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Breeding Behavior of the Wood Warbler in Relation to the Social Environment


Buckley Luepold, Shannon. Breeding Behavior of the Wood Warbler in Relation to the Social Environment. 2022, University of Zurich, Faculty of Science.

Abstract

Most animals exist in some type of social environment. The composition of this environment can impact diverse traits and behaviors, and is increasingly recognized as an important modulator of ecological and evolutionary processes. In this thesis, I examine the interplay between spatial and vocal behavior of male Wood Warblers and three different elements of the social environment: conspecific males, conspecific females, and closelyrelated heterospecifics. In Chapter 2, I investigate three hypotheses for conspecific attraction in male Wood Warblers (Phylloscopus sibilatrix): the habitat location cues hypothesis, the habitat quality cues hypothesis, and the female preference hypothesis. The habitat location cues hypothesis posits that the presence of conspecifics provides social information that indicates the location of potentially suitable habitat, and is thus useful during the search phase of habitat selection. The habitat quality cues hypothesis suggests that conspecific presence provides social information that the local habitat is suitable, and is thus useful during the assessment phase of habitat selection. The female preference hypothesis proposes that males are attracted to settle near conspecifics because females prefer to mate with males in aggregations. My colleagues and I used a combination of a two-year playback experiment, spatial point process models and mate choice models to test the above hypotheses. The results showed that spatial variation in habitat quality was a better predictor of male settlement patterns than proximity to simulated conspecifics, and that aggregated males were not more successful in attracting females. Taken together, the results are most consistent with the habitat location cues hypothesis. In Chapter 3, I explore the relationship between the within-season movements of male birds and mate searching. I suggest that mate searching may be a conceptual framework that can unify temporary movements associated with polyterritoriality and extra-territorial forays as well as permanent movements associated with breeding dispersal. I test four predictions derived from this framework by analyzing the relationship between emigration decisions of male Wood Warblers, ecological conditions in the current territory and mating potential in the current territory. Male choices to emigrate were strongly related to cues that mating potential in the current territory was low, as predicted by the mate searching hypothesis. In Chapter 4, I examine how mixed singing in Wood Warblers affects their ability to co-occur with their locally more abundant sister species, the Western Bonelli’s Warbler (“Bonelli’s Warbler,” P. bonelli). It has been hypothesized that an increase in interspecific acoustic similarity (e.g., via mixed singing) might facilitate co-occurrence via either an increase in competitor recognition (promoting interspecific territoriality) or reduced aggression (due to enhanced neighbor recognition). Alternatively, it has also been suggested that interspecific asymmetries in aggression (which could result from an asymmetry in acoustic similarity) cause competitive exclusion of the less aggressive species. To determine which if any of these scenarios might be occurring between Wood and Bonelli’s Warblers, I conducted a song playback experiment, calculated levels of interspecific territory overlap and determined patterns of co-occurrence at the study site level. The results were not consistent with any of the hypotheses tested, suggesting that mixed singing in Wood Warblers neither helps nor hinders co-occurrence with Bonelli’s Warblers. By considering the multi-faceted nature of the social environment, this thesis brings together diverse topics for a more comprehensive understanding of social influences on the breeding behavior of migratory songbirds. The social environment of most species has and continues to be altered by human-induced global change. Thus, it remains an ongoing and important task to try to understand the behavioral, ecological and evolutionary consequences of these changes.

Abstract

Most animals exist in some type of social environment. The composition of this environment can impact diverse traits and behaviors, and is increasingly recognized as an important modulator of ecological and evolutionary processes. In this thesis, I examine the interplay between spatial and vocal behavior of male Wood Warblers and three different elements of the social environment: conspecific males, conspecific females, and closelyrelated heterospecifics. In Chapter 2, I investigate three hypotheses for conspecific attraction in male Wood Warblers (Phylloscopus sibilatrix): the habitat location cues hypothesis, the habitat quality cues hypothesis, and the female preference hypothesis. The habitat location cues hypothesis posits that the presence of conspecifics provides social information that indicates the location of potentially suitable habitat, and is thus useful during the search phase of habitat selection. The habitat quality cues hypothesis suggests that conspecific presence provides social information that the local habitat is suitable, and is thus useful during the assessment phase of habitat selection. The female preference hypothesis proposes that males are attracted to settle near conspecifics because females prefer to mate with males in aggregations. My colleagues and I used a combination of a two-year playback experiment, spatial point process models and mate choice models to test the above hypotheses. The results showed that spatial variation in habitat quality was a better predictor of male settlement patterns than proximity to simulated conspecifics, and that aggregated males were not more successful in attracting females. Taken together, the results are most consistent with the habitat location cues hypothesis. In Chapter 3, I explore the relationship between the within-season movements of male birds and mate searching. I suggest that mate searching may be a conceptual framework that can unify temporary movements associated with polyterritoriality and extra-territorial forays as well as permanent movements associated with breeding dispersal. I test four predictions derived from this framework by analyzing the relationship between emigration decisions of male Wood Warblers, ecological conditions in the current territory and mating potential in the current territory. Male choices to emigrate were strongly related to cues that mating potential in the current territory was low, as predicted by the mate searching hypothesis. In Chapter 4, I examine how mixed singing in Wood Warblers affects their ability to co-occur with their locally more abundant sister species, the Western Bonelli’s Warbler (“Bonelli’s Warbler,” P. bonelli). It has been hypothesized that an increase in interspecific acoustic similarity (e.g., via mixed singing) might facilitate co-occurrence via either an increase in competitor recognition (promoting interspecific territoriality) or reduced aggression (due to enhanced neighbor recognition). Alternatively, it has also been suggested that interspecific asymmetries in aggression (which could result from an asymmetry in acoustic similarity) cause competitive exclusion of the less aggressive species. To determine which if any of these scenarios might be occurring between Wood and Bonelli’s Warblers, I conducted a song playback experiment, calculated levels of interspecific territory overlap and determined patterns of co-occurrence at the study site level. The results were not consistent with any of the hypotheses tested, suggesting that mixed singing in Wood Warblers neither helps nor hinders co-occurrence with Bonelli’s Warblers. By considering the multi-faceted nature of the social environment, this thesis brings together diverse topics for a more comprehensive understanding of social influences on the breeding behavior of migratory songbirds. The social environment of most species has and continues to be altered by human-induced global change. Thus, it remains an ongoing and important task to try to understand the behavioral, ecological and evolutionary consequences of these changes.

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Additional indexing

Item Type:Dissertation (cumulative)
Referees:Jenni Lukas, Pasinelli Gilberto, Kokko Hanna, Keller Lukas, Price Trevor
Communities & Collections:07 Faculty of Science > Institute of Evolutionary Biology and Environmental Studies
UZH Dissertations
Dewey Decimal Classification:570 Life sciences; biology
590 Animals (Zoology)
Language:English
Place of Publication:Zürich
Date:2022
Deposited On:26 Apr 2022 12:23
Last Modified:26 Apr 2022 12:23
Number of Pages:167
OA Status:Closed