Black kites not only ascend in circles before beginning their crossing of the Strait, but they also use the 'waves' of warm air to 'surf' them linearly and thus position themselves at the necessary height to fly over the sea, as verified by a study of the Migres Foundation.
The organization stated in a press release that this is one of the discoveries that the transmitters installed on these large birds of prey have allowed to be published, specifically in the specialized journal 'Scientific Reports'.
«"The 'leap' of the kites to the other continent, occurring over the sea, that is, without warm air currents, requires them to carefully secure their departure position. Even so, GPS-GSM transmitters (which download the information via mobile phones) confirm that the last leg is not done by gliding, but by flapping their wings, in a tremendous expenditure of energy, sometimes insufficient and therefore deadly," he explained.
The Migres Foundation reported that surfing is a third form of upward flight that had not been verified, after the more common ones of climbing in a circle, and taking advantage of the winds on the slope.
He added that in the last week of July, the cages used to capture black kites will be set up again this year to collect data and mark them. This year, instead of transmitters, they will be fitted with rings. This task, carried out by experts from the Migres Foundation, will be assisted by collaborators who conduct the summer count of migratory birds between the two continents.
Birds of prey are difficult to tag in large numbers and even more difficult to recover, which is why information on their origins and destinations is still very incomplete. Tagging allows us to determine their migration dates, whether they migrate differently depending on their age or sex, their physical condition, or their migration strategies.
The 2018 banding operation will use a baited cage. When there are enough kites inside, and approximately every ten days, the cage will be closed for banding, which will also include Egyptian vultures, griffon vultures, and red kites.
Depending on the season, it has been achieved in some 200 to 500 kites, an extraordinary figure, which adds up to more than 3,000 over the years.
Around 51% of the captured birds were ringed in other countries, just as those tagged by the Migres Foundation have been analyzed in Europe and Africa, from Germany to Ivory Coast. Scientists from this foundation—dedicated to the study of migrations in the Strait of Gibraltar and, in general, of the most common birds in the region—have also verified that the kite molts during migration, something very unusual given the energy expenditure involved during such a critical period.
If you're interested in this topic, don't miss this year's third International Congress on Bird Migration and Global Change, which will coincide with the post-nuptial migration of black kites and will take place from September 3rd to 5th at the International Center for Bird Migration (CIMA), run by the Migres Foundation in Tarifa. Registration for the event is open until August 20th.
In the activities we offer from Explore Nature, We'll show you many details and aspects of different species, introducing children to how life develops in nature. We hope you find it interesting.
