Kevin Wood | Wildfowl & Wetlands Trust (original) (raw)

Papers by Kevin Wood

Ecosystem Services, 2024

Wetlands make a disproportionately large contribution to global biodiversity and provide critical... more Wetlands make a disproportionately large contribution to global biodiversity and provide critical ecosystem services for humanity. Yet, our understanding of the cultural ecosystem services (CES) provided by wetlands remains limited, with benefits often only recognised at local scales. To address this knowledge gap, we conducted a global systematic review of wetland CES. Our synthesis addressed key questions related to the provision of CES by different types of wetlands, their economic value, their co-occurrence and associations with other ecosystem services, threats to the provision of CES by wetlands, as well as the availability and use of CES information. Based on 861 published papers (1968–2022) in 17 languages, we found evidence of CES provided by wetlands in 175 countries and territories, highlighting that wetlands are globally important for the provision of CES. Recreation/tourism was the most frequently reported CES (40 %), with cultural identity/heritage (16 %) and education/learning/knowledge (13 %) also well-represented. In contrast, examples of sense of place (4 %) and bequest (4 %) were least frequent. Our synthesis of published estimates yielded a mean of £57262 ha−1 yr−1 for the cultural benefits of wetlands; however, this mean should be interpreted with caution given that we documented a very wide range of estimates for each CES type of <£1–£1065205 ha−1 yr−1. Threats to wetland CES were documented in 45 % of papers, and included wetland destruction, pollution, and climate change. The probability that a CES paper would be available open access, and the probability that a published paper featured at least one author affiliated with the country where the study was conducted, both varied significantly among continents and publication years. Conservation outcomes related to CES featured in 13 % of papers, whilst 10 % made policy/management recommendations. Our study highlights the links between wetlands and human culture, emphasising their importance in motivating future wetland creation and restoration.

Ibis, 2024

Protected areas are one of the major tools used in the conservation of biodiversity, but animals ... more Protected areas are one of the major tools used in the conservation of biodiversity, but animals are unlikely always to remain within these human-made boundaries. Understanding when and why species choose to leave protected areas can help us to improve the effectiveness of these management tools. Here, we investigate the use of protected and non-protected areas by two migratory species undergoing rapid wintering population changes in northwest Europe: Whooper Swans Cygnus cygnus and Bewick's Swans Cygnus columbianus bewickii. Global positioning system tags were fitted to 15 Whooper Swans in winter 2008/09 and to 18 Bewick's Swans from winter 2013/14 to 2014/15 at the Ouse Washes Special Protection Area (an internationally important roost for wintering waterbirds) and on adjacent fields in southeast England. Here, swans feed on farmland during the day but return to designated reserves to roost at night, where they receive protection from predators and disturbance within managed roost habitats. When swans roost elsewhere at alternative sites, they may face more adverse conditions, and so understanding the extent and causes of the use of alternative roosts is important for swan conservation efforts. The alternative roosting proportion, defined as the proportion of nights spent outside protected reserves, was 0.237 for Bewick's Swans and challenging to quantify accurately for Whooper Swans. A generalized additive mixed model to model repeated measurements on individuals showed that the proportion of time that Bewick's Swans spent at alternative roosts correlated positively with river level and negatively with temperature. Competition and foraging flight distances are thought to drive these relationships, as swans seek access both to roost space and to nearby feeding habitats. Our findings improve our understanding of the environmental conditions under which migratory waterbirds may choose to roost outside protected areas.

Global Change Biology, 2024

Williamson et al. (2024) queried elements of our article in Global Change Biology (Mason et al. 2... more Williamson et al. (2024) queried elements of our article in Global Change Biology (Mason et al. 2024), where we used data from 431 articles to quantify global and regional carbon benefits from saltmarsh restoration.

Applied Animal Behaviour Science, 2024

Flamingos (Phoenicopteriformes) are relatively well studied species of bird, both in the wild and... more Flamingos (Phoenicopteriformes) are relatively well studied species of bird, both in the wild and in captive environments. Arguably, the two most famous anecdotes surrounding flamingo behaviour concerns their time spent on one leg (what is this related to?) and time spent preening (is it more than other species of waterbird?). We conducted an observational study at WWT Slimbridge Wetland Centre on five species of flamingos to test whether empirical evidence supported these anecdotes. We coupled this observational study with a global metaanalysis of published data on waterbird preening behaviour to allow a comparison of flamingos with other large waterbird taxa (Anseriformes, Ciconiiformes, Gruiformes, and Pelecaniformes). Analysis using zero-inflated generalised linear models indicated that flamingo unipedal behaviour was more common inside housing and on water. Preening effort varied markedly between flamingo species, but we detected no influence of any of the weather variables that were tested. Furthermore, our meta-analysis of waterbird behaviour indicated an interaction between latitude and season, whereby birds spent more time preening at higher latitudes during the nonbreeding season, but the opposite trend was detected during the breeding season. Contrary to the popular perception, we found no evidence that flamingos spend more time preening than other waterbirds; indeed, our analysis indicated that, among the five waterbird orders assessed, Pelecaniformes preened the most. However, waterbird preening effort was higher for captive populations (across all species) relative to their free-living counterparts. Our study provides new insight into long-held perceptions of the behaviour of flamingos and other waterbirds.

Ecology and Evolution, 2024

Access to high-quality food is critical for long-distance migrants to provide energy for migratio... more Access to high-quality food is critical for long-distance migrants to provide energy for migration and arrival at breeding grounds in good condition. We studied effects of changing abundance and availability of a marine food, common eelgrass (Zostera marina L.), on an arctic-breeding, migratory goose, black brant (Brant bernicla nigricans Lawrence 1846), at a key non-breeding site, Bahía San Quintín, Mexico. Eelgrass, the primary food of brant, is consumed when exposed by the tide or within reach from the water's surface. Using an individual-based model, we predicted effects of observed changes (1991–2013) in parameters influencing food abundance and availability: eelgrass biomass (abundance), eelgrass shoot length (availability, as longer shoots more within reach), brant population size (availability, as competition greater with more birds), and sea level (availability, as less food within reach when sea level higher). The model predicted that the ability to gain enough energy to migrate was most strongly influenced by eelgrass biomass (threshold January biomass for migration = 60 g m−2 dry mass). Conversely, annual variation in population size (except for 1998), was relatively low, and variation in eelgrass shoot length and sea level were not strongly related to ability to migrate. We used observed data on brant body mass at Bahía San Quintín and annual survival to test for effects of eelgrass biomass in the real system. The lowest observed values of body mass and survival were in years when biomass was below 60 g m−2, although in some years of low biomass body mass and/or survival was higher. This suggests that the real birds may have some capacity to compensate to meet their energy demands when eelgrass biomass is low. We discuss consequences for brant population trends and conservation.

