McKinnon et al 2011 Reproductive success, moult and autumn migration of Wood Thrushes


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  • Fast birds arrive 14 and 22 Oct, slow birds arrive 10 Nov, 6 Dec.
  • Closed circles are ASY
  • McKinnon et al 2011 Reproductive success, moult and autumn migration of Wood Thrushes

    1. 1. The influence of reproductive success and moult on autumn migration strategy in a songbird<br />Emily A. McKinnon1<br />Kevin C. Fraser1<br />Elizabeth A. Gow1,2<br />Maggie MacPherson1<br />Calandra Q. Stanley1<br />T. Kurt Kyser3<br />Bridget J. M. Stutchbury1<br />1York University, Toronto, Canada<br />2Current: University of Saskatchewan, Saskatoon, Canada<br />3Queen’s University, Kingston, Canada<br /><br />1<br />
    2. 2. Outline<br />Previous work on Wood Thrushes (Hylocichlamustelina)<br />Double-brooding<br />Migration using geolocators<br />Research questions<br />Methods: geolocators and SIA<br />Results<br />Conclusions and future work<br />2<br />
    3. 3. Wood thrush (Hylocichlamustelina)<br />Nearctic-Neotropical migrant<br />Population has declined 40% over 40 years<br />3<br />
    4. 4. Reproductive success and carry-over effects<br />86% of successful females attempt a second brood<br />Costs for moult and migration? <br />4<br />E. Gow. Thesis, York University, Toronto, Canada<br />E. Gow et al. submitted to Auk<br />
    5. 5. Wood Thrush moult<br />Energetic/time constraints at breeding sites could promote delayed moultor moult during migration<br />5<br />
    6. 6. Wood thrush migration<br />Rate <br />Total (fall) stopover days<br />Arrival dates<br />Routes <br />6<br />Stutchbury et al. 2009 Science 323:896<br />Stutchbury et al. 2011. Proc. R. Soc. B. 278:131-137.<br />Stutchbury Lab unpubl. data<br />
    7. 7. Fast vs. slow fall migration<br />7<br />
    8. 8. Research Questions <br />Does reproductive output influence moult and or fall migration? <br />Is variation in fall migration strategy explained by moult south of breeding site? <br />8<br />
    9. 9. Methods: reproductive output, moult<br />Reproductive output measured by following nests in 2008<br />Moult scored in August (# of new feathers present/growing)<br />Geolocators deployed on birds to collect data on migration<br />9<br />
    10. 10. Methods: geolocator analysis<br />Geolocator light data analysed for:<br />fall migration rate (overall km/day)<br />arrival date at winter site<br />total number of fall stopover days<br />10<br />
    11. 11. Methods: moulting south of breeding site<br />4 feathers in a moult sequence were sampled<br />11<br />Tertial clip<br />Primary clip<br />Secondary clip<br />
    12. 12. Methods: stable-isotope analysis<br />Feathers analysed for ratios of stable-hydrogen isotopes (δD)<br />Birds classified as moult migrants if at least 1 feather grown south<br />12<br />δD<br />
    13. 13. Results: Does reproductive output influence moult?<br />13<br />Yes.<br />Late breeding/double-brooding = late moulting<br /><ul><li> = SY
    14. 14. = ASY</li></ul>Stutchbury et al. 2011. Proc. R. Soc. B. 278:131-137.<br />
    15. 15. Does reproductive output does influence fall migration? <br />Late breeders ( rep. output) farther N on 10 Oct<br />Late fall migration departure<br />No relationship between breeding and winter arrival<br />Why? <br />14<br />Stutchbury et al. 2011. Proc. R. Soc. B. 278:131-137.<br />
    16. 16. What predicts winter arrival?<br />15<br />Fall migration appears to be related to # stopover days.<br />Why such long stopovers?<br />Stutchbury et al. 2011. Proc. R. Soc. B. 278:131-137.<br />
    17. 17. Evidence of moult south of breeding sites<br />16<br />5/31 (16%) individuals moulted feathers south of breeding sites<br />δD<br /><br />
    18. 18. Moult and migration<br />No significant differences in winter arrival date or migration rate<br />Moult-migrants arrived later, migrated faster<br />17<br />
    19. 19. Moult and migration<br />No significant difference in # stopover days<br />Moult-migrants had more stopover days<br />2 birds with > 3 week stopovers both grew feathers south<br />18<br />
    20. 20. Conclusions<br />High reproductive output delays moult, and perhaps fall migration departure<br />High reproductive output does not influence winter arrival<br />Winter arrival date driven by # stopover days<br />16% birds moulted feathers south; no significant relationship with migration rate, winter arrival or total stopover days<br />However, small sample sizes and trends suggest more sampling needed<br />19<br />
    21. 21. Implications and future work<br />If not for moult, why do some WOTH take fall ‘vacations’? <br />WOTH on extended stopover captured in Belize in October 2010 and radio-tagged<br />physiology, body condition <br />More geolocators and moult data: >100 geolocators deployed in Belize, Costa Rica, and Canada in 2011<br />+ n=25 in-hand awaiting analysis<br />Expect ~30-50 returns in winter 11/12 and summer 2012<br />20<br />
    22. 22. Questions and comments<br />Thank you!<br /><br />21<br />
    23. 23. Acknowledgements<br />Funding: NSERC, York University, Molson Fund, Canada Research Chair, proceeds from Silence of the Songbirds<br />Many hard-working field and lab assistants<br />Queen’s Facility for Isotope Research (QFIR)<br />22<br />
    24. 24. Does rep. success influence moult location? <br />5/8 double-brooded birds grew at least 1 feather S of breeding site<br />2/7 single-brooded birds show moult S of breeding site<br />Not significantly different (X2 = 3.355, p = 0.07)<br />Double-brooding does not appear to influence moult location. <br />23<br />E. Gow et al. submitted to Auk.<br />
    25. 25. Winter arrival date – unimportant?<br />24<br />
    26. 26. Wood thrush migration routes<br />25<br />Fall <br />Spring<br />
    27. 27. Do birds moult at long stopovers? <br />11 of 13 birds have stopovers 7 days or longer<br />2 of 13 birds stop for > 3 weeks<br />26<br />Moult in Belize<br />