New research from the Universities of Cambridge and Exeter reveals for the first time that, contrary to current models used to explain the movement of flocks, the differences between bird species and social relationships between individuals play a critical role in determining the dynamics of mixed-species flocks.
The unified behaviour of bird flocks has puzzled scientists for hundreds of years. One naturalist from the turn of the century even suggested telepathy may be involved. There have since been more logical explanations, including mathematical models that show that repeated interactions among individuals following simple rules can generate coordinated group movements. However, these models usually rely on the assumption that individuals within groups are identical and interact independently, which may not reflect reality.
Jolle Jolles, a PhD student at the University of Cambridge's Department of Zoology and author of the paper, said: "Spectacular collective behaviour can be found in a large range of animal species, and we now know that often these complex coordinated group movements may be the result of individuals following simple rules. However, rarely are the individual characteristics and social relationships within them taken into account. Our research highlights that these striking displays of group behaviour are much more complex."
By analysing high-resolution photographs of mixed flocks of rooks and jackdaws (both from the corvid family), the researchers found that rather than individuals interacting in a consistent fashion throughout the flock, interactions depended on social dynamics between the different species as well as relationships within a species.
The researchers discovered that birds prefer to fly close to members of their own species, and that the larger and more dominant rooks take the lead by flying near the front of flocks. Additionally, the lifelong, monogamous pair bonds that are characteristic of both species seem to be reflected in flight, as birds often fly particularly close to a single, same-species partner.
Dr Alex Thornton, principal investigator of the Cambridge Jackdaw Project, now at the University of Exeter and author of the paper, said: "Together, our findings demonstrate that to understand the structure of groups – such as bird flocks – we need to consider the characteristics and relationships of the individuals within them."
The research, which was funded by the British Ecological Society and the BBSRC, was published in the journal Animal Behaviour.
For additional information please contact:
Genevieve Maul, Office of Communications, University of Cambridge
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Notes to editors:
1. The paper 'Heterogeneous structure in mixed-species corvid flocks in flight' will be published in the March edition of Animal Behaviour. http://dx.doi.org/10.1016/j.anbehav.2013.01.015
2. About the University of Exeter
The Sunday Times University of the Year 2012-13, the University of Exeter is a Russell Group university and in the top one percent of institutions globally. It combines world-class research with very high levels of student satisfaction. Exeter has over 18,000 students and is ranked 7th in The Sunday Times University Guide, 10th in the UK in The Times Good University Guide 2012 and 10th in the Guardian University Guide. In the 2008 Research Assessment Exercise (RAE) 90% of the University's research was rated as being at internationally recognised levels and 16 of its 31 subjects are ranked in the top 10, with 27 subjects ranked in the top 20.
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For further information:
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3. About BBSRC - BBSRC is the UK funding agency for research in the life sciences and the largest single public funder of agriculture and food-related research.
Sponsored by Government, in 2010/11 BBSRC is investing around £470 million in a wide range of research that makes a significant contribution to the quality of life in the UK and beyond and supports a number of important industrial stakeholders, including the agriculture, food, chemical, healthcare and pharmaceutical sectors.
BBSRC provides institute strategic research grants to the following:
The Babraham Institute, Institute for Animal Health, Institute for Biological, Environmental and Rural Studies (Aberystwyth University), Institute of Food Research, John Innes Centre, The Genome Analysis Centre, The Roslin Institute (University of Edinburgh) and Rothamsted Research.
The Institutes conduct long-term, mission-oriented research using specialist facilities. They have strong interactions with industry, Government departments and other end-users of their research.
For more information see: http://www.bbsrc.ac.uk
Journal
Animal Behaviour