Jacquie A. Clark

British Trust for Ornithology | BTO · Demography

The dynamics of wild populations are governed by demographic rates which vary spatially and/or temporally in response to environmental conditions. Conservation actions for widespread but declining populations could potentially exploit this variation to target locations (or years) in which rates are low, but only if consistent spatial or temporal va...

A single formal estimate of the size of the world population of the Critically Endangered Spoon-billed Sandpiper Calidris pygmaea has been published. This used a Lincoln-Petersen method, which combined a global mark-resighting analysis with a scan survey to estimate the proportion of birds with individual marks observed at a post-breeding moult and...

Wildlife conservation policies directed at common and widespread, but declining, species are difficult to design and implement effectively, as multiple environmental changes are likely to contribute to population declines. Conservation actions ultimately aim to influence demographic rates, but targeting actions towards feasible improvements in thes...

Critically Endangered Spoon-billed Sandpipers Calidris pygmaea migrate from their breeding grounds in Arctic and subarctic Russia along the East Asian-Australasian Flyway to winter in coastal habitats in south-east Asia. To describe the use of migration stopover and wintering sites during the post-breeding migration, we tracked six adults equipped...

In this study, we investigated whether birds could be vectors facilitating long‐distance spread of Phytophthora ramorum in Britain. Migratory bird species associated with the main sporangium‐producing host plants and most likely to pick up P. ramorum spores were considered. Swabs were taken from the flank and “feet” of 1,014 birds over a 12‐month p...

All ecological measurements are subject to error; the effects of missed detection (false negatives) are well known, but the effects of mistaken detection (false positives) are less understood. Long-term capture–recapture datasets provide valuable ecological insights and baselines for conservation and management, but where such studies rely on nonin...

Bird ringing was established more than a century ago to gather information on bird movements. Since then, ornithologists have systematically collected huge databases of records of birds ringed and subsequently re-encountered, but, to date, there have been few quantitative attempts to identify migratory routes from ringing data. Here, we develop a n...

This is the 81st annual report of the British Trust for Ornithology’s Ringing Scheme, incorporating the report of the Nest Record Scheme and covering work carried out and data collected and processed in 2017. Demographic data contributed to several research studies during the year, including a review of the conservation status of Raven Corvus corax...

Mist netting is the most commonly used method for catching birds for scientific ringing, but despite decades of use, there have been few attempts to quantify the associated potential risks to the individuals caught. Any incidence of mortality through capture and handling, however low, is of potential ethical concern and may also introduce biases in...

This is the 80th annual report of the British Trust for Ornithology's Ringing Scheme, incorporating the report of the Nest Record Scheme and covering work carried out and data processed in 2016. BTO and JNCC have used seabird population data to investigate how demographic processes drive population changes, enabling improved population models to be...

Biometrics, particularly wing length, are commonly used to assign the sex of many birds in species where the plumage is similar for males and females. Virtually all species show some measurement overlap between the sexes, however, and measurement error can add further uncertainty into data sets. This can result in individuals being misclassified as...

This is the 79th annual report of the British Trust for Ornithology’s Ringing Scheme, incorporating the report of the Nest Record Scheme and covering work carried out and data processed in 2015. Constant Effort Sites (CES) data from across Europe, relating to eight common warblers, were analysed to investigate large-scale variation in survival rate...

Between December 2013 and February 2014, a series of storm events occurred in areas of the North Atlantic frequented by migratory seabirds. Prolonged exposure to sustained storm conditions was followed by an unprecedented level of seabird mortality, apparently due to starvation, exhaustion and drowning. A total of 54,982 wrecked birds was recorded...

Figure S1. The association between estimates of male and female recapture probability at the 34 CE sites (black line is the line of unity). Figure S2. Annual variation in the random effect of year included in models of adult annual survival of male (black circles) and female (open circles) willow warblers at CE sites. Appendix S1. jags code used...

Male‐biased sex ratios occur in many bird species, particularly in those with small or declining populations, but the causes of these skews and their consequences for local population demography are rarely known. Within‐species variation in sex ratios can help to identify the demographic and behavioural processes associated with such biases. Small...

The European Union for Bird Ringing (EURING) coordinates bird ringing at a continental scale and operates the EURING Data Bank (EDB) to facilitate large-scale analyses of movements and demography. The EDB contains over 10 million individual encounter records which are summarised on a publicly available website, the EDB index. EURING welcomes applic...

