Ravens: Non-breeders live in highly dynamic social groups
Several recent studies have revealed that ravens are among the most intelligent species of birds and even species in general. But which factors caused the evolution of intelligence? According to a common hypothesis life in social groups can drive brain evolution especially when individuals benefit from remembering the identity of conspecifics and the interactions with them. With such knowledge, animals can avoid conflicts with higher ranking group members or develop alliances to gain better access to resources.
Researchers around Thomas Bugnyar in Austria and colleagues in France outfitted around 30 ravens with little "backpacks", which measured with GPS the position of the animal every hour. The devices were charged with solar power and the data were transmitted using the GSM network for mobile phones. During the last four years of data collection movements up to 160 kilometers per day were observed. In addition in Austria and Italy a total number of 332 ravens have been marked individually with colored rings and wing-tags and their presence patterns in two study sites were monitored over years.
Conclusion of the biologists: While some non-breeding ravens seem to stay only in relatively small areas, others may move thousands of kilometers per year. Still many ravens meet repeatedly in different locations usually at rich food sources (e.g. landfills, compost stations) and adjacent common night roosts. "We were surprised about the similarity to humans: Some people prefer to spend their entire life in a single city or even a small village, while others want to travel and explore the world. We find exactly the same in non-breeding ravens", says lead-author Matthias Loretto.
When ravens form groups they make friends but also fight heavily with other group members for access to resources. "Every time a raven joins a group of conspecifics at food sources, it can benefit from remembering previous interactions to decide who is friend or foe. The combination of social bonds within non-breeders and such a highly dynamic system might have driven brain evolution in ravens", ends Loretto.
Publication in "Scientific Reports"
Loretto, M.-C., Schuster, R., Itty, C., Marchand, P., Genero, F. and Bugnyar, T. 2017: Fission-fusion dynamics over large distances in raven non-breeders. Scientific Reports 7: XX
Published online 23 March 2017.
The University of Vienna, founded in 1365, is one of the oldest and largest universities in Europe. About 9,500 employees, 6,700 of who are academic employees, work at 19 faculties and centres. This makes the University of Vienna Austria's largest research and education institution. About 94,000 national and international students are currently enrolled at the University of Vienna. With more than 175 degree programmes, the University offers the most diverse range of studies in Austria. The University of Vienna is also a major provider of continuing education. In 2015, the Alma Mater Rudolphina Vindobonensis celebrates its 650th Anniversary. http://www.univie.ac.at
Matthias-Claudio Loretto, Ph.D.