Until now, scientists had observed that some large birds showed a social character between individuals. But a new study shows that this peculiarity is also confirmed in smaller birds like Siskins, who are able to establish links for several years and move together over long distances. This familiarity could favor the reproduction and facilitate local adaptation processes.
The social character of geese or corvids was well known and studied by scientists. These large birds tend to create stable bonds over long periods of time.However, he had not seen in small birds, such as the Siskin (Carduelis spinus). A study published in Bird Study reveals that this species tends to travel in groups for several years and across long distances.
So far, researchers at the Natural Science Museum of Barcelona, who leads the work had found that females prefer to mate with Siskins known captive males. But there was toshow that in nature these birds live for periods of time long enough to interact and know each other.
“In this paper we show how the Siskin can maintain stable relations group for periods of several years, moving together at distances of over 1,000 km,” notes Juan Carlos Senar, lead study author and scientist at the museum.
The researchers used the records of the European Union for Bird Ringing (EURING) European -institution charge of banding and tracking birds – to examine data Siskins 42,707 registered between 1907 and 2011. To respond more accurately, experts they limited the study to the birds that traveled a distance of over 50 km from their place of banding, a figure that exceeds the maximum distance that these birds often travel in one day (10-40 km).
The results showed that the Siskins can stay together in the same group up to four years and can travel with other individuals distances up to 1,300 km. As for the type of group, the records showed they could be both same-sex and mixed.
“The important thing is that several groups of individuals traveling together hundreds of kilometers were detected and they were both a male and a female (potential partners) and copies of the same sex, which implies that the associations were not only partners, but they could also be groups of friends with a social bond, “notes Senar.
Flying at the same place is not coincidence
So far, some studies have shown a marked sociability in small birds like the American Siskin (Carduelis pinus) and sicerín Linnet (Acanthis flammea), but the studies were conducted in the same winter, and therefore travel distances were relatively small and lasted only a few months.
Senar and his team wanted to replicate these results in the Siskin, using shifts throughout the life period and throughout the life of an individual. “An additional importance of having carried out the work with Siskins is that this species, unlike the goldfinches (Carduelis carduelis) or verderones (Carduelis chloris), is nomadic, so that every year his people move to a different site” , says the scientist.
Therefore, “if two individuals together hundreds of kilometers from where they were first captured is recaptured, it is not because the two go into hibernation at the same site independently and simply match, but necessarily have had to move together “explains the researcher.
The study also reveals that individuals prefer to mate with others who are familiar. This may be an important mechanism for local adaptation. To this end, the requirement is that individuals interact for long periods of time, which, as evidenced by the work, also meet these small birds.