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Universität Hamburg (2018)

Social information use in an unpredictable environment - a case study on wild zebra finches

Brandl, Hanja B.

Titre : Social information use in an unpredictable environment - a case study on wild zebra finches

Der Nutzen sozialer Information in einer fluktuierenden Umwelt - eine Fallstudie an wilden Zebrafinken

Auteur : Brandl, Hanja B.

Université de soutenance : Universität Hamburg

Grade : Doctor of Natural Sciences 2018

Résumé
The use of social information in habitat choice has often been studied in species breeding in temperate environments which underlie a relatively stable periodicity. In these highly seasonal habitats, it is a common strategy for birds, but also many species from other taxa, to prospect for high quality breeding sites, before commencing a reproductive attempt. That means that individuals visit many nests of conspecifics, or sometimes even nests of heterospecifics, and use their reproductive success as a predictor for the quality of this habitat in the future, which can enhance their fitness. This, however, requires that the quality of the habitat remains stable until the next reproductive period, which in breeders of the Northern hemisphere means the following year. If environmental conditions change meanwhile, as it can be expected in a highly fluctuating and unpredictable habitat, the predictions regarding the habitat quality might not hold true, and the social information can thus be regarded as unreliable. The aim of my thesis was to investigate whether and how social information use can be a successful and adaptive strategy in an unpredictable habitat. I performed a series of field experiment and correlational studies on a wild population of zebra finches in the Australian outback and used an electronic monitoring system (based on RFID technology) at nest boxes to monitor the prospecting activity in two consecutive years. Overall, the results of my field studies on wild zebra finches provide various new insights into the role of social information use in unpredictable habitats. I have demonstrated for the first time that high levels of prospecting activity can occur, even in fluctuating conditions and that similarities, but also differences exist to social information use in highly seasonal habitats. The role of social information in unpredictable environments might be even more complex and dynamic than previously assumed and could involve several potentially fitness enhancing mechanisms. Zebra finches are highly adapted to the harsh environment of the arid zone, and only well adapted behavioural mechanisms can explain their success and widespread occurrence across the Australian continent. The results in this thesis will hopefully facilitate and encourage more research on information use in this important model species, but also comparative studies are needed to explore the evolutionary background of information use in unpredictable habitats.

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