Carry-over effects of seasonal migration on reproductive success through breeding site retention in a partially migratory bird.

Acknowledgments We thank everyone who contributed to data collection, most particularly Raymond Duncan, Moray Souter, Adrian Breeman and Doug Grant. Work was supported the University of Aberdeen, UK Centre for Ecology & Hydrology, Royal Society, Norwegian Research Council (project 223257), and a Marie Curie Postdoctoral Fellowship awarded to JM (895904)Peer reviewe

Among-individual and within-individual variation in seasonal migration covaries with subsequent reproductive success in a partially migratory bird

Acknowledgements: We thank Raymond Duncan (Grampian Ringing Group), whose insatiable enthusiasm for ringing was inspirational. We thank everyone who contributed to fieldwork, especially Mike Harris and David Hunter; Roger Pradel for generous advice on CMR mixture models; and UK Natural Environment Research Council for funding (NE/R000859/1, NE/P009719/1). Data accessibility Data are available from the Dryad Digital Repository: https://doi.org/10.5061/dryad.pvmcvdnhv [46]. Electronic supplementary material is available online at https://doi.org/10.6084/m9.figshare.c.5054649.Peer reviewedPostprin

Within-year and among-year variation in impacts of targeted conservation management on juvenile survival in a threatened population

Acknowledgements We thank all Islay landowners and farmers who allowed access to nest sites and supported supplementary feeding, especially Donald Jones and Robert and Tom Epps, and everyone who contributed to fieldwork and data collection. We thank NatureScot for funding supplementary feeding, led by Rae McKenzie, Jess Shaw and Des Thompson, and Royal Society for the Protection of Birds for logistic support. This work was supported by a Natural Environment Research Council iCASE studentship (NE/P009719/1) with NatureScot, and the Scottish Government’s 2011-2016 and 2016-2021 Strategic Research Programmes. Open access via Wiley agreement.Peer reviewedPublisher PD

Integrating advances in population and evolutionary ecology with conservation strategy through long-term studies of red-billed choughs

Acknowledgements The long-term study could not have been achieved without long-term support from numerous people, including Islay farmers and land-owners who facilitated access to nest sites and observation locations; all current and previous members of the Scottish Chough Forum; and NatureScot and RSPB (summarised in Appendix S2). We particularly thank Rae McKenzie of NatureScot, without whose enthusiasm and willingness to engage with apparently abstract ideas we would likely never have got beyond phase 1. Aspects of the work were funded by Natural Environment Research Council, NatureScot, University of Aberdeen, University of Glasgow, RSPB, Scottish Government’s Strategic Research Programme, Scotland’s Rural College, Killam Trusts and the Royal Society (details in Appendix S2). We thank David Jardine for his valuable contributions, and Rae McKenzie, Jess Shaw and Morven Laurie (NatureScot), and Jen Smart, Gillian Gilbert, Jack Fleming and Paul Walton (RSPB) for commenting on a manuscript draft.Peer reviewedPublisher PD

Carry‐over effects of seasonal migration on reproductive success through breeding site retention in a partially migratory bird

•1. Understanding the maintenance and dynamics of phenotypic polymorphisms requires unpicking key ecological mechanisms shaping the fitness costs and benefits of expressing alternative phenotypes, generating selection. Seasonal migration versus year-round residence expressed in partially migratory populations represents one common polymorphism that can experience strong selection through differential reproductive success. Yet, key hypothesised pathways that could generate such selection remain to be empirically tested. •2. One hypothesis is that migratory tactics affect subsequent reproductive success through carry-over effects on breeding site retention and resulting breeding dispersal. By remaining in breeding areas all year round, residents could retain their preferred breeding site between years, and consequently have higher reproductive success. Conversely, migrants that escape harsh non-breeding season conditions could return in better condition, with high resource holding potential, and outcompete residents to retain their site. Such effects could further depend on migration timing and vary between years. Yet, such pathways have not been quantified, precluding empirical parameterisation of partial migration theory. •3. We used 4 years of breeding and non-breeding season data from partially migratory European shags (Gulosus aristotelis) to test whether the three most frequent migratory tactics in this population (full resident, early migrant departing soon after breeding, and late migrant departing in late autumn) differed in their breeding site retention; whether site retention predicted reproductive success; and hence whether effects of migratory tactic on reproductive success were explicable through site retention. •4. Overall, residents were much more likely to retain their breeding site between years than both early and late migrants, and site retention was associated with increased reproductive success. Yet, these effects varied somewhat among years: late migrants were always least likely to retain their site but had variable relative reproductive success. Path analyses revealed that effects of migratory tactic on reproductive success were only partly attributable to breeding site retention. •5. These results indicate that multiple mechanisms underlie reproductive selection on migratory tactics, potentially contributing to maintaining behavioural polymorphisms. Yet, the clear associations between migratory tactics and local breeding dispersal reveal that these movements can be strongly interlinked across seasons, shaping overall spatioseasonal dynamics in partially migratory systems

Collateral benefits of targeted supplementary feeding on demography and growth rate of a threatened population

1. Effective evidence-based conservation requires full quantification of the impacts of targeted management interventions on focal populations. Such impacts may extend beyond target individuals to also affect demographic rates of non-target conspecifics (e.g. different age classes). However, such collateral (i.e. unplanned) impacts are rarely evaluated despite their potential to substantially alter conservation outcomes. Subsequent management decisions may then be poorly informed or erroneous. 2. We used 15 years of individual-based demographic data in a ‘before-after control-impact’ (BACI) analysis to quantify collateral demographic impacts of a targeted multi-year supplementary feeding programme designed to increase sub-adult survival and hence viability of a small, threatened red-billed chough Pyrrhocorax pyrrhocorax population. Specifically, we assessed whether the intervention also affected adult survival and reproductive success, and whether such collateral effects were themselves sufficient to stabilize population size and hence achieve short-term conservation aims. 3. The probabilities of adult survival and successful reproduction increased substantially between the ‘before-feeding’ and ‘during-feeding’ periods in those choughs associated with supplementary feeding, but not otherwise. Overall breeding success (i.e. number of chicks fledged per occupied territory) also tended to increase, even though brood sizes did not increase. These relationships, which were detectible only through BACI analyses, suggest that supplementary feeding targeted at sub-adults had unplanned positive impacts on adult demographic rates. 4. Deterministic matrix models designed to project population growth demonstrate that these estimated collateral effects were sufficient to make a substantial contribution to increasing population growth rate and achieving short-term population stability. 5. Synthesis and applications. Our results indicate substantial positive collateral impacts of a targeted supplementary feeding intervention on population viability, despite no a priori expectation that the non-target adults were food-limited. This casestudy illustrates how thorough assessment of collateral impacts of targeted interventions can affect assessment of short-term efficacy and reveal new opportunities for future interventions, thereby informing subsequent management decisions