Summary 0[ The present study investigated breeding success and causes of breeding failure of curlew\ a species for which the UK holds internationally important breeding numbers[ Studies were undertaken between 0882 and 0884 in two areas of Northern Ireland\ where the species| breeding range has recently contracted and breeding numbers are declining[ Avian nest predators were abundant in both areas\ whereas foxes were abundant on the Antrim study area but generally were absent from the Lough Erne study area\ which was mainly islands[ 1[ Productivity was estimated to be 9=03Ð9=15~edglings per pair in Antrim and 9=19Ð 9=36~edglings per pair on Lough Erne[ These _gures are lower than most estimates of productivity from other studies of breeding curlew[ The di}erences between the recorded productivity levels and those estimated to be required to maintain a stable population are su.cient to account for the observed decline in Northern Ireland|s breeding curlew population[ 2[ Predation was the main proximate cause of breeding failure\ with nest predation being of most importance in reducing productivity[ Only 2=5Ð08=9) of all nests hatched on each study area in each year\ with nest predation accounting for 74Ð86) of failures[ Survival of chicks from hatching to 20 days of age was 27=4) in Antrim and 08=0Ð18=1) on Lough Erne[ Predation accounted for 63) of chick mortality[ 3[ Nest failure rates were not related to the vegetation height around nests nor to clutch laying date on either study area[ They di}ered among the islands and one shoreside site on Lough Erne[ Almost all nest predation on Lough Erne was attribu! table to avian predators\ but in Antrim foxes probably accounted for most nest predation[ The likelihood of predation on chicks was not related to their hatching date\ hatching weight or body condition[ 4[ The results from this study suggest that predation rates on curlew nests in Northern Ireland may have increased in recent decades[ Levels of predator control in Northern Ireland have declined but there have also been considerable changes in land!use that could bene_t generalist predator species or increase the vulnerability of curlew nests to predation[ It is recommended that large!scale trials of legalized predator control and land!use manipulation should be undertaken to identify appropriate conservation management methods[ Key!words] breeding waders\ nesting success\ population decline\ predation[ Journal of Applied Ecology "0888# 25\ 48Ð63

Capsule Empirical support is provided for the design and field methods associated with a replicated supplementary feeding experiment.Aims We tested assumptions associated with a supplementary feeding experiment in which counts of House Sparrows were used to infer impacts of feeding mealworms and seed on reproductive output and population size. Methods Supplementary food was provided at 33 House Sparrow colonies spread across suburban London, with 33 unfed colonies serving as controls. We compared the characteristics of fed and unfed colonies and tested whether competition for mealworms increased with colony size. We tested whether counts of young sparrows reflected variation in reproductive output and whether supplementary feeding affected the distribution of young sparrows. Results Fed and unfed colonies were similar with respect to habitat, cat density, background feeding and initial colony size. Intensity of feeder usage increased with colony size. Counts of fledglings and juveniles were positively correlated with counts of active nests. Supplementary feeding influenced the distribution of juveniles but not that of recent fledglings. Conclusions Fed and unfed colonies were similar in character. Competition for mealworms was greater at larger colonies and fledgling counts provided a useful measure of variation in reproductive output across colonies.Supplementary feeding is a commonly used research technique to assess the effects of food limitation on birds and other animals (Boutin 1990, Robb et al. 2008. A large number and variety of studies have recorded mainly positive impacts of supplementary feeding on various components of avian breeding performance, including earlier laying, larger clutches, increased chick growth rates and higher fledging success (Newton 1998, Robb et al. 2008) although a few negative impacts have also been reported (Harrison et al. 2010). Most studies have focused entirely on impacts on reproductive success and have been conducted over small spatial and temporal scales. Fewer studies have measured impacts of supplementary feeding outside of the breeding season or on population density (van Balen 1980, Jansson et al. 1981, Brittingham & Temple 1988, Siriwardena et al. 2007. Furthermore, remarkably little is known about the impacts on birds of the ubiquitous global phenomenon of supplementary feeding of garden birds despite concerns about potential negative impacts such as increased disease transmission and 'dependency' on anthropogenic food sources (Jones & Reynolds 2008).While it is relatively straightforward to provide accessible and palatable food in supplementary feeding experiments, interpretation of apparent impacts requires knowledge of the intensity and geographical scale of the utilization of that food (Boutin 1990, Newton 1998. If the distances over which target species travel in order to exploit supplementary food exceed the distances between experimental units (fed and unfed areas), there is a risk of treatment 'contamination' and compromise of study design.