Wildfowl, 2023

Analyses of 2,108 re-encounters made during 2013-2021 of 1,042 Canada Geese Branta canadensis mar... more Analyses of 2,108 re-encounters made during 2013-2021 of 1,042 Canada Geese Branta canadensis marked at Windermere, Cumbria, in summers 2013-2021 are used to describe their post-moult migration site linkages. Birds moulting at Windermere were subsequently sighted in 34 counties, although post-moult migration was mainly to the counties of Lancashire, Cheshire and Cumbria itself. The proportions of re-encounters in each direction away from Windermere differed statistically from the pattern expected for random dispersal, for seven out of eight directions. Resightings at Windermere showed that the number of marked individuals returning to moult decreased during the study, although numbers moulting on Windermere remained consistent throughout. We also provide new and updated information on the survival and mean dispersal distance for non-breeding Canada Geese. The mean dispersal distance away from Windermere for all marked individuals was 76 km (95% CI = 14.2). Annual mean survival rates ranged between 0.510 and 0.875 over the study period, with a geometric mean of 0.654 ± 0.199 (95% CI = 0.556-0.751). The results significantly improve our knowledge of the demography of the nonnative British Canada Goose population.

Global Change Biology, 2023

Coastal saltmarshes are found globally, yet are 25%–50% reduced compared with their historical co... more Coastal saltmarshes are found globally, yet are 25%–50% reduced compared with their historical cover. Restoration is incentivised by the promise that marshes are efficient storers of ‘blue’ carbon, although the claim lacks substantiation across global contexts. We synthesised data from 431 studies to quantify the benefits of saltmarsh restoration to carbon accumulation and greenhouse gas uptake. The results showed global marshes store approximately 1.41–2.44 Pg carbon. Restored marshes had very low greenhouse gas (GHG) fluxes and rapid carbon accumulation, resulting in a mean net accumulation rate of 64.70 t CO2e ha−1 year−1. Using this estimate and potential restoration rates, we find saltmarsh regeneration could result in 12.93–207.03 Mt CO2e accumulation per year, offsetting the equivalent of up to 0.51% global energy-related CO2 emissions—a substantial amount, considering marshes represent <1% of Earth's surface. Carbon accumulation rates and GHG fluxes varied contextually with temperature, rainfall and dominant vegetation, with the eastern coasts of the USA and Australia particular hotspots for carbon storage. While the study reveals paucity of data for some variables and continents, suggesting need for further research, the potential for saltmarsh restoration to offset carbon emissions is clear. The ability to facilitate natural carbon accumulation by saltmarshes now rests principally on the action of the management-policy community and on financial opportunities for supporting restoration.

Ecology and Evolution, 2023

Cost-effective use of limited conservation resources requires understanding which data most contr... more Cost-effective use of limited conservation resources requires understanding which data most contribute to alleviating biodiversity declines. Interventions might reasonably prioritise life-cycle transitions with the greatest influence on population dynamics, yet some contributing vital rates are particularly challenging to document. This risks managers making decisions without sufficient empirical coverage of the spatiotemporal variation experienced by the species. Here, we aimed to explore whether the number of studies contributing estimates for a given life-stage transition aligns with that transition's demographic impact on population growth rate, λ. We parameterised a matrix population model using meta-analysis of vital rates for the common eider (Somateria mollissima), an increasingly threatened yet comparatively data-rich species of seaduck, for which some life stages are particularly problematic to study. Female common eiders exhibit intermittent breeding, with some established breeders skipping one or more years between breeding attempts. Our meta-analysis yielded a breeding propensity of 0.72, which we incorporated into our model with a discrete and reversible ‘nonbreeder’ stage (to which surviving adults transition with a probability of 0.28). The transitions between breeding and nonbreeding states had twice the influence on λ than fertility (summed matrix-element elasticities of 24% and 11%, respectively), whereas almost 15 times as many studies document components of fertility than breeding propensity (n = 103 and n = 7, respectively). The implications of such mismatches are complex because the motivations for feasible on-the-ground conservation actions may be different from what is needed to reduce uncertainty in population projections. Our workflow could form an early part of the toolkit informing future investment of finite resources, to avoid repeated disconnects between data needs and availability thwarting evidence-led conservation.

Ringing and Migration, 2023

This study aims to determine the level of movement of individuals between the Icelandic and North... more This study aims to determine the level of movement of individuals between the Icelandic and Northwest Mainland European (NWME) Whooper Swan Cygnus cygnus populations, and to assess the extent to which this interchange affects total population estimates. Ringing, resighting and recovery data for Whooper Swans ringed across Europe since the early 1900s were compiled from the EURING Data Bank, national ringing schemes and individual ringers. Birds were assigned to the biogeographical population (Icelandic or NWME) in which they were ringed. Of >18 000 Whooper Swans ringed in 17 European countries, 172 individuals (0.94%) were later found outside the nominal range of their assigned biogeographical population. The proportion of ringed swans from the Icelandic population that were subsequently found ‘out of range’ did not differ significantly from the proportion recorded for the NWME population, indicating no directional bias in population interchange. Population switching by Whooper Swans in western Europe occurs consistently, but currently at very low levels. Our results reinforce the view that such levels of population interchange are unlikely to have caused major inaccuracies or biases in the total numbers recorded during the coordinated censuses used to estimate population size.

Hydrobiologia, 2023

No previous study has examined the large-scale distributional drivers of the entire global pool o... more No previous study has examined the large-scale distributional drivers of the entire global pool of 3,499 macrophyte species, despite the obvious importance of this for understanding the macroecology of these plants. To assess the hypothesis that natural rather than human-related transfer vectors act as the primary long-distance drivers of global movement of aquatic macrophytes, we analysed current macrophyte species distributions in relation to a set of human-related and natural transfer vectors. Most macrophytes (2,492 species: 71.2% of the global total) are endemic to a single ecozone, and generally lack the various functional adaptations needed for successful long-distance propagule transport. Such traits are, however, common in the 1,007 (28.8%) species native in > 1 ecozone. In total, 779 species (22.3%) are introduced, naturalised or invasive (I species) in one or more ecozones outwith their native range. The proportion of I species varies between ecozones and is best predicted by annual temperature and longitude. A migratory bird transfer vector and climatic variables strongly predict global native macrophyte species occurrence. Some native species of Miocene origin (or older) may have had their world distribution influenced by ancient vicariance events, while inter-ecozone hydrochory and Late Quaternary climate change are also relevant factors influencing a few species.

