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Behavioural responses of non-breeding waterbirds to marine traffic in the near-shore environment
Bird Study
Abstract
Capsule
Recording of behavioural responses to ferry traffic for 11 target species showed that Red-throated Diver Gavia stellata, Slavonian Grebe Podiceps auratus, and Black-throated Diver Gavia arctica were most likely to react to passing vessels.
Aim
To provide information on how responses to marine traffic vary between waterbird species to inform marine spatial planning and environmental impact assessments in the near-shore environment.
Methods
We recorded behavioural responses to ferry traffic for 11 target species in near-shore waters: Common Eider Somateria mollissima, Goldeneye Bucephala clangula, Long-tailed Duck Clangula hyemalis, Velvet Scoter Melanitta fusca, Red-breasted Merganser Mergus serrator, Black-throated Diver, Great Northern Diver Gavia immer, Red-throated Diver, European Shag Gulosus aristotelis, Slavonian Grebe and Black Guillemot Cepphus grylle. Responses were analysed using generalized linear models and mixed models.
Results
Red-throated Diver, Black-throated Diver and Slavonian Grebe were the most likely species to exhibit a response to passing vessels. While Red-throated Divers and Slavonian Grebes were highly likely to flush, Black-throated Divers and Great Northern Divers rarely took flight, instead favouring swim or dive responses. In rougher sea conditions birds were more likely to take flight, and the propensity to respond declined across the wintering period.
Conclusions
This research provides comparative evidence on the behavioural responses of waterbirds to marine traffic. The results support previous studies which highlighted the high sensitivity of diver species to disturbance and provide new evidence that Slavonian Grebe may also be a high sensitivity species.
... A survey of Inner Galway Bay indicated that Great Northern Divers in that site are not very sensitive to disturbance from boat traffic (Gittings et al. 2015), while general anecdotal observations indicate that all three of the above species are not highly sensitive to disturbance from marine traffic in inshore waters around Ireland (personal observations). A more detailed study of responses to ferry traffic in Scotland reported higher disturbance sensitivity by Great Northern Divers and various other waterbird species (Jarrett et al., 2022). More evidence is required to properly assess the potential disturbance sensitivities of these species and to provide the level of certainty that is required for Appropriate Assessments of projects that may cause increased levels of marine traffic. ...
... The rarity of flush responses by Great Northern Divers in this study, as in previous studies (Gittings et al. 2015, Jarrett et al. 2022, could partially be explained by their moult strategy. Adults moult their flight feathers simultaneously, making them temporarily flightless for an unspecified period, between February and April (Appleby et al. 1985). ...
... However, I have regularly observed commuting Great Northern Divers flying into / out of the harbour past Roches Point throughout the winter, including during the February -April period, so there are always likely to be some Great Northern Divers present that are capable of flight. Also, Jarrett et al. (2022) found no effect of time on year on the probability of flush responses by Great Northern Divers. ...
The objectives of this study were to provide quantitative data on the incidence of waterbird disturbance responses that can be used to inform assessments of marine activities. The responses were recorded of Great Northern Diver, Cormorant and Shag to marine traffic following the navigation channel at Roches Point, Cork Harbour. Disturbance responses occurred in 13% of Great Northern Diver, 15% of Cormorant and 11% of Shag observations. Most responses occurred within 300 m of the passing vessel and the probability of a response decreased from 32% within 0-100 m to 12% at a distance of 200-300 m. There were higher probabilities of responses by non-feeding birds and for larger vessels. No differences were detected between species in the probability of a response, but, when a response did occur, it was initiated at much greater distances from the approaching vessel in Great Northern Divers compared to Cormorants and Shags. These results will help to inform assessments of developments that will cause increases in marine traffic in, or near, important coastlines for wintering waterbirds.
... For example, Red-throated Loon shows a high individual site fidelity and low adaptability to abiotic changes . Consequently, anthropogenic stressors, such as marine traffic disturbance Jarrett et al. 2021), offshore wind farm development (Heinänen et al. 2020) or bycatch could cause cumulative negative impacts on loons. The wintering population is locally low, with a fluctuation of only 8-12 individuals in the peak period of occurrence between December and January. ...
Bycatch, the incidental capture of non-target species in fishing gear, has been recognised as the most significant global conservation threat affecting seabird species. Geographically, bycatch rates vary widely, depending on local fishing efforts, environmental features, and seabird community composition. Regional and local research is essential due to the complexity of accurately extrapolating general conclusions regarding the impacts of bycatch. Existing European bycatch research predominantly focuses on northern regions, leaving a significant knowledge gap regarding bycatch in the Mediterranean Sea. This work presents findings of wintering diving seabirds as bycatch of small-scale fisheries in a coastal area of the northern Adriatic Sea, based on data collected between 2021 and 2023. Seabird distribution varied along the depth profile. The bathymetric range between 3 m and 5 m was the most exploited by fishermen. Bycatch of seabirds was confirmed in the study area, with five species recorded, i.e. Black-necked Grebe Podiceps nigricollis, Red-throated Loon Gavia stellata, Black-throated Loon Gavia arctica, Mediterranean Shag Gulosus aristotelis desmarestii, and Great Crested Grebe Podiceps cristatus. Our results suggest that bathymetry likely plays a strong influence on bycatch occurrence. Incidental captures were not widespread but appeared concentrated in the shallowest depths <5 m and the range <2.5 m was identified as particularly susceptible due to the low associated fishing effort and the majority of bycatch events recorded. We estimate that between 46 and 108 birds were incidentally captured during the research period. This study identifies key factors shaping the areas of bycatch vulnerability and risk, proposing a spatial–temporal mitigation framework within Natura 2000 sites and highlighting the value of local stakeholders’ engagement.
Ship traffic in Northwestern European seas is intense and continuing to increase, posing a threat to vulnerable seabird species as a result of disturbance. However, information on species-specific effects of ship traffic on seabirds at sea is limited, and tools are needed to prioritize species and areas to support the integration of conservation needs in Marine Spatial Planning. In this study, we investigated the responses of 26 characteristic seabird species in the German North and Baltic Seas to experimental ship disturbance using large datasets collected as part of the Seabirds at Sea counts. We developed a Disturbance Vulnerability Index (DVI) for ship traffic combining indicators for species’ shyness, escape costs, and compensatory potential, and analyzed the relationships among shyness, escape costs, and vulnerability. The DVI was calculated using the following eight indicators: escape distance, proportion of escaping birds, proportion of birds swimming prior to disturbance, wing loading, habitat use flexibility, biogeographic population size, adult survival rate, European threat and conservation status. Species-specific disturbance responses differed considerably, with common scoters (Melanitta nigra) and red-throated loons (Gavia stellata) showing the longest escape distances and highest proportions of escaping individuals. Red-throated loon, black guillemot (Cepphus grylle), Arctic loon (Gavia arctica), velvet scoter (Melanitta fusca), and red-breasted merganser (Mergus serrator) had the highest DVI values, and gulls and terns had the lowest. Contrary to theoretical considerations, shyness correlated positively with escape costs, with the shyest species also being the most vulnerable among the species studied. The strong reactions of several species to disturbance by ships suggest the need for areas with little or no disturbance in some marine protected areas, to act as a refuge for vulnerable species. This DVI can be used in combination with distribution data to identify the areas most vulnerable to disturbance.
