Stable isotope ratios indicate that body condition in migrating passerines is influenced by winter habitat

Although predicted some time ago, there has been little success in demonstrating that the overall fitness of migratory birds depends on the combined influences of their experiences over all seasons. We used stable carbon isotope signatures (δ<sup>13</sup>C) in the claws of migrating black-throated blue warblers <i>Dendroica caerulescens</i> to infer their wintering habitats and investigated whether winter habitat selection can be linked to condition during migration. Resident bird species with low δ<sup>13</sup>C corresponded to selection of more mesic habitats, and migrating birds with low δ<sup>13</sup>C were in better condition than conspecifics with higher δ<sup>13</sup>C signatures. These findings concur with empirical observations on the wintering grounds, where dominants (mostly males) tend to exclude subordinates from mesic areas (considered to be high-quality habitats). We believe that variation in condition during migration may be one of the key factors determining differences in arrival times and condition at the breeding areas, which in turn have a major influence on reproductive success

A forensic approach to understanding habitat use from stable isotope analysis of (avian) claw material

1. The potential of using stable isotope signatures of avian claws in order to infer diet and habitat use was investigated. 2. Highly significant relationships observed between stable carbon and nitrogen isotope ratios (13C, 15N) in the claws and body feathers of resident birds were expected since it was predicted that they were synthesized in the same habitat and approximately the same time of year. 3. Likewise the non-significant relationships observed between 13C and 15N in the claws and tertial feathers of neotropical migrant birds were also predicted since the claws were synthesized in the wintering area and the tertials in the breeding area. 4. The growth rates measured in the claws of five species of palearctic passerines provide evidence that this tissue should integrate dietary and habitat information over a medium temporal scale (probably weeks to months). 5. It is suggested that claws may offer a unique combination of attributes to the isotope ecologist: they are non-invasively sampled; metabolically inert but grow continuously, and are therefore a more flexible tool than feathers. 6. It is also suggested that that the stable isotope signatures in the claws of mammals and reptiles may provide similar information. 6. It is also suggested that that the stable isotope signatures in the claws of mammals and reptiles may provide similar information

Determining trophic niche width: a novel approach using stable isotope analysis

1. Although conceptually robust, it has proven difficult to find practical measures of niche width that are simple to obtain, yet provide an adequate descriptor of the ecological position of the population examined. 2. Trophic niche has proven more tractable than other niche dimensions. However, indices used as a proxy for trophic niche width often suffer from the following difficulties. Such indices rarely lie along a single scale making comparisons between populations or species difficult; have difficulty in combining dietary prey diversity and evenness in an ecologically meaningful way; and fail to integrate diet over ecological time-scales thus usually only comprise single snapshots of niche width. 3. We propose an alternative novel method for the comparison of trophic niche width: the use of variance of tissue stable isotope ratios, especially those of nitrogen and carbon. 4. This approach is a potentially powerful method of measuring trophic niche width, particularly if combined with conventional approaches, because: it provides a single measure on a continuous axis that is common to all species; it integrates information on only assimilated prey over time; the integration period changes with choice of tissue sampled; and data production is theoretically fast and testing among populations simple. 5. Empirical studies are now required to test the benefits of using isotopic variance as a measure of niche width, and in doing so help refine this approach

Insights into antimicrobial resistance among long distance migratory East Canadian High Arctic light-bellied Brent geese (Branta bernicla hrota)

This is the final version of the article. Available from BioMed Central via the DOI in this record.BACKGROUND: Antimicrobial resistance (AMR) is the most significant threat to global public health and ascertaining the role wild birds play in the epidemiology of resistance is critically important. This study investigated the prevalence of AMR Gram-negative bacteria among long-distance migratory East Canadian High Arctic (ECHA) light-bellied Brent geese found wintering on the east coast of Ireland. FINDINGS: In this study a number of bacterial species were isolated from cloacal swabs taken from ECHA light-bellied Brent geese. Nucleotide sequence analysis identified five species of Gram-negative bacteria; the dominant isolated species were Pantoea spp. (n = 5) followed by Buttiauxella agrestis (n = 2). Antimicrobial susceptibility disk diffusion results identified four of the Pantoea spp. strains, and one of the Buttiauxella agrestis strains resistant to amoxicillin-clavulanic acid. CONCLUSION: To our knowledge this is the first record of AMR bacteria isolated from long distance migratory ECHA light-bellied Brent geese. This indicates that this species may act as reservoirs and potential disseminators of resistance genes into remote natural ecosystems across their migratory range. This population of geese frequently forage (and defecate) on public amenity areas during the winter months presenting a potential human health risk.SB is funded by a European Research Councils consolidators grant (STATEMIG: 310820)