PLOS ONE, 2022

Individual animals engage in many behaviours which are mutually exclusive, and so where individua... more Individual animals engage in many behaviours which are mutually exclusive, and so where individuals increase the duration of time spent on one type of behavioural activity, this must be offset by a corresponding decrease in at least one other type of behaviour. To understand the variation observed in animal behaviour, researchers need to know how individuals trade-off these mutually-exclusive behaviours within their time-activity budget. In this study, we used remotely collected behavioural observations made from a live-streaming webcam to investigate trade-offs in the behaviour of two bird species, the mute swan (Cygnus olor) and whooper swan (Cygnus cygnus). For both species, we tested for correlations in the duration of time spent on key mutually exclusive behaviours: aggression, foraging, maintenance, and resting. We detected a negative association between aggression and resting behaviours in both species, indicating that increased aggression is achieved at the expense of resting behaviour. In contrast, there was no apparent trade-off between aggression and foraging, aggression and maintenance, or maintenance and resting. Foraging and resting behaviours were negatively correlated in both species, highlighting a trade-off between these distinct modes of behaviour. A trade-off between foraging and maintenance behaviours was detected for the sedentary mute swans, but not the migratory whooper swans. Our findings show how birds can trade-off their time investments in mutually exclusive behaviours within their time-activity budgets. Moreover, our study demonstrates how remotely-collected data can be used to investigate fundamental questions in behavioural research.

Ecological Solutions and Evidence, 2021

1. This database collates vital rate estimates for the common eider (Somateria mollissima), provi... more 1. This database collates vital rate estimates for the common eider (Somateria mollissima), providing a complete demographic parameterization for this slow life-history species. Monitored across its circumpolar range, the common eider represents a data-rich exemplar species for the less-studied seaducks, many of which are under threat.

2. The database contains estimates of the following vital rates: first-year survival; second-year survival; adult annual survival; first breeding (both age-specific recruitment probability, and breeding propensity across potential recruitment ages); breeding propensity of established female breeders; clutch size; hatching success; and fledging success. These estimates are drawn from 134 studies, across the scientific and grey literature, including three previously inaccessible datasets on clutch size that were contributed in response to a call for data through the IUCN Species Survival Commission's Duck Specialist Group.

3. Although clutch size has been much studied, the contributed datasets have enhanced coverage of studies reported in non-English languages, which were otherwise only represented when cited in English-language publications. Breeding propensity has been little studied, perhaps because adult females are often assumed to attempt breeding every year; we obtained a mean breeding propensity of 0.72. Our synthesis highlights the following gaps in data availability: juvenile and male survival; population change; and studies from Russia (at least accessible in English).

4. The database is intended to serve population modellers and scientists involved in the policy and practice of seaduck conservation and management.

Wildfowl, 2021

The eighth international census of Whooper Swans Cygnus cygnus wintering in Britain, Ireland and ... more The eighth international census of Whooper Swans Cygnus cygnus wintering in Britain, Ireland and Iceland (also including the Isle of Man and the Channel Islands) took place in January 2020, to update the estimates of the size, midwinter distribution, habitat use and breeding success of the Icelandic Whooper Swan population. The total of 43,255 swans counted represented a 27.2% increase in numbers since the previous census in 2015. Overall, 36.8% of the population (15,927 birds) was recorded in England, 33.4% (14,467) in the Republic of Ireland, 11.7% (5,052) in Scotland, 10.7% (4,644) in Northern Ireland and 6.8% (2,923) in Iceland, with < 1% (242) in Wales, the Isle of Man and the Channel Islands combined. Despite numbers increasing in both the Republic of Ireland and Northern Ireland since 2015, the proportion of the total population in the Republic of Ireland was significantly lower in 2020 and no significant difference was detected for Northern Ireland, whereas proportions in England and Scotland were significantly higher in 2020 and lower in Iceland. Breeding success was not associated with temperatures on either the breeding or wintering grounds. It also showed no clear trend over time, suggesting that increased survival may be the demographic driver of the population growth.

Oryx, 2022

Illegal killing of wildlife is a major conservation issue that, to be addressed effectively, requ... more Illegal killing of wildlife is a major conservation issue that, to be addressed effectively, requires insight into the drivers of human behaviour. Here we adapt an established socio-psychological model, the theory of planned behaviour, to explore reasons for hunting the Endangered Bewick's swan Cygnus columbianus bewickii in the European Russian Arctic, using responses from hunters to a questionnaire survey. Wider ecological, legal, recreational and economic motivations were also explored. Of 236 hunters who participated overall, 14% harboured intentions to hunt Bewick's swan. Behavioural intention was predicted by all components of the theory of planned behaviour, specifically: hunters' attitude towards the behaviour, perceived behavioural control (i.e. perceived capability of being able to perform the behaviour) and their subjective norms (perception of social expectations). The inclusion of attitude towards protective laws and descriptive norm (perception of whether other people perform the behaviour) increased the model's predictive power. Understanding attitudes towards protective laws can help guide the design of conservation measures that reduce non-compliance. We conclude that conservation interventions should target the sociopsychological conditions that influence hunters' attitudes, social norms and perceived behavioural control. These may include activities that build trust, encourage support for conservation, generate social pressure against poaching, use motivations to prompt change and strengthen peoples' confidence to act. This approach could be applied to inform the effective design, prioritization and targeting of interventions that improve compliance and reduce the illegal killing of wildlife.

Nature, 2021

The shift from a ‘reader pays’ to an ‘author pays’ model of scientific publishing presents a fina... more The shift from a ‘reader pays’ to an ‘author pays’ model of scientific publishing presents a financial threat to environmental nongovernmental organizations (eNGOs). Many of these support, conduct and publish applied research on real-world solutions to the planet’s most pressing challenges. Funded mainly by donations, eNGOs must now choose between taking conservation action and publishing more research papers.
A more equitable publishing system is needed. Platinum and diamond open access (see L. Barnes Open Book Publishers https://doi.org/g3tb; 2018), financed by a third party such as a scientific society, avoid article-processing charges (APCs) for authors and paywalls for readers, and can offer the lowest-cost option for eNGOs. Alternatively, journals could offer APC waivers for authors at eNGOs.
Discussions at this year’s United Nations biodiversity conference (COP15) and climate-change conference (COP26) are informed by eNGO research. Mandatory APCs risk pricing eNGOs out of scientific publishing at a time when their research output is most urgently needed.

Avian Research, 2021

Background: The long-term monitoring of demographic changes in waterbird populations remains limi... more Background: The long-term monitoring of demographic changes in waterbird populations remains limited, but such information can be valuable for conservationists and waterbird managers. Biased sex ratios can indicate differences in survival rates between sexes. In particular, differences in the sex ratios of fledged juveniles and adults can provide insight into the development of male bias among populations.

Methods: In this study, we used data from individual birds captured over a 57-year period to assess the extent, and temporal variability in male bias in nine populations of ducks wintering in the United Kingdom: Gadwall (Mareca strepera), Northern Mallard (Anas platyrhynchos), Northern Pintail (Anas acuta), Common Pochard (Aythya ferina), Common Shelduck (Tadorna tadorna), Northern Shoveler (Spatula clypeata), Eurasian Teal (Anas crecca), Tufted Duck (Aythya fuligula), and Eurasian Wigeon (Mareca penelope).