Shipping routes in the ocean are analogous to terrestrial roads, in that they are regularly used thoroughfares that concentrate the movement of vessels between multiple locations. We applied a terrestrial road ecology framework to examine the ecological impacts of increased global shipping on “marine giants” (ie great whales, basking sharks [Cetorhinus maximus], and whale sharks [Rhincodon typus]). This framework aided in identifying where such “marine roads” and marine giants are likely to interact and the consequences of those interactions. We also reviewed known impacts of shipping routes on these species, and then applied the road ecology framework to detect unknown and potentially threatening processes. In the marine environment, such a framework can be used to incorporate knowledge of existing shipping impacts into management practices, thereby reducing the detrimental effects of future expansion of shipping routes on marine giants.
Marine aquaculture presents an opportunity for increasing seafood production in the face of growing demand for marine protein and limited scope for expanding wild fishery harvests. However, the global capacity for increased aquaculture production from the ocean and the relative productivity potential across countries are unknown. Here, we map the biological production potential for marine aquaculture across the globe using an innovative approach that draws from physiology, allometry and growth theory. Even after applying substantial constraints based on existing ocean uses and limitations, we find vast areas in nearly every coastal country that are suitable for aquaculture. The development potential far exceeds the space required to meet foreseeable seafood demand; indeed, the current total landings of all wild-capture fisheries could be produced using less than 0.015% of the global ocean area. This analysis demonstrates that suitable space is unlikely to limit marine aquaculture development and highlights the role that other factors, such as economics and governance, play in shaping growth trajectories. We suggest that the vast amount of space suitable for marine aquaculture presents an opportunity for countries to develop aquaculture in a way that aligns with their economic, environmental and social objectives.
Marine traffic is threatening cetaceans on a local and global scale. The Istanbul Strait is one of the busiest waterways, with up to 2,500 vessels present daily. This is the first study to assess the magnitude of short- and long-term behavioural changes of the endangered Black Sea harbour porpoises (Phocoena phocoena relicta) in the presence of marine vessels within the Istanbul Strait. Markov chains were used to investigate the effect of vessel presence on the transition probability between behavioural states (diving, surface-feeding and travelling), and to quantify the effect on the behavioural budget and bout length (duration of time spent in a given state) of porpoises. Further, the changes on swimming directions of porpoises in relation to vessel speed and distance was investigated using generalized linear models. In vessel presence, porpoises were less likely to remain in a given behavioural state and instead more likely to switch to another state. Because of this, the bout length of all three behavioural states decreased significantly in the presence of vessels. The vessel effect was sufficiently large to alter the behavioural budget, with surface-feeding decreasing significantly in the presence of vessels. However, when taking into account the proportion of time that porpoises were exposed to vessels (i.e. 50%), the measured effect size was not large enough to significantly alter the animals’ cumulative (diurnal) behavioural budget. Additionally, vessel speed and distance had a significant effect on the probability of porpoises showing a response in their swimming directions. The southern and middle sections of the Istanbul Strait, which have the heaviest marine traffic pressure, had the lowest porpoise sightings throughout the year. Conversely, northern sections that were exposed to a lesser degree of marine traffic hold the highest porpoise sightings. The effect shown in this study in combination with increasing human impacts within the northern sections should be considered carefully and species-specific conservation actions, including establishment of protected areas, should be put in place to prevent the long-term consequences of marine traffic on the Black Sea harbour porpoise population.
Observations were made of 45 interactions between Red-breasted Mergansers Mergus serrator and boat traffic in Wexford Harbour; 71% of these observations showed a disturbance response and 49% showed a flush response. The percentage of observations showing a disturbance response increased from 29% at lateral distances of more than 500 m from the boat route, to 90% at lateral distances of less than 250 m. The present study shows that mergansers have a high degree of behavioural sensitivity to disturbance from marine traffic. This sensitivity should be taken into account in the assessment of any proposed activities that may cause increased levels of marine traffic during the winter period in areas frequented by important concentrations of this species.
A survey of Great Northern Divers Gavia immer at Inner Galway Bay (57 observations of 64 birds) indicate that they do not show a ‘flush' response to boat traffic, even when the survey boat passed within 10 to 20 m of some birds, although some did show a ‘dive' response. However, two of three Red-throated Divers Gavia stellata showed a ‘flush' response at distances of about 15 m, and just over 100 m, from the survey boat.
We conducted the first validation of the deuterium dilution method as a nonlethal technique for estimating body composition of a sea duck. We captured male (n = 11) and female (n = 8) American common eiders (Somateria mollissima dresseri) during winters of 2011–2012 and 2012–2013 in southern New England, USA, and compared their directly measured body composition with that estimated using deuterium-dilution. The best-supported linear regression models predicted wet lean and fat mass with, on average, 2.0% and 20.2% relative errors, respectively. The deuterium dilution method provides field biologists and managers with a nonlethal method for accurately estimating body composition of common eider during winter. The method is broadly applicable to other migratory birds and can be used to evaluate the effects of ecological and anthropogenic drivers on body composition dynamics.
Animals living in urbanized habitats often show reduced fear responses to humans compared with their rural conspecifics. This
is usually assumed to be the result of habituation, but may also be explained by differential colonization or local adaptation.
To contrast these hypotheses, we studied the fear responses of urban and rural house sparrows (Passer domesticus) to humans, by measuring flight initiation distances (FID) in free-living flocks and observing the hiding behavior of wild-caught
individuals in response to repeated human disturbance in captivity. We found that although sparrows had shorter FID at urban
compared with rural sites, sparrows from both habitat types were equally likely to hide when they were disturbed for the first
time in the new captive situation. Both urban and rural sparrows decreased their time spent hiding over the course of 8 trials,
but the decrease was faster in urban sparrows. This difference was primarily due to a decrease in the sparrows’ immediate
response (reactivity) to the disturbance, whereas the speed of recovery after disturbance increased similarly over trials
in urban and rural birds. These results demonstrate that urban individuals habituate faster to human disturbance than their
rural conspecifics. Our findings suggest that the reduced fear of urban animals is the result of behavioral plasticity, whereas
we found no evidence for their higher intrinsic boldness as predicted by differential colonization and local adaptation.
