In group-living species, social stability is an important trait associated with the evolution of complex behaviours such as cooperation. While the drivers of stability in small groups are relatively well studied, little is known about the potential impacts of unstable states on animal societies. Temporary changes in group composition, such as a social group splitting and recombining (i.e. a disturbance event), can result in individuals having to re-establish their social relationships, thus taking time away from other tasks such as foraging or vigilance. Here, we experimentally split socially stable groups of captive zebra finches (Taeniopygia guttata), and quantified the effects of repeated disturbance events on (1) group foraging efficiency, and (2) co-feeding associations when subgroups were recombined. We found that the efficiency of groups to deplete a rich, but ephemeral, resource patch decreased after just a single short disturbance event. Automated tracking of individuals showed that repeated disturbances reduced efficiency by causing social relationships to become more differentiated and weaker, resulting in fewer individuals simultaneously accessing the patch. Our experiment highlights how short-term disturbances can severely disrupt social structure and group functionality, revealing potential costs associated with group instability that can have consequences for the evolution of animal societies.

Recent advances in technology allow researchers to automate the measurement of animal behaviour. These methods have multiple advantages over direct observations and manual data input as they reduce bias related to human perception and fatigue, and deliver more extensive and complete datasets that enhance statistical power. One major challenge that automation can overcome is the observation of many individuals at once, enabling whole‐group or whole‐population tracking. We provide a detailed description of an automated system for tracking birds. Our system uses printed, machine‐readable codes mounted on backpacks. This simple, yet robust, tagging system can be used simultaneously on multiple individuals to provide data on bird identity, position and directionality. Furthermore, because the backpacks are printed on paper, they are very lightweight. We show that our method is reliable, relatively easy to implement and monitor, and with proper handling, has proved to be safe for the birds over long periods of time. We describe the deployment procedure of this system for a captive population of songbirds. We test different camera options, and discuss their advantages and disadvantages. In particular, we highlight how using single‐board computers to control the frequency and duration of image capture makes this system affordable and adaptable to a range of study systems and research questions. The ability to automate the measurement of individual positions has the potential to significantly increase the power of both observational and experimental studies. The system can capture both detailed interactions (using video recordings) and repeated observations (e.g. once per second for the entire day) of individuals over long timescales (months or potentially years). This approach opens the door to tracking life‐long relationships among individuals, while also capturing fine‐scale differences in behaviour.

Highlights d We conducted a cultural evolution experiment using captive great tits d Gradual replacement of individuals promoted the spread of efficient cultural variants d Immigrants played a role as adopters rather than innovators of efficient variants d Turnover might be a general mechanism in the cultural evolution of efficiency

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121. Recent advances in technology allow researchers to automate the measurement of animal 13 behaviour. These methods have multiple advantages over direct observations and manual data 14 input as they reduce bias related to human perception and fatigue, and deliver more extensive 15 and complete data sets that enhance statistical power. One major challenge that automation 16 can overcome is the observation of many individuals at once, enabling whole-group or whole-17 population tracking. 18 2. We provide a detailed description for implementing an automated system for tracking birds. Our 19 system uses printed, machine-readable codes mounted on backpacks. This simple, yet robust, 20 tagging system can be used simultaneously on multiple individuals to provide data on bird 21 identity, position and directionality. Further, because our codes and backpacks are printed on 22 paper, they are very lightweight. 23 3. We describe the implementation of this automated system on two flocks of zebra finches. We 24 test different camera options, and describe their advantages and disadvantages. We show that 25 our method is reliable, relatively easy to implement and monitor, and with proper handling, has 26 proved to be safe for the birds over long periods of time. Further, we highlight how using single-27 . CC-BY-NC-ND 4.0 International license It is made available under a (which was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint . http://dx.doi.org/10.1101/201590 doi: bioRxiv preprint first posted online Oct. 11, 2017; board computers to control the frequency and duration of image capture makes this system 28 affordable, flexible, and adaptable to a range of study systems. 29 4. The ability to automate the measurement of individual positions has the potential to 30 significantly increase the power of both observational and experimental studies. The system can 31 capture both detailed interactions (using video recordings) and repeated observations (e.g. once 32per second for the entire day) of individuals over long timescales (months or potentially years). 33This approach opens the door to tracking life-long relationships among individuals, while also 34 capturing fine-scale differences in behaviour. 35 36 Introduction 37

