The effects of urbanization and human disturbance on problem solving in juvenile house finches (Haemorhous mexicanus)
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Urbanization exposes wildlife to unfamiliar environments, including novel structures and food sources. Adapting to such anthropogenic conditions may require superior innovation and problem-solving skills (e.g., for navigating, foraging). Human presence in urban areas is a particular biotic challenge that may impact problem-solving capabilities in wildlife. Urban animals may be superior problem solvers in the face of human disturbance, due to familiarity with—and reduced fear of—humans. Alternately, rural animals may be better innovators if heightened fear responses from unfamiliar humans facilitate problem solving. Here, we studied the relationship between human disturbance, urbanization, and the ability to solve a novel foraging problem in wild-caught juvenile house finches (Haemorhous mexicanus). This songbird is a successful urban dweller and native of the American desert southwest. In captivity, juvenile finches from urban and rural populations were presented with a novel foraging task (sliding a lid covering their typical food dish) and then exposed to regular periods of high or low human disturbance over several weeks before again being presented with the task. We found that rural, high-disturbance birds showed reduced task performance compared to highly disturbed urban finches. This is consistent with the hypothesis that urban birds are less affected by human disturbance due to habituation or adaptation. Additionally, we found that the best behavioral predictor of solving success was related to visual inspection of the problem and that urban low-disturbance birds exhibited this behavior more than rural high-disturbance birds. Overall, these findings suggest that urbanization and habituation to humans predict avian response to novel problems.
As Earth’s landscapes become more urbanized, wildlife is exposed to many new anthropogenic challenges. In particular, animals in cities may have to locate food in unique ways and/or cope with increased human presence. We tested the effects of urbanization and human disturbance on problem solving in juveniles of a common urban and rural songbird (the house finch, H. mexicanus). We found that, when subjected to high levels of human disturbance, urban birds outperformed rural conspecifics on a novel foraging task (sliding open a lid to uncover food). We also found that task focus (i.e., average bout length of inspecting the dish) was an important predictor of problem solving. Our results suggest that acclimation to humans may be important for the superior behavioral performance of urban house finches and ultimately their colonization of many North American cities.
KeywordsForaging Human impacts Urban ecology Behavioral plasticity
We would like to thank Ellen Brooks, Kali Fardell, Megan Ipson, Krisjanis Malins, Sarah Shirota, Autumn Tullock, and Jeremiah Wetherby for their help in capture and care of the birds, Arizona State University Department of Animal Care and Technologies for housing the birds, and three anonymous referees for their constructive comments on an earlier version of this paper. This work was supported by Barrett, the Honors College of ASU and the ASU School of Life Sciences Undergraduate Research Grant. This material is based upon work supported by the National Science Foundation under grant number BCS-1026865, Central Arizona-Phoenix Long-Term Ecological Research (CAP LTER).
Compliance with ethical standards
All procedures performed in studies involving animals were in accordance with the ethical standards of the institution or practice at which the studies were conducted (Arizona State University). All birds were ethically treated at each step, including capture, housing, treatment, testing, and release. At the end of the study, all surviving birds were released at their original sites of capture. All applicable international, national, and/or institutional guidelines for the care and use of animals were followed during this study.
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