Published in the latest issue of Genome Biology and Evolution, our new study uses gene expression data to identify key regulatory pathways related to adaptations for migration.

Despite the wealth of information available about migration physiology, there is little known about how migration is seasonally controlled at the molecular level. Comparing gene expression at specific stages of avian migration provides an opportunity to identify a large number of genes and potential regulatory pathways involved in important aspects of a species’ life history.

Using a whole blood transcriptomic approach, we found that top expressed genes during migration are involved in important pathways regarding adaptations to migration at high altitudes such as increase of aerobic capacity and angiogenesis. Comparison of gene expression profiles largely reflected the migration states of birds with several enzymes involved in different aspects of metabolic activity being differentially expressed between lean and fat birds providing several candidate genes for future functional studies.

Finally, we were able to identify genes involved in important pathways that represent significant adaptive mechanisms such as migration at high altitudes, water conservation during long-distance flight through protein catabolism and several hub genes that could be involved in the extraordinary phenotypic flexibility in organ mass displayed by avian migrants.

Our latest project experiment was completed successfully! We kept very lean Garden warblers in cages for five days while in fattening stage and gathered data regarding body mass rate of change, food consumption and fuel deposition rates.

Furthermore, using custom made PIR motion sensors we quantified each bird’s migratory restlessness. These data will help us study individuals’ migration strategy regarding stopover duration.

Will our results be consistent with Optimal Migration Theory?  How fast are Garden Warblers refuelling? What genes are implicated in this process? Soon our samples will be sequenced and these questions will be answered, so stay tuned!

Sample collection may be progressing well but ultimately what we need is good quality RNA to run our analyses. This is a great challenge since bird blood is nucleated, therefore whole blood RNA is prone to degradation due to endogenous nucleases. Furthermore RNA is inherently unstable under field conditions.

In our new article in British Poultry Science, we evaluate three commercially available RNA preservation and extraction methods applied to avian whole-blood samples kept in different storage conditions to identify the most suitable ones for use in field studies and specifically this project.

Read more here: https://www.tandfonline.com/doi/full/10.1080/00071668.2022.2061838

Published in the latest issue of Animal Migration, our new study underlines the significance of small islands and coastal areas in the Mediterranean as obligatory refuelling sites while their conservation value for migratory birds is highlighted under the perspective of climate change.

Migration is indeed the most energy-demanding task in a bird’s life cycle. When facing the Sahara Desert, a bird can cross it by intermittent flight, whereas the Mediterranean Sea must be crossed in non-stop continued flight. Small and large islands scattered in the Mediterranean Sea are often the first stopovers available for rest and refuel that migratory birds encounter after crossing the Sea and the desert.

Using empirical data coupled with avian flight models and ringing data, we were able to calculate the lean body mass of birds captured after having crossed vast ecological barriers, and then estimate the percentage of birds of the studied species that would not be able to resume their migration without refuelling on any of the three small Greek islands: Gavdos, situated in the Libyan sea, Strofades in the Ionian Sea and Antikythira, where the Anikythira Bird Observatory is based in the Aegean sea.

We estimated that almost 185 million birds of the studied species would migrate through Greece during spring. Of those, the proportion of birds from different species that would not be able to continue their migration unless they performed an obligatory stopover at one of these three insular stopover sites, was calculated at 14% or almost 30 million.

These findings point to a potentially alarming increase in bird mortality, as many migratory bird species may or may not successfully adapt to even small changes on these island habitats as those expected from increased global warming, but also underline the importance of on-going monitoring projects to further understand the evolutionary mechanisms through which climate change will affect individuals and populations.