Many species rely on information-bearing cues from both conspecific and heterospecific group members to locate foraging resources. In North America, mixed-species foraging groups of birds are particularly prevalent in winter when food resources are scarce. In such mixed-species flocks, calls produced by different members of the flock can have the effect of initiating flock formation. However, the details of how different calls lead to the recruitment of conspecific and heterospecific flock members are often lacking. We examined the effect of calls on arrival patterns of multiple species using novel feeders coupled with playback stimuli from (1) a nuclear species, the black-capped chickadee, (2) a satellite species, the white-breasted nuthatch, or (3) white noise; and monitored birds using videos and radio frequency identification (RFID) loggers. Overall, black-capped chickadee calls led to mixed-species flocking birds discovering feeders faster and attracted more birds. We found the strongest effect of chickadee calls on the arrival of conspecifics and a weaker effect on heterospecifics (i.e., white-breasted nuthatches and downy woodpeckers). In contrast, the arrival of American goldfinches, another common feeder species that does not participate in mixed-species flocks, was affected by temperature but not by playback stimuli. Our results indicate a differential response from receivers to vocalizations of species that play distinct functional roles in mixed-species flocks. These findings suggest a positive effect of chickadee calls on flock recruitment and support the hypothesis that their calls facilitate social foraging in mixed-species flocks. This work extends our understanding of the functions of vocalizations and interspecific communication networks through a field experiment. Our study provides the first experimental evidence that black-capped chickadee calls recruit foragers to novel food patches, while calls of a ‘follower’ species (white-breasted nuthatch) do not. We found that this recruitment effect is stronger for conspecifics and weaker for ‘follower’ species of mixed-species flocks, while a species that does not join mixed-species flocks was not affected. Our results hold for both the latency for species to arrive at novel feeders, as well as the number of unique birds arriving during the experimental period. Our study provides empirical support for the functional utility of black-capped chickadee calls in a foraging context and helps delineate the extent of a communication network within North American winter mixed-species flocks.

Delayed dispersal is a critical first step in the formation of both cooperative breeding and family-living groups. However, disentangling the multiple and potentially co-occurring factors that influence the dispersal of young individuals is often difficult and can require several data sources. We combine data from a long-term mark-recapture study and field experiments to address the patterns, fitness consequences, and proximate causes of delayed dispersal in the splendid fairywren (Malurus splendens melanotus). Splendid fairywren males remained as helpers more often, for more years, and settled closer to their natal territories than females. We found that the number of years males spent as helpers was positively correlated with persistence (a proxy for survival) within the population, illustrating a fitness benefit for delaying dispersal. By experimentally producing breeding vacancies for young males, we tested whether male-biased sex ratios and limited breeding opportunities constrained dispersal in this system. Only half of the vacancies created were filled, and dispersal took, on average, approximately three days. These findings illustrate that ecological constraints, benefits of philopatry, and life history may all be acting within the same system to shape dispersal patterns. Delayed dispersal is a major life decision for individuals in cooperatively breeding species. Splendid fairywren males are more likely to be helpers, spend more time as helpers, and settle much closer to their natal territories than females. Young males who became breeders persisted in the population longer if they had spent one or more years as a helper. When given the opportunity to disperse, young males disperse only half the time, suggesting that a lack of breeding opportunities is insufficient to explain delayed dispersal alone; instead, delayed dispersal in male splendid fairywrens is likely shaped by a combination of factors, including the availability of breeding vacancies, habitat familiarity, and fitness benefits gained from group living.

Understanding and predicting population responses to climate change is a crucial challenge. A key component of population responses to climate change are cases in which focal biological rates (e.g. population growth rates) change in response to climate change due to non-compensatory effects of changes in the underlying components (e.g. birth and death rates) determining the focal rates. We refer to these responses as non-compensatory climate change effects. As differential responses of biological rates to climate change have been documented in a variety of systems and arise at multiple levels of organization within and across species, non-compensatory effects may be nearly ubiquitous. Yet, how non-compensatory climate change responses combine and scale to influence the demographics of populations is often unclear and requires mapping them to the birth and death rates underlying population change. We provide a flexible framework for incorporating non-compensatory changes in upstream rates within and among species and mapping their consequences for additional downstream rates across scales to their eventual effects on population growth rates. Throughout we provide specific examples and potential applications of the framework. We hope this framework helps to enhance our understanding of and unify research on population responses to climate change.

Behavioural plasticity can modulate the costs and benefits of sociality and thus may play a prominent role in mediating competition and facilitation during social interactions in mixed-species groups. However, investigations of assembly patterns of mixed-species groups typically treat species' behavioural attributes as static rather than dynamic features that can change in social contexts. We investigate four axes of behavioural plasticity that may modulate interactions within mixed-species groups: (1) species' selective preference for joining certain groups, (2) species' ability to flexibly change their behaviour in response to groupmates' behaviour and (3) shifts and/or (4) flexibility of species' niche breadth resulting in either shrinking or expansion when foraging with conspecifics versus when foraging with heterospecifics. We assess variation in these axes of behavioural plasticity in an Australian mixedspecies avian community. All species had selective preferences for flocks of certain strata, and some flexibly matched their flockmates' foraging strata. Three species exhibited patterns of niche shift, and one species showed niche expansion. These findings suggest that species converge in strata in mixed-species flocks despite the potential for increased competition and emphasize that species can plastically react to changes in their social environment in numerous ways. Acknowledgment of such plasticity is likely integral to understanding the nuances of heterospecific interactions. (c) 2024 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Climate change has contributed to increased wildfires1,2. Wildfire smoke exposes wildlife to hazards and mortality from particulate matter on a scale larger than the area impacted by fire3,4. Using automated radiotelemetry, we illustrate how smoky conditions are associated with changes in behavior of acorn woodpeckers (Melanerpes formicivorus), a flagship species of oak (Quercus spp.) savannas of western North America. On smoky days, birds spent more time at their home territory and reduced visitation to others, especially to distant territories. Associations between birds decreased, and individuals were less assorted by group in co-visitation networks, suggesting less inter-individual coordination on smoky days. We show that between 2016 and 2020, ∼14% of the acorn woodpecker population in the US experienced fire, potentially exposing on average 89.42% of the range to atmospheric smoke annually. These findings highlight how potential effects of smoke on animal behavior may be widespread and exacerbate negative impacts of increasingly common "megafires", even in fire-adapted ecosystems.

Avian mixed-species flocks are ubiquitous across habitats and a model for studying how heterospecific sociality influences the behavior and composition of animal communities. Here, we review the literature on mixed-species flocks and argue that a renewed focus on individual-level interactions among flock members can transform our understanding of this iconic, avian social system. Specifically, we suggest that an individual perspective will further our understanding of (1) how inter- and intraspecific variation in flock participation links to fitness costs and benefits, (2) the implications of familiarity between individuals in structuring mixed-species flock communities, and (3) how social roles within mixed-species flocks are related to social behavior within and across species. We summarize studies that use an individual perspective in each of these areas and discuss knowledge from conspecific social behavior to posit more broadly how individuals may shape mixed-species flocks. We encourage research approaches that incorporate individual variation in traits, relationships, and social roles in their assessment of mixed-species flocking dynamics. We propose that the analysis of individual variation in behavior will be particularly important for explicitly identifying fitness outcomes that led to the evolution of mixed-species flocks, which in turn affect community structure and resilience. Lay Summary center dot Across the world, many birds form mixed-species flocks that serve as information centers, facilitating foraging, and anti-predation behaviors for multiple species. Such social groups provide a prime example of how sociality can extend beyond species boundaries. center dot Most research on this topic focuses on species-level questions (e.g., how different species fill different roles in the flock) without accounting for the importance of individual-level traits and relationships in mixed-species flocks. center dot We argue that an increased focus on the individuals in mixed-species flocks is needed to understand how flock participation is linked to the evolution of traits and behaviors, how social relationships matter in interactions between species, and to reveal hidden social structure at the level of ecological communities. center dot We demonstrate how techniques such as social network analysis can be used in conjunction with experiments and observations of individuals to explore the importance of individual variation and social recognition in the social dynamics of mixed-species flocks.

Cooperatively breeding species exhibit a range of social behaviours associated with different costs and benefits to group living, often in association with different environmental conditions. For example, recent phylogenetic studies have collectively shown that the evolution and distribution of cooperative breeding behaviour is related to the environment. However, little is known about how environmental variation may drive differences in social systems across populations within species, and how the relationship between environmental conditions and sociality may differ across species. Here, we examine variation in social group size along a steep environmental gradient for two congeneric cooperatively breeding species of fairywrens (Maluridae) and show that they exhibit opposing ecogeographic patterns. Purple-backed fairywrens, a species in which helpers increase group productivity, have larger groups in hot, dry environments and smaller groups in cool, wet environments. By contrast, superb fairywrens, a species with helpers that do not increase group productivity despite the presence of alloparental care, exhibit the opposite trend. We suggest differences in the costs and benefits of sociality contribute to these opposing ecogeographical patterns and demonstrate that comparisons of intraspecific patterns of social variation across species can provide insight into how ecology shapes social systems.

Haemosporidian parasites of birds are geographically widespread, have been detected in a phylogenetically diverse array of hosts, and have been the focus of extensive research due to both their impacts on birds and their similarity to vector-borne diseases of humans. Advances in molecular diagnostic tools have created a greater awareness of the genetic diversity of haemosporidian infections. Yet in spite of their more or less global distribution, comparatively little is known about the haemosporidians affecting birds in Australia. We screened blood from 889 birds (23 species) for haemosporidian blood parasite infections during the 2019 breeding season at Brookfield Conservation Park, South Australia. We examined the genetic (lineage) diversity of haemosporidian infections in this behaviourally and ecologically diverse host assemblage and examined the congruence between parasite and host phylogenies. We identified seven Haemoproteus mitochondrial cytochrome b lineages, five of which were novel. Four birds had simultaneous co-infections by two Haemoproteus lineages each. The Haemoproteus lineages clustered at the host family level. Two Plasmodium lineages were also identified, each of which had been previously detected in different avian host species in Australasia. We did not detect any Leucocytozoon infections in our sample. This study supplies critical baseline data on host-parasite associations in a poorly-surveyed geographic region.

Ornithologists have long been fascinated by avian hybrids and this interest has increased in recent years with advances in our understanding of the potential evolutionary consequences of hybridisation. To date there are only four published records of hybridisation between currently recognised species in the Australian fairy-wrens Malurus spp., including one involving limited gene flow between two closely related species. Here we present three new records of hybridisation among Australian fairy-wrens and provide further information on a previous report.

Mixed-species groups are hypothesized to allow animals to minimize competitive interactions and maximize facilitative interactions. Individuals’ participation in mixed-species groups may reduce rates of competition and increase the social information available about predators or food availability. Behavioral plasticity may further increase these benefits as plastic species alter their rates of niche overlap with group mates. We investigate two axes of behavioral plasticity that may modulate how species interact with group mates in mixed-species groups—flexibility and selectivity. Specifically, we assess avian species’ patterns of selective preferences for participation in flocks of certain strata and whether behavioral flexibility in foraging strata corresponds with the foraging strata of flock mates. All species in our study maintained or increased their foraging strata overlap with flock mates, supporting the hypothesis that facilitation plays an important role in flock formation. Notably, the methods that species used varied: some species moved closer to flock mates via flexibly matching their flock mates’ behavior, some showed selectivity for flocks of certain stratums, and others did both. Ultimately, we show that species balance facilitative and competitive interactions with flock mates via multiple methods and that consideration of behavioral plasticity is integral to understanding the nuances of mixed-species flock interactions.

Advances in data‐logging technologies have provided a way to monitor the movement of individual animals at unprecedented spatial and temporal scales. When used in conjunction with social network analyses, these data can provide deep insight into the structure and dynamics of animal social systems. Emergence of these new technologies demands concomitant progress in workflows to translate data streams from automated systems to social networks, based on biologically relevant metrics. Here we outline key considerations for constructing social networks from automated telemetry data. We highlight the need for paying particular attention to the spatial arrangement of receiver stations with respect to the ecology of study system and developing appropriate criteria for quantifying associations. We provide a case study for constructing social networks from automated telemetry data collected over 1 month during a study of acorn woodpeckers Melanerpes formicivorus , a cooperatively breeding bird. The data consisted of detections of known birds near receiver stations placed within core areas of group territories. We use this system to demonstrate how to build social networks to investigate biological questions about patterns of associations between group members and territory visitors across the landscape.

There are very few reports on mortality of young southern hairy-nosed wombats. We describe the appearance of six young wombats that died when rainfall was well below average in 2017–19. Some of the wombats appeared malnourished, and most died around the age of weaning, which we conclude is a vulnerable time for them. A crude and lower estimate of the mortality of wombats born in 2016 was 31%.

Abstract Historically, bird song complexity was thought to evolve primarily through sexual selection on males; yet, in many species, both sexes sing and selection pressure on both sexes may be broader. Previous research suggests competition for mates and resources during short, synchronous breeding seasons leads to more elaborate male songs at high, temperate latitudes. Furthermore, we expect male–female song structure and elaboration to be more similar at lower, tropical latitudes, where longer breeding seasons and year‐round territoriality yield similar social selection pressures in both sexes. However, studies seldom take both types of selective pressures and sexes into account. We examined song in both sexes in 15 populations of nine‐fairy‐wren species (Maluridae), a Southern Hemisphere clade with female song. We compared song elaboration (in both sexes) and sexual song dimorphism to latitude and life‐history variables tied to sexual and social selection pressures and sex roles. Our results suggest that song elaboration evolved in part due to sexual competition in males: male songs were longer than female songs in populations with low male survival and less male provisioning. Also, female songs evolved independently of male songs: female songs were slower paced than male songs, although only in less synchronously breeding populations. We also found male and female songs were more similar when parental care was more equal and when male survival was high, which provides strong evidence that sex role similarity correlates with male–female song similarity. Contrary to Northern Hemisphere latitudinal patterns, male and female songs were more similar at higher, temperate latitudes. These results suggest that selection on song can be sex specific, with male song elaboration favored in contexts with stronger sexual selection. At the same time, selection pressures associated with sex role similarity appear to favor sex role similarity in song structure.

1. Advances in datalogging technologies have provided a way to monitor the movement of individual animals at unprecedented spatial and temporal scales, both large and small. When used in conjunction with social network analyses, these data can provide insight into fine scale associative behaviors. The variety of technologies demand continuous progress in workflows to translate data streams from automated systems to social networks, based on biologically relevant metrics. 2. Here we present a workflow for generating flexible association matrices from automated radio-telemetry data that can be parsed into both spatial and temporal dimensions. These can then be used to generate and compare social networks across space and time. 3. We illustrate this workflow using data collected from an automated telemetry study of acorn woodpeckers (Melanerpes formicivorus), a cooperatively breeding bird. The data were collected continuously over two years at base stations placed within social group territories. We use this system to demonstrate how this flexible data structure can be used to answer a number of biological questions, specifically 1) how assortative are social associations at the population scale, 2) how do association patterns among territory visitors vary across territories, 3) and how does seasonality affect assortative affiliation within groups? 4. This flexible method allows one to generate social networks that can be used to ask a variety of biological questions pertinent to a wide range of animal systems, exploiting the investigative power that can be gained by using automated radio-telemetry in conjunction with social network analyses.

Demographic processes play a key role in shaping the patterns of social relations among individuals in a population. Social network analysis is a powerful quantitative tool for assessing the social structure formed by associations between individuals. However, demographic processes are rarely accounted for in such analyses. Here, we summarize how the structure of animal social networks is shaped by the joint effects of social behavior and turnover of individuals and suggest how a deeper understanding of these processes can open new, exciting avenues for research. Death or dispersal can have the direct effect of removing an individual and all its social connections, and can also have indirect effects, spurring changes in the distribution of social connections between remaining individuals. Recruitment and integration of juveniles and immigrant into existing social networks are critical to the emergence and persistence of social network structure. Together, these behavioral responses to loss and gain of social partners may impact how societies respond to seasonal or catastrophic turnover events. The fitness consequences of social position (e.g., survival and reproductive rates) may also create feedback between the social network structure and demography. Understanding how social structure changes in response to turnover of individuals requires further integration between long-term field studies and network modeling methods. These efforts will likely yield new insights into the connections between social networks and life history, ecological change, and evolutionary dynamics.

Cooperative breeding, in which auxiliary group members help rear related, but nondescendent young, is often explained by kin selection. Reproductive monogamy is predicted in cooperatively breeding systems, as monogamy increases intragroup relatedness and maximizes auxiliary inclusive fitness. While monogamy is observed across many systems, including eusocial insects and cooperatively breeding mammals, some cooperatively breeding birds exhibit high rates of extrapair paternity. Here we quantify paternity and examine the role of auxiliaries on extrapair paternity in the highly cooperative variegated fairy-wren, Malurus lamberti, a species with both male and female auxiliaries. Extrapair paternity occurred in 55.4% of nests, and 39.8% of offspring were the result of extrapair matings. The presence of both male and female auxiliaries had a positive relationship with the percentage of within-pair young sired by dominant males, however, the presence of male auxiliaries had a stronger impact than the presence of females. The number of extrapair young sired by dominant males decreased as the number of male auxiliaries increased. The total number of young sired by dominant males, however, was not predicted by group size or relatedness to their social partner, nor did group composition or relatedness to the breeding pair predict the reproductive success of subordinate males. We hypothesize that breeders use alternative reproductive strategies in the presence or absence of auxiliaries. Males and females may seek extrapair reproductive opportunities when no help is available in their group and nest survival is expected to be low. When help is available, breeders may reduce extrapair paternity, either to increase intragroup relatedness or because confidence in nest survival is high. Our data suggest that group composition is important in understanding extrapair paternity rates in cooperatively breeding birds and that variation in extrapair paternity rates may be the result of flexible breeding strategies when auxiliary presence and identity varies. (c) 2018 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Although heterospecific associations beneficial to one or both species involved (e.g. commensalisms or mutualisms) are common, it is generally assumed that interactions between species are transient and not particular to individuals. However, long-term interactions between individuals of different species do occur. In such heterospecific social groups, discrimination between heterospecific individuals may be beneficial, allowing individuals to direct beneficial or aggressive behaviors towards appropriate targets. Here, we describe heterospecific groups composed of splendid and variegated fairy-wrens (Malurus splendens and M. lamberti) and provide the first experimental evidence that recognition of heterospecific group members occurs across species. In these species, family groups live on overlapping territories and co-defend shared territories against both heterospecific and conspecific intruders. Individuals on shared territories were frequently observed traveling and foraging together. Socially dominant males of both species responded more aggressively to songs of neighboring and foreign heterospecific fairy-wrens than they did to those of their co-resident hetero-specifics. Although splendid fairy-wrens did not change their behavior when associating with heterospecifics, variegated fairy-wrens spent more time foraging, were less vigilant, had greater first-nest fledging success, and fewer extra-group young. These findings suggest heterospecific associations between these 2 species benefit the variegated fairy-wren. Our findings are novel and show that recognition and discrimination among individuals, often considered a prerequisite for conspecific cooperation, can occur across species.

Extra‐pair paternity (EPP), where offspring are sired by a male other than the social male, varies enormously both within and among species. Trying to explain this variation has proved difficult because the majority of the interspecific variation is phylogenetically based. Ideally, variation in EPP should be investigated in closely related species, but clades with sufficient variation are rare. We present a comprehensive multifactorial test to explain variation in EPP among individuals in 20 populations of nine species over 89 years from a single bird family (Maluridae). Females had higher EPP in the presence of more helpers, more neighbours or if paired incestuously. Furthermore, higher EPP occurred in years with many incestuous pairs, populations with many helpers and species with high male density or in which males provide less care. Altogether, these variables accounted for 48% of the total and 89% of the interspecific and interpopulation variation in EPP. These findings indicate why consistent patterns in EPP have been so challenging to detect and suggest that a single predictor is unlikely to account for the enormous variation in EPP across levels of analysis. Nevertheless, it also shows that existing hypotheses can explain the variation in EPP well and that the density of males in particular is a good predictor to explain variation in EPP among species when a large part of the confounding effect of phylogeny is excluded.

Abstract Behavioral shifts can initiate morphological evolution by pushing lineages into new adaptive zones. This has primarily been examined in ecological behaviors, such as foraging, but social behaviors may also alter morphology. Swallows and martins (Hirundinidae) are aerial insectivores that exhibit a range of social behaviors, from solitary to colonial breeding and foraging. Using a well‐resolved phylogenetic tree, a database of social behaviors, and morphological measurements, we ask how shifts from solitary to social breeding and foraging have affected morphological evolution in the Hirundinidae. Using a threshold model of discrete state evolution, we find that shifts in both breeding and foraging social behavior are common across the phylogeny of swallows. Solitary swallows have highly variable morphology, while social swallows show much less absolute variance in all morphological traits. Metrics of convergence based on both the trajectory of social lineages through morphospace and the overall morphological distance between social species scaled by their phylogenetic distance indicate strong convergence in social swallows, especially socially foraging swallows. Smaller physical traits generally observed in social species suggest that social species benefit from a distinctive flight style, likely increasing maneuverability and foraging success and reducing in‐flight collisions within large flocks. These results highlight the importance of sociality in species evolution, a link that had previously been examined only in eusocial insects and primates.