Risk-taking behavior, urbanization and the pace of life in birds
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Despite growing appreciation of the importance of considering a pace-of-life syndrome (POLS) perspective to understand how animals interact with their environment, studies relating behavior to life history under altered environmental conditions are still rare. By means of a comparative analysis of flight initiation distances (i.e., the distance at which an animal takes flight when a human being is approaching) across > 300 bird species distributed worldwide, we document here the existence of a POLS predicted by theory where slow-lived species tend to be more risk-averse than fast-lived species. This syndrome largely emerges from the influence of body mass, and is highly dependent on the environmental context. Accordingly, the POLS structure vanishes in urbanized environments due to slow-lived species adjusting their flight distances based on the perception of risk. While it is unclear whether changes in POLS reflect plastic and/or evolutionary adjustments, our findings highlight the need to integrate behavior into life history theory to fully understand how animals tolerate human-induced environmental changes.
Animals can often respond to changing environmental conditions by adjusting their behavior. However, the degree to which different species can modify their behavior depends on their life history strategy and on the environmental context. Species-specific perception of risk is a conspicuous example of adjustable behavior tightly associated with life history strategy. While there is a general tendency of higher risk aversion in rural than city-dwelling birds, it is dependent on the species’ life history strategy. Slow-lived species are more prone to adjust their flight initiation distances based on the perception of risk, allowing humans to approach closer in urban than rural environments. Behavior must therefore be taken into account together with life history to reliably assess species’ vulnerability at the face of ongoing environmental change.
KeywordsLife history theory Phenotypic plasticity Human-induced rapid environmental changes Learning
We wish to thank Melanie Dammhahn, Denis Réale, Niels Dingemanse, and Petri Niemela for kindly inviting us to the workshop “Towards a general theory of the pace-of-life syndrome” funded by Volkswagen Foundation—VolkswagenStiftung, which stimulated the discussions that prompted the present study, and Niels Dingemanse and three reviewers for insightful comments in previous versions of the manuscript.
DS was supported by the project CGL2013-47448-P from the Spanish Government, AGV by project 2013–4834 from the Swedish Research Council and project IA201716 from PAPIIT, UNAM, IMC by the Fonds de Recherches du Quebec—Nature et Technologies (FQRNT) programme and by Harvard University, and LZG was supported by funds from The Ministry of Economy and Competitiveness (Spain) (CGL2015-70639-P) and The National Research, Development and Innovation Office (Hungary) (K-115970).
Compliance with ethical standards
The study was conducted in accordance with the current laws in all visited countries. We recorded FID by approaching birds in the field until they flew away. However, this activity is similar to what birds experience when people walk around in urban environments, and there are no known negative effects of such activities on the behavior of birds.
Conflict of interest
The authors declare that they have no conflicts of interest.
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