Richard A Stillman

Bournemouth University | BU · School of Applied Sciences

In this period of rapid human‐induced environmental change, it is vital that influences of habitat on the distribution and productivity of threatened species are understood. Ground‐nesting birds are declining more rapidly across Europe than any other group, with large‐bodied birds at the greatest risk of extinction. Productivity and adult survival...

The red fox ( Vulpes vulpes ) is a generalist mesopredator found throughout the UK. It has been linked to national declines in native wildlife, especially ground-nesting birds such as waders. In the New Forest National Park, nest predation and poor chick survival is primarily responsible for low breeding success of Eurasian curlew ( Numenius arguat...

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...

The major aim of this study is to demonstrate the usefulness of applying an IBM in an EIA. Using the Fehmarn Belt Fixed Link project as a case-study, we predict the impact of tunnel construction work on the population of wintering Common Eider in the Fehmarn Belt. Using the software MORPH (Stillman, 2008), we define two scenarios i.e. with and with...

Poole Harbour supports a diverse and numerous waterbird assemblage. This assemblage includes internationally important numbers of non-breeding waterbirds, including Shelduck Tadorna tadorna and Black-tailed Godwit Limosa limosa, and nationally important numbers of Pied Avocet Recurvirostra avosetta, Eurasian Spoonbill Platalea leucorodia and Little...

Poole Harbour is protected and recognised, both nationally and internationally, for its ecological importance. However, it has also been classified as polluted and ‘eutrophic’. These twin designations – protected yet polluted – exemplify the condition of many English estuaries, making Poole Harbour a useful case study for elucidating the circumstan...

Drivers of environmental change are causing novel combinations of pressures on ecological systems. Prediction in ecology often uses understanding of past conditions to make predictions to the future, but such an approach can breakdown when future conditions have not previously been encountered. Individual‐based models (IBMs) consider ecological sys...

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 int...

Many species of large herbivore rely on agricultural land for their feeding habitats, but available food resources are highly variable in space and time. The conservation and management of farmland-dependant herbivores would therefore benefit from predictions about how species will respond to changes in their environment. We developed an individual...

The Overview, Design concepts and Details (ODD) protocol for describing Individual- and Agent-Based Models (ABMs) is now widely accepted and used to document such models in journal articles. As a standard- ized document for providing a consistent, logical and readable account of the structure and dynamics of ABMs, some research groups also find it...

Green macroalgal mats are a consequence of increased nutrient input into estuarine ecosystems and can cover extensive areas of intertidal habitats. The extent and biomass of mats is a key metric for estuarine ecological condition assessment. We measured macroalgal mats in Poole Harbour Marine Protected Area (MPA) from 2013 to 2015. Peak biomass rea...

Disturbance of wildlife is a potential cause of conservation concern, not least to overwintering waders Charadrii inhabiting estuaries close to conurbations where human recreational and economic activities are often concentrated. Disturbance from people on and alongside intertidal foraging areas could make it more difficult for birds to survive unt...

The Manila clam Ruditapes philippinarum is one of the most commercially valuable bivalve species worldwide and its range is expanding, facilitated by aquaculture and fishing activities. In existing and new systems, the species may become commercially and ecologically important, supporting both local fishing activities and populations of shorebird p...

• A combined empirical and modelling approach was used to investigate the value of a Pacific oyster reef to feeding shorebirds and to observe and predict the impact of reef clearance on bird populations in the Colne Estuary, a protected area in south‐east England. Macro‐invertebrate biomass and numbers of feeding birds were measured on a Pacific oy...

The role of herbivores in regulating aquatic plant dynamics has received growing recognition from researchers and managers. However, the evidence for herbivore impacts on aquatic plants is largely based on short-term exclosure studies conducted within a single plant growing season. Thus, it is unclear how long herbivore impacts on aquatic plant abu...

Predictive models can take many years to develop, yet as practitioners we need to address conservation problems urgently. Our Letter highlights the need of practitioners for the insights of predictive models, and how conservation scientists can work with practitioners to overcome obstacles that can prevent their implementation. Without the concerte...

Herbivory is a fundamental process that controls primary producer abundance and regulates energy and nutrient flows to higher trophic levels. Despite the recent proliferation of small-scale studies on herbivore effects on aquatic plants, there remains limited understanding of the factors that control consumer regulation of vascular plants in aquati...

Local alteration of species abundance in natural communities due to anthropogenic impacts may have secondary, cascading effects on species at higher trophic levels. Such effects are typically hard to single out due to their ubiquitous nature and, therefore, may render impact assessment exercises difficult to undertake. Here we describe how we used...

