Migratory birds with late sexual maturity become sedentary on the islands to avoid extinction of the community. This is the conclusion reached by an international team from the Higher Council for Scientific Research (CSIC) after analyzing more than 500 species of birds from around the world and comparing the behaviors between island and continental birds.
To carry out the study, scientists have analyzed the migratory patterns of 563 different species of birds from around the world, comparing the different behaviors in areas surrounded by water and in continental populations.
As explained by the CSIC researcher, Miguel Ferrer, from the Doñana Biological Station, “if the species has a short period of immaturity, typical of small species, the young return to the reproductive population, whether they are migratory or sedentary, one year after being born. For this reason, passerines, small birds, may or may not be migratory on the islands, while larger species such as large birds of prey, herons or storks, have to be sedentary to survive. “
In addition, according to the study, the difference in behavior causes population fluctuations to be greater among migratory birds than among sedentary ones. For this reason, sedentary lifestyle is basic on the islands, since large changes in the size of the community can put them in danger.
Species from around the world
This fact causes different species in different parts of the world to behave differently. For example, the booted eagle ( Aquila pennata ) in Mallorca or the Egyptian vulture in the Canary Islands are sedentary on the islands and migratory on the Iberian Peninsula. Which is repeated throughout the world with various species.
By not migrating, a genetic isolation is caused that accelerates the processes of species differentiation. As Miguel Ferrer points out, “the change in migratory behavior is a process that affects the speed with which new species of birds appear, which turns the islands into factories of biodiversity”.
The study has been led by researchers from the CSIC and has been published in the latest issue of the journal PLoS ONE.
