Raquel is a postdoc at the Museo Nacional de Ciencias Naturales, Spain. She is a biogeographer and macroecologist with an interest in migratory birds. Raquel shares her recent work on historical shifts in the migratory behaviour of bird species that undergo Euro-African migrations.
Institute. Museo Nacional de Ciencias Naturales (CSIC)
Academic life stage. Postdoc.
Major research themes. Macroecology, birds, biogeography, migration, islands.
Current study system. I am interested in all groups of birds. During my PhD, I studied birds that migrate from Africa to Eurasia. The fascinating thing about them is that they not only perform journeys of thousands of kilometres but also face extreme conditions during their journey (like crossing the Sahara desert). There is a great diversity of migratory Euro-African species, making them ideal to understand general behavioural patterns in birds. Currently, I am broadening my interests towards island biogeography and diversification in birds.
Recent paper in JBI. Ponti, R, Arcones, A, Ferrer, X, Vieites, DR. Lack of evidence of a Pleistocene migratory switch in current bird long‐distance migrants between Eurasia and Africa. Journal of Biogeography. 2020; 47: 1564– 1573. https://onlinelibrary.wiley.com/share/author/DQGGVVFKZP2YAKYZKUJG?target=10.1111/jbi.13834
Motivation for this paper. Current and past climatic changes have shaped bird distributions and migratory behaviours. Migratory behaviour can shift to sedentary behaviour relatively quickly during the evolutionary history of birds. In this context, some hypotheses suggest that North American birds stopped migrating during glaciations, remaining sedentary in their wintering grounds, and regaining their migratory behaviour in warmer periods. We wanted to test this hypothesis for Euro-African migratory birds, as the geography of both continents are different from the Americas.
A White stork (Ciconia ciconia)during thebreeding season in Lombardia (Italy). Photo: Marco Sannolo
Key methodologies. In this study, we used species distribution models to infer present and past breeding and wintering distribution of every Euro-African migratory bird species. We created maps of probability of occurrence for the present and the Last Glacial Maximum based on the climate that species currently experience in their breeding and wintering distributions. If we know which climatic conditions birds face in the present, we can infer where in Europe or Africa these conditions might have occurred in the past. We evaluated the differences between present and past distributions and measured the distances between both breeding and wintering ranges. We predicted that breeding and wintering distributions would overlap if there had been a change in migratory behaviour to sedentary status during glaciation events. We also reviewed the bird fossil record from the Plio-Pleistocene covering Europe and Africa. This provided us an independent corroboration of our models.
Major results. We found that bird migratory species did not stop migrating during the glacial periods of the Pleistocene. Euro-African migratory birds reduced their migratory distances, as part of the north Hemisphere were covered by ice. However, unlike American migratory birds, Euro-African birds continued migrating, remaining in the Mediterranean basin during the breeding season and crossing the Sahara belt until their wintering areas. This finding indicates that the geography of the continents may play an important role in the evolution of migratory behaviour, and that current migratory routes probably were established during the Pleistocene or before (at least the Eurasian-African flyways).
An Egyptian vulture (Neophron percnopterus) during the breeding in August in the “Hoces del Duratón” Natural Park in Segovia (Spain). Photo: Marco Sannolo
Challenges of this research. Making conclusions with climatic based modelling is challenging because the models offer us a view of how species could distribute if they followed the same climatic conditions as in the present time. However, we cannot be sure how conditions were in the past nor how species were distributed. Therefore, to study historical processes we had to make assumptions and provide a plausible explanation considering the reduced evidence of fossils. In our case, we chose to create a climatic envelop considering only the climate of the months of the breeding and wintering season, but we did not know how long breeding and wintering seasons were in the past. Hence, we created plausible average breeding and wintering seasons for all species, assuming that this season would not substantially differ from the actual ones.
Next steps. This study opens further questions about the lability of migratory behaviour under climatic changes. Given the current climate change scenario, we wonder how birds will respond to an increase of temperatures or intermittent droughts. We are interested in determining if migratory birds will change their migratory behaviour and increase their migratory distance. Furthermore, we also want to study the effect of global change in migratory arctic-bird distributions, such as shorebirds, which breed in very high latitudes and could not further change their breeding distributions to northern areas. The first step to answer these questions could be modelling bird distributions under possible global change scenarios and evaluating the distributional changes compared with the present.
If you could study any organism on Earth, what would it be? I would love to expand my research towards endemic birds from islands and their evolution and adaptation to new environments. In one of my studies, I found that almost all migratory species and subspecies that colonize an island remain sedentary and greatly change their morphological features. This opened me a new world that I would like to develop in the future. Although I mostly study bird species, I am also interested in other groups, like reptiles. If I had the opportunity to develop new research focused on biogeography and macroecology I would not say no to include other groups!