One of the most relevant focuses of the initiative is to study the distributions of birds throughout the year, including migrations, in Europe.
Migratory birds and some species that arrive in Catalonia in autumn
There are birds that travel the world year after year. They are nomadic by nature: they move to find the most favorable climatic conditions, flee from adverse ones, seek shelters where they can reproduce and areas rich in food. Some travel unimaginable distances. The Arctic tern ( Sterna paradisaea ), for example, pursues eternal summer and individuals have been found to travel up to 90,000 kilometers from the time they leave their breeding site until they return the following year.
Depending on the time of year and the reason for the trip, we can differentiate between prenuptial migration, which occurs in the spring, seeking to "return" from the areas where they have spent the winter to territories favorable for reproduction and breeding, and postnuptial migration, in the fall, where they move in search of warmer areas to winter.
However, from a local point of view, we differentiate between migratory species of passage , which travel great distances and only stop briefly in the territory before continuing their journey; wintering species, which stay in the territory to spend the winter; and summer species, which are here during the warm and reproductive period, and leave when winter arrives for warmer areas. We can also find species that have sedentary or resident populations, that is, they are there all year round, but that part of their population migrates and others do not. They are usually short-distance migrations or movements and there is a wide range of cases. For example, in the Pyrenees, adult tits are residents, they stay there because they have learned to find local resources and, on the other hand, the young are not as capable of staying in cold areas and have to make small migrations to lower areas where they can find food.
Before migrating, birds accumulate fat (energy reserve) and usually renew their plumage to facilitate flight, characteristics that ornithologists measure and record in scientific ringing. In Catalonia, scientific ringing is coordinated by the Catalan Institute of Ornithology and SEO/BirdLife does it in Spain, coordinated with EURING, the information center on ringing in Europe and promoter of The Eurasian African Bird Migration Atlas .
Some migratory birds have even developed hunting strategies around migration. A curious case is that of the Eleonora's falcon ( Falco eleonorae ): ornithologists have observed that it feeds on birds in migration and takes advantage of this moment to feed its chicks on sea cliffs. This species breeds in the Balearic Islands and other Mediterranean islands and the Canary Islands and, when breeding is finished, goes to Madagascar to spend the winter.
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How do birds know when to migrate?
How do birds know when to migrate?
Well, it is marked by food, whether it is available or scarce, and the photoperiod, that is, the length of the day . All of this becomes an internal signal encoded genetically, and the most exciting thing is that we now know that this encoding can change if environmental conditions change. Do you want a very curious example?
The cap-headed warbler ( Sylvia atricapilla ) came from Scandinavia to spend the winter in Catalonia, but in the United Kingdom, a country with a strong tradition of putting feeders in gardens for decades, the warblers have found endless and always available food. This simple change has modified the genetics of the warblers in a few generations, so that they no longer winter here, but instead stay in the United Kingdom!
And how can we learn about bird migrations?
And how can we learn about bird migrations?
This information is obtained thanks to dozens of volunteer ornithologists who, every migration season, in autumn and spring, dedicate hours to capturing these birds and ringing them to know where they travel in case they are recaptured , or to read the information on the ring if the specimen already has one. For example, from the Canal Vell Biological Station, in the Ebro Delta, their movements have been monitored since 1996. To find out this information, they place a stretch of Japanese nets, made with almost invisible threads, which intercept the birds. These nets are now strictly prohibited for hunting activities, because they were used before and were too effective! For this reason, today they are exceptionally authorized for these scientific tasks and are used by ornithologists to capture birds that fly over the monitoring points. To do this in a respectful way, they check and collect the birds that are trapped every fifteen minutes throughout the six hours during which the nets remain operational, between sunrise and noon.
What birds arrive in Catalonia in autumn?
What birds arrive in Catalonia in autumn?
Some migratory species that can be observed this autumn in Catalonia and that we are receiving on the RitmeNatura platform are: the little sandpiper, the common wagtail, the red-tailed hawk, the crane, the scoop-tailed duck and the great cormorant. In addition, birds of prey such as the black kite, the osprey, the hawk and the falcon can also be observed.
However, resident species that receive wintering or passing individuals are the sparrowhawk, the common jay, the common kestrel, the robin, the common wagtail and the cowbird.
Chitona vulgaris (Actitis hypoleucos) - Author: Aurea & Ramon, CC-BY-NC.