Additional methodology for regional integrated population models

Additional methodology for regional integrated population models

Telemetry has become an important method for studying the biology and ecology of animals. However, the impact of tracking devices and their method of attachment on different species across multiple temporal scales has seldom been assessed. We compared the behavioural and demographic responses of two species of seabird, Lesser Black-backed Gull Laru...

This is the 78th annual report of the British Trust for Ornithology's Ringing Scheme, incorporating the report of the Nest Record Scheme and covering work carried out and data processed in 2014. Many species have shifted their range towards the Earth's poles in response to global temperature increases. Data from four European Constant Effort Sites...

We describe the methods we have developed over 40 years for making decoys from freshly dead birds for attracting waders to the catching area of cannonnets. These have proved far more effective than decoys modelled in plastic and other materials, although less-realistic decoys work well in poor light conditions.

Capsule: Breeding Willow Warblers, Phylloscopus trochilus, in the UK have advanced in timing of breeding but with little impact on overall productivity. Aims: To quantify the impact of shifts in timing of breeding on changes in Willow Warbler productivity across the UK. Methods: Using records of ∼7000 nests from the British Trust for Ornithology Ne...

Warmer temperatures resulting from climate change have led to predictions that the duration of the breeding season of many temperate bird species may be changing. However, the extent to which breeding seasons can be altered will also depend on the degree of flexibility in processes occurring at other points in the annual cycle. In particular, plast...

Tracking devices are useful in studying the movement and behaviour of birds throughout the year. However, the effects of device attachment must be monitored for bird welfare and the scientific veracity of information gathered. We report on a trial of three different harness types (leg-loop, body and wing) for attaching GPS devices to Lesser Black-b...

Lesser Black-backed Gull Larus fuscus numbers in England have fluctuated in recent decades. Both breeding and wintering populations rose sharply in the latter half of the twentieth century, mostly due to increases at a small number of colonies and changes in migratory behaviour. However, there was a decline in breeding birds between 2000 and 2013 (...

Migration is a fundamental stage in the life history of several taxa, including birds, and is under strong selective pressure. At present, the only data that may allow for both an assessment of patterns of bird migration and for retrospective analyses of changes in migration timing are the databases of ring recoveries. We used ring recoveries of th...

Aim Recent, rapid population declines in many Afro‐Palaearctic migratory bird species have focussed attention on changing conditions within Africa. However, processes influencing population change can operate throughout the annual cycle and throughout migratory ranges. Here, we explore the evidence for impacts of breeding and non‐breeding condition...

Capsule Stable isotope composition of feathers grown in Africa indicates that Willow Warblers, Phylloscopus trochilus, breeding in areas of Britain experiencing different population trends may vary in their distribution, timing of moult and/or use of prey resources during the non-breeding season. Aims To compare stable isotope ratios of feathers of...

This is the 75th annual report of the British Trust for Ornithology's Ringing Scheme, covering data received and work carried out in 2011. A review of priorities for the Scheme identified the need to increase submission of nest records through the Nest Record Scheme and to extend the network of Retrapping Adults for Survival (RAS) studies. Collecti...

This is the 74th annual report of the British Trust for Ornithology's Ringing Scheme, covering data received and work carried out in 2010. Analytical work in the year concentrated on considering how we can improve demographic monitoring, an increasing focus for the Scheme. A broad review of the availability of demographic and count data for terrest...

Recent, unprecedentedly rapid climate change has frequently been invoked as the cause of changes in the phenology of bird migration as well as population decline. Birds would be expected to respond to milder climatic conditions at their breeding grounds by reducing the length of their migration. Here, we exploit the largest ringing recovery databas...

The bi-annual crossing of the Sahara desert is a considerable energetic challenge faced by approximately a quarter of Europe's total bird population, as they migrate to and from sub-Saharan non-breeding grounds. Where, when and how migratory birds prepare for the crossing remains to be defined in many species, especially in sub-Saharan Africa. Here...

For migratory birds, regulation of energy reserves is crucial for survival during the migratory journey, and may also affect subsequent stages of the life cycle. Although Barn Swallows Hirundo rustica are able to feed en route, recent studies in Italy and Spain have demonstrated that they accumulate fat stores prior to departing for the wintering g...

Aim Over the past three decades, evidence has been growing that many Afro‐Palaearctic migratory bird populations have suffered sustained and severe declines. As causes of these declines exist across both the breeding and non‐breeding season, identifying potential drivers of population change is complex. In order to explore the roles of changes in r...