Conditions during adulthood affect cohort-specific reproductive success in an Arctic-nesting goose population

This is the final version of the article. Available from the publisher via the DOI in this record.Variation in fitness between individuals in populations may be attributed to differing environmental conditions experienced among birth (or hatch) years (i.e., between cohorts). In this study, we tested whether cohort fitness could also be explained by environmental conditions experienced in years post-hatch, using 736 lifelong resighting histories of Greenland white-fronted geese (Anser albifrons flavirostris) marked in their first winter. Specifically, we tested whether variation in age at first successful reproduction, the size of the first successful brood and the proportion of successful breeders by cohort was explained by environmental conditions experienced on breeding areas in west Greenland during hatch year, those in adulthood prior to successful reproduction and those in the year of successful reproduction, using North Atlantic Oscillation indices as proxies for environmental conditions during these periods. Fifty-nine (8%) of all marked birds reproduced successfully (i.e., were observed on wintering areas with young) only once in their lifetime and 15 (2%) reproduced successfully twice or thrice. Variation in age at first successful reproduction was explained by the environmental conditions experienced during adulthood in the years prior to successful reproduction. Birds bred earliest (mean age 4) when environmental conditions were 'good' prior to the year of successful reproduction. Conversely, birds successfully reproduced at older ages (mean age 7) if they experienced adverse conditions prior to the year of successful reproduction. Hatch year conditions and an interaction between those experienced prior to and during the year of successful reproduction explained less (marginally significant) variation in age at first successful reproduction. Environmental conditions did not explain variation in the size of the first successful brood or the proportion of successful breeders. These findings show that conditions during adulthood prior to the year of successful reproduction are most important in determining the age at first successful reproduction in Greenland white-fronted geese. Very few birds bred successfully at all (most only once), which suggests that May environmental conditions on breeding areas have cohort effects that influence lifetime (and not just annual) reproductive success.This research was funded through a joint PhD studentship from the Wildfowl & Wetlands Trust and the University of Exeter, and undertaken by MD Weegman. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Variation in movement strategies: Capital versus income migration.

This is the final version. Available from Wiley via the DOI in this record. DATA AVAILABILITY STATEMENT: Data used to produce Figure 3 were accessed at the online Mendeley Data repository https://data.mendeley.com/datasets/wkv96vcvnj/1 Lameris (2018b).Animal migrations represent the regular movements of trillions of individuals. The scale of these movements has inspired human intrigue for millennia and has been intensively studied by biologists. This research has highlighted the diversity of migratory strategies seen across and within migratory taxa: while some migrants temporarily express phenotypes dedicated to travel, others show little or no phenotypic flexibility in association with migration. However, a vocabulary for describing these contrasting solutions to the performance trade-offs inherent to the highly dynamic lifestyle of migrants (and strategies intermediate between these two extremes) is currently missing. We propose a taxon-independent organising framework based on energetics, distinguishing between migrants that forage as they travel (income migrants) and those that fuel migration using energy acquired before departure (capital migrants). Not only does our capital:income continuum of migratory energetics account for the variable extent of phenotypic flexibility within and across migrant populations, but it also aligns with theoreticians' treatment of migration and clarifies how migration impacts other phases of the life cycle. As such, it provides a unifying scale and common vacabulary for comparing the migratory strategies of divergent taxa

Measures of oxidative state are primarily driven by extrinsic factors in a long-distance migrant

This is the author accepted manuscript. The final version is available from the Royal Society via the DOI in this recordData accessibility: Data are available from the Dryad Digital Repository: https://doi.org/10.5061/dryad.j4k3t6f/1 [20].Oxidative stress is a likely consequence of hard physical exertion and thus a potential mediator of life-history trade-offs in migratory animals. However, little is known about the relative importance of intrinsic and extrinsic stressors on the oxidative state of individuals in wild populations. We quantified the relationships between air temperature, sex, body condition and three markers of oxidative state (malondialdehyde, superoxide dismutase and total antioxidant capacity) across hundreds of individuals of a long-distance migrant (the brent goose Branta bernicla hrota) during wintering and spring staging. We found that air temperature and migratory stage were the strongest predictors of oxidative state. This emphasizes the importance of extrinsic factors in regulating the oxidative state of migrating birds, with differential effects across the migration. The significance of abiotic effects demonstrates an additional mechanism by which changing climates may affect migratory costs.European Commissio

Ecological Responses to Extreme Flooding Events: A Case Study with a Reintroduced Bird.