Aerodynamics results in two characteristic speeds of flying birds: the minimum power speed and the maximum range speed. The minimum power speed requires the lowest rate of energy expenditure per unit time to stay airborne and the maximum range speed maximizes air distance traveled per unit of energy consumed. Therefore, if birds aim to minimize the cost of transport under a range of wind conditions, they are predicted to fly at the maximum range speed. Furthermore, take-off is predicted to be strongly affected by wind speed and direction. To investigate the effect of wind conditions on take-off and cruising flight behavior, we equipped 14 European shags Phalacrocorax aristotelis with a back-mounted GPS logger to measure position and hence ground speed, and a neck-mounted accelerometerto record wing beat frequencyand strength. Local wind conditions were recorded during the deployment period. Shags always took off into the wind regardless of their intended destination and take-off duration was correlated negatively with wind speed. We combined ground speed and direction during the cruising phase with wind speed and direction to estimate air speed and direction. Whilst ground speed was highly variable, air speed was comparatively stable, although it increased significantly during strong head winds, because of stronger wing beats. The increased air speeds in head winds suggest that birds fly at the maximum range speed, not at the minimum power speed. Our study demonstrates that European shags actively adjust their flight behavior to utilize wind power to minimize the costs of take-off and cruising flight.
· The coastal and offshore waters of the UK are of global importance for several species of seabirds. The United Nations Law of the Seas and the establishment of Exclusive Economic Zones gives coastal states extensive rights but also obligations over marine areas, including the assessment of potential effects of activities on the marine environment. The Crown Estate, as landowner of the seabed out to the 12 nautical mile territorial limit plays an important role in the development of the offshore wind industry by leasing areas of seabed for the placing of turbines. The planned erection of large numbers of offshore wind turbines has underlined our lack of knowledge relating to the distribution, abundance and habitat requirements (foraging ecology) of marine birds.
· As part of the Environmental Impact Assessments for offshore wind farms, the need for detailed knowledge on spatial and temporal patterns in seabird distribution has been identified. Dedicated censuses to sample the numbers and distribution of seabirds are a basic requirement for developers, to describe bird densities within, and in the immediate vicinity of, the construction area. Studies performed need to be related to some greater area studies, in order to assess the relative and the actual importance of the construction area for the species involved.
· This document evaluates existing census techniques and determine the best currently available methods for defining bird distribution and abundance at sea. The underlying question is twofold: (1) what are the research objectives and what data are required for EIAs for offshore wind farms, and (2) how good are existing census techniques at fulfilling the objectives?
· In order to assess the potential impact of the construction of an offshore wind farm and to understand how such a construction is likely to affect the birds associated with a site, dedicated research is required. The coupling of bird census data with geographical, hydrographical, and biological measurements is essential to begin to understand how an offshore construction such as a wind farm is likely to affect an area and how the seabirds associated with a site are most likely to respond. Natural variability issues are addressed and existing census techniques have been evaluated for their potential to provide data that can be used to describe habitat characteristics and area usage by seabirds.
· The two observation tools discussed in this study, aerial and ship-based surveys, potentially provide similar data for as far as basic seabird counts are concerned (accurate numbers, accurate maps). Census techniques are similar (distance techniques using parallel bands of known width), but the level of detail for individual species is considerably less during aerial surveys. Aerial surveys are quick, so enabling coverage of larger areas per unit time, and relatively cheap, whereas ship-surveys are more time-consuming.
· Data obtained during aerial surveys may be combined with environmental parameters in a correlative approach, whereas the advantage of a ship is that such parameters can often be collected simultaneously. The slower approach with vessels allows detailed observations on seabird behaviour (habitat utilisation, feeding conditions) and diurnal/tidal fluctuations in seabird abundance and distribution.
· The acquisition of information about migration routes, direction or height of flight, detailed spatial and temporal distribution require intensive radar and direct observation in the vicinity of a proposed wind farm development to determine bird use of the area and to predict collision impact probabilities under a range of differing temporal (day/night) and weather conditions. Similarly, assessment of actual collision risk and collisions after construction necessitates static measuring devices (such as infra-red movement triggered video surveillance and vibration detection equipment currently under development). However, these tools are not addressed further in this report.
http://www.offshorewindfarms.co.uk/Downloads/1352_bird_survey_phase1_final_04_05_06.pdf
Human pressures on the ocean are thought to be increasing globally, yet we know little about their patterns of cumulative change, which pressures are most responsible for change, and which places are experiencing the greatest increases. Managers and policymakers require such information to make strategic decisions and monitor progress towards management objectives. Here we calculate and map recent change over 5 years in cumulative impacts to marine ecosystems globally from fishing, climate change, and ocean- and land-based stressors. Nearly 66% of the ocean and 77% of national jurisdictions show increased human impact, driven mostly by climate change pressures. Five percent of the ocean is heavily impacted with increasing pressures, requiring management attention. Ten percent has very low impact with decreasing pressures. Our results provide large-scale guidance about where to prioritize management efforts and affirm the importance of addressing climate change to maintain and improve the condition of marine ecosystems.
People have long been fascinated by sea ducks because of their spectacular courtship displays, brightly colored and patterned plumage, remarkable variation in life history traits, remote northern breeding locations, unique migrations, and the many mysteries that remain about their ecology and behavior. However, the past decade has witnessed a dramatic increase in the interest and attention directed toward the 15 species of North American sea ducks, which include four species of eiders, the Harlequin Duck, three species of scoters, Long-tailed Duck, Bufflehead, two species of goldeneyes, and three species of mergansers that breed largely in arctic and subarctic habitats across the continent. We were motivated to produce this book, in large part, by the conservation concerns associated with simultaneous declines in several sea duck species and populations. Additionally, we wanted to synthesize the considerable research that has recently been conducted on this small tribe of ducks. These studies form the basis for identifying factors that may be limiting population recovery and will help to develop a conservation strategy for sea ducks in North America. We thus felt it was imperative to capture the current state of knowledge and to offer future research directions for researchers, managers, students, conservationists, and avian enthusiasts. Ecology and Conservation of North American Sea Ducks is a collection of 15 linked chapters focused on population dynamics, ecology, and behavior of sea ducks in North America. When we outlined this volume, we brought together researchers and managers who had field and laboratory experiences with all members of the sea duck tribe Mergini in North America. This in turn led to collaborations among specialists from different geographic areas of the continent to develop comprehensive treatises on key life history and management topics important for the conservation of sea duck species and their diverse marine and freshwater habitats. The chapter authors have combined the summaries of published accounts with new data, as well as presented additional analyses, models, and interpretations to
advance our understanding of sea duck population dynamics and genetics, infectious diseases and parasites, breeding costs and cross-seasonal effects, contaminant burdens, foraging behavior and energetics, migration strategies, molt ecology, breeding systems and reproductive behavior, harvest history and contemporary trends, and habitat affinities and dynamics, and to document conservation concerns. We hope this volume of the Studies in Avian Biology series will stimulate further interest and research on the sea ducks of North America and worldwide.
