviour through use of acoustic transmitters offers potential to expand current conceptual models of critical spawning habitat.

Ecology of Freshwater Fish↗
USGS2021

Dynamics of the seasonal migration of Round Goby (Neogobius melanostomus, Pallas 1814) and implications for the Lake Ontario food web

Seasonal migrations of fish populations can have large effects on lake nutrient budgets and food web dynamics, but the addition of a migrating non‐native species may alter these dynamics. The Round Goby ( Neogobius melanostomus ) arrived in Lake Ontario (USA/Canada) about 20 years ago with a documented history of annual offshore–inshore migrations in its native range. Here we combined nearshore, fixed‐plot video with offshore trawl data to document the annual migration of this population over multiple years. This behaviour was correlated with seasonal, nearshore temperature changes. The population size structure and mean fish length of returning fish were smaller than those of out‐migrating fish. The out‐migrating population contained an estimated 37.7 metric tonnes of phosphorous; and we estimated roughly 20 metric tonnes were translocated to and remained in offshore waters over the winter months, representing an important nutrient subsidy to a variety of offshore piscivorous fish. Lake Sturgeon ( Acipenser fulvescens ) have incorporated Round Goby extensively into their diet and consume a size range of fish matching the size range of missing Round Goby that fail to return to the nearshore. We conclude Round Goby are an important prey within the food web of Lake Ontario and translocate roughly 6.5% of the monthly total phosphorous load entering from surface waters. Further investigations of the nutrient content, population size structure and fate of migrating Round Goby in Lake Ontario are warranted to clarify the extent of this prey and nutrient subsidy in ongoing assessments of lake condition.

Lake Ontario↗
USGS2021

Diversity in spawning habitat use among Great Lakes Cisco populations

Cisco ( Coregonus artedi ) once dominated fish communities in the Laurentian Great Lakes. Restoring the abundance and distribution of this species has emerged as a management priority, yet our understanding of Cisco spawning habitat use is insufficient to characterise habitat needs for these populations and assess whether availability of suitable spawning habitat could be a constraint to recovery. We characterised the distribution of incubating Cisco eggs in situ across gradients of depth and substrate types to describe the spawning habitat used by three Great Lakes populations. In Chaumont Bay, Lake Ontario, eggs were concentrated on shallow bedrock shoals and not found on deeper silt or sand substrate. In contrast, eggs in Thunder Bay, Lake Superior, and Elk Rapids, Lake Michigan, were found on deeper fine grain sediments with low utilisation of shallow rocky and cobble habitats. These patterns of egg incubation habitat use suggest a broad spawning habitat niche at the species level but distinct spawning habitat preferences at the population level. While our results indicate some historical diversity in spawning habitat use has been maintained across the species’ range in the Great Lakes, comparisons of contemporary spawning habitat utilisation against historical accounts raise questions as to whether some spawning habitat use behaviours may no longer be prevalent within specific lakes. Thus, characterising the portfolio of spawning strategies remaining within lakes may improve our understanding of habitat needs and identify opportunities to maintain population diversity while supporting Cisco rehabilitation.

Michigan, New York↗
USGS2023

Larval cisco and lake whitefish exhibit high distributional overlap within nursery areas

Coregonine fishes, including lake whitefish ( Coregonus clupeaformis ) and cisco ( C. artedi ), are socioecologically important in the Laurentian Great Lakes and of conservation concern, but the processes driving recruitment variability are unclear. In Lake Ontario, cisco and lake whitefish exhibit similar spawning behaviours and early life histories, but population trajectories are diverging. One hypothesis is that sympatric cisco and lake whitefish larvae occupy distinct habitats and experience dissimilar local environmental conditions, despite co-occurrence within nursery areas. We described the spatiotemporal distributions of larval cisco and lake whitefish among multiple Lake Ontario embayment nursery areas, characterised physical habitat features associated with their distributions, determined the degree of spatial habitat partitioning between species and evaluated how habitat niche divergence occurred along an ontogenetic progression. Both species were widely distributed across larval nursery areas, though lake whitefish were less abundant and more narrowly distributed than cisco. Within the yolk sac stage, lake whitefish occupied more nearshore, shallower and colder waters than cisco, indicating potential habitat niche partitioning between congeners. However, distributional differences were subtle and likely driven by differential hatch timing and staggered ontogenetic habitat shifts. Combined, our results illustrate similar habitat use between cisco and lake whitefish through the larval stage and demonstrate that ontogeny and species-specific phenology influence habitat use for these species. This study provides additional evidence that the early life histories of cisco and lake whitefish are highly similar and does not support the hypothesis that larval habitat use differences are a major driver of differential recruitment success for these species.

