Research ArticleECOLOGY

Unravelling migration connectivity reveals unsustainable hunting of the declining ortolan bunting

See allHide authors and affiliations

Science Advances  22 May 2019:
Vol. 5, no. 5, eaau2642
DOI: 10.1126/sciadv.aau2642
  • Fig. 1 Range, genetic population structure, and migration flyways of European ortolan buntings Emberiza hortulana as revealed by light loggers and stable isotopes.

    (A) Top left: Distribution range (orange) during the breeding season (Europe) and winter (Africa). Black triangles locate sites where autumn migrants were sampled. Dots indicate studied breeding populations: dark blue, western genetic cluster; red, eastern genetic cluster; green, northern genetic cluster. (B) Top right: Tracks of 46 migrant buntings obtained with light loggers. Blue, western flyway; green, eastern flyway; orange, putative central flyway. Black dots, INTIGEO loggers; open dots, SOI loggers. (C) Bottom left: Assignment to origin of ortolan bunting feathers using δ2H measurements in feathers collected in populations using the western flyway. Europe: 74 migrating individuals sampled in autumn 2012–2015 in France. Africa: 238 individuals sampled from various breeding populations of the western and eastern genetic clusters in spring 2013–2015. Assignment probabilities were rescaled from 0 to 1 according to the maximum value obtained in a pixel during the assignation process, for each continent, separately. (D) Bottom right: Assignments to origin of ortolan bunting feathers using δ2H measurements in feathers collected in populations using the eastern flyway. Europe: 78 migrating individuals sampled in Kuwait in fall 2015. Africa: 297 individuals sampled in various breeding populations of the eastern genetic cluster in spring 2013–2015. Assignment probabilities were rescaled to range from 0 to 1 according to the maximum value obtained in a pixel during the assignment process, for each continent, separately.

  • Fig. 2 The 100-year extinction risk of northern ortolan bunting breeding populations with respect to various scenarios of increased survival probability (decreased illegal harvesting).

    Different scenarios of increased habitat quality, and hence breeding performance (increased clutch size and more balanced sex ratio) are shown with different symbols, based on population viability analyses conducted with vital rates drawn from population dynamic research carried out in Norway (triangles; clutch size of 4.25 eggs, sex ratio with one male out of two finding a mate) and in Finland (squares; clutch size of 4.57 eggs, sex ratio with two males out of three successfully pairing), while further more optimistic scenarios are shown with circles (first with a larger clutch size of 4.9 eggs and then also with a more balanced sex ratio, with three of four males successfully pairing, as would happen in populations hypothetically well connected within a metapopulation system). Increased survival probability is shown in terms of the number of additional individuals (first and second values of the x axis legend) surviving the autumn migration (second value) or until the next spring (first value). The red rectangle encompasses the range of known and/or suspected harvested numbers in southwest France (estimated between 15,000 and 30,000 ortolans per autumn). The colors depict the IUCN Red List status of the population as estimated from maximum extinction probability after 10, 20, and 100 years and three and five generations (see Materials and Methods for details; green, Least Concern; orange, Vulnerable; red, Endangered). In the best demographic scenario, the extinction risk is predicted to drop from 100 to 66% if 15,000 additional buntings survive the fall or to only 15% if 30,000 additional buntings survive the fall migration. Photo credits: S. Minkevicius.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/5/eaau2642/DC1

    Supplementary Texts 1 and 2

    Fig. S1. Boxplot of average δ2Hf in body coverts/scapulars of ortolan buntings captured during the breeding season by country where birds were captured (birds captured in Israel and Kuwait were spring migrants).

    Fig. S2. Genetic assignment of breeding individuals to the eastern, western, and northern clusters following cross-validation.

    Fig. S3. Genetic assignment of individuals sampled during migration along the eastern and western flyways to a breeding population.

    Fig. S4. Genetic assignment of individuals sampled during migration in France (western flyway) to a breeding population other than the eastern cluster (as stable isotopes and archival light loggers excluded an eastern breeding origin for western migrants).

    Fig. S5. 100-year extinction probability for various demographic and hunting scenarios.

    Table S1. Number of geolocators deployed and retrieved by country (region) and year when data were retrieved from the logger and logger model.

    Table S2. Summary of base demographic parameters values for Vortex population viability analysis

    Table S3. Best model structures for survival analyses.

    Data file S1. Estimates of population sizes and trends.

  • Supplementary Materials

    The PDF file includes:

    • Supplementary Texts 1 and 2
    • Fig. S1. Boxplot of average δ2Hf in body coverts/scapulars of ortolan buntings captured during the breeding season by country where birds were captured (birds captured in Israel and Kuwait were spring migrants).
    • Fig. S2. Genetic assignment of breeding individuals to the eastern, western, and northern clusters following cross-validation.
    • Fig. S3. Genetic assignment of individuals sampled during migration along the eastern and western flyways to a breeding population.
    • Fig. S4. Genetic assignment of individuals sampled during migration in France (western flyway) to a breeding population other than the eastern cluster (as stable isotopes and archival light loggers excluded an eastern breeding origin for western migrants).
    • Fig. S5. 100-year extinction probability for various demographic and hunting scenarios.
    • Table S1. Number of geolocators deployed and retrieved by country (region) and year when data were retrieved from the logger and logger model.
    • Table S2. Summary of base demographic parameters values for Vortex population viability analysis
    • Table S3. Best model structures for survival analyses.

    Download PDF

    Other Supplementary Material for this manuscript includes the following:

    • Data file S1 (Microsoft Excel format). Estimates of population sizes and trends.

    Files in this Data Supplement:

Navigate This Article