This is the 73rd annual report of the British Trust for Ornithology's Ringing Scheme, covering data received and work carried out in 2009. Much of the research carried out during the year looked at ways to improve the analysis of ringing data to understand population change. This included producing survival rates from the Constant Effort Sites (CES...

A major focus of national ringing schemes is the large‐scale analysis of survival rates, primarily from recoveries of birds found dead. We demonstrate, based on analyses of birds ringed in Britain and Ireland between 1960 and 1998, a pronounced and consistent decline in the numbers of ringed birds found dead and reported across a wide range of spec...

Climate change within the UK will affect winter starvation risk because higher temperatures reduce energy budgets and are likely to increase the quality of the foraging environment. Mass regulation in birds is a consequence of the starvation-predation risk trade-off: decreasing starvation risk because of climate change should decrease mass, but thi...

Capsule The birds that died were generally smaller.Aims To look for selective mortality of waders in severe weather.Methods Biometric measurements of birds found dead in a local severe weather event in February 1991 on The Wash Estuary, UK, were compared with measurements of the same species caught alive in February in previous and following years....

Scientific bird ringing was initiated to study the movements of birds, particularly annual migrants. When a ringed bird is reported to the ringing scheme we have the location of that bird at two points in time - where and when it was ringed and where and when it was found. The collation of reports of ringed birds (recoveries) allows patterns of loc...

The broad agenda for bird and biodiversity conservation, together with wider environmental issues such as global environmental change and disease control, will continue to set the context and priorities for research based on marked birds. We outline the ways in which the British Trust for Ornithology (BTO) Ringing Scheme will address these issues a...

Capsule Variations in regional nest survival rates, natal philopatry, first-year and adult survival cannot explain regional Northern Lapwing population declines. Aims To assess whether regional nest survival rates, natal dispersal, and first-year and adult survival rates could explain regional variations in population declines. Methods Nest monitor...

It is theoretically and empirically well established that body mass variation in small birds reflects a trade-off between starvation risk and predation risk. This occurs because carrying increased fat reserves reduces starvation risk but also results in a higher predation risk due to reduced escape flight performance and/or the increased foraging e...

1. In long-lived animals with delayed maturity, the non-breeding component of the population may play an important role in buffering the effects of stochastic mortality. Populations of colonial seabirds often consist of more than 50% non-breeders, yet because they spend much of their early life at sea, we understand little about their impact on the...

This is the 70th annual report of the British Trust for Ornithology's Ringing Scheme, covering work carried out, and data received, in 2006. During the year recoveries of ringed birds were used to assess the possibility of highly pathogenic Avian Influenza H5N1 being spread across Europe and into Britain by wild birds. Recovery reports were vital i...

In theory, survival rates and consequent population status might be predictable from instantaneous behavioural measures of how animals prioritize foraging vs. avoiding predation. We show, for the 30 most common small bird species ringed in the UK, that one quarter respond to higher predation risk as if it is mass-dependent and lose mass. Half respo...

Understanding demography is critical for understanding the causes underlying population declines, and for initiating and monitoring policies to reverse them. A method of fitting demographic models directly to avian count data recorded at a sample of census sites is described. The model is applied to national and regional counts of Common Starling S...

This is the 69th annual report of the British Trust for Ornithology's Ringing Scheme, covering work carried out, and data received, in 2005. Important research on Oystercatchers Haematopus ostralegus in North Wales showed that survival of adults, recruitment of juveniles and mass of both adults and juveniles were lower during winters when there was...

Millions of shorebirds migrate each year through a small number of highly productive staging areas where they often conflict with fisheries interests. Delaware Bay, USA, is a major shorebird stopover site where, in spring, many thousands of shorebirds undergo rapid mass gain by feeding on the eggs of commercially harvested horseshoe crabs Limulus p...

Long-distance migrants have evolved complex strategies for the timing of their annual moult, fattening and migration cycles. These strategies are likely to vary at different stages of a bird's life. Ringing data on 6079 Grey Plovers Pluvialis squatarola, caught on the Wash, England, between 1959 and 1996, were analysed to relate migratory strategie...

House sparrow (Passer domesticus) numbers have declined rapidly in both rural and urban habitats across Western Europe over the last 30 years, leading to their inclusion on the UK conservation red list. The decline in farmland has been linked to a reduction in winter survival caused by reduced food supply. This reduction in food supply is associate...

In de loop van 2005 is de aziatische variant van het hoog pathogene Aviarie Influenzavirus (PAI H5N1) verspreid van zuidoost Azië, via zuidwest Siberië, Kazakstan en de zuidelijke Oeral. He vermoeden bestaat dat trekvogels een rol hebben gespeeld in de verspreiding van de ziekte. Dit betekent dat de Europese Unie gevaar loopt, omdat een aantal wate...

