Search

How anthropogenic change affects animal social behavior, including communication is an important question. Urban noise often drives shifts in acoustic properties of signals but the consequences of noise for the honesty of signals—that is, how well they predict signaler behavior—is unclear. Here we examine whether honesty of aggressive signaling is compromised in male urban song sparrows (Melospiza melodia). Song sparrows have two honest close-range signals: the low amplitude soft songs (an acoustic signal) and wing waves (a visual signal), but whether the honesty of these signals is affected by urbanization has not been examined. If soft songs are less effective in urban noise, we predict that they should predict attacks less reliably in urban habitats compared to rural habitats. We confirmed earlier findings that urban birds were more aggressive than rural birds and found that acoustic noise was higher in urban habitats. Urban birds still sang more soft songs than rural birds. High rates of soft songs and low rates of loud songs predicted attacks in both habitats. Thus, while urbanization has a significant effect on aggressive behaviors, it might have a limited effect on the overall honesty of aggressive signals in song sparrows. We also found evidence for a multimodal shift: urban birds tended to give proportionally more wing waves than soft songs than rural birds, although whether that shift is due to noise-dependent plasticity is unclear. These findings encourage further experimental study of the specific variables that are responsible for behavioral change due to urbanization. Soft song, the low amplitude songs given in close range interactions, is an honest threat signal in urban song sparrows. Given its low amplitude, soft songs may be a less effective signal in noisy urban habitats. However, we found that soft song remained an honest signal predicting attack in urban habitats. We also found that birds may use more visual signals (rapid fluttering of wings) in urban habitats to avoid masking from acoustic noise. [ABSTRACT FROM AUTHOR]

Eavesdropping by predators imposes a major cost on signalers, which in turn have evolved a number of strategies to deal with this cost. These strategies however, have not been well studied in the context of aggressive signaling. Here, we report an experiment on male song sparrows (Melospiza melodia) in which we experimentally increased the perceived predation risk by playing Cooper's hawk (Accipiter cooperi) calls or control Northern flicker (Colaptes auratus) calls in the midst of a simulated conspecific territorial intrusion and assessed the change in signaling strategies. We found that song sparrows clearly discriminated between the hawk call and the flicker call. Specifically, subjects decreased number of songs and wing wave displays (a visual signal of aggressive intent) and increased alarm calling during the hawk playback. However, the change in signaling behaviors did not persist when the simulated intruder resumed his challenge, despite the fact that the subjects were still alarmed as indicated by high rates of alarm calling. Additionally, we found no evidence for the eavesdropping avoidance hypothesis as an explanation for the low amplitude of soft song, the most reliable signal of aggression in this species. These results suggest that male song sparrows flexibly adjust their signaling effort in response to both the predation risk and the need to defend their territory against an intruder. [ABSTRACT FROM AUTHOR]

Information about an animal's home range (the geographical area in which it accesses resources for survival and reproduction) is vital broadly for understanding animal behavior and specifically for developing conservation management plans. Although personality traits—consistent individual differences in behavior across time and contexts—may affect an animal's home range size, we still lack a breadth of empirical studies across systems to fully appreciate this influence. Here, we tested the relationship between behavioral responses and home range size in two Darwin's finch species on Floreana Island: the critically endangered and range-restricted Medium Tree Finch (Camarhynchus pauper) and the common and widespread Small Ground Finch (Geospiza fuliginosa). Using a combination of rapid-assessment assays during both short-term captivity and in the field, we measured exploration and aggressiveness in males from both species. We then used radio telemetry to measure each bird's home range size over a week-long period. We predicted that (1) fast-exploring individuals would have larger home ranges, and (2) more aggressive individuals would have smaller home ranges. We found that Medium Tree Finches had smaller home ranges than Small Ground Finches, that exploratory behavior was positively correlated with home range size only in Small Ground Finches, and that, in both species, individuals' aggressiveness was negatively correlated with home range size, whereby the more aggressive individuals occupied smaller home ranges. We conclude that behavioral responses that align with major personality traits can predict home range size, which may provide an important tool for the conservation and management of endangered species when, for example, selecting individuals with different personality profiles for reintroduction. [ABSTRACT FROM AUTHOR]

The climate crisis and appeals to tackle it are often framed in moral terms, but few studies tested whether individual variation in moral intuitions correlate with pro-environmental behaviours that may affect the climate commons. In the present study we ask whether moral intuitions regarding harm (care and compassion), fairness, in-group loyalty, stance towards authority, and purity, as quantified by the Moral Foundations Theory, correlate with pro-environmental behaviours. Participants played 10 rounds of a public goods game framed as extraction of a mineral that affects climate commons negatively. We found that participants' extraction in the first round of the game was positively related to loyalty and authority moral foundations. Average extraction over all ten rounds of the game was negatively related to harm and positively related to loyalty moral foundations with small to moderate effect sizes. The fairness dimension was only weakly related to extraction in the first round and not related to average extraction over the entire game. Purity dimension did not relate to extraction neither in the first round nor on average. These results suggest that intrinsic factors such as moral intuitions are likely to play an important role in fostering pro-environmental behaviours to address the climate crisis. • We combined a climate commons game with a Moral Foundations Theory survey. • Harm foundation (care & compassion) positively predicts pro-environmental behaviour. • Loyalty foundation is negatively associated with pro-environmental behaviour. • Purity foundation does not correlate with extraction. • Individual variations in moral intuitions are important elements for climate policy. [ABSTRACT FROM AUTHOR]