The drive towards sustainable energy has seen rapid development of marine renewable energy devices (MREDs). The NERC/Defra collaboration FLOw, Water column and Benthic ECology 4-D (FLOWBEC-4D) is investigating the environmental and ecological effects of installing and operating wave and tidal energy devices. The FLOWBEC sonar platform combines several instruments to record information at a range of physical and multitrophic levels for durations of two weeks to capture an entire spring-neap tidal cycle. An upward-facing multifrequency Simrad EK60 echosounder is synchronized with an upward-facing Imagenex Delta T multibeam sonar. An acoustic Doppler ve-locimeter (ADV) provides local current measurements and a fluorometer measures chlorophyll (as a proxy for phytoplankton) and turbidity. The platform is self-contained, facilitating rapid deployment and recovery in high-energy sites and flexibility in gathering baseline data. Five 2-week deployments were completed in 2012 and 2013 at wave and tidal energy sites, both in the presence and absence of renewable energy structures at the European Marine Energy Centre (EMEC), Orkney, U.K. Algorithms for target tracking have been designed and compared with concurrent , shore-based seabird observations used to ground truth the acoustic data. The depth preference and interactions of birds, fish schools and marine mammals with MREDs can be tracked to assess whether individual animals face collision risks with tidal stream turbines, and how animals generally interact with MREDs. These results can be used to guide marine spatial planning, device design, licensing and operation, as different device types are tested, as individual devices are scaled up to arrays, and as new sites are considered.
Furness, R. W., Wade, H. M., Robbins, A. M. C., and Masden, E. A. 2012. Assessing the sensitivity of seabird populations to adverse effects from tidal stream turbines and wave energy devices. – ICES Journal of Marine Science, 69: .
Tidal turbines and wave energy devices may affect seabird populations through collision mortality, disturbance and habitat loss. Given the pressures to harness tidal and wave energy, especially in Scottish waters, there is an urgent need to assess population-level impacts on seabird species. With a lack of deployed devices to monitor in areas of importance for seabirds, our approach uses data from scientific literature on seabird ecology and conservation importance likely to influence population vulnerability to “wet renewables” in Scottish waters. At this stage however, we can only infer likely interactions with tidal and wave devices. We identify black guillemot, razorbill, European shag, common guillemot, great cormorant, divers and Atlantic puffin as the species most vulnerable to adverse effects from tidal turbines in Scottish waters. We identify divers as the species most vulnerable to adverse effects from wave energy devices in Scottish waters. Wave energy devices seem likely to represent a lesser hazard to seabirds than tidal turbines, and both forms of energy capture seem likely to represent a lower hazard to seabirds than offshore wind farms (wind-power plants). The indices developed here for Scottish seabird populations could be applied to populations elsewhere. This approach will help in identifying likely impacts of tidal and wave energy deployments on seabirds, and in optimizing deployment of resources for compulsory environmental monitoring.
Marine dredging is an excavation activity carried out worldwide by many industries. Concern about the impact dredging has on marine life, including marine mammals (cetaceans, pinnipeds, and sirenians) exists, but effects are largely unknown. Through consulting available literature, this review aims to expand on existing knowledge of the direct and indirect, negative and positive impacts on marine mammals. In terms of direct effects, collisions are possible, but unlikely, given the slow speed of dredgers. Noise emitted is broadband, with most energy below 1 kHz and unlikely to cause damage to marine mammal auditory systems, but masking and behavioural changes are possible. Sediment plumes are generally localized, and marine mammals reside often in turbid waters, so significant impacts from turbidity are improbable. Entrainment, habitat degradation, noise, contaminant remobilization, suspended sediments, and sedimentation can affect benthic, epibenthic, and infaunal communities, which may impact marine mammals indirectly through changes to prey. Eggs and larvae are at highest risk from entrainment, so dredging in spawning areas can be detrimental, but effects are minimized through the use of environmental windows. Sensitive environments such as seagrass beds are at risk from smothering, removal, or damage, but careful planning can reduce degradation. Assessing impacts of contaminant remobilization is difficult, but as long as contaminated sediments are disposed of correctly, remobilization is limited in space and time. Effects of suspended sediments and sedimentation are species-specific, but invertebrates, eggs, and larvae are most vulnerable. Positive effects, including an increase in food, result from greater nutrient loads, but are often short term. Dredging has the potential to impact marine mammals, but effects are species and location-specific, varying also with dredging equipment type. In general, evidence suggests that if management procedures are implemented, effects are most likely to be masking and short-term behavioural alterations and changes to prey availability.
Marine ecosystems are under increasing anthropogenic pressures from marine and terrestrial activities. Ship traffic, the major cause of change in the open ocean, and its temporal evolution are still largely unknown because of lack of data. Altimeter data provide a new powerful tool to detect and monitor the ship traffic through a method of analysis of echo waveform. The archive of seven altimeter missions has been processed to create a 2-decade database of ship locations. The estimated annual density maps compare well with the ones obtained from Automatic Identification System. The ship traffic analysis shows a global fourfold growth between 1992 and 2012, the largest increase being observed in the Indian Ocean and the Chinese seas reflecting the world trade change. Although mainly concentrated along lanes, the traffic has a direct impact on the atmosphere, e.g. on the growth of tropospheric nitrogen dioxide in the Indian Ocean.
Offshore wind power provides a valuable source of renewable energy that can help reduce carbon emissions. Technological advances are allowing higher capacity turbines to be installed and in deeper water, but there is still much that is unknown about the effects on the environment. Here we describe the lessons learned based on the recent literature and our experience with assessing impacts of offshore wind developments on marine mammals and seabirds, and make recommendations for future monitoring and assessment as interest in offshore wind energy grows around the world. The four key lessons learned that we discuss are: 1) Identifying the area over which biological effects may occur to inform baseline data collection and determining the connectivity between key populations and proposed wind energy sites, 2) The need to put impacts into a population level context to determine whether they are biologically significant, 3) Measuring responses to wind farm construction and operation to determine disturbance effects and avoidance responses, and 4) Learn from other industries to inform risk assessments and the effectiveness of mitigation measures. As the number and size of offshore wind developments increases, there will be a growing need to consider the population level consequences and cumulative impacts of these activities on marine species. Strategically targeted data collection and modeling aimed at answering questions for the consenting process will also allow regulators to make decisions based on the best available information, and achieve a balance between climate change targets and environmental legislation.
Maximum likelihood or restricted maximum likelihood (REML) estimates of the
parameters in linear mixed-effects models can be determined using the lmer
function in the lme4 package for R. As for most model-fitting functions in R,
the model is described in an lmer call by a formula, in this case including
both fixed- and random-effects terms. The formula and data together determine a
numerical representation of the model from which the profiled deviance or the
profiled REML criterion can be evaluated as a function of some of the model
parameters. The appropriate criterion is optimized, using one of the
constrained optimization functions in R, to provide the parameter estimates. We
describe the structure of the model, the steps in evaluating the profiled
deviance or REML criterion, and the structure of classes or types that
represents such a model. Sufficient detail is included to allow specialization
of these structures by users who wish to write functions to fit specialized
linear mixed models, such as models incorporating pedigrees or smoothing
splines, that are not easily expressible in the formula language used by lmer.
