Each winter, birds called European rollers (Coracias garrulus) make long trips to the southernmost parts of Africa to escape Europe's cold temperatures. That's not all they are trying to escape, though. Many of their natural habitats have been destroyed by deforestation, and as these fragile birds travel ten thousand kilometers from Europe to Africa they encounter even more problems: hunters in the Mediterranean, lack of resources at resting stops and overlap with too many relatives along the way. It seems these brightly colored birds just cant seem to catch a break.
European rollers feed primarily on beetles, crickets, locusts, caterpillars, flies and spiders. However, they are also known to prey on frogs, lizards, snakes and even smaller birds. They perch on high branches to search for potential prey and may even follow farmers as they plow, knowing that a tasty treat or two might be uneartherd. European rollers mate monogamously and are very protective of their breeding grounds. Generally they build their nests in a tree hole, on cliffs or riverbanks. Between May and June, females can lay upwards of seven eggs, which they then incubate for the next 17 to 19 days. After the chicks hatch, they develop feathers within 25 to 30 days but remain under their parents' care for another three weeks. Recently, however, agriculture has led to the loss of trees and hedges which provide potential nest sites and perches for hunting, and pesticides killed off their preferable source of food.
For their recent study, researchers from the Spanish Foundation for Science and Technology (FECYT) used geolocators and satellite transmissions to follow the birds along their migratory routes for the first time after fitting thirty four of the birds with tracking devices. In doing so, they found that after the birds breed in Europe, they cross the Mediterranean using a variety of routes but when they reach Sub-Saharan Africa, they rest for a short time before continuing their journey further south. In total, the migratory birds cover close to ten thousand kilometers, according to a news release. When spring rolls around, they begin the long journey back home. (Scroll to read more...)
This study has allowed researchers to "uncover migration routes, resting areas and wintering grounds in addition to the degree of migratory connectivity in different populations of this species," Deseada Parejo, co-author of the study from the University of Extremadura in Spain, explained. "Migratory connectivity represents the degree to which specimens from the same breeding population winter together. Thus, a high connectivity indicates that specimens from different breeding populations practically do not mix together at wintering grounds."
Researchers discovered that European rollers from Western Europe had a low rate of connectivity. Researchers considered this to be a "positive" indication that not all migrating birds are sensitive to local habitat losses at wintering grounds. However, rollers from Eastern Europe ran into each other more frequently and exhibited a greater sensitivity to changes in the local habitat during the winter, researchers noted in their study.
This will help researchers locate specific areas that pose threats to wintering European rollers, so that conservationists can better protect the threatened species. Their findings were recently published in the Diversity and Distributions journal.
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