Agri-environmental measures and the breeding ecology of a declining farmland bird

Agricultural intensification is a key cause of the population declines shown by many farmland bird species across Europe. Changes in land management through agri-environment schemes (AES) are frequently cited as the best tool to reverse these trends, to date however they have received mixed support. This study tested whether AES options in England that provide winter seed food or insect-rich foraging during the breeding season, were associated with improved breeding performance in tree sparrow, Passer montanus, and/or the formation of larger breeding colonies. Breeding attempts (n = 428) representing 210 pairs of tree sparrow comprising 22 colonies were compared in Wiltshire, England in 2013 and 2014. The area of margin AES, an insect-rich habitat, was positively correlated with fledgling success per breeding attempt and per breeding pair. Colony size increased with increasing wild bird seed mix AES area, a winter seed food resource, but this option negatively affected hatching success and the number of fledglings produced per breeding attempt. The observed association between colony size and this habitat was expected given that wild bird seed mixtures provide important seed food resources for granivorous birds during winter. The negative correlation with fledgling success, on the other hand, requires further investigation to determine whether this relationship relates to a lack of invertebrate and seed food during the breeding period. These results highlight the importance of providing a suite of AES habitats that are appropriately located to deliver both overwintering and breeding requirements of target, declining farmland birds

Assessing rates of parasite coinfection and spatiotemporal strain variation via metabarcoding: insights for the conservation of European turtle doves Streptopelia turtur

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

Identifying mismatches between habitat selection and habitat quality in a ground-nesting farmland bird

Human-induced habitat changes often generate novel or radically altered habitat characteristics, which can impair the ability of organisms to differentiate between suitable and unsuitable sites. This phenomenon, often termed an ecological trap, has been identified as a potential driver of biodiversity loss worldwide. However, few unequivocal examples have been documented, even in agricultural environments where contemporary habitat changes have been rapid and significant. Several problems complicate the detection of ecological traps in the field, including difficulties in measuring key parameters such as relative habitat preference. Here, we assess habitat selection preferences and breeding success of the yellow wagtail Motacilla flava, a UK red-listed declining passerine, in arable farmland. We combine habitat-specific density indices with measures of home range exclusivity to make inferences on relative habitat preference that are robust to the confounding effect of competitive exclusion. Using multiple measures of breeding success, we identify maladaptive habitat selection patterns at the scale of both territory and nest site choice. Yellow wagtails showed a preference for establishing territories within field bean crops, but subsequently suffered high nest predation rates. Similarly, pairs showed a preference for nesting close to tramlines within cereal fields, but nests further from tramlines achieved higher success due to lower predation rates. We found no evidence of competitive exclusion among neighbouring pairs, suggesting that density-based indices provided an accurate reflection of relative habitat preferences. Our findings highlight the potential role of maladaptive habitat selection in suppressing breeding success among farmland species

Mid-season shifts in the habitat associations of Yellow Wagtails Motacilla flava breeding in arable farmland

Declines in habitat quality through the breeding season within a bird's home-range can limit overall productivity. In environments where multiple breeding opportunities arise during the course of a season, these effects can be buffered by a shift to different breeding sites or habitats. We studied the distribution and habitat associations of a crop-nesting farmland bird, the Yellow Wagtail Motacilla flava, across an arable-dominated farming region in eastern England using both field-scale territory mapping and large-scale transect surveys. Surveys were repeated at monthly intervals to measure changes in both distribution and habitat use during the course of the season. The distribution of breeding birds changed markedly at both regional and field-scales, coinciding with a shift in crop preference. Initially, most territorial birds were recorded in autumn-sown cereal fields, but this crop was subsequently abandoned in favour of potato crops, which were more patchily distributed. Other habitat features influencing Yellow Wagtail distribution included local crop diversity, hedgerow presence and soil type, with organic soils supporting higher abundance than alluvial clays or silts. The mid-season switch in habitat associations might allow individuals to maximize the number of breeding attempts made in a single year by using multiple habitats sequentially. The use of multiple habitats could influence population regulation by buffering the effects of local within-season declines in habitat suitability. Seasonal habitat switching may be more prevalent than is currently recognized in seasonal environments