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May 9, 2018
» Birds migrate to save energy
Birds migrate in order to optimise the balance between their energy intake and expenditure, finds a paper published online this week in Nature Ecology & Evolution. EGI postdoctoral researcher Marius Somveille and his collaborators from Cambridge and Montpellier, found that this rule also applies to non-migratory species, and provides a general explanation for the global distribution of all birds.
Around 15% of the world’s bird species migrate between breeding and non-breeding habitats, allowing them, for example, to escape food shortages and unfavourable weather during winter months. However, identifying driving factors that are common to the movement of all migratory and non-migratory species has not been possible until now. Marius Somveille and colleagues designed a model that simulates a ‘virtual world’ in which birds distribute in an optimal fashion with regards to energy. The outputs of this model match very well the true (i.e. empirical) seasonal distribution patterns of birds, in contrast to the outputs of other ‘virtual worlds’ in which species do not optimise their annual energy balance. These results provide strong support for the important role of energy efficiency in determining the way birds distribute on the planet. The authors also suggest that the model is general enough to be applicable to other highly mobile animals such as fish and whales. Link to the paper here.
March 22, 2018
» Frontiers for Young Minds – How do birds cope with losing members of their group?
‘Frontiers for Young Minds’ is a new, free-to-publish, open-access journal which aims to make the latest scientific discoveries accessible to children. Through collaboration with a primary school teacher, the EGI has made its first contribution to this new initiative in a new article explaining how great tits in Wytham Woods cope with losing members of their group. You can read the article here. The paper explains the original manuscript (published in Proceedings of the Royal Society B) which examined how wild birds adjust their social network positions in response to experimental removal of their flockmates and the consequences of this for understanding the resilience of animal societies. You can read the original article here. For more information regarding this how to contribute to making the latest scientific research accessible to children using this new sci-comm method, please visit the Frontiers for Young Minds information page here or contact Josh Firth.
August 18, 2017
» Birds choose their neighbours based on personality
Birds of a feather nest together, according to a new study which has found that male great tits (Parus major) choose neighbours with similar personalities to their own. Oxford University researchers investigated whether the personality of birds influences their social lives – in particular who they choose to nest near. The study involved analysing social network structure in a population of wild great tits at Wytham Woods over six consecutive breeding seasons. Lead author and doctoral student Katerina Johnson explained: “We found that males, but not females, were picky about personalities, with males opting for like-minded neighbours. Our results emphasise that social interactions may play a key role in animal decisions.”
This tendency for males to associate with other males of similar personality may be particularly important during the breeding season when aggression peaks. Males fiercely defend their territories and compete for opportunities to mate with females and so shyer males may avoid setting up home near bolder, more aggressive individuals. Females, however, likely choose where to nest based on the attractive qualities of males.
The results also showed that this personality assortment amongst males was not affected by local environmental conditions. “Just like students choosing their flatmate”, Katerina commented, “birds may pay more attention to who they share their living space with than simply location.” She added: “Animal personalities can influence their social organisation and humans are likewise known to form social networks based on shared attributes including personality.”
Just like us, animals display individual behavioural differences that are consistent over time and stable across different situations and so may be thought of as personality traits. The researchers test the personality of great tits by introducing them to a novel environment and measuring how they respond. Whilst bold birds are keen to actively explore their new surroundings, shy birds tend to be more hesitant and cautious.
Katerina said: “This novel research finding may also help explain the evolution of personality and why individuals in a population differ in their behaviour. Rather than one particular personality type being favoured by natural selection as ‘the best’, different behavioural strategies may be equally good depending on who you choose to be your friends and neighbours.” Perhaps by nesting closer to others of similar character, this may improve a bird’s chances of survival and passing on their genes to the next generation. For example, although having bold neighbours may result in more skirmishes between males, they might also gain a shared benefit by more effectively repelling intruders. Link to paper here.
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August 18, 2017
» Pre- and postcopulatory sexual selection favour aggressive, young males in polyandrous groups of red junglefowl
Darwin recognised that in many species, males compete intensely for mating opportunities with females. He suggested that this competition is responsible for the evolutionary diversification and elaboration of male sexual characters. We now understand that in polyandrous populations, where females mate with multiple males, this competition continues after mating as the ejaculates of different males compete to fertilise ova. However, the way in which competition before and after mating interact to shape male reproductive success and drive evolutionary responses remains unclear. Using fine-grain behavioural observations and molecular parentage data in replicate, age-structured groups of red junglefowl (Gallus gallus) we show that males that were younger and more aggressive to other males had the most female partners. Moreover, younger and more aggressive males were also the most successful at fertilising ovabecause they are able to mate with the same females more often and produce more competitive ejaculates. These results show thatâ€”in these populationsâ€” intrasexual competition after mating reinforces competition before mating, consistently promoting younger and more aggressive males across pre- and post-mating episodes of sexual selection. Link to the paper here.