Birds often advertise their quality to potential mates through sexual displays that complement their colorful plumage. Some species use materials to enhance their attractiveness, such as the use of colorful fruits and anthropogenic materials in the display bowers across bowerbirds. Here we report the first observations of anthropogenic materials in sexual displays by two fairy-wren species. On two separate occasions and sites, we witnessed a White-winged and Red-backed male carrying a piece of plastic as a substitute for a flower petal during a petal display, which are used across Malurus to enhance reproductive fitness. Given increasing plastic pollution globally, the use of anthropogenic materials as part of extended phenotypes in birds and other animals will likely increase and it will be important to understand the effect this has on populations. ### Competing Interest Statement The authors have declared no competing interest.

Signals in vocal communication systems range from innate to learned. Although innate and learned signals are often assumed to be independent, Darwin speculated that they could be evolutionarily related, with the former being the foundation of the latter even in our own communication system, language. Here we test this hypothesis by studying the vocal communication systems of avian hosts of brood parasites. First, we show that 21 bird species separated by approximately 53 million years of evolution produce structurally similar 'whining' vocalizations towards their respective brood parasites. Exploring the social correlates of whining vocalization production, we find that species that produce this vocalization often exist in areas with dense parasite-host networks, suggesting that its production facilitates interactions among host species. Experiments across three continents show that this vocalization is referential towards brood parasites in multiple host species, that hearing them elicits an innate rapid recruiting response, and that host species from different continents respond equally to the whining vocalizations of each other, indicating that convergent use facilitates cooperative defences across species. Our results provide an example of a referential animal vocalization for which sound production in the correct context is learned but for which hearing it elicits an innate response, representing an intermediate between innate and learned signals.

Emotions coordinate our behavior and physiological states during survival-salient events and pleasurable interactions. Even though we are often consciously aware of our current emotional state, such as anger or happiness, the mechanisms giving ...Emotions are often felt in the body, and somatosensory feedback has been proposed to trigger conscious emotional experiences. Here we reveal maps of bodily sensations associated with different emotions using a unique topographical self-report method. In ...

Cleanerfish support coral reef ecosystems by providing important services to client fishes. Cleanerfish species often coexist, but how interspecies dynamics influence cleaning networks across life-history stages remains largely unknown. Here, we investigated the effects of interspecific competition on the behaviour of two juvenile cleaner wrasