Does urbanization facilitate individual recognition of humans by house sparrows?
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Wild animals living in proximity to humans may benefit from recognizing people individually and adjusting their behaviour to the potential risk or gain expected from each person. Although several urban-dwelling species exhibit such skills, it is unclear whether this is due to pre-existing advanced cognitive abilities of taxa predisposed for city life or arises specifically in urban populations either by selection or through ontogenetic changes facilitated by exposure to humans. To test these alternatives, we studied populations of house sparrows (Passer domesticus) along the urbanization gradient. We manipulated the birds’ experience (hostile or not) associated with humans with different faces (masks) and measured their behavioural responses to the proximity of each person. Contrary to our expectations, we found that while rural birds showed less fear of the non-hostile than of the hostile or an unfamiliar person, urban birds made no distinction. These results indicate that house sparrows are less able to recognize individual humans or less willing to behaviourally respond to them in more urbanized habitats with high human population density. We propose several mechanisms that may explain this difference, including reduced pay-off of discrimination due to a low chance of repeated interactions with city people, or a higher likelihood that city people will ignore them.
KeywordsUrban–rural gradient Avian cognition Human disturbance House sparrow
We thank András Péter for providing Solomon Coder. Birds were housed at Veszprém Zoo. The research was financed by the Hungarian Scientific Research Fund (OTKA, K84132). During the study, A.L. was supported by a Marie Curie Intra-European Fellowship. During the preparation of the manuscript, we were supported by the European Union, with the co-funding of the European Social Fund (S.P., B.P., and E.V. by TÁMOP-4.2.2.A-11/1/KONV-2012-0064, and V.B. by TÁMOP-4.2.4.A/2-11/1-2012-0001 ‘National Excellence Program’).
Conflict of interest
The authors declare that they have no conflict of interest.
All procedures were in accordance with Hungarian laws and licensed by the Middle Transdanubian Inspectorate for Environmental Protection, Natural Protection and Water Management (permission number: 31559/2011).
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