Wild zebra finches do not use social information from conspecific reproductive success for nest site choice and clutch size decisions
Information about the quality of local habitat can greatly help to improve an individual’s decision-making and, ultimately, its fitness. Nevertheless, little is known about the mechanisms and significance of information use in reproductive decisions, especially in unpredictable environments. We tested the hypothesis that perceived breeding success of conspecifics serves as a cue for habitat quality and hence influences breeding decisions (nest site choice and clutch size), using the zebra finch (Taeniopygia guttata) as a model species. Zebra finches breed opportunistically in the unpredictable, arid zone of Australia. They often inspect the nests of conspecifics, potentially to prospect on conspecific reproductive success, i.e., to collect social information. We conducted a clutch and brood size manipulation to experimentally create the perception of high and low quality areas. In six areas, clutch sizes of almost 300 zebra finch nests were either all increased (N = 3 areas) or reduced (N = 3 areas) throughout one breeding season. The number of breeding pairs and sizes of newly laid clutches were not significantly affected by the manipulated reproductive success of the areas. Thus, zebra finches did not use social cues for their reproductive decisions, which contrasts with findings of species in temperate zones, and could be an adaptation to the high unpredictability of their habitat. Even the personal experience of rebreeding birds did not directly affect their clutch size. Our study suggests that zebra finches employ a high level of opportunism as a key strategy for reproduction. Further, this is the first study to our knowledge using an experimental approach in the wild to demonstrate that decision-making in unpredictable natural environments might differ from decision-making in temperate environments with seasonal breeding.
Social information can help to optimize the behavior of animals. Birds in temperate climates with seasonality use breeding success of others to predict where they should breed. However, very little is known about information use in less predictable environments. In a field experiment, we created a patchy environment by increasing and decreasing brood sizes of wild zebra finches to test if social information is also used in unpredictable conditions. We found no evidence that zebra finches in the Australian outback use social information from their conspecifics when deciding on nest site and clutch size. They probably gather personal information on environmental parameters and the current availability of resources, which might be more reliable than social information.
KeywordsBrood size manipulation Decision-making Fluctuating conditions Information use Prospecting Unstable environment
We thank Anika Immer, Marie Hardenbicker, and Kathryn Peiman for valuable assistance in the field. We thank two anonymous reviewers for their constructive comments which helped to improve the quality of this manuscript. This work was supported by “Deutsche Forschungsgemeinschaft” (SCHU 2927/3-1 to WS and SCG).
Compliance with ethical standards
All applicable international, national, and/or institutional guidelines for the care and use of animals were followed. 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. The work was approved by the Macquarie University Animal Ethics Committee (Animal Research Authority 2015/017) and the Australian Bird and Bat Banding Scheme.
Conflict of interest
The authors declare that they have no conflict of interest.
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