Sparrowhawk ( Accipiter nisus ). Author: Merisolano, CC-BY-NC
Kestrel ( Falco tinnunculus ). Author: Claudia Fenández Bagan, CC-BY-NC
Robin ( Erithacus rubecula ) - Author: Cristian Grijalba, CC-BY-NC
You too can help follow migrations with RitmeNatura
You too can help follow migrations with RitmeNatura
However, if you are not an ornithologist, you can collaborate by observing migratory bird species thanks to the citizen science project RitmeNatura . The initiative collects observations from citizens to study seasonal changes in nature in Catalonia and understand how phenology is changing, that is, the moments in the life cycle of plants and animals in relation to the climate.
Other species that are phenologically relevant in Catalonia and of which the project already has observations are the common mosquito, of which sedentary and wintering populations can be found, or the common wagtail, resident in Catalonia and the Peninsula, and which receives individuals from Central Europe and more northern areas during the wintering period, and some individuals continue their migration by passing the Strait of Gibraltar.
There is also the Ornito.cat portal, coordinated by the Catalan Institute of Ornithology (ICO), which collects thousands of data that people observe on migrations throughout the year and which is linked to the EuroBirdPortal - a platform of the European Bird Census Council (EBCC) that gathers bird observation data from 21 European countries -.
Tracing the routes of European species
Tracing the routes of European species
CREAF also participates in European projects that monitor migratory birds. One of them is Life Reinforcement , which improves the quality and quantity of data collected by the EuroBirdPortal (EBP) project . “One of the most relevant focuses of the initiative is to study the distributions of birds throughout the year, including migrations, in Europe,” highlights Sergi Herrando, a CREAF researcher, part of the project and president of the European Bird Census Council.
The European projects wildE and SPEAR also study migratory birds, in collaboration with the Centre de Ciència i Tecnologia Forestal de Catalunya (CTFC) , the Institut Català d'Ornitologia and the European Bird Census Council . Based on data collected by the European Bird Portal, they are working on creating weekly maps that show how migratory bird distributions change over time and in response to factors such as climate and habitat.
Interactions between fauna and flora are essential to understanding how ecosystems can adapt to the impacts of climate change and maintain biodiversity in the future.
In addition, they are exploring a little-known function: the ability of migratory birds to disperse seeds over long distances . Migratory birds could help plants follow climate change , moving them to areas with more favorable climatic conditions. “ Interactions between fauna and flora are essential to understanding how ecosystems can adapt to the impacts of climate change and maintain biodiversity in the future,” highlights Ella Plumanns-Pouton , CREAF researcher and member of the project teams.
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Some frequently asked questions
Some frequently asked questions
How do birds know when to migrate?
Birds detect changes in their environment: when the days get shorter (photoperiod), the weather changes or there is less food. These external signals activate internal responses: they accumulate fat (energy) and become more active, preparing for the journey.
Can climate change and anthropization affect migration?
Yes, climate change can alter the migratory patterns of birds. There are two important elements, one of which is that migrations are altered in the sense that sometimes birds no longer need to migrate in search of areas to the south that have food. This is important because it conditions the distribution of birds, which do not need to go to the south to winter and stay further north. For example, in Central Europe, ponds used to freeze and birds came to the warmth of the Mediterranean, but now there is no more ice and they stay in the north.
With regard to resources, there may be a mismatch, for example, when the birds arrive in the spring, the peak of caterpillar production may have already passed and this results in a lower capacity to feed the young.
Regarding urbanization, it can also modify natural habitats, making migration more difficult, creating new routes or even eliminating the migration process completely.
What is scientific ringing?
It consists of temporarily capturing birds, studying them and marking them with a non-invasive identification ring, by ornithologists (scientists who study birds). This allows them to follow their migratory routes, learn more about populations, study their habits and behaviors and help with their conservation. In Catalonia, scientific ringing is coordinated by the Catalan Institute of Ornithology and SEO/BirdLife does it in Spain, coordinated with EURING, the information center on ringing in Europe and promoter of The Eurasian African Bird Migration Atlas.
How can we help study bird migrations?
Anyone can help track migrations through citizen science projects. At CREAF we have RitmeNatura, which studies the impacts of climate change on the phenology (such as migration) of living beings. There is also the Ornito.cat portal, coordinated by the Catalan Institute of Ornithology (ICO), which collects thousands of data points that people observe on migrations throughout the year and which is linked to the EuroBirdPortal - a platform of the European Bird Census Council (EBCC) that gathers bird observation data from 21 European countries.
What are bird migratory routes?
The migratory routes of birds are the paths they follow during their annual migrations. These routes are usually long and complex, but we can also find partial or altitudinal migrations such as that of the mountain wagtail.
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