Published onlineJournal ArticleIn recent years numerous studies have documented the effects of a changing climate on the world's biodiversity. Although extreme weather events are predicted to increase in frequency and intensity and are challenging to organisms, there are few quantitative observations on the survival, behaviour and energy expenditure of animals during such events. We provide the first data on activity and energy expenditure of birds, Eurasian cranes Grus grus, during the winter of 2013-14, which saw the most severe floods in SW England in over 200 years. We fitted 23 cranes with telemetry devices and used remote sensing data to model flood dynamics during three consecutive winters (2012-2015). Our results show that during the acute phase of the 2013-14 floods, potential feeding areas decreased dramatically and cranes restricted their activity to a small partially unflooded area. They also increased energy expenditure (+15%) as they increased their foraging activity and reduced resting time. Survival did not decline in 2013-14, indicating that even though extreme climatic events strongly affected time-energy budgets, behavioural plasticity alleviated any potential impact on fitness. However under climate change scenarios such challenges may not be sustainable over longer periods and potentially could increase species vulnerability.We thank Mitch Weegman, Miguel Villoslada and Anne Harrison for technical support and advice; to Jorge S. Gutierrez for helpful suggestions on the drafts of the manuscript; and to Damon Bridge and RSPB (Royal Society for the Protection of Birds) volunteers for providing survival and breeding data. We also thank the Environmental Agency for allowing us access to water gauge measurements in the study area. We are grateful to Larry Griffin, Amy King, Harry Nevard and numerous volunteers for assistance with telemetry deployments. SB is funded by an EU consolidator’s grant: STATEMIG 310820. ASR is supported by a joint predoctoral grant from the University of Exeter, the Wildfowl and Wetlands Trust (WWT) and the RSPB

Integrated population modelling reveals a perceived source to be a cryptic sink

This is the final version of the article. Available from the publisher via the DOI in this record.Demographic links among fragmented populations are commonly studied as source-sink dynamics, whereby source populations exhibit net recruitment and net emigration, while sinks suffer net mortality but enjoy net immigration. It is commonly assumed that large, persistent aggregations of individuals must be sources, but this ignores the possibility that they are sinks instead, buoyed demographically by immigration. We tested this assumption using Bayesian integrated population modelling of Greenland white-fronted geese (Anser albifrons flavirostris) at their largest wintering site (Wexford, Ireland), combining capture-mark-recapture, census and recruitment data collected from 1982 to 2010. Management for this subspecies occurs largely on wintering areas; thus, study of source-sink dynamics of discrete regular wintering units provides unprecedented insights into population regulation and enables identification of likely processes influencing population dynamics at Wexford and among 70 other Greenland white-fronted goose wintering subpopulations. Using results from integrated population modelling, we parameterized an age-structured population projection matrix to determine the contribution of movement rates (emigration and immigration), recruitment and mortality to the dynamics of the Wexford subpopulation. Survival estimates for juvenile and adult birds at Wexford and adult birds elsewhere fluctuated over the 29-year study period, but were not identifiably different. However, per capita recruitment rates at Wexford in later years (post-1995) were identifiably lower than in earlier years (pre-1995). The observed persistence of the Wexford subpopulation was only possible with high rates of immigration, which exceeded emigration in each year. Thus, despite its apparent stability, Wexford has functioned as a sink over the entire study period. These results demonstrate that even large subpopulations can potentially be sinks, and that movement dynamics (e.g. immigration) among winters can dramatically obscure key processes driving subpopulation size. Further, novel population models which integrate capture-mark-recapture, census and recruitment data are essential to correctly ascribing source-sink status and accurately informing development of site-safeguard networks.This research was funded through a joint PhD studentship to M.D.W. from the Wildfowl & Wetlands Trust and the University of Exeter, and through a NERC grant (NE/L007770/1) to D.J.