Results: Overall, eight of these populations were significantly male-biased and adults were more male-biased than first-winter juveniles for all nine populations. The increased male bias among adults is consistent with the hypothesis that factors such as higher mortality of reproductive-age females during the breeding season is a major cause of male bias in duck populations. However, such predation cannot explain the male bias detected in first-winter juveniles in four of the populations. The temporal trends in male bias differed between adults and first-winter juveniles in Northern Mallard, Northern Pintail, Common Pochard, Common Shelduck, Eurasian Teal, Tufted Duck, and Eurasian Wigeon. Over the study period we found increased male bias among adult Northern Mallard, Northern Pintail, Common Pochard, Common Shelduck, and Tufted Duck as well as both adult and first-winter juvenile Northern Shoveler.

Conclusions: We provide evidence that among wintering duck populations, sex ratios are typically male-biased, with adults exhibiting stronger male-biased sex ratios than first-winter juveniles. Improved monitoring of sex ratios of wintering waterbirds would help to increase our understanding of changes in waterbird demography, population structure, and observed population trends; our study shows that birds caught during ringing projects can be a valuable source of such data.

Avian Research, 2021

Background: Winter numbers of the northwest European population of Bewick's Swans (Cygnus columbi... more Background: Winter numbers of the northwest European population of Bewick's Swans (Cygnus columbianus bewickii) declined recently by c. 40%. During the same period, numbers of two sympatric and ecologically-similar congeners, the Mute Swan (Cygnus olor) and Whooper Swan (Cygnus cygnus) showed increases or stability. It has been suggested that these opposing population trends could have a causal relationship, as Mute and Whooper Swans are larger and competitively dominant to Bewick's Swans in foraging situations. If so, effects of competition of Mute and Whooper Swans on Bewick's Swans should be detectable as measurable impacts on behaviour and energetics. Methods: Here, we studied the diurnal behaviour and energetics of 1083 focal adults and first-winter juveniles ("cygnets") of the three swan species on their winter grounds in eastern England. We analysed video recordings to derive time-activity budgets and these, together with estimates of energy gain and expenditure, were analysed to determine whether individual Bewick's Swans altered the time spent on key behaviours when sharing feeding habitat with other swan species, and any consequences for their energy expenditure and net energy gain. Results: All three swan species spent a small proportion of their total time (0.011) on aggressive interactions, and these were predominantly intraspecific (≥ 0.714). Mixed-effects models indicated that sharing feeding habitat with higher densities of Mute and Whooper Swans increased the likelihood of engaging in aggression for cygnet Bewick's Swans, but not for adults. Higher levels of interspecific competition decreased the time spent by Bewick's Swan cygnets on foraging, whilst adults showed the opposite pattern. When among low densities of conspecifics (< c. 200 individuals/km 2), individual Bewick's Swans spent more time on vigilance in the presence of higher densities of Mute and Whooper Swans, whilst individuals within higher density Bewick's Swan flocks showed the opposite pattern. Crucially, we found no evidence that greater numbers of interspecific competitors affected the net energy gain of either adult or cygnet Bewick's Swans. Conclusions: We found no evidence that Bewick's Swan net energy gain was affected by sharing agricultural feeding habitat with larger congeners during winter. This was despite some impacts on the aggression, foraging and vigilance behaviours of Bewick's Swans, especially among cygnets. It is unlikely therefore that competition between Bewick's Swans and either Mute or Whooper Swans at arable sites in winter has contributed to the observed decline in Bewick's Swan numbers. Further research is needed, however, to test for competition in other parts of the flyway, including migratory stopover sites and breeding areas.

International Journal of Environmental Research and Public Health, 2021

The health benefits associated with spending time in natural environments have been highlighted d... more The health benefits associated with spending time in natural environments have been highlighted during the COVID-19 pandemic. Lockdowns and restrictions to safeguard public health have exacerbated the pre-existing mental health crisis and rise of non-communicable diseases. Thus, the importance of nature as a health resource has been elevated, hastening calls for a better understanding of how health benefits might differ across user groups and nature provisions. In this regard, urban green spaces have become the greatest research focus; however, blue spaces, especially inland freshwater (e.g., wetlands), remain less studied. First-hand user experiences are also under-represented. This exploratory study examines the motivations and benefits of active wetland centre users in the UK, both during and after visits. Responses to three open-ended questions were collated online from 385 participants, and a qualitative content analysis was conducted based on an existing taxonomy from users of urban green spaces. The results showed strong motivations to visit due to the biodiversity at the site (mainly the birdlife), while less tangible nature (e.g., fresh air) and amenities were also important. In contrast to other studies on natural environments, physical activity was a less influential motivation. Salient derived effects included positive and intensely positive emotions, relaxation and mental restoration. After visits to wetland centres, feelings of vitality and satisfaction were the most prominent effects that emerged. For decision-makers looking to leverage inland blue spaces for public health benefit, our results highlight the broad range and relative prominence of the reasons for use and the associated perceived health benefits derived by users of UK wetland centres. They highlight how biodiversity, abiotic nature and good amenities are important qualities to consider when planning, managing and encouraging people to use natural environments for health benefit, qualities that may also provide important environmental co-benefits.

Ringing & Migration, 2021

Analyses of 2280 re-encounters made during 2014–20 of 300 adult British Greylag Geese Anser anser... more Analyses of 2280 re-encounters made during 2014–20 of 300 adult British Greylag Geese Anser
anser marked at Windermere, Cumbria, in summers 2013–16 are used to describe the patterns
of their moult migration. Results show that birds moulting at Windermere are migrating mainly
from the nearby counties of Lancashire, North Yorkshire and West Yorkshire, and from within
Cumbria itself. Resightings at Windermere showed that the number of individuals returning to
moult decreased during the study: possible reasons for this are given. We also provide new and
updated information on the survival and mean dispersal distance for non-breeding British
Greylag Geese. The mean dispersal distance away from Windermere for all marked individuals
was 83.3 km (95% CI 73.4–93.2). Annual mean survival rates ranged between 0.568 and 0.872
over the study period, with a mean of 0.680 (95% CI 0.584–0.775). Results from this study
contribute to improving our knowledge of the demography of the British Greylag Goose
population.

Ecosphere, 2021

Climate change is driving worldwide shifts in the distribution of biodiversity, and fundamental c... more Climate change is driving worldwide shifts in the distribution of biodiversity, and fundamental changes to global avian migrations. Some arctic-nesting species may shorten their migration distance as warmer temperatures allow them to winter closer to their high-latitude breeding grounds. However, such decisions are not without risks, since this intensifies pressure on resources when they are used for greater periods of time. In this study, we used an individual-based model to predict how future changes in food abundance, winter ice coverage, and human disturbance could impact an Arctic/sub-Arctic breeding goose species, black brant (Branta bernicla nigricans, Lawrence 1846), and their primary food source, common eel-grass (Zostera marina L.), at the Izembek Lagoon complex in southwest Alaska. Brant use the site during fall and spring migrations, and increasingly, for the duration of winter. The model was validated by comparing predictions to empirical observations of proportion of geese surviving, proportion of geese emigrating, mean duration of stay, mean rate of mass gain/loss, percentage of time spent feeding, number of bird days, peak population numbers, and distribution across the complex. The model predicted that reductions >50% of the current decadal (2007-2015) mean of eelgrass biomass, which have been observed in some years, or increases in the number of brant, could lead to a reduction in the proportion of birds that successfully migrate to their breeding grounds from the site. The model also predicted that access to eelgrass in lagoons other than Izembek was critical for overwinter survival and spring migration of brant, if overall eelgrass biomass was 50% of the decadal mean biomass. Geese were typically predicted to be more vulnerable to environmental change during winter and spring, when eelgrass biomass is lower, and thermoregulatory costs for the geese are higher than in fall. We discuss the consequences of these predictions for goose population trends in the face of natural and human drivers of change.

Ecosystem Services, 2024

Ibis, 2024

Global Change Biology, 2024

Applied Animal Behaviour Science, 2024

Ecology and Evolution, 2024

Wildfowl, 2023

Global Change Biology, 2023

Ecology and Evolution, 2023

Ringing and Migration, 2023

Hydrobiologia, 2023

PLOS ONE, 2022

Ecological Solutions and Evidence, 2021

4. The database is intended to serve population modellers and scientists involved in the policy and practice of seaduck conservation and management.

Wildfowl, 2021

Oryx, 2022

Nature, 2021

Avian Research, 2021

International Journal of Environmental Research and Public Health, 2021

Ringing & Migration, 2021

Ecosphere, 2021

Plants are of fundamental importance to the structure, functioning and service provision of many ... more Plants are of fundamental importance to the structure, functioning and service provision of many ecosystems. However, herbivores can have negative ecological and socioeconomic effects on plant communities through consumption, trampling and alteration of nutrient cycles. In this thesis I address a particular herbivore-plant interaction: the grazing of plants in chalk river catchments, principally the submerged macrophyte water crowfoot (Ranunculus penicillatus ssp. pseudofluitans (Syne) S.D. Webster) and terrestrial pasture grass species, by flocks of non-breeding mute swans (Cygnus olor Gmelin, 1789). This research was carried out over two years in the River Frome catchment (Dorset, UK).

Based on a meta-analysis of previous waterfowl grazing studies I show that waterfowl biomass density (kg ha-1) rather than individual density (ind. ha-1) is a better predictor of reductions in plant standing crop. Most studies to date have analysed such reductions using only individual densities, despite large between-taxa variation in waterfowl body mass, diet and intake rates.

I quantified the abundance, species richness, evenness, flowering and dominance of the chalk river aquatic plant community in relation to biotic and abiotic factors during the growth-, peak-, and recession-phases of the growth cycle. The relative importance of herbivory, riparian shading, water temperature and distance downstream varied between different phases of the plant growth cycle, highlighting the importance of seasonal patterns in regulation of plant community structure.
The River Frome swan population varied seasonally, being highest in the winter. The population was dominated by non-breeding adults and juveniles that lived in flocks. These flocks exhibited strong seasonal habitat switches between terrestrial pasture in winter and spring, and river in summer and autumn. I provided evidence that this switch was linked to the seasonal decrease in water velocity between spring and summer, which reduced the metabolic costs of river feeding and increased the relative profitability of aquatic food resources.

I used a mathematical population model and an individual-based behavioural model respectively to explore two management options for the alleviation of the swan grazing conflict in chalk rivers: population control and habitat alterations. Population control measures, such as clutch manipulations, fertility control, culling or translocations, were predicted to be unsuccessful except at impractically high levels of management effort, due to the effects of immigration and high survival rates in offsetting removed eggs or individuals. Habitat alterations, in particular the narrowing of river channels to cause a local increase in water velocity and thus swan foraging costs, are more promising management options as they require lower management effort, are less ethically controversial, and address the fundamental reason why swans select their food resources, the rate of net energy gain (‘profitability’).

There is a global trend towards greater use of renewable energy, such as wind power, as part of e... more There is a global trend towards greater use of renewable energy, such as wind power, as part of efforts to mitigate the impacts of climate change. However, energy infrastructure such as wind turbines and power lines can pose a hazard to flying wildlife. There is a need to assess the impacts of energy infrastructure on wildlife populations at large spatial and temporal scales. Individual-based models (IBMs) are spatially- and temporally-explicit simulations of the interactions between individuals and their environment, and include stochasticity in animal behaviour (e.g. movement probabilities and site selections), and so IBMs can estimate the uncertainty associated with the mean predictions of mortality, in contrast to deterministic collision risk models. Here, we developed an IBM of Bewick’s Swans (Cygnus columbianus bewickii Yarrell, 1830), a species that underwent a c.39% decline in numbers in northwest Europe, to predict the cumulative collision mortality on the winter grounds and migratory stopover areas within Europe. The IBM was informed by telemetry data from 80 tagged individuals over seven successive winters between 2013/14 and 2019/20.
The calibrated version of our model predicted that a mean (±95% CI) of 874 (± 10) individual Bewick’s Swans would be killed over the course of the simulation (i.e. between September and the following June) in collisions with energy infrastructure across the winter and staging grounds in Europe. This mean predicted mortality represented 4.3% of the total wintering northwest European Bewick’s Swan population. The predicted mortality caused by wind farms and power lines therefore represents approximately 19% of the total annual mortality of the northwest European Bewick’s Swan population, which is in line with the findings of earlier studies that collisions with energy infrastructure represent one of the major causes of death among swans.
In the absence of differing avoidance rate estimates for swans encountering wind turbines compared with power lines, we did not separate avoidance rates for these structures in the models. On this basis, the total predicted mortality was comprised of 376 (± 7) individuals killed in collisions with onshore turbines, 193 (± 6) with offshore turbines, and 305 (± 5) with power lines. The model also predicted considerable variation in the mortality associated with each country. In particular, the Netherlands and Germany accounted for 43% and 33%, respectively, of the total deaths due to onshore turbines, whilst the waters around Germany were also associated with 69% of the deaths caused by offshore turbines. In contrast, the mortality associated with power lines was more broadly distributed, with no single country accounting for more than 24% (Russia) of the total number killed by power lines.
The mortality predictions of our model were highly sensitive to variations in the avoidance rate used, as even a small increase in the avoidance rate from 0.998 to 0.999 decreased the predicted mean mortality from 874 to 445 individuals. The high sensitivity of collision estimates to the avoidance rate highlights the need for accurate, precise measurements of this parameter for collision risk assessments.
Our report illustrates how avian telemetry data can be combined with a simulation-modelling approach to assess the cumulative collision mortality of an entire population at a large spatial scale.