Recent decades have seen great advances in ecological modelling and computing power, enabling ecologists to build increasingly detailed models to more accurately represent ecological systems. To better inform environmental decision-making, it is important that the predictions of these models are expressed in simple ways that are straightforward for...

Kleptoparasitism involves the theft of resources such as food items from one individual by another. Such food-stealing behaviour can have important consequences for birds, in terms of individual fitness and population sizes. In order to understand avian host–kleptoparasite interactions, studies are needed which identify the factors which modulate t...

Effective environmental decision-making, in the form of evidence-based management and policy, is a key prerequisite to help balance nature conservation, natural resource management, and human socio-economic activities (Sutherland et al. 2004). To aid such decision-making, the need for predictive tools that are accurate, robust, and parsimonious has...

On page 516, in the second paragraph of the subsection (b) Half-asymptote constant, and for a reason that it has proved impossible to discover, there is a significant error. The equation: log e half-asymptote constant = −24 77 + 6.307log e body mass + 5.030log e prey mass + 10.594 dummy variable oystercatcher = 1 is completely wrong and, instead, w...

Changes in climate, food abundance and disturbance from humans threaten the ability of species to successfully use stopover sites and migrate between non-breeding and breeding areas. To devise successful conservation strategies for migratory species we need to be able to predict how such changes will affect both individuals and populations. Such pr...

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 b...

The crystal clear waters of the chalk rivers of southern and eastern England are dominated by a keystone plant species, water crowfoot Ranunculus penicillatus ssp. pseudofluitans, which supports an ecosystem of high conservation value, including abundant invertebrates and fish (Berrie, 1992). This ecosystem has supported the development of economic...

The intertidal areas of UK coasts are important habitats for shellfish species, such as cockles Cerastoderma edule and mussels Mytilus edulis. Commercial harvesting of shellfish is worth an annual £250 million to the UK economy, providing both food and employment (DEFRA, 2013). These shellfish are also the principal food resource for overwintering...

Coastal Special Protection Areas (SPAs) are important sites for many wintering and passage wildfowl and waders. While birds value these sites for rich intertidal food resources and safe roosting sites, humans value them for diverse recreational opportunities. New housing can lead to increases in recreational pressures to these sites, such as walkin...

Effective wildlife management is needed for conservation, economic and human well-being objectives. However, traditional population control methods are frequently ineffective, unpopular with stakeholders, may affect non-target species, and can be both expensive and impractical to implement. New methods which address these issues and offer effective...

Waterbirds can move into and exploit new areas of suitable habitat outside of their native range. One such example is the little egret (Egretta garzetta), a piscivorous bird which has colonised southern Britain within the last 30 years. Yet, habitat use by little egrets within Britain, and how such patterns of habitat exploitation compare with nati...

The evidence shows that swan grazing can reduce plant abundance, prevent flowering, reduce water depth and reduce fishery value. However, these effects seem to be limited to a small number of sites on larger chalk streams. The results of attempted management have been disappointing, and we currently have no simple effective means of preventing graz...

Foragers typically attempt to consume food resources that offer the greatest energy gain for the least cost, switching between habitats as the most profitable food resource changes over time. Optimal foraging models require accurate data on the gains and costs associated with each food resource to successfully predict temporal shifts. Whilst previo...

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 mode...

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 rep...

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 pr...

Abundant herbivores can damage plants and so cause conflict with conservation, agricultural, and fisheries interests. Management of herbivore populations is a potential tool to alleviate such conflicts but may raise concerns about the economic and ethical costs of implementation, especially if the herbivores are 'charismatic' and popular with the p...

Understanding plant community responses to combinations of biotic and abiotic factors is critical for predicting ecosystem response to environmental change. However, studies of plant community regulation have seldom considered how responses to such factors vary with the different phases of the plant growth cycle. To address this deficit we studied...

High natural variability in space and time can make accurate measurements of macrophyte standing crop difficult. Accuracy of such measurements could be improved by quantifying the relationships between the different methods of measuring standing crop which are available to researchers. In this study we compare cover, volume, and biomass as measures...

Foraging mute swans Cygnus olor can cause a substantial reduction of aquatic macrophyte biomass in chalk rivers in southern England. To reduce the adverse effects of this on ecology, hydrology and fisheries interests a river management strategy needs to be able to predict where and when grazing pressure will be greatest. To assess the suitability o...

Current measures used to estimate the risks of toxic chemicals are not relevant to the goals of the environmental protection process, and thus ecological risk assessment (ERA) is not used as extensively as it should be as a basis for cost-effective management of environmental resources. Appropriate population models can provide a powerful basis for...

