Wild birds recognize individual humans: experiments on magpies, Pica pica
The ability to distinguish among heterospecific individuals has been reported in only a few animal species. Humans can be viewed as a special type of heterospecifics because individuals differ widely in behavior, ranging from non-threatening to very threatening toward animals. In this study, we asked whether wild magpies can recognize individual humans who had accessed their nests. We compared the behavior of breeding pairs toward individual humans before and after the humans climbed up to the birds’ nests, and also toward climbers and non-climbers. We have evidence for (i) aggressive responses of the magpie pairs toward humans who had repeatedly accessed their nests (climbers) and a lack of response to humans who had not accessed the nest (non-climbers); (ii) a total lack of scolding responses toward climbers by magpie pairs whose nests had not been accessed; (iii) a selective aggressive response to the climber when a climber and a non-climber were presented simultaneously. Taken together, these results suggest that wild magpies can distinguish individual humans that pose a threat to their nests from humans that have not behaved in a threatening way. The magpie is only the third avian species, along with crows and mockingbirds, in which recognition of individual humans has been documented in the wild. Here, we propose a new hypothesis (adopted from psychology) that frequent previous exposure to humans in urban habitats contributes to the ability of birds to discriminate among human individuals. This mechanism, along with high cognitive abilities, may predispose some species to learn to discriminate among human individuals. Experimental tests of these two mechanisms are proposed.
KeywordsCognition Predation Individual recognition Pre-exposure effect Magpie
We are grateful to Changku Kang, Choongwon Jeong, Changsoo Yang, and Woncheol Song for serving as “non-climbers” and Kyungseon Seo, Jihyun Oh for participating in the work. We thank magpie team members Woohjung Kim, Giran Ko, and Yoonsook Lee for their continuing efforts on the breeding survey. We particularly thank Dr. Susan Lappan for linguistic help and Youngeun Jo, Hyunkyung Cha, and Soyon Hwang for providing data from the 2008 gaze experiment. We also thank Byungsoon Jang, Hongsup Shin, Heeyoon Kim, and Changseok Han for discussions and comments. PGJ thanks the Dean, Faculty, and Administration of the School of Biological Sciences, and especially Prof. Sa-Ouk Kang and Prof. Jung-Hye Roe for help, advice, and patience during his adaptation to life at a Korean University. This work was funded by the Long-term Ecological Monitoring Program on Animal Populations, Research Grant of 2007 from the Korean Ministry of Environment from Ewha Womans University, Korean Research Foundations grant No. KRF-0409-20090137, KRF-0409-20070120, National Research Foundation Grant No. NRF-2010-0029613, KRF-0409-20080118 and NRF-2010-K001149, NRF-2010-0009006, the Brain Korea 21 Project 2009, and Research Grants (3344-20090054, 3344-20080067, 3344-20070018 and 3344-20100051) from the College of Natural Sciences, Seoul National University.
Conflict of interest
The authors declare that they have no conflict of interest.
The experiments described in this report comply with the current laws of the country in which they were performed—South Korea.
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