The UK supports globally significant numbers of migratory waterbirds and has a requirement to mai... more The UK supports globally significant numbers of migratory waterbirds and has a requirement to maintain favourable conservation status for these species in the face of climate change and other threats. The growing number of wind turbines are key to the UK’s power supply and play an important role in the UK’s actions on climate change. However, together with overhead power lines, wind turbines may also represent a collision risk for flying animals such as geese. Therefore, as part of efforts to maintain favourable conservation status of key species and to identify issues with existing or planned infrastructure developments, it is critical to be able to assess the cumulative impacts of collisions with energy infrastructure on wildlife.
Here, in a study funded by Ørsted, we developed an individual-based model (IBM) of the UK’s overwintering population of Pink-footed Geese (Anser brachyrhynchus) in order to predict the cumulative mortality each winter due to collisions with onshore and offshore wind turbines and overhead power lines. IBMs are spatially- and temporally-explicit models that simulate the interactions between individuals and their environment, informed by the behaviour of their real-world counterparts. Our model was informed by information on the movements and flight heights of 73 geese fitted with GPS-GSM tags, together with census data on the total numbers and key regions used by the birds, as well as some key parameter values from the extensive literature on collision risk. We tested our model against real-world data on goose distributions across the UK; model fit was improved via calibration.
Our calibrated IBM predicted that a mean ± 95% CI of 99 ± 10 Pink-footed Geese would be killed in collisions with all wind turbines (considering onshore and offshore together) and 674 ± 33 geese would be killed in collisions with power lines each winter across the UK. Given the total population size of 479,361 that was considered in our study (mean of the three winter counts from 2016 – 2018), these mean mortality estimates associated with wind turbines and power lines account for just 0.02% and 0.14%, respectively, of the total UK wintering population. Only 1.1% of the total predicted mortality (1 bird) was associated with the offshore wind farms in the NE Irish Sea, an area crossed only during a relatively low number of long-distance flights (and not during the more numerous short-distance daily feeding flights). These mortality estimates for the UK wintering population are lower than suggested previously. For comparison, it is estimated that up to c.50,000 Pink-footed Geese are shot each winter in the UK during the recreational shooting season.
The collision mortality estimates were obtained from simulations using an avoidance rate of 99.8%, as recommended by Scottish Natural Heritage for collision risk studies of geese. However, no single avoidance rate estimate is accepted universally by all stakeholders; therefore, we also ran simulations with alternative avoidance rate values, covering the range commonly suggested for collision risk studies, for comparison. As expected, simulations that were run with lower avoidance rates resulted in higher estimates of collision mortality, i.e. for an avoidance rate of 95% our IBM predicted that a mean ± 95% CI of 2,363 ± 63 Pink-footed Geese would be killed in collisions with wind turbines and 16,664 ± 147 geese would be killed in collisions with power lines each winter. However, an important caveat is that the model was parameterized for typical weather conditions, as we do not currently have sufficient information to model collision risk during atypical conditions (e.g. high density fog). Collision risk during such atypical weather events could be higher than indicated by our simulations.
Future scenarios (under the 99.8% avoidance rate) in which the numbers of turbines and power lines encountered during flights were increased indicated that even a simultaneous doubling of the numbers of all turbines and power lines encountered during flights (relative to the baseline scenarios informed by the tagged geese), which would represent a substantial expansion of the existing network, would have a relatively small effect on the predicted cumulative mortality. The careful siting of any such new energy infrastructure outside of known flight paths and migration routes would reduce these impacts further.

This Initial Report describes the findings of a systematic literature review to synthesise data f... more This Initial Report describes the findings of a systematic literature review to synthesise data for developing the metrics of a United Kingdom (UK) Saltmarsh Carbon Code. The review targeted published data on the key drivers of variation in carbon stock, sequestration and greenhouse gas (CO2, CH4 and N2O) fluxes for natural as well as restored saltmarsh systems in the UK.

The 61st consecutive annual census of Greenland/Iceland Pink-footed Geese and Iceland Greylag Gee... more The 61st consecutive annual census of Greenland/Iceland Pink-footed Geese and Iceland Greylag Geese took place during autumn and early winter 2020. Sites holding Pink-footed Geese were surveyed in October and November, whilst those holding Greylag Geese were primarily surveyed in November. Coverage in Britain was good, with all of the key sites covered. During the time of the census, weather conditions were generally considered good, and little disturbance was reported from sites during the October and November periods with very few sites reporting underestimated counts. Count data were also received from Ireland and Southwest Norway, and from Iceland where an aerial census was conducted in favourable flying conditions. The additional spring census that was due to take place in 2021 was cancelled due to the various restrictions in place across Britain and Ireland as a result of the Covid-19 pandemic. Maxima of 485,509 Pink-footed Geese and 92,582 Greylag Geese were counted in October and November, respectively. The Greylag Goose figure was adjusted to account for the estimated number of British/Irish Greylag Geese likely to have been counted during this census, resulting in population estimates of 485,509 Pink-footed and 60,061 Greylag Geese. Compared to the previous year, the 2020 figures represent a decrease of 3.1% in the Pink-footed Goose population and a decrease of 18.1% in the Iceland Greylag Goose population. The possible explanations for these changes in population size are discussed in this report. Fifteen sites in Britain held 10,000 or more Pink-footed Geese in October, with Montrose Basin, Angus, holding the largest number during the census (55,980 birds). Combined counts from 27 sites that supported numbers exceeding 1% of the 2020 Pink-footed Goose population estimate accounted for 82.1% of the total October count. During the November census, 71.0% of the Iceland Greylag Goose population was present in North Scotland, principally in Orkney. The breeding success of Pink-footed Geese was assessed for flocks wintering at locations in Scotland and England from October to early December, with 15.4% young found amongst those flocks sampled: this being slightly lower than the previous year and lower than the previous tenyear mean of 17.4%. The mean brood size of successful pairs was 2.37 goslings. Due to the increasing difficulty in monitoring the breeding success of Iceland Greylag Geese on the wintering grounds, no age assessment data were collected during 2020.