1. Routine vigilance is an important component of foraging for many species and can occupy a large proportion of this time. Vigilance can conflict with some aspects of foraging (i.e. searching) and, consequently, has the potential to reduce feeding rates by interrupting foraging behaviours. However, for animals that handle food in an upright postur...

1. Conservation objectives for non-breeding shorebirds (waders) are determined from their population size. Individual-based models (IBMs) have accurately predicted mortality rate (a determinant of population size) of these species, and are a tool for advising coastal management and policy. However, due to their complexity, the use of these IBMs has...

1. Functional response models that predict the relationship between feeding rate and food density often include only two behavioural parameters, handling time and searching rate. However, vigilance can occupy a large proportion of foraging time and, consequently, may affect the functional response. Previous functional response models of granivorous...

This study was commissioned by Natural England to monitor and report on the condition of the notified intertidal sediment features (excluding saltmarsh) within the Poole Harbour Site of Special Scientific Interest (SSSI) and Special Protection Area (SPA), using Common Standards Monitoring guidance.

Interference competition is often due to kleptoparasitism (food stealing). In which case, the attack distance, the distance over which one animal attacks another in an attempt to steal food, determines to a large extent the competitor density range over which interference significantly affects the intake rate of foraging animals.We develop a simple...

Current approaches to ecological risk assessment (ERA) are not sufficient to address environmental protection goals stated in current regulations in the European Union, North America and elsewhere. For example, the data used to estimate the likelihood of adverse ecological effects typically include responses of survival, growth, or reproduction of...

Conservation objectives for non-breeding coastal birds (shorebirds and wildfowl) are determined from their population size at coastal sites. To advise coastal managers, models must predict quantitatively the effects of environmental change on population size or the demographic rates (mortality and reproduction) that determine it. As habitat associa...

Decisions taken during migration can have a large effect on the fitness of birds. Migration must be accurately timed with food availability to allow efficient fueling but is also constrained by the optimal arrival date at the breeding site. The decision of when to leave a site can be driven by energetics (sufficient body stores to fuel flight), tim...

This paper describes an individual-based model, MORPH, that has been designed to predict the effect of environmental change on foraging animal populations. The key assumptions of MORPH are that individuals within populations behave in order to maximise their perceived fitness, but that perceived fitness may not always be positively related to the a...

1. Many farmland bird species have undergone significant declines. It is important to predict the effect of agricultural change on these birds and their response to conservation measures. This requirement could be met by mechanistic models that predict population size from the optimal foraging behaviour and fates of individuals within populations....

Conservation managers need to be able to assess and prioritize issues that may affect their target habitats and species. In the Baie de Somme, France, conservation issues affecting overwintering shorebirds include hunting pressure, cockle fishing, recreational disturbance, Spartina encroachment, and changing sediment levels. We used an individual-b...

Individual‐based models (IBMs) predict how animal populations will be affected by changes in their environment by modeling the responses of fitness‐maximizing individuals to environmental change and by calculating how their aggregate responses change the average fitness of individuals and thus the demographic rates, and therefore size of the popula...

1. This study describes the early summer foraging behaviour of mute swans (Cygnus olor) on the River Frome, a highly productive chalk stream in southern England in which Ranunculus penicillatus pseudofluitans is the dominant macrophyte. 2. A daily maximum of 41 ± 2.5 swans were present along the 1.1 km study reach during the study period (late May...

1. Functional responses -- the relationship between resource intake rate and resource abundance -- are widely used in explaining predator-prey interactions yet many studies indicate that resource availability is crucial in dictating intake rates. 2. For time-stressed migrant birds refuelling at passage sites, correct decisions concerning patch use...

Introductions of non-native species are seen as major threats to ecosystem function and biodiversity. However, invasions of aquatic habitats by non-native species are known to benefit generalist consumers that exhibit dietary switches and prey upon the exotic species in addition to or in preference to native ones. There is, however, little knowledg...

Conservation managers responsible for estuaries are often required to monitor their site to ensure that the conservation status of any bird species for which the site is considered important is not affected by deterioration of their habitat or by disturbance of the birds themselves. Here, we use an individuals-based model to predict the quality of...

Assessments of whether disturbance is having a deleterious effect on populations have often measured behavioural responses to disturbance and assumed that populations with a larger behavioural response are more susceptible to disturbance. However, there is no guarantee that the behavioural response to disturbance is related to the population conseq...

In behavior-based individual-based models (IBMs), demographic functions are emergent properties of the model and are not built into the model structure itself, as is the case with the more widely used demography-based IBMs. Our behavior-based IBM represents the physiology and behavioral decision making of individual animals and, from that, predicts...