Shipping emissions are currently increasing and will most likely continue to do so in the future due to the increase of global-scale trade. Ship emissions have the potential to contribute to air quality degradation in coastal areas, in addition to contributing to global air pollution. With the aim to quantify the impacts of shipping emissions on urban air quality in coastal areas in Europe, an in depth literature review was carried out focussing on particulate matter and gaseous pollutants but also reviewing the main chemical tracers of shipping emissions, the particle size distribution of ship-derived particulates and their contributions to population exposure and atmospheric deposition. Mitigation strategies were also addressed. In European coastal areas, shipping emissions contribute with 1-7% of ambient air PM10 levels, 1-14% of PM2.5, and at least 11% of PM1. Contributions from shipping to ambient NO2 levels range between 7 and 24%, with the highest values being recorded in the Netherlands and Denmark. Impacts from shipping emissions on SO2 concentrations were reported for Sweden and Spain. Shipping emissions impact not only the levels and composition of particulate and gaseous pollutants, but may also enhance new particle formation processes in urban areas. (C) 2014 The Authors. Published by Elsevier Ltd.
The rate of biological invasions has strongly increased during the last decades, mostly due to the accelerated spread of species by increasing global trade and transport. Here, we combine the network of global cargo ship movements with port environmental conditions and biogeography to quantify the probability of new primary invasions through the release of ballast water. We find that invasion risks vary widely between coastal ecosystems and classify marine ecoregions according to their total invasion risk and the diversity of their invasion sources. Thereby, we identify high-risk invasion routes, hot spots of bioinvasion and major source regions from which bioinvasion is likely to occur. Our predictions agree with observations in the field and reveal that the invasion probability is highest for intermediate geographic distances between donor and recipient ports. Our findings suggest that network-based invasion models may serve as a basis for the development of effective, targeted bioinvasion management strategies.
Escape distances (EDs) have been used to study sensitivity of waterbirds to different sources of disturbance, to design reserves for waterbirds, and to define eco-targets for the Wadden Sea management plan. However, the use of ED as an index of sensitivity has been criticised because it can be highly variable. Although some factors affecting variation in the EDs of species have been studied, there is still a need for further analysis of factors that may affect it. In this study, we analysed the EDs of 19 waterbird species (geese, ducks, waders and gulls) exposed to a walking person (N = 1,371) during autumn and spring 1980–1984 under controlled conditions in the Danish Wadden Sea. We analysed how EDs varied between species in relation to body mass and hunting and within species in relation to flock size and weather conditions. EDs increased significantly with species body mass, and quarry species (dabbling ducks, curlew Numenius arquata, golden plover Pluvialis apricaria, common gull Larus canus and black-headed gull L. ridibundus) had longer EDs than non-quarry species when corrected for body mass. EDs increased with flock size in dabbling ducks and nine waterbird species in autumn and two waterbird species in spring. In autumn an inverse relationship was found between visibility and ED for dabbling ducks and five wader species. An inverse relationship was also found between wind force and ED for three wader species, but this relationship was found to be positive for two wader species. Several factors affected EDs, and EDs measured in one region may not apply to other regions. Based on our results it is recommended that reserve borders (core area and buffer zones) are designed to take into account mean EDs as well as variation in EDs, with respect to local disturbance levels, flock size and target species.
One potential approach to combat the impacts of climate change is the expansion of renewable energy installations, leading to an increase in the number of wave-powered marine renewable energy installations (MREIs). The consequences of increased use of these devices for birds are unknown. Here we describe the wave-powered energy-generating devices currently either operational or in development and review the potential threats and benefits of these to marine birds, their habitats and prey. Direct negative effects include risk of collision, disturbance, displacement and redirection during construction, operation and decommissioning. Above-water collision is a particular concern with wind-powered devices, but, because of their low profiles, the collision risk associated with wave-powered devices is likely to be much lower. Conversely, wave devices also pose the novel threat of underwater collision. Wave-energy-generating devices may indirectly impact marine birds by altering oceanographic processes and food availability, with implications for trophic cascades. Through appropriate mitigation, wave-powered MREIs offer the potential to enhance habitats. Direct positive effects may include provision of roosting sites, and indirect positive effects may include prey aggregation due to suitable substrates for sessile organisms or because they act as de facto protected areas. The cumulative effect of these could be the improvement and protection of foraging opportunities for marine birds. Recent studies have been critical of the methods used in the assessment of wind-powered MREI impacts, which lack sufficient sample sizes, controls or pre-development comparisons. Here we suggest solutions for the design of future studies into the effects of MREIs. Wave-powered MREIs are certain to become part of the marine environment, but with appropriate planning, mitigation and monitoring they have the potential to offer benefits to marine birds in the future.
1. The evidence for anthropogenically induced climate change is overwhelming with the production of greenhouse gases from burning fossil fuels being a key driver. In response, many governments have initiated programmes of energy production from renewable sources.
2. The marine environment presents a relatively untapped energy source and offshore installations are likely to produce a significant proportion of future energy production. Wind power is the most advanced, with development of wave and tidal energy conversion devices expected to increase worldwide in the near future.
3. Concerns over the potential impacts on biodiversity of marine renewable energy installations (MREI) include: habitat loss, collision risks, noise and electromagnetic fields. These factors have been posited as having potentially important negative environmental impacts.
4. Conversely, we suggest that if appropriately managed and designed, MREI may increase local biodiversity and potentially benefit the wider marine environment. Installations have the capacity to act as both artificial reefs and fish aggregation devices, which have been used previously to facilitate restoration of damaged ecosystems, and de facto marine-protected areas, which have proven successful in enhancing both biodiversity and fisheries.
5. The deployment of MREI has the potential to cause conflict among interest groups including energy companies, the fishing sector and environmental groups. Conflicts should be minimized by integrating key stakeholders into the design, siting, construction and operational phases of the installations, and by providing clear evidence of their potential environmental benefits.
6. Synthesis and applications. MREI have the potential to be both detrimental and beneficial to the environment but the evidence base remains limited. To allow for full biodiversity impacts to be assessed, there exists an urgent need for additional multi and inter-disciplinary research in this area ranging from engineering to policy. Whilst there are a number of factors to be considered, one of the key decisions facing current policy makers is where installations should be sited, and, dependent upon site, whether they should be designed to either minimize negative environmental impacts or as facilitators of ecosystem restoration.
Capsule
In the winter of 2015/16, the fourth survey of the UK’s wader populations of the open coast – the Non-estuarine Waterbird Survey (NEWS III) – was undertaken.
Aim
To provide abundance estimates for thirteen key wader species wintering on the open coast alongside a comparison with former surveys and an assessment of abundance change.
Methods
Counts of all non-breeding waterbirds in the intertidal and landward components of previously designated count stretches of coast were carried out. Abundance estimates were derived with bootstrapped confidence intervals and data from previous surveys re-analysed to allow direct comparison. Generalized linear mixed models were used to assess changes in abundance through paired analyses at a count stretch level across the surveys.