The long-term monitoring of wildlife populations provides critical data used to inform conservati... more The long-term monitoring of wildlife populations provides critical data used to inform conservation policy and action. Within the UK, the Goose & Swan Monitoring Programme (GSMP) and affiliated schemes monitor the abundance (i.e. population size) and breeding success of native, migratory species of geese and swans through co-ordinated winter counts and age assessments at key sites. Typically, GSMP reports definitive annual estimates of the total population size based on the numbers of individuals counted, and the breeding success of the population based on the relative numbers of adults and juveniles (i.e. individuals born during the previous breeding season) in the surveyed population. However, to date there have been no attempts to estimate the uncertainty associated with these estimates of abundance or breeding success produced by GSMP.
A widely-used approach to quantifying uncertainty associated with an estimate is to calculate a confidence interval, which indicates the likely range in which the mean estimate would be found if the sampling exercise was repeated. More specifically, if the same population was surveyed on multiple occasions and the 95% confidence intervals were estimated for each occasion, the resulting confidence intervals would contain the true population parameter in approximately 95% of the cases. To date, the estimation of confidence intervals for GSMP data has proven difficult, as for many of the monitored populations only a single survey of each site can be undertaken each winter, and the deployment of additional survey effort to repeat the surveys (which could be used to estimate the variance between surveys) is not practical. Even where multiple surveys are currently undertaken, the use of a consistent approach to the estimation of confidence intervals would facilitate meaningful comparisons among different populations. Approaches that would allow the estimation of comparable confidence intervals for all of the populations would therefore be beneficial.
In this report, we compare two methods of estimating confidence intervals for the breeding success or abundance produced by GSMP. These two methods were (i) simple analytical expressions (based on binomial and Poisson distributions), and (ii) alternative approaches based on simulation (bootstrap resampling or Monte Carlo simulations). Both methods could be used for the data that have been routinely collected by GSMP and affiliated schemes. Comparison of the confidence intervals produced indicated broad similarity between the two methods, for juvenile proportion and abundance estimates. Indeed, the confidence intervals estimated by the two methods for the proportions of juveniles within populations were identical in 7 of the 12 populations considered, given the precision with which such estimates have been typically reported (i.e. a percentage given to one decimal place or a proportion given to three decimal places), with only minor deviations of ≤0.009 in the remaining 5 populations.
Similarly, for annual estimates of total abundance, in all populations we found close matches between the size of the confidence intervals derived by Poisson tests and simulation. The mean difference between the sizes of the 95% CI values produced by the two methods did not exceed 7 individuals for any of the populations considered.
As expected, smaller 95% confidence intervals for the proportion of juveniles within a population were found where greater numbers of birds were aged, indicating a trade-off between sampling effort and uncertainty. Moreover, samples containing higher proportions of juveniles had larger confidence intervals for a given total number of aged birds; hence, for populations with higher breeding success greater sample sizes would be required to achieve more precise confidence intervals. For abundance, the absolute size of the confidence interval increased with population size (i.e. higher population sizes have larger confidence intervals). However, when confidence intervals were expressed as a percentage of the population size, their size decreased as total abundance increased.
Based on the findings in our report, we make a series of recommendations for the future development of GSMP and affiliated monitoring schemes. In particular, we recommend the use of binomial and Poisson 95% confidence intervals for age assessment and abundance data, respectively. These analytical methods can be implemented rapidly and require little prior knowledge of statistics or programming to implement. Furthermore, we recommend that consideration should be given to the trade-off between sampling effort and the size of confidence intervals, based on the information presented in this report, in order to optimise the deployment of survey effort as part of GSMP.

The purpose of this project was to assess the mussel (Mytilus edulis) food requirements of oyster... more The purpose of this project was to assess the mussel (Mytilus edulis) food requirements of oystercatcher (Haematopus ostralegus) in the Exe Estuary, which has been designated a Special Protection Area for overwintering waterbirds, including oystercatcher. The overwintering oystercatcher population of the Exe Estuary has been well-studied, and the birds are known to feed predominantly upon mussels in intertidal areas. There have been recent declines in the population size of oystercatcher in the Exe Estuary, mirroring wider declines throughout Europe, the reasons for which are unknown.

The study comprised:
• The collection of new data on the area of mussel beds, the density and size distribution of mussels on these beds, and the numbers and behaviour of oystercatcher on these beds;
• The collation of existing data on the food supply of oystercatchers in the Exe Estuary;
• The development of models to predict the food requirements of oystercatcher;
• Running simulations of the models to predict whether there is / could be any effect on oystercatcher survival of the current / potential future ways of managing the mussel fishery on the Exe Estuary.

The current mussel fishery on the Exe provides a feeding resource for oystercatcher on intertidal lays that are exposed on spring tides. Two potential management options that could be effective at improving the feeding conditions of oystercatcher would be to increase the number and area of intertidal mussel lays, and / or to place mussel discards at a relatively high shore level close to the oystercatcher roost.

This project documented a number of changes that have occurred to the Exe Estuary mussel and oystercatcher populations including:
• The number and size of mussel beds have decreased since traditional methods of maintaining mussel beds in the estuary have ceased.
• The density of mussels within the size range consumed by the birds has generally decreased, but the density of the larger mussels within this size range, which are more profitable to oystercatcher, has generally increased.
• Oystercatcher lose a higher proportion of mussels to attacks by carrion crows and herring gulls than they have in the past.
• The number of oystercatcher wintering in the estuary has declined, but the number of birds feeding on the mussel beds has been relatively stable.

The models developed in the project predict that the present day mussel population is sufficient to support the number of oystercatcher that were observed to feed on mussels.

The presence of mussel lays provides extra food for oystercatcher when these lays are exposed on spring tides. The present area, or increases in the area of mussel lays could increase the survival rate of oystercatcher if the number of birds feeding on mussels was over 2000. Below this threshold, starvation was predicted to affect 0 % of the population and so additional food resources cannot further reduce the starvation. The effect over 2000 birds is relatively small because the lays are only exposed for a short time, and so oystercatcher will obtain the majority of their food from mussel beds that are higher on the shore, and hence exposed for longer. Simulations were not run in which lays were positioned higher on the shore because this would not be commercially viable from a fishery perspective; the growth rate of mussels declines as they are positioned further up the shore because they are inundated with water for less time and so have less time to feed.

Factors that would affect the beneficial effect of discards include the size of the discards, the size of the discard bed and the date from which discards are replenished. Our simulations predicted that larger discards spread at lower density over a larger bed increased oystercatcher survival by the greatest amount. This happened because interference competition excluded some birds from smaller patches, and oystercatcher can maintain high intake rate down to low mussel densities. It is unlikely that the size of discards could be increased, but the simulations suggest that the greatest benefit to oystercatchers could be achieved by spreading discards over a larger area. Our simulations predicted that making discards available from January increased oystercatcher survival by the same amount as making them available from September. This was because the feeding conditions of birds deteriorate through winter as, for example, the ash-free dry mass of prey declines, interference competition intensifies and day length shortens. The intake rate of birds feeding on discards was not measured during the study, but we recommend that this is done to between understand the potential benefit of discards. We recommend that the best place for the discard bed would be along the top of the shore on an area of gravel (and hence of relatively low food value to the birds), to the south of Cockwood. This is south of an area where discards have been laid and exploited by oystercatcher in the past, but would experience lower levels of disturbance from human activity.