This is the 68th annual report of the British Trust for Ornithology's Ringing Scheme, covering work carried out, and data received, in 2004. During the year, changes in bird survival in relation to winter weather were studied. In almost all cases, there was a greater influence of weather on first‐year than adult survival. A paper providing guidelin...

It is theoretically well established that body mass in birds is the consequence of a trade‐off between starvation risk and predation risk. There are, however, no studies of mass variation from sufficiently large wild populations to model in detail the range of diurnal and seasonal mass change patterns in natural populations and how these are linked...

Periods of severe weather can result in significant mortality in bird populations. In Britain there is a system of voluntary, followed by official, bans on wildfowl hunting in coastal areas during periods of severely cold weather, in order to minimise disturbance to bird populations during these periods of energetic stress. The effectiveness of suc...

Ring recovery data were used to describe a seabird mortality event (or'wreck) affecting mainly Shags Phalacrocorax aristotelis and Guillemots Uria aalge in the North Sea during February and March 1994. Stormy weather and onshore winds are thought to have caused this mortality. Most Shags and Guillemots were recovered along the North Sea coast of th...

This is the 67 annual report of the British Trust for Ornithology's Ringing Scheme, covering work carried out, and data received, in 2003. During the year, reports of ringed birds were used to assess the post‐release survival of rehabilitated individuals. Varying proportions of different species were able to re‐enter the population, with Mute Swan...

The Wash, in eastern England, supports internationally important populations of 11 species of shorebird. A major commercial shellfishery provides potential conflict between fishermen and nature conservation interests. During the 1990s, high fishing mortality and low recruitment substantially reduced the stocks of cockle (Cerastoderma edule) and mus...

The EURING code, which has been the European standard coding system for observations on marked birds, has undergone a major revision and extension resulting in the EURING EXCHANGE CODE 2000. Major aspects of change have a background in computer-technology, a shift in scientific questions and in the interaction between the two. Over the last decades...

This is the 65th annual report of the British Trust for Ornithology's Ringing Scheme covering work carried out and data received in 2001. As part of the BTO's production of the landmark Migration Atlas: movements of the birds of Britain & Ireland, which will review movements of birds using Britain & Ireland, novel approaches to the investigation of...

This is the 72nd annual report of the British Trust for Ornithology's Ringing Scheme, covering work carried out, and data received, in 2008. Research carried out in 2008 included developing methods to combine ringing data with data from other monitoring schemes to detect the causes of population change. This approach was used for Song Thrush Turdus...

This is the 60th annual report of the British Trust for Ornithology's Ringing Scheme, presenting the data received in 1996. The development and implementation of a Scientific Strategy for the Ringing Scheme is discussed, together with examples of future work and data analysis. The strategy provides a coherent approach to the collection of data need...

This is the 62(nd) annual report of the British Trust for Ornithology's Ringing Scheme, presenting research carried out and data received in 1998. A study of fish-eating birds, initiated because of a perceived increase of predation on fish populations in inland waterbodies, established that there has been an increase in the proportion of ringed Cor...

1. This strategy aims to increase the contribution which ringing makes to conservation science and ornithological research, recognising that the primary outputs of the scheme are scientific publications based on data gathered by volunteer ringers. The strategy envisages a greater involvement of ringers in planned projects that are designed to provi...

We review the development of scientific and conservation objectives for the British and Irish Ringing Scheme, which has been run by the BTO since 1937. A brief introduction to the workings and growth of the scheme is provided. The types of data collected via ringing and their status within the Scheme are discussed. We demonstrate how ringing contri...

This is the 60th annual report of the British Trust for Ornithology's Ringing Scheme, presenting the data received in 1996. The development and implementation of a Scientific Strategy for the Ringing Scheme is discussed, together with examples of future work and data analysis. The strategy provides a coherent approach to the collection of data need...

This is the 61st annual report of the British Trust for Ornithology's Ringing Scheme, presenting research carried out and data received in 1997. Work examining the survival rates of 31 farmland passerines in relation to longterm changes in abundance suggested that changes in survival rates for 16 species had, to some extent, influenced their abunda...

The BTO IPM programme seeks to combine information on numbers, breeding performance and survival rates in order to monitor the size of the populations of a wide range of bird species breeding in the UK. It aims to (a) establish thresholds that will be used to notify conservation bodies of the need for further research or conservation action, (b) id...