As field determinations take much effort, it would be useful to be able to predict easily the coefficients describing the functional response of free-living predators, the function relating food intake rate to the abundance of food organisms in the environment. As a means easily to parameterise an individual-based model of shorebird Charadriiformes...

Simulation models that describe autonomous individual organisms (individual based models, IBM) or agents (agent-based models, ABM) have become a widely used tool, not only in ecology, but also in many other disciplines dealing with complex systems made up of autonomous entities. However, there is no standard protocol for describing such simulation...

An individuals-based model, MORPH, was used to assess the quality of Poole Harbour, UK, for five overwintering shorebirds: dunlin Calidris alpina, redshank Tringa totanus, black-tailed godwit Limosa limosa, oystercatcher Haematopus ostralegus and curlew Numenius arquata. Site quality, and the effect of environmental change, was measured as predicte...

Mechanistic models may be able to predict how changes in agricultural practice influence farmland bird populations. A key component of these models is the link between food and competitor densities and the rate at which birds consume food, i.e. the functional response. This paper tests whether the functional response of a farmland bird, the rook Co...

Offshore wind farms are proposed around the coast of the UK and elsewhere in Europe. These sites tend to be located in shallow coastal waters that often coincide with areas used by over-wintering Common Scoter Melanitta nigra. A large-scale study was undertaken to ascertain the relationship of the spatial distribution of Common Scoter in Liverpool...

Poole Harbour is a Special Protection Area (SPA) because of its importance to breeding and wintering waders and wildfowl. English Nature commissioned the Centre for Ecology and Hydrology to survey the intertidal food resources of these birds. Macro-invertebrate populations were sampled at 80 stations across the harbour. Cirratulis filiformis and Tu...

A behaviour-based model was used to explore the effect of an extension of the port at Le Havre (Port 2000), and the effect of proposed mitigation measures, on the mortality and body condition of the three main shorebird species that overwinter in the estuary of the river Seine, France. In the model, a 20% reduction in the area of mudflats on the no...

It is increasingly important to be able to monitor and maintain the quality of estuaries for overwintering shorebirds. Bird numbers alone are not sufficient to indicate quality nor, as recent research shows, can it be assumed that site quality is being maintained simply because there is enough food to meet the birds’ physiological demands; i.e., th...

The overall aim of this project was to provide for policy-makers and their scientific advisors a suite of field-tested predictive population models with which they can devise local and Europe-wide management plans for maintaining the biodiversity of migratory (wintering/on passage) coastal birds (waders and wildfowl) that feed on inter-tidal and, o...

Bottom cultivation of mussels on intertidal flats is practiced throughout the world. This often generates conflicts between commercial interests and competing birds such as oystercatchers. At the Menai Strait, United Kingdom, the overwinter consumption of 242 tonnes (1 metric tonne = 1000 kg) of commercially harvestable mussels (>40 mm) by oysterca...

This paper presents a modification of the behaviour-based individuals model of Oystercatchers on the Exe Estuary, England which was adapted to the Seine estuary for three species of waders: Oystercatcher, Curlew and Dunlin. The purpose of this model was to analyze, in the future, the impact of the construction of Port 2000 at le Havre on the mortal...

This paper presents a modification of the behaviour-based individuals model of Oystercatchers on the Exe Estuary, England which was adapted to the Seine estuary for three species of waders: Eurasian Oystercatcher, Eurasian Curlew and Dunlin. The purpose of this model was to analyse, in the future, the impact of the construction of Port 2000 at le H...

The debate over the interaction between shellfishing and shorebirds is long‐running. Behaviour‐based models predict how animal populations are influenced by environmental change from the behavioural responses of individual animals to this change. These models are a potential tool for addressing shellfishery problems, but to be of value they must pr...

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 s...

Interference is a key component of food competition, but is difficult to measure in natural animal populations. Using data from a long‐term study, we show that interference between common cranes Grus grus L., feeding on patches of cereal seeds, reduces intake rates at high competitor densities, and that the strength of interference is unrelated to...

To assess the long-term effects of human disturbance on birds, ways of predicting its impacts on individual fitness and population size must be found. In this paper we use a behaviour-based model to predict the impact of human disturbance on oystercatchers (Haematopus ostralegus) on their intertidal feeding grounds in the Exe estuary in winter. The...

Summary • Interference between foraging animals can be quantified directly only through intensive studies. A quicker alternative is to predict the strength of interference using behaviour-based models. We describe a field method to parameterize an interference model for shorebirds, Charadrii. • Kleptoparasitic attack distance is the main factor aff...