New York↗
USGS2023

Native fish abundance and habitat selection changes in the presence of nonnative piscivores

We compared abundance patterns and developed resource selection models for imperilled native southwestern (USA) fishes in the presence and absence of Black Bass ( Micropterus spp.) to evaluate how fishes alter their selection for habitats when sympatric with a nonnative piscivore. We collected data using snorkel surveys and in-stream habitat sampling in Fossil Creek (AZ), upstream (native fish only) and downstream (native and nonnative fish) of a fish barrier. The abundance of all Roundtail Chub ( Gila robusta ), small (≤127 mm total length [TL]; vulnerable to predation) Sonora Sucker ( Catostomus insignis ) and Speckled Dace ( Rhinichthys osculus ) was significantly reduced, but the abundance of both small and large (>127 mm TL; invulnerable to predation) Desert Sucker ( Catostomus clarkii ) was similar in sampling reaches with and without Black Bass. When sympatric with Black Bass, small Roundtail Chub increased their selection for riffles by 2.57 times and small Desert Sucker reduce their selection for pools by 6.90 times while also selecting for faster flow velocity and finer substrates in lotic mesohabitats. Large native fishes altered selection least, notwithstanding an increased selection for canopy cover in sampling reaches with Black Bass. Observed shifts in resource selection are consistent with predator avoidance strategies. Our study highlights the behavioural consequences of nonnative piscivores on native fish communities and stresses the importance of maintaining lotic mesohabitats as potential refugia for vulnerable native fishes when nonnative piscivores are present.

Arizona↗
USGS2024

Deposited sediment influences occurrence of functional traits of stream fishes

To better understand stream-fish sensitivity to fine sediment, we documented assemblage-wide responses by selected traits along a sedimentation gradient. We then discuss the management implications of these ‘dose–response’ relations in the contexts of biotic assessments and conservation of sediment-sensitive species. We identified a spatial gradient in sediment deposition among streams within the upper Piedmont of the Roanoke River basin in North Carolina and Virginia. We assessed fine-sediment sensitivity of 81 species based on eight species traits stratified by four attributes: food preference, feeding location, spawning substrate and spawning behaviour. We then ranked each trait and scored each species with respect to its sediment sensitivity. Using data from electrofishing surveys during 2018–2019, we calculated proportional abundances of traits observed at 30 sites throughout the study area and grouped species by their aggregate sensitivity scores. We assessed relations between embeddedness and silt cover and occurrences of species and traits using a combination of regression and ordination approaches. All traits tested responded to embeddedness or silt cover, or both. Feeding traits exhibited the strongest responses to embeddedness, while reproductive traits exhibited the strongest responses to silt cover. Our findings indicate that negative responses of the probability of presence for high-sensitivity traits to embeddedness and silt cover were linear, with no apparent thresholds. Additionally, proportional abundances of species with multiple high-sensitivity traits were inversely related to embeddedness and silt cover. Overall, our findings regarding population-level responses to sedimentation were consistent with our findings for trait-specific responses. Our analysis of species sensitivity to fine sediment corroborated the patterns we saw in our trait-specific analyses, indicating that population responses to sedimentation can be predicted from combinations of species traits. The ‘dose–response’ relations we documented may be applicable to managing sediment impacts on fishes, especially in the contexts of biotic assessments and conservation of sediment-sensitive species.

North Carolina, Virginia↗
USGS2016

Costs of fear: Behavioral and life-history responses to risk and their demographic consequences vary across species

Behavioural responses to reduce predation risk might cause demographic &lsquo;costs of fear&rsquo;. Costs differ among species, but a conceptual framework to understand this variation is lacking. We use a life-history framework to tie together diverse traits and life stages to better understand interspecific variation in responses and costs. We used natural and experimental variation in predation risk to test phenotypic responses and associated demographic costs for 10 songbird species. Responses such as increased parental attentiveness yielded reduced development time and created benefits such as reduced predation probability. Yet, responses to increased risk also created demographic costs by reducing offspring production in the absence of direct predation. This cost of fear varied widely across species, but predictably with the probability of repeat breeding. Use of a life-history framework can aid our understanding of potential demographic costs from predation, both from responses to perceived risk and from direct predation mortality.

Ecology Letters↗