Factors affecting avian demography and abundance in urban landscapes are poorly understood and this hinders attempts to manage urban bird communities. Several recent studies indicate that lack of invertebrate prey in urban landscapes may constrain avian productivity and fitness relative to that in other habitats. House Sparrow Passer domesticus populations have undergone large declines in many European urban centres and inadequate reproductive success linked to invertebrate availability has been postulated as a potential cause of these declines. We conducted a replicated supplementary feeding experiment to test whether the availability of invertebrate prey limits the breeding success and adult abundance (colony size) of House Sparrows in suburban London, where House Sparrow populations declined by 60% during the decade preceding our study. Daily mealworm provision over two successive breeding seasons, sufficient to provide 82% of chick energy requirements of House Sparrow pairs nesting within 50 m of feeders, had a large positive impact on the abundance of recently fledged birds (+62%), but only a small positive impact, limited mainly to small colonies, on the overall abundance of territorial males. Colony growth was only weakly related to fledgling abundance in the previous year and did not appear to be constrained by nest‐site availability. Conservation interventions that enhance invertebrate availability for suburban House Sparrows may increase reproductive success but are unlikely, on their own, to lead to population growth or recovery.

Little is known about the environmental factors that limit the demography and abundance of wild vertebrates in highly modified urban environments. The House Sparrow Passer domesticus is a globally widespread species whose urban populations have recently undergone substantial declines particularly in Europe. The environmental drivers of these declines remain unknown. In a previous study we showed that invertebrate availability during the breeding season limited reproductive success but not population size in a suburban sparrow population. In this study we test experimentally whether year-round food availability limits demography and population size. Supplementary feeding involved the provision of invertebrate prey (during the breeding season) plus unlimited high-energy seed (year-round) at 33 sparrow colonies spread across suburban London over two successive calendar years. Thirty-three unfed colonies served as controls. Supplementary feeding increased fledgling abundance, but had no impact on overwinter survival or population size. We conclude that this depleted suburban sparrow population is not limited by food availability, and conservation efforts based primarily on food provision are unlikely to succeed. We also tested whether cross-colony variation in sparrow abundance was correlated with a set of potential environmental stressors including measures of predator abundance and pollution. Sparrows were more abundant, or showed more positive temporal changes in abundance, at localities containing large areas of seed-rich habitat and low levels of nitrogen dioxide air pollution. Further research is merited into the potential impacts of air pollution on the fitness of urban birds.

Understanding the frequency, spatiotemporal dynamics and impacts of parasite coinfections is fundamental to developing control measures and predicting disease impacts. The European turtle dove (Streptopelia turtur) is one of Europe's most threatened bird species. High prevalence of infection by the protozoan parasite Trichomonas gallinae has previously been identified, but the role of this and other coinfecting parasites in turtle dove declines remains unclear. Using a high‐throughput sequencing approach, we identified seven strains of T. gallinae, including two novel strains, from ITS1/5.8S/ITS2 ribosomal sequences in turtle doves on breeding and wintering grounds, with further intrastrain variation and four novel subtypes revealed by the iron‐hydrogenase gene. High spatiotemporal turnover was observed in T. gallinae strain composition, and infection was prevalent in all populations (89%–100%). Coinfection by multiple Trichomonas strains was rarer than expected (1% observed compared to 38.6% expected), suggesting either within‐host competition, or high mortality of coinfected individuals. In contrast, coinfection by multiple haemosporidians was common (43%), as was coinfection by haemosporidians and T. gallinae (90%), with positive associations between strains of T. gallinae and Leucocytozoon suggesting a mechanism such as parasite‐induced immune modulation. We found no evidence for negative associations between coinfections and host body condition. We suggest that longitudinal studies involving the recapture and investigation of infection status of individuals over their lifespan are crucial to understand the epidemiology of coinfections in natural populations.