Results
NEWS III covered 9183 km or 53% of the UK’s non-estuarine coast. The following abundance estimates and confidence limits were calculated (in decreasing order of abundance): Oystercatcher Haematopus ostralegus 69,905 (64,204–75,545), Curlew Numenius arquata 44,344 (38,324–50,613), Turnstone Arenaria interpres 25,988 (23,552–29,324), Dunlin Calidris alpina 19,415 (12,737–26,634), Redshank Tringa totanus 18,513 (17,122–19,758), Golden Plover Pluvialis apricaria 18,513 (11,238–30,825), Lapwing Vanellus vanellus 17,490 (14,148–22,178), Ringed Plover Charadrius hiaticula 16,203 (13,245–18,541), Sanderling Calidris alba 12,903 (10,248–17,268), Purple Sandpiper Calidris maritima 10,184 (7,780–13,945), Bar-tailed Godwit Limosa lapponica 6,217 (4,314–9,501), Knot Calidris canutus 2,683 (1,213–4,484) and Grey Plover Pluvialis squatarola 1,012 (675–1,481). A total of 4,848 (4,097–5,769) was derived for Common Snipe Gallinago gallinago but this is likely to be an underestimate. Overall, four species of waders wintering on the non-estuarine coasts of the UK have decreased or shifted their range since the winter of 2006/07: Lapwing (−57%), Curlew (−31%), Redshank (−37%) and Turnstone (−32%). Only one species increased: Sanderling (+79%).
Conclusions
The periodic non-estuarine waterbird surveys, alongside the Wetland Bird Survey (WeBS), have been critical in providing population estimates and trends of wintering waterbirds in the UK. More regular monitoring through NEWS, particularly those sites designated for their importance for non-breeding waterbirds, is crucial for understanding why losses of key wader species are occurring and would bring about greater alignment with the WeBS monitoring scheme.
Capsule: Non-breeding waterbirds are more likely to respond to drone approach when in larger flocks, and responses are more likely in arable and coastal habitats than at inland lochs.
Aims: To investigate the extent to which drones are a potential source of disturbance to non-breeding waterbirds.
Methods: Using a commercially available quadcopter drone, we approached waterbird flocks of varying sizes in coastal, freshwater, and arable habitats following a standardized protocol.
Results: Waterbirds at coastal sites and in arable fields were more likely to respond to drone approach than those at inland freshwater bodies. Larger flocks were more likely to respond to drone approach and responded at a greater distance than smaller flocks.
Conclusion: Repeated drone use at coastal and arable sites with large aggregations of feeding or roosting waterbirds could cause energetically costly flight responses, increased stress, and effective loss of available habitat. At such sites, it may be beneficial to regulate recreational and commercial drone use to minimize potential disturbance effects.
Seabirds select suitable habitats at sea, but these habitats may be strongly impacted by marine spatial planning, including the construction of offshore wind farms (OWFs) and the associated ship traffic. Loons (Gavia spp.) are particularly vulnerable to anthropogenic activities and are also of high conservation status, making them particularly relevant to marine planning processes. We investigated the effects of OWF construction and ship traffic on Loon distributions in the German North Sea on a large spatial scale, using a 'before-after' control impact analysis approach and a long-term data set. Many OWFs were built in or close to core areas of Loon distributions. Loons showed significant shifts in their distribution in the 'after' period and subsequently aggregated between two OWF clusters, indicating the remaining suitable habitat. The decrease in Loon abundance became significant as far as about 16 km from the closest OWF. Ship traffic also had a significant negative impact on Loons, indicating that OWFs deterred Loons through the combined effect of ship traffic and the wind turbines themselves. This study provides the first analysis of the extensive effects of OWFs and ships on Loons on a large spatial scale. The results provide an essential baseline for future marine spatial planning processes in the German North Sea and elsewhere.
We use a unique multi-method natural experiment to measure economic, social, and environmental impacts of cruise tourism on a local community. Through the measurement of multidimensional indicators before and after the opening of a cruise ship port, and using control groups, we compare community impacts with greater detail and control than previous studies. Although theory and industry multiplier estimates predict gains in employment, income, and related measures, we find little evidence of improvement. The ability of the local population to provide for necessities and obtain sufficient food worsened, corruption increased, and there were substantial negative environmental impacts. One observed benefit to communities was a decrease in crime due to an increase in government expenditure on policing. Our results show that in low taxation and regulation environments with an absence of community development and involvement initiatives, large cruise tourism projects can fail to provide benefits for local populations.
The black guillemot Cepphus grylle has been identified as a species likely to interact with marine renewable energy devices, specifically tidal turbines, with the potential to experience negative impacts. This likelihood is primarily based on the species being a diving seabird, and an inshore, benthic forager often associating with tidal streams. These behavioural properties may bring them into contact with turbine blades, or make them susceptible to alterations to tidal current speed, and/or changes in benthic habitat structure. We examine the knowledge currently available to assess the potential impacts of tidal stream turbines on black guillemot ecology, highlight knowledge gaps and make recommendations for future research. The key ecological aspects investigated include: foraging movements, diving behaviour, seasonal distribution, other sources of disturbance and colony recovery. Relating to foraging behaviour, between studies there is heterogeneity in black guillemot habitat use in relation to season, tide, diurnal cycles, and bathymetry. Currently, there is also little knowledge regarding the benthic habitats associated with foraging. With respect to diving behaviour, there is currently no available research regarding how black guillemots orientate and manoeuvre within the water column. Black guillemots are considered to be a non-migratory species, however little is known about their winter foraging range and habitat. The effect of human disturbance on breeding habitat and the metapopulation responses to potential mortalities are unknown. It is clear further understanding of black guillemot foraging habitat and behaviour is needed to provide renewable energy developers with the knowledge to sustainably locate tidal turbines and mitigate their impacts.
Scientific investigation is of value only insofar as relevant results are obtained and communicated, a task that requires organizing, evaluating, analysing and unambiguously communicating the significance of data. In this context, working with ecological data, reflecting the complexities and interactions of the natural world, can be a challenge. Recent innovations for statistical analysis of multifaceted interrelated data make obtaining more accurate and meaningful results possible, but key decisions of the analyses to use, and which components to present in a scientific paper or report, may be overwhelming.
We offer a 10‐step protocol to streamline analysis of data that will enhance understanding of the data, the statistical models and the results, and optimize communication with the reader with respect to both the procedure and the outcomes. The protocol takes the investigator from study design and organization of data (formulating relevant questions, visualizing data collection, data exploration, identifying dependency), through conducting analysis (presenting, fitting and validating the model) and presenting output (numerically and visually), to extending the model via simulation. Each step includes procedures to clarify aspects of the data that affect statistical analysis, as well as guidelines for written presentation. Steps are illustrated with examples using data from the literature.