Adaptive memory retains information that would increase survival chances and reproductive success, resulting in the survival processing effect. Less is known about whether the reliability of the information interacts with the survival processing effect. From an adaptive point, information from reliable sources should lead to better encoding of information, particularly in a survival context. In Turkish, specific linguistic components called evidentiality markers encode whether the information presented is firsthand (direct) or not (indirect), providing insight into source reliability. In two experiments, we examined the effect of evidentiality markers on recall across survival and nonsurvival (moving) contexts, predicting that the survival processing effect would be stronger for information marked with evidentiality markers indicating direct information. Results of both experiments yielded a robust survival processing effect, as the sentences processed for their relevance to survival were better remembered than those processed for their relevance to nonsurvival events. Yet the marker type did not affect retention, regardless of being tested as a between- or within-subject factor. Specifically, the survival processing effect persisted even with evidentiality markers indicating indirect information, which suggests that the processing of survival-related information may be privileged even if potentially unreliable. We discuss these results in the context of recent studies of the interaction of language with memory. [ABSTRACT FROM AUTHOR]

Abstract: Biparental care presents an interesting case of cooperation and conflict between unrelated individuals. Several models have been proposed to explain how parents should respond to changes in each other's parental care to maximize their own fitness, predicting no change, partial compensation, or matching effort as a response. Here, we present an experiment in tree swallows (Tachycineta bicolor) in which we increased the offspring provisioning of females by presenting them, but not their mates, with additional nestling begging calls using automated playbacks. We performed this experiment in two populations differing in future breeding opportunities. We found that in response to a temporary increase in female parental effort, males in the northern population (with lower future breeding opportunities and thus higher brood value) matched the increased effort, whereas males in the southern population did not. We also found that increases in parental care during playbacks were driven by the females (i.e., females initiated the increased effort and their mates followed them) in the northern population but not the southern population. These results support the idea that with incomplete information about the brood value and need, cues or signals from the partner might become important in coordinating parental care.Significance statement: Male tree swallows increase parental effort when their mates need to work harder. Using an automated system, we broadcast playback of hungry nestling calls only when the female parent was visiting the nest. In a population where the value of the current brood was high, males significantly increased their provisioning rate, much more than their partners did. Since only the females could hear the playbacks, and the begging of the nestlings did not change in response to the treatment, we suggest that either the males used their partner's feeding rate as a cue or the females may have communicated to their mates that they should work harder. These results suggest that cues or signals from the partner may be important in coordinating parental care. [ABSTRACT FROM AUTHOR]

Nesting success tends to increase with age in birds, in part because older birds select more concealed nest sites based on experience and/or an assessment of prevailing predation risk. In general, greater plant diversity is associated with more biodiversity and more vegetation cover. Here, we ask if older Darwin's finch males nest in areas with greater vegetation cover and if these nest sites also have greater avian species diversity assessed using song. We compared patterns in Darwin's Small Tree Finch (Camarhynchus parvulus) and Darwin's Small Ground Finch (Geospiza fuliginosa) as males build the nest in both systems. We measured vegetation cover, nesting height, and con- vs. heterospecific songs per minute at 55 nests (22 C. parvulus, 33 G. fuliginosa). As expected, in both species, older males built nests in areas with more vegetation cover and these nests had less predation. A novel finding is that nests of older males also had more heterospecific singing neighbors. Future research could test whether older males outcompete younger males for access to preferred nest sites that are more concealed and sustain a greater local biodiversity. The findings also raise questions about the ontogenetic and fitness consequences of different acoustical experiences for developing nestlings inside the nest. [ABSTRACT FROM AUTHOR]

Snake fungal disease (SFD) is an emerging threat to snake populations in the United States. Fungal pathogens are often associated with a physiological stress response mediated by the hypothalamopituitary-adrenal axis (HPA), and afflicted individuals may incur steep coping costs. The severity of SFD can vary seasonally; however, little is known regarding (1) how SFD infection relates to HPA activity and (2)how seasonal shifts in environment, life history, or HPA activity may interact to drive seasonal patterns of infection severity and outcomes. To test the hypothesis that SFD is associated with increased HPA activity and to identify potential environmental or physiological drivers of seasonal infection, we monitored baseline corticosterone, SFD infection severity, foraging success, body condition, and reproductive status in a field-active population of pigmy rattlesnakes. Both plasma corticosterone and the severity of clinical signs of SFD peaked in the winter. Corticosterone levels were also elevated in the fall before the seasonal rise in SF Dseverity. Severely symptomatic snakeswere inlowbody condition and had elevated corticosterone levels compared to moderately infected and uninfected snakes. The monthly mean severity of SFD in the populationwas negatively related to populationwide estimates of body condition and temperature measured in the precedentmonth and positively correlated with corticosterone levels measured in the precedent month. Symptomatic femaleswere less likely to enter reproductive bouts compared to asymptomatic females. We propose the hypothesis that the seasonal interplay among environment, host energetics, and HPA activity initiates trade-offs in the fall that drive the increase in SFD prevalence, symptomseverity, and decline in condition observed in the population through winter. [ABSTRACT FROM AUTHOR]

