João L. Guilherme

I enjoy watching birds and studying their amazing migrations. I am a biologist with a background in conservation and ecology and had the opportunity to collaborate with different projects in Portugal, Africa and Central Asia. I am particularly interested in animal movement, the role of common species in modified ecosystems and conservation biogeography.

To address the problem of the declines of the Afro-Palearctic migratory birds I will take a multi-species approach and use tracking data of multiple species from different populations across Europe. Besides benefiting from the extensive experience of my supervisors and partners, I am collaborating with an extensive network of researchers from all over Europe.


PhD project: Understanding declines of Afro-Palearctic migratory birds

Understanding the causes of population declines of Afro-Palearctic migratory birds is a major scientific challenge. The future of many of these species hinges on our success in ensuring their conservation from the breeding grounds, through migratory pathways, to non‐breeding areas1. Identifying these links is critical to assess how past threats affected population trends, predict how future environmental stressors may affect migratory species and prioritize conservation action2,3.

Example migration tracks of Common Cuckoos breeding in England, Germany, Belarus and China illustrating the diversity of migration routes within breeding populations, convergence to a relatively restricted winter range and use of a restricted area of West Africa in spring (by European populations), indicative of potential conservation hotspot. Unpublished data from BTO (UK & China), LBV (Germany) and APB (Belarus).

In recent years, advances in tracking technologies allowed unprecedented insights on the annual cycles4, connectivity patterns5,6, demographics7,8, migratory strategies9 and annual cycle scheduling10 of many Afro-Palearctic migratory birds. This information has been key in threat assessment11 and conservation planning for single species12. However, to date, only few studies used tracking data to assess multispecies patterns (e.g.13,14), or to identify important areas for their conservation (namely for marine birds15).

This PhD project builds on the collaboration of an extensive network of researchers, maximizing the conservation value of existing tracking data to identify important areas for the conservation of Afro-Palearctic migratory birds, shed light on the causes underlying the recent declines of many populations of these species. Specifically, taking a multi-species analytical approach and using tracking data of multiple species from different populations across Europe, I will:

  • Investigate how migratory landbirds connect countries along the Afro-Palearctic flyway and which countries are the main responsible for their conservation.
  • Identify which areas en route and in the African wintering grounds, congregate more birds and highlight priority areas for the conservation of multiple species/populations.
  • Examine which commonalties (e.g. migratory traits) declining species have that may explain the severe population declines of some migratory birds observed in the European breeding grounds.

I hope my project will help identifying research gaps, as well as contribute to inform policy, prioritise conservation action at the flyway scale, and help achieving global conservation goals.


Related references

  1. Doswald et al.2009: Potential impacts of climatic change on the breeding and non-breeding ranges and migration distance of European Sylvia Journal of Biogeography 36
  2. Hallworth and Marra 2015: Miniaturized GPS tags identify non-breeding territories of a small breeding migratory songbird. Scientific Reports 5, 11069.
  3. Vickery et al. 2014: The decline of Afro-Palaearctic migrants and an assessment of potential causes. Ibis, 156, 1–22.
  4. Willemoes et al. 2014: Narrow-Front Loop Migration in a Population of the Common Cuckoo Cuculus canorus, as Revealed by Satellite Telemetry. PLOS ONE 9.
  5. Hahn et al. 2013: Strong migratory connectivity and seasonally shifting isotopic niches in geographically separated populations of a long-distance migrating songbird. Oecologia 173, 1217–1225.
  6. Kramer et al. 2018: Population trends in Vermivora warblers are linked to strong migratory connectivity. PNAS 115, E3192–E3200.
  7. Hewson et al. 2016: Population decline is linked to migration route in the Common Cuckoo. Nature Communications 7, 12296.
  8. Souchay et al. 2018: Identifying drivers of breeding success in a long-distance migrant using structural equation modelling. Oikos 127, 125–133.
  9. Adamík et al. 2016: Barrier crossing in small avian migrants: individual tracking reveals prolonged nocturnal flights into the day as a common migratory strategy. Scientific Reports 6: 21560.
  10. Briedis et al. 2016: Breeding latitude leads to different temporal but not spatial organization of the annual cycle in a long-distance migrant. Journal of Avian Biology 47, 743–748.
  11. Jiguet et al. 2019: Unravelling migration connectivity reveals unsustainable hunting of the declining ortolan bunting. Science Advances 5: eaau2642.
  12. Choi et al. 2019: Where to draw the line? Using movement data to inform protected area design and conserve mobile species. Biological Conservation 234: 64–71.
  13. Thorup et al. 2017: Resource tracking within and across continents in long-distance bird migrants. Science Advances 3, e1601360.
  14. Briedis et al. 2019: A full annual perspective on sex-biased migration timing in long-distance migratory birds. Proc. R. Soc. B 286: 20182821.
  15. Lascelles et al. 2016: Applying global criteria to tracking data to define important areas for marine conservation. Diversity and Distributions 22, 422–431.



Academic Host

Centre National de la Recherche Scientifique
Montpellier, France
Ana Rodrigues


BirdLife International
Cambridge, UK
Vicky Jones
Maria Dias
Stu Butchart
Instituto Superior de Agronomia
Lisbon, Portugal
Inês Catry


Royal Society for the Protection of Birds

Sandy, UK

Juliet Vickery
Member of Student Thesis Committee
 Steffen Oppel
  British Trust for Ornithology
Thetford, UK
Chris Hewson
Member of Student Thesis Committee