In this report we use a recently-developed spreadsheet model to predict the overwinter food requi... more In this report we use a recently-developed spreadsheet model to predict the overwinter food requirements of two shorebird species, oystercatcher (Haematopus ostralegus) and red knot (Calidris canutus), within the Solway Firth. The model is based on the energy requirements of the birds together with the energy value of their shellfish food. The model predicts the quantity of shellfish required to maintain high survival rates, and hence avoid significant mortality events within the oystercatcher and knot populations.
Knot were assumed to consume 5-14mm cockles (Cerastoderma edule L.), 5-24mm mussels (Mytilus edulis L.) and 8-16 mm tellin (Macoma balthica L.). Oystercatcher were assumed to consume >15mm cockles, 30-60mm mussels and >12mm tellin. The biomasses of invertebrate prey were derived from intertidal surveys of the site. The population sizes of the bird species were derived from Wetland Bird Survey (WeBS) core counts. Predictions were for the winter of 2013-2014. Shellfishing was assumed to exploit >28mm cockles.
The food requirements of oystercatcher and knot were predicted for different combinations of food supply. All scenarios assumed that the birds could consume cockles, mussels and tellin. Alternative scenarios assumed that knot and oystercatcher could consume other food from upshore areas, or that oystercatcher could consume food from terrestrial habitats. Cockle and tellin biomasses were estimated within Solway Firth, and at Wigtown Bay, a site outside the area in which bird population sizes were estimated. Further scenarios therefore assumed that birds either could, or could not, consume food from Wigtown Bay.
In each scenario the model initially predicted the amount of shellfish biomass not required by the birds. This was then converted into the biomass potentially available for fishing, accounting for the fact that the size range exploited by fishing did not overlap completely with that consumed by the birds. In the case of knot there was no overlap, and so the amount available to fishing was only calculated from the biomass of shellfish not required by oystercatcher.
The model predicted that approximately 700 tonnes of >28mm cockles could potentially be exploited by shellfishing during the winter of 2013-2014, after taking into account the food requirements of the birds, excluding cockle and tellin biomass in Wigtown Bay, and assuming that oystercatcher consumed cockles, mussels, tellin and prey from upshore areas and terrestrial habitats. This was considered to be the most realistic scenario given that oystercatcher can potentially feed on terrestrial and upshore habitats, and given the distance between Wigtown and the area in which oystercatcher population size was estimated. The cockle, mussel and tellin surveys did not cover the entire extent of the Solway Firth, not recording cockles or tellin in English waters or mussels or the Scottish side, and so it is likely that a higher biomass of shellfish food is available to the birds in reality. However, without a more extensive survey it is not possible to quantify this.
The spreadsheet model’s predictions for the winter of 2007-2008 were also compared with those of a more complex individual-based model that was developed for oystercatcher and knot in the Solway Firth based on shellfish biomass during 2005 to 2007. The individual-based model predicted that knot survival was 100% in all simulations for the winter of 2007-2008, consistent with the prediction of the spreadsheet model that 18038 tonnes of shellfish were not required by the birds during this winter. The spreadsheet model predicted that the oystercatcher population required all of the shellfish food available during the winter of 2007-2008. Similarly, the individual-based model predicted that oystercatcher were relatively sensitive to the amount of biomass removed by fishing during this winter. With a shellfishing Total Allowable Catch (TAC) set at 1000 tonnes there was a predicted reduction in survival and TACs set at 500, 750 and 1000 tonnes were predicted to reduce body mass. The spreadsheet model predicted that birds required all of the food during 2007-2008 and hence that any TAC would reduce survival. This demonstrates that the spreadsheet model is capable of producing broadly similar predictions to the more complex individual model, although the latter is more sensitive when stock levels are more critical.

In UK estuaries conflicts have routinely occurred between economic and conservation interests reg... more In UK estuaries conflicts have routinely occurred between economic and conservation interests regarding shellfish such as cockles Cerastoderma edule and mussels Mytilus edulis. The harvest of these species is economically important, but shellfish also constitute the main overwinter food supply of the oystercatcher Haematopus ostralegus. In this report we use a simplified spreadsheet model to predict the overwinter food requirements of oystercatchers in the Dee Estuary and compare the predictions of this model with those of an individual-based model which has been used to advise the setting of Total Allowable Catch in the Dee Estuary over recent years.
The models are based on the energy requirements of the birds and the energy value of their shellfish food. The spreadsheet model predicts the amount of shellfish required to maintain high survival rates within the oystercatcher population. The individual-based model predicts how the survival rate within the oystercatcher population is related to the amount of shellfish food and the amount removed by shellfishing. Although more complicated, the individual-based model represents the system in a more realistic way and can simulate specific shellfishing scenarios.
The models produced relatively similar predictions, especially when it was assumed that birds fed on upshore and terrestrial food in addition to cockles. As the biomass of cockles has declined since 2008, the models predicted that the amount required by the birds became close to the total available in 2012. The cockle biomass during 2013 was lower than that during 2012 and the spreadsheet model predicted that the birds required virtually all of the cockle stocks available.

In northwest Europe conflicts have routinely occurred between economic and conservation interests... more In northwest Europe conflicts have routinely occurred between economic and conservation interests regarding shellfish such as cockles and mussels. The harvest of these species is economically important, but shellfish also constitute the main overwinter food supply of the oystercatcher Haematopus ostralegus. In this report we describe attempts to produced a simplified modelling approach to predict the quantities of shellfish which need to be left unharvested in order to ensure high overwinter survival of oystercatcher.
We review oystercatcher diet and prey selection in order to quantify the dependence of this species on shellfish, and determine the size ranges of shellfish which the birds consume. We also review the food requirements of oystercatchers, based on their energetic needs and the nutritional quality of shellfish. In general the data agree well with those used in previous oystercatcher modelling studies. However, there is a possibility that the daily energy requirements, calculated from an all bird allometric equation, may yield an underestimate of oystercatcher food requirements. A comparison of the physiological food requirements, i.e. the quantity directly consumed, and the ecological food requirements, i.e. the quantity required to avoid high mortality, indicated that the ecological food requirement was between 2.0 and 7.8 times greater, with the value depending on the proportion of cockles Cerastoderma edule and mussels Mytilus edulis in a site. These ratios are calculated from empirical data on oystercatcher survival and the predictions of individual-based models predicting the relationship between mortality rate and the abundance of the food supply. Data from the Burry Inlet indicated that the mean ecological food requirement was 3.3 times greater at this site.
We describe a simplified spreadsheet model, which we used to predict the food requirements of the oystercatcher population of the Burry Inlet, and thus the quantity of shellfish which must be left unharvested in order to maintain low mortality rate. The model is based on parameter values derived from the literature reviews in this study, including the energy requirements of the birds, the energy content of shellfish, the minimum size of cockles and mussels consumed, and the ratio of the ecological and physiological requirements. We describe the assumptions and limitations of the model, and compare the model with more detailed individual-based models that can be used to predict the mortality rate of shorebirds in relation to the amount of food available.

European Breeding Bird Atlas 2: Distribution, Abundance and Change, 2020

Native to the Palearctic region, including Europe, the Mute Swan has also been introduced to area... more Native to the Palearctic region, including Europe, the Mute Swan has also been introduced to areas beyond its native range, most notably to North America. During the Middle Ages, wild birds were present in NE parts of Europe, but in the NW birds were typically bred in captivity. However, the Mute Swan has re-established itself as a wild species and has spread steadily throughout Europe.