Informationsgebrauch in einer unvorhersehbaren Umwelt: eine Fallstudie an freilebenden Zebrafinken
Zusammenfassung der Projektergebnisse
Information is central to adaptation. Collecting information can help reduce uncertainty and make adaptive decisions. Individuals can collect information by trial-and error (personal information) and/or from observing other individuals (social information). Given the importance of information use for almost all aspects of life, it is important to understand information use and decision-making, especially by individuals in their natural habitat. Where and when individuals reproduce are important decisions. Thus, individuals should invest considerable effort into information gathering before making reproductive decisions. In species living in temperate zones, with predictable environmental conditions and fixed schedules for reproduction caused by seasonality, individuals often visit each other’s breeding site to prospect on conspecific breeding success. Experimental evidence suggests that this social information serves as a cue for the quality of the site and is used by a prospector for making its own future breeding decisions. In contrast to temperate zones, little is known about information use in unpredictable environments. The aim of this project was to shed first light into information use in a less predictable environment, the arid zone of Australia, using wild zebra finches as model species. Zebra finches are opportunistic breeders that can initiate breeding as soon as environmental conditions become favourable. Zebra finches breed in loose colonies with low levels of synchrony. We recorded temporal and spatial prospecting patterns of >200 zebra finches to conspecific nests over two months each in two years. Adults frequently prospected on nest boxes, primarily at those that were at early or late breeding stages (pre-fledging) and large broods. To understand the mechanisms underlying the attraction of prospectors to large broods, we experimentally tested whether prospectors are attracted by begging calls and discriminate between calls of smaller and larger broods. As predicted, zebra finches were primarily attracted to playback recordings of begging calls of large broods. Visual cues mimicking variation in earlier breeding stages did not influence prospecting patterns during the experiment. This study provides the first experimental evidence that prospectors are attracted to acoustic cues and that they might use those to pre-identify large broods at late breeding stages (i.e. a time when the brood size should be a good indicator of the actual reproductive success). Given the results from above studies, we tested whether social information gathered during prospecting visits is used to make breeding decisions about where to breed and how much to invest into a brood. We carried out a large clutch and brood size manipulation using ca. 300 nests to experimentally create perceived high- and low-quality areas where either all breeding pairs received large or small clutches. Based on the decisions of new breeders, we assessed whether the zebra finches relied on social information. Neither the number of initiated nest or sizes of newly laid clutches were affected by the manipulation, suggesting that the birds did not rely on the social information provided. The birds might have instead used an opportunistic breeding strategy, investing as much as possible per brood. Our results suggest for the first time that decision-making in unpredictable environments differs from decision-making in more predictable environments. In another experiment we identified a mechanism underlying prospecting peaks during early breeding stages: in fluctuating environments, social information gathered from prospecting might serve as a cue for temporal coordination. In an experiment, we allowed pairs to choose to breed next to active nest boxes of different breeding stages. For the first time, we showed that birds choose to preferentially breed next to those zebra finches at early breeding stages, indeed suggesting that prospecting can be used to synchronise breeding. We could show that such synchronised breeding leads to long-term social ties in another context, social foraging. Here, we used RFID data collected from feeder stations to show with social network analyses, that those individuals that were more synchronised in one study year, had stronger social ties at feeders during breeding and that these effects carried over to the next year. Further, we demonstrated that individuals that had different early life experiences, by growing up in either small or large broods, exhibited differences in their social behaviour later in life. Birds from large broods, that experienced more competition, had more social interactions after fledging, but were less choosy in whom to interact with. This might promote early independence from harsh conditions. Overall, we used a variety of experiments to provide first insights into information use in relation to breeding decisions in a less predictable environment. The results of our project have greatly advanced our understanding of information use in a broader range of environmental conditions and might prove crucial for predicting influences of increasing unpredictable climatic events on information use, decision-making and their fitness consequences.
Projektbezogene Publikationen (Auswahl)
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(2020) Estimating food resource availability in arid environments with Sentinel 2 satellite imagery. PeerJ 8 e9209
Funghi, Caterina; Heim, René H. J.; Schuett, Wiebke; Griffith, Simon C.; Oldeland, Jens
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(2018). Wild zebra finches do not use social information from conspecific reproductive success for nest site choice and clutch size decisions. Behavioral Ecology and Sociobiology 72, 114
Brandl, HB, Griffith, SC & W Schuett
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(2019). Begging calls provide social cues for prospecting conspecifics in wild zebra finches. The Auk 136(2), 1-13
Brandl, HB, Griffith, SC, Laaksonen T & W Schuett
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(2019). Earlylife social environment predicts social network position in wild zebra finches. Proceedings of the Royal Society B 286, 20182579
Brandl, HB, Farine, DR, Funghi, C, Schuett, W & SC Griffith
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(2019). High air temperatures induce temporal, spatial, and social changes in the foraging behaviour in of wild zebra finches. Animal Behaviour 149, 33-43
Funghi, C, McCowan, LSC, Schuett, W & SC Griffith
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(2019). Wild zebra finches choose neighbours for synchronized breeding. Animal Behaviour 151, 21-28
Brandl, HB, Griffith, SC & W Schuett
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(2019). Wild zebra finches that nest synchronously have long-term stable social ties. Journal of Animal Ecology
Brandl, HB, Griffith, SC, Farine, DR & W Schuett
