Coming soon: An atlas of Spain's migratory birds
Bird conservation’s key pillars are knowledge of the area of distribution, abundance, trend and size of the populations of birds. In countries like Spain, which see a large number of migratory birds, knowledge of migration routes and resting sites is also necessary. SEO (BirdLife in Spain) has been working for decades with the collaboration of thousands of volunteers to collect data.
SEO’s Bird Monitoring Unit launched the Migra initiative in 2011 to describe the movements of each migratory bird species that breeds or winters in Spain over one or several years. This means tracking, among other things, which species undertake long trips, their migration routes, resting areas during the trip, and wintering areas. In the short term, SEO aims to use Migra data and results from previous studies to compile and publish an atlas of bird migration in Spain.
Migra’s new marking systems – which include satellite transmitters, GPS data loggers and geolocators – establish the location of the bird several times a day for several years, allowing us to know exactly how long they stay in their breeding and wintering areas, when they begin their migration, the route they follow, their speed and altitude, how climate change and weather conditions affect migration, and whether the birds use the same route each time.
The data is stored in the device and can be recovered by recapturing the bird carrying it, downloading over a small distance or receiving them through a satellite system via the Internet. While these devices have their drawbacks and problems of their own (difficulty in recapturing birds to extract data; necessity of the device to be small, very lightweight and aerodynamic; batteries only last a few years), they have yielded much critical information. Since 2011, Migra has tracked data from 332 birds (98 are still active) belonging to 24 species, totalling 634,460 recorded locations (at the time of publishing).
Migra also helps fill the gaps in avian information: There is more data available for certain highly endangered and rare species, very limited information for many medium or large birds and virtually non-existent records for most small Spanish birds. It is important to know the migratory behaviour of each species as soon as possible, because without that information, we will lose track of what existed before and we will not have the basic information available to understand the changes in their biology.
What has been confirmed in recent decades is that many species have changed their migratory behaviour annually. Some of them have shortened their movements and do not cross to Africa (an increasing number of White Storks, Black Storks and Booted Eagles spend the winter on the Mediterranean coast or in the lower course of River Guadalquivir). These changes are thought to be at least partially due to climate change, resulting in milder winters and more food in the breeding areas.
But Migra is not only useful for scientific research. It can also be used as a tool for people to understand the spectacular phenomenon of migration. To this end, SEO proposes to expand the Migra website from Spain to all of Europe, Asia and Africa, across BirdLife International partners. Spreading awareness about migration and the perils migratory birds face among people not familiar with the subject could be a huge conservation tool.