Culturally transmitted communication signals – such as human language or bird song – can change over time through cultural drift, and the resulting dialects may consequently enhance the separation of populations. However, the emergence of song dialects has been considered unlikely when songs are highly individual-specific, as in the zebra finch (Taeniopygia guttata). Here we show that machine learning can nevertheless distinguish the songs from multiple captive zebra finch populations with remarkable precision, and that ‘cryptic song dialects’ predict strong assortative mating in this species. We examine mating patterns across three consecutive generations using captive populations that have evolved in isolation for about 100 generations. We cross-fostered eggs within and between these populations and used an automated barcode tracking system to quantify social interactions. We find that females preferentially pair with males whose song resembles that of the females’ adolescent peers. Our study shows evidence that in zebra finches, a model species for song learning, individuals are sensitive to differences in song that have hitherto remained unnoticed by researchers.

Culturally transmitted communication signals, such as human language or bird song, can change over time through a process of cultural drift, and may consequently enhance the separation of populations, potentially leading to reproductive isolation. Local song dialects have been identified in bird species with relatively simple songs where individuals show high cultural conformity. In contrast, the emergence of cultural dialects has been regarded as unlikely for species with more variable song, such as the zebra finch (Taeniopygia guttata). Instead, it has been proposed that selection for individual recognition and distinctiveness may lead to a complete spread across the space of acoustic and syntactical possibilities. However, another possibility is that analytical limitations have meant that subtle but possibly salient group differences have not yet been discovered in such species. Here we show that machine learning can distinguish the songs from multiple captive zebra finch populations with remarkable precision, and that these cryptic song dialects drive strong assortative mating in this species. We studied mating patterns across three consecutive generations using captive populations that have evolved in isolation for about 100 generations. Cross-fostering eggs within and between these populations and quantifying social interactions of the resulting offspring later in life revealed that mate choice primarily targets cultural traits that are transmitted during a short developmental time window. Detailed social networks showed that females preferentially approached males whose song resembled that of their adolescent peers. Our study shows that birds can be surprisingly sensitive to cultural traits for mating that have hitherto remained cryptic, even in this well-studied species that is used as a model for song-learning.

Parasites can impact the behavior of animals and alter the interplay with ecological factors in their environment. Studying the effects that parasites have on animals thus requires accurate estimates of infections in individuals. However, quantifying parasites can be challenging due to several factors. Laboratory techniques, physiological fluctuations, methodological constraints, and environmental influences can introduce measurement errors, in particular when screening individuals in the wild. These issues are pervasive in ecological studies where it is common to sample study subjects only once. Such factors should be carefully considered when choosing a sampling strategy, yet presently there is little guidance covering the major sources of error. In this study, we estimate the reliability and sensitivity of different sampling practices at detecting two internal parasites— Serratospiculoides amaculata and Isospora sp.—in a model organism, the great tit Parus major . We combine field and captive sampling to assess whether individual parasite infection status and load can be estimated from single field samples, using different laboratory techniques—McMaster and mini‐FLOTAC. We test whether they vary in their performance, and quantify how sample processing affects parasite detection rates. We found that single field samples had elevated rates of false negatives. By contrast, samples collected from captivity over 24 h were highly reliable (few false negatives) and accurate (repeatable in the intensity of infection). In terms of methods, we found that the McMaster technique provided more repeatable estimates than the mini‐FLOTAC for S. amaculata eggs, and both techniques were largely equally suitable for Isospora oocysts. Our study shows that field samples are likely to be unreliable in accurately detecting the presence of parasites and, in particular, for estimating parasite loads in songbirds. We highlight important considerations for those designing host–parasite studies in captive or wild systems giving guidance that can help select suitable methods, minimize biases, and acknowledge possible limitations.