Following this protocol will reduce the organization, analysis and presentation of what may be an overwhelming information avalanche into sequential and, more to the point, manageable, steps. It provides guidelines for selecting optimal statistical tools to assess data relevance and significance, for choosing aspects of the analysis to include in a published report and for clearly communicating information.
People have written about habituation, a process that leads to decreased responsiveness to a stimulus, as well as its counterpart, sensitization, or an increased responsiveness to a stimulus, for over 2000 years. And, while intensive research in the last century has led to well-supported generalizations about mechanisms of habituation, we have not developed a ‘natural history’ of habituation and tolerance that would help us predict, based on life history and natural history variation, how species will respond to humans and anthropogenic stimuli. The need for predictive models has never been greater. In this essay I will review generalizations about these learning processes and point out how a clear understanding of mechanism can be used to inform wildlife management and generate testable management interventions. I will also highlight unanswered questions about habituation and sensitization, and establish the groundwork for developing a natural history of habituation and tolerance.
The effects of marine renewable energy developments (MREDs) on seabirds are uncertain because of the relative infancy of the industry. This uncertainty can delay the consenting process as regulators adopt a precautionary approach. This study uses novel methods to demonstrate uncertainty in two indices that ranked the vulnerability of seabird populations to MREDs. The study also consolidates recently available data with information from the two indices to consider developments in our understanding of how seabirds respond to MREDs and to present up-to-date vulnerability predictions. Results indicate greater uncertainty in data regarding displacement caused by vessels and/or helicopters, and use of tidal races by seabirds, than in data regarding the percentage of flight overlapping with wind turbine blades and the level of displacement caused by structures. Results also indicate varying uncertainty among species. Overall vulnerability rankings remained broadly the same, with some minor changes. The uncertainty indices highlight areas lacking data, identify robust predictions, and indicate where particular caution in interpreting vulnerability indices should be adopted. They are a useful tool to inform impact assessment and identify strategic research and monitoring priorities.
Many small birds perform short flights, for which takeoffs, ascents and descents form a targe component of the total flight time and which are characterised by low airspeeds. Using the doubly-labelled water technique, zebra finches Taeniopygia guttata engaging in repeated short flights were found to expend 13.65 kJ more than 'non-flying' controls, which equated to a flight expenditure of 27.8 times their basal metabolic rate. This is over three times the predicted flight expenditure derived from existing aerodynamic models. These data were used to determine a coefficient (0.11) for converting the mechanical power derived from aerodynamic models into metabolic power. An equation is presented, based on body mass, which can be used to predict the costs of short flights in ecological and behavioural studies of birds.
Human offshore activities are increasingly threatening waterbird conservation interests. The impacts of disturbance by high-speed ferries on Common Eiders Somateria mollissima and Common Scoters Melanitta nigra were studied at a wintering site in the Kattegat Sea, Denmark. Spatial patterns of winter site use, close-range distribution patterns relative to ferry passages and escape distances were examined using aerial surveys and ferry-based observations. For Common Eiders, there was a suggestion of major disturbance impacts, i.e. birds displacing in response to the passage of ferries, within 500-1,000 m of the ferry route: a considerable proportion of flocks (> 10%) located within 400 m took flight in response to a passing ferry, and distributional impacts, including birds responding by swimming, were occasionally suggested within a distance of 500-1,000 m. Although distributional impacts could not be demonstrated with statistical significance within the Hjelm area (partly because of an apparently limited food supply in the area around the ferry route), it is concluded that high-speed ferry disturbance, had the potential to reduce significantly habitat use within 500 m of the ferry route. Common Scoters tended to take flight further from the ferry route than Common Eiders, however, data were limited and no conclusions could be made on displacement distances or possible impacts on habitat use. The results show that high-speed ferries may be an important source of disturbance that should be given due attention when the cumulative effects of offshore activities on site use by sea ducks are considered.
The R function glm uses step-halving to deal with certain types of convergence problems when using iteratively reweighted least squares to fit a generalized linear model. This works well in some circumstances but non-convergence remains a possibility, particularly with a nonstandard link function. In some cases this is because step-halving is never invoked, despite a lack of convergence. In other cases step-halving is invoked but is unable to induce convergence. One remedy is to impose a stricter form of stephalving than is currently available in glm, so that the deviance is forced to decrease in every iteration. This has been implemented in the glm2 function available in the glm2 package. Aside from a modified computational algorithm, glm2 operates in exactly the same way as glm and provides improved convergence properties. These improvements are illustrated here with an identity link Poisson model, but are also relevant in other contexts.
1. Wintering shorebirds are often disturbed by people and raptorial predators, causing them to loose feeding time and making it more difficult for them to meet their high energy demands. Previous work on captive oystercatchers, Haematopus ostralegus, suggests that they may be able to compensate for the lost time by increasing the rate at which they feed, but it is not known whether free-living oystercatchers can do so. This paper tests this possibility on five individually marked wild oystercatchers feeding on mussels Mytilus edulis. 2. Each marked bird was monitored continuously throughout tidal exposure periods between August 1993 and February 1994 on days during which disturbance either did or did not occur. The disturbance was either natural (raptors) or human, this either arising from shellfishermen or being experimentally induced. 3. A multiple regression model was built for each bird rising data only from undisturbed days to establish trends in intake rate associated with environmental factors, such as competitor density, the season and state of the tide. These were used to predict the intake rate that would have been expected to occur, had the disturbance not taken place. These expected 'undisturbed rates' were then compared to the actual rates after a disturbance had occurred. 4. The 'disturbed' and 'undisturbed' rates were not significantly different, either in the immediate post-disturbance period or over the remainder of the exposure period. Plots of cumulative biomass consumption showed that individual birds on disturbed days took longer to achieve a given consumption than on undisturbed days. Contrary to the hypothesis, there is no evidence that these birds increased their rate of feeding to compensate for lost feeding time. Instead, they extended their feeding time by remaining longer on the mussel bed. When time losses due to disturbance are rather short (30 60 min), the results suggest that there is some 'slack' in the system which oystercatchers are able to exploit to compensate for time lost through disturbance. 5. Studies on three sites with differing frequency of disturbance by people suggest that the birds are able to habituate to the frequent presence of people and to reduce the distance at which they take flight, thus reducing the amount of time lost to disturbance in the first place.
1. The extent and consequences of human disturbance on populations of vertebrates are contentious issues in conservation. As recreational and industrial uses of the countryside continue to expand, it is becoming increasingly important that the effects of such disturbance on wildlife are quantified. 2. This study describes a method of quantifying the effect of disturbance, based on measuring the trade-off between resource use and risk of disturbance. This approach is based on one used by ethologists to study the effects of predation risk on patch use. 3. Pink-footed geese, Anser brachyrhynchus, feeding on arable fields, are highly responsive to disturbance from surrounding roads. The extent to which these fields are exploited declines linearly with increasing risk of disturbance. The reduction in use of these feeding grounds caused by disturbance can be quantified by translating the biomass of food not exploited into the number of birds that this food could have supported 4. This approach allows both quantification of the impact of disturbance on a population, and exploration of the potential consequences of changes in disturbance on the size of populations.
