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    PublicationOpen Access
    Aggression and multi-modal signaling in noise in a common urban songbird
    (Springer, 2022) Department of Media and Visual Arts; Department of Psychology; Akçay, Çağlar; Yelimlieş, Alper; Önsal, Çağla; Faculty Member; Department of Media and Visual Arts; Department of Psychology; College of Social Sciences and Humanities; 272053; N/A; N/A
    Anthropogenic noise may disrupt signals used to mediate aggressive interactions, leading to more physical aggression between opponents. One solution to this problem is to switch signaling effort to a less noisy modality (e.g., the visual modality). In the present study, we investigate aggressive behaviors and signaling in urban and rural male European robins (Erithacus rubecula) in response to simulated intrusions with or without experimental noise. First, we predicted that urban birds, living in noisier habitats, would be generally more aggressive than rural birds. We also predicted that during simulated intrusions with experimental noise, robins would increase their physical aggression and show a multi-modal shift, i.e., respond with more visual threat displays and sing fewer songs. Finally, we expected the multi-modal shift in response to noise to be stronger in urban birds compared to rural birds. The results showed that urban birds were more aggressive than rural robins, but an increase in aggression with experimental noise was seen only in the rural birds. Urban but not rural birds decreased their song rate in response to noise. Contrary to the multi-modal shift hypothesis, however, there was no evidence of a concurrent increase in visual signals. These results point to a complex role of immediate plasticity and longer-term processes in affecting communication during aggressive interactions under anthropogenic noise. Significance statement Human activity has an enormous effect on wildlife, including on their social behavior. Animals living in urban areas often tend to be more aggressive than those living in rural areas, which may be due to urban acoustic noise making communication between individuals more difficult. In a study with a common songbird, the European robin, we investigated the role of urban acoustic noise in aggression and territorial communication. Urban robins were more aggressive than rural robins, and additional noise in the territory increased aggression in rural but not urban robins. While urban robins decreased their singing effort with additional noise, they did not increase visual signals concurrently. These results suggest that noise can indeed make animals behave more aggressively although the effect may depend on how noisy it is already. These results further our understanding of how human-made noise changes animal communication and social behavior.
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    PublicationMetadata only
    Elevational changes in the avian community of a mesoamerican cloud forest park
    (Wiley, 2018) Neate-Clegg, Montague H. C.; Jones, Samuel E. I.; Burdekin, Oliver; Jocque, Merlijn; Department of Molecular Biology and Genetics; Şekercioğlu, Çağan Hakkı; Faculty Member; Department of Molecular Biology and Genetics; College of Sciences; 327589
    Harboring many range-restricted and specialized species, high elevation tropical cloud forests are diverse habitats represented in many protected areas. Despite this, many such areas receive little practical protection from deforestation and land conversion. Moreover, montane species may be more sensitive to climate change owing to various factors affecting community assembly across elevational gradients. Few studies have used annual monitoring to assess how biological communities in cloud forests may be shifting in response to habitat or climate change or assessed the efficacy of protected areas in buffering these effects. We analyzed avifaunal community trends in a 10-yr dataset of constant-effort bird point-count data in a cloud forest national park in Honduras, Central America. We found that species richness and diversity increased at higher elevations, but decreased at lower elevations. Abundances of most dietary and forest-dependency groups exhibited similar trends, and many key cloud forest species shifted upslope and/or increased in abundance. Taken together, our results suggest that the avian community is moving upslope and species composition is changing. Results for species richness and diversity were similar when only nondegraded transects were considered, suggesting the role of climate change as an important driver. At lower elevations, however, many species may be negatively affected by increased habitat degradation, favoring species with low forest dependency. Continued habitat conversion and climate change could push the cloud forest bird community further upslope, potentially resulting in increased competition, mortality, and even extirpation of some species. Increased protection is unlikely to mitigate the effects of climate change.
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    PublicationOpen Access
    Song overlapping, noise, and territorial aggression in great tits
    (Oxford University Press (OUP), 2020) Avşar, Alican; Bilgin, C. Can; Department of Psychology; Akçay, Çağlar; Porsuk, Yasin Kağan; Çabuk, Dilan; Faculty Member; Teaching Faculty; Department of Psychology; College of Social Sciences and Humanities; Graduate School of Social Sciences and Humanities; 272053; N/A; N/A
    Communication often happens in noisy environments where interference from the ambient noise and other signalers may reduce the effectiveness of signals which may lead to more conflict between interacting individuals. Signalers may also evolve behaviors to interfere with signals of opponents, for example, by temporally overlapping them with their own, such as the song overlapping behavior that is seen in some songbirds during aggressive interactions. Song overlapping has been proposed to be a signal of aggressive intent, but few studies directly examined the association between song overlapping and aggressive behaviors of the sender. In the present paper, we examined whether song overlapping and ambient noise are associated positively with aggressive behaviors. We carried out simulated territorial intrusions in a population of great tits (Pares major) living in an urban-rural gradient to assess signaling and aggressive behaviors. Song overlapping was associated negatively with aggressive behaviors males displayed against a simulated intruder. This result is inconsistent with the hypothesis that song overlapping is an aggressive signal in this species. Ambient noise levels were associated positively with aggressive behaviors but did not correlate with song rate, song duration, or song overlapping. Great tits in noisy urban habitats may display higher levels of aggressive behaviors due to either interference of noise in aggressive communication or another indirect effect of noise.
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    PublicationOpen Access
    The influence of ecological traits and environmental factors on the co-occurrence patterns of birds on islands worldwide
    (Wiley, 2020) Sato, Eri; Kusumoto, Buntarou; Kubota, Yasuhiro; Murakami, Masashi; Department of Molecular Biology and Genetics; Şekercioğlu, Çağan Hakkı; Faculty Member; Department of Molecular Biology and Genetics; College of Sciences
    To understand the mechanisms shaping global species diversity patterns, we focused on species assembly of bird communities on islands, which are ideal for detecting ecological and historical processes. We tested the hypotheses that species traits and island environments interactively shape the phylogenetic structure of island bird assemblages through a variety of ecological processes: habitat filtering, in-situ speciation, extinction, dispersal limitation and competitive exclusion. We assessed the effects of species ecological traits and environment factors on the phylogenetic fields, which defined as phylogenetic distance between individual bird species and co-occurred species within each island, using phylogenetic generalized linear mixed models. Climate and isolation were the most important factors driving the co-occurrence patterns of island bird species: the species' phylogenetic fields were significantly clustered on tropical and/or isolated islands. We also found that the phylogenetic fields strongly correlated with the ecological traits especially for the diet and habitat preferences: the phylogenetic fields tended to over-disperse for granivores and species inhabiting in wetlands or coasts, while frugivores showed clustered phylogenetic fields. Moreover, mobility and body size had substantial effects on species assemblages: long-distance dispersers had clustered phylogenetic fields and small-bodied species showed overdispersed phylogenetic fields.