The fearful ape hypothesis proposes that heightened fearfulness in humans is adaptive. However, despite its attractive anthropocentric narrative, the evidence presented for greater fearfulness in humans versus other apes is not sufficient to support this claim. Conceptualization, context, and comparison are strongly lacking in Grossmann's proposal, but are key to understanding variation in the fear response among individuals and species. [ABSTRACT FROM AUTHOR]

ABSTRACT Animal acoustic communication often takes the form of complex sequences, made up of multiple distinct acoustic units. Apart from the well-known example of birdsong, other animals such as insects, amphibians, and mammals (including bats, rodents, primates, and cetaceans) also generate complex acoustic sequences. Occasionally, such as with birdsong, the adaptive role of these sequences seems clear (e.g. mate attraction and territorial defence). More often however, researchers have only begun to characterise - let alone understand - the significance and meaning of acoustic sequences. Hypotheses abound, but there is little agreement as to how sequences should be defined and analysed. Our review aims to outline suitable methods for testing these hypotheses, and to describe the major limitations to our current and near-future knowledge on questions of acoustic sequences. This review and prospectus is the result of a collaborative effort between 43 scientists from the fields of animal behaviour, ecology and evolution, signal processing, machine learning, quantitative linguistics, and information theory, who gathered for a 2013 workshop entitled, ' Analysing vocal sequences in animals'. Our goal is to present not just a review of the state of the art, but to propose a methodological framework that summarises what we suggest are the best practices for research in this field, across taxa and across disciplines. We also provide a tutorial-style introduction to some of the most promising algorithmic approaches for analysing sequences. We divide our review into three sections: identifying the distinct units of an acoustic sequence, describing the different ways that information can be contained within a sequence, and analysing the structure of that sequence. Each of these sections is further subdivided to address the key questions and approaches in that area. We propose a uniform, systematic, and comprehensive approach to studying sequences, with the goal of clarifying research terms used in different fields, and facilitating collaboration and comparative studies. Allowing greater interdisciplinary collaboration will facilitate the investigation of many important questions in the evolution of communication and sociality. [ABSTRACT FROM AUTHOR]

Recent years have seen a dramatic rise in the use of passive acoustic monitoring (PAM) for biological and ecological applications, and a corresponding increase in the volume of data generated. However, data sets are often becoming so sizable that analysing them manually is increasingly burdensome and unrealistic. Fortunately, we have also seen a corresponding rise in computing power and the capability of machine learning algorithms, which offer the possibility of performing some of the analysis required for PAM automatically. Nonetheless, the field of automatic detection of acoustic events is still in its infancy in biology and ecology. In this review, we examine the trends in bioacoustic PAM applications, and their implications for the burgeoning amount of data that needs to be analysed. We explore the different methods of machine learning and other tools for scanning, analysing, and extracting acoustic events automatically from large volumes of recordings. We then provide a step-by-step practical guide for using automatic detection in bioacoustics. One of the biggest challenges for the greater use of automatic detection in bioacoustics is that there is often a gulf in expertise between the biological sciences and the field of machine learning and computer science. Therefore, this review first presents an overview of the requirements for automatic detection in bioacoustics, intended to familiarise those from a computer science background with the needs of the bioacoustics community, followed by an introduction to the key elements of machine learning and artificial intelligence that a biologist needs to understand to incorporate automatic detection into their research. We then provide a practical guide to building an automatic detection pipeline for bioacoustic data, and conclude with a discussion of possible future directions in this field., (© 2024 The Author(s). Biological Reviews published by John Wiley & Sons Ltd on behalf of Cambridge Philosophical Society.)

Memory systems serve an adaptive function for the fitness of organisms. A good example of this is the Survival Processing Effect (SPE) which points to increased retention of information when it is processed in a survival context compared to other contexts. Survival processing may also affect metacognitive processes, by increasing confidence judgments as well as increasing metacognitive sensitivity. No previous study, however, has directly examined whether processing information for survival also has an effect on metacognitive processes. Here we ask whether SPE extends to the metacognitive system in terms of both metacognitive sensitivity and confidence bias. In Experiment 1 participants were asked to rate a list of words in terms of relevance in a survival scenario or a moving scenario. In a surprise old/new recognition test, they were given one word at a time and asked to indicate if they have rated the presented word before and state how confident they are in that choice. Surprisingly, the results did not reveal a SPE, which may have been due to high overall performance in the recognition task. In Experiment 2 we increased the level of difficulty of the memory task, which resulted in a robust SPE, but could not find this effect in metacognitive monitoring. Together, these results suggest that survival processing may not affect metacognitive processes in a reliable fashion., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)