The response of foraging animals to human disturbance can be considered as a trade-off between the increased perceived predation risk of tolerating disturbance and the increased starvation risk of not feeding and avoiding disturbance. We show how the response of overwintering oystercatchers Haematopus ostralegus to disturbance is related to their starvation risk of avoiding disturbance. As winter progresses, oystercatcher energy requirements increase and their feeding conditions deteriorate. To survive they spend longer feeding and so have less spare time in which to compensate for disturbance. Later in winter, birds approach a disturbance source more closely and return more quickly after a disturbance. Their behavioural response to disturbance is less when they are having more difficulty surviving and hence their starvation risk of avoiding disturbance is greater. These results have implications for studies which assume that a larger behavioural response means that a species is more vulnerable to disturbance. The opposite may be true. To more fully understand the impact of disturbance, studies should measure both behavioural responses and the ease with which animals are meeting their requirements. Conservation effort should be directed towards species which need to spend a high proportion of their time feeding, but still have a large response to disturbance.
Offshore wind farms may affect bird populations through collision mortality and displacement. Given the pressures to develop offshore wind farms, there is an urgent need to assess population-level impacts on protected marine birds. Here we refine an approach to assess aspects of their ecology that influence population vulnerability to wind farm impacts, also taking into account the conservation importance of each species. Flight height appears to be a key factor influencing collision mortality risk but improved data on flight heights of marine birds are needed. Collision index calculations identify populations of gulls, white-tailed eagles, northern gannets and skuas as of particularly high concern in Scottish waters. Displacement index calculations identify populations of divers and common scoters as most vulnerable to population-level impacts of displacement, but these are likely to be less evident than impacts of collision mortality. The collision and displacement indices developed here for Scottish marine bird populations could be applied to populations elsewhere, and this approach will help in identifying likely impacts of future offshore wind farms on marine birds and prioritising monitoring programmes, at least until data on macro-avoidance rates become available.
Recent theoretical modelling has provided important insights into how habitat loss may affect local populations through impacts on individual fitness (survival, body condition, fecundity). Despite this, attempts to provide empirical evidence of such impacts on displaced individuals have been limited. Using a before‐after‐control‐impact (BACI) approach, we report how a sudden loss of wintering habitat impacted on the body condition and survival of redshank Tringa totanus .
The intertidal mudflats of Cardiff Bay, UK, were inundated with freshwater in November 1999 following impoundment by a barrage, resulting in the displacement of c . 300 redshank to adjacent habitat on the Severn Estuary. Movements and the survival of these birds were monitored through observations of colour‐marked individuals. Comparative survival rates were calculated for marked populations at the main recipient site, Rhymney, and a control site.
Displaced redshank had difficulty maintaining their mass in the first winter post‐barrage closure: adults previously only recorded at Cardiff Bay were significantly lighter than those previously recorded at Rhymney.
Survival rates of displaced redshank also declined. The estimated annual survival of adult Cardiff Bay redshank fell from 0·846 in the 2 years pre‐barrage closure to 0·778 in the 3 following years because of a significant decline in winter survival ( P = 0·0006). In comparison, there was no significant change in the survival of adult Rhymney redshank, and adult survival at the control site was actually greater post‐barrage closure than beforehand. The lack of decline in these rates and the similarity between those of Cardiff Bay adults pre‐barrage closure and Rhymney adults indicate that the increase in winter mortality of Cardiff Bay birds resulted from their displacement.
Synthesis and applications. This study provides the first conclusive empirical evidence that habitat loss can impact individual fitness in a bird population. Adult redshank displaced from Cardiff Bay experienced poor body condition and a 44% increase in mortality rate. Without an increase in the recruitment of first‐winter birds, such a change is likely to reduce substantially local population size. The results reported here should help to inform governments, planners and non‐governmental organizations (NGOs) seeking to understand how developments might impact on animal populations.
1. While teaching statistics to ecologists, the lead authors of this paper have noticed common statistical problems. If a random sample of their work (including scientific papers) produced before doing these courses were selected, half would probably contain violations of the underlying assumptions of the statistical techniques employed.
2. Some violations have little impact on the results or ecological conclusions; yet others increase type I or type II errors, potentially resulting in wrong ecological conclusions. Most of these violations can be avoided by applying better data exploration. These problems are especially troublesome in applied ecology, where management and policy decisions are often at stake.
3. Here, we provide a protocol for data exploration; discuss current tools to detect outliers, heterogeneity of variance, collinearity, dependence of observations, problems with interactions, double zeros in multivariate analysis, zero inflation in generalized linear modelling, and the correct type of relationships between dependent and independent variables; and provide advice on how to address these problems when they arise. We also address misconceptions about normality, and provide advice on data transformations.
4. Data exploration avoids type I and type II errors, among other problems, thereby reducing the chance of making wrong ecological conclusions and poor recommendations. It is therefore essential for good quality management and policy based on statistical analyses.
The strength of an animal's behavioural response to human presence has often been used as an index of an animal's susceptibility to disturbance. However, if behavioural responsiveness is positively related to the animal's condition, this may be an inappropriate index, as individuals showing little or no response may in fact be those with most to lose from changing their behaviour. We tested the link between individual state and responsiveness by manipulating condition via the provision of supplementary food for turnstones, Arenaria interpres, on rocky shores. Birds at one site were fed 450 g of mealworms at low tide every day for 3 days while birds at another site acted as a control. On the fourth day, using a standardized disturbance protocol, we recorded flush distances, flight lengths and the amount of time between predator scans for birds in both flocks. After a break of 3 days, the treatments were then swapped between sites and the procedure repeated for a total of six trials. Birds whose condition had been enhanced showed greater responsiveness to standardized human disturbance, flying away at greater distances from the observer, scanning more frequently for predators and flying further when flushed. These findings suggest that our current management of the impact of human disturbance may be based on inaccurate assessments of vulnerability, and we discuss the implications of this for refuge provision.
The North Atlantic right whale (Eubalaena glacialis) is the most critically endangered large cetacean and is threatened by vessels that travel in their habitats and migration paths. A need to address the endangered population status of the right whale emerges as current management mandates have proven ineffective at preventing vessel-strikes to right whales and current rates of strike-induced mortality can slow or prevent recovery of the species. This paper identifies the need for an internationally acceptable management strategy to minimize vessel-strikes to right whales in Canadian waters.
The effect of human disturbance on animals is frequently measured in terms of changes in behaviour in response to human presence. The magnitude of these changes in behaviour is then often used as a measure of the relative susceptibility of species to disturbance; for example species which show strong avoidance of human presence are often considered to be in greater need of protection from disturbance than those which do not. In this paper we discuss whether such changes in behaviour are likely to be good measures of the relative susceptibility of species, and suggest that their use may result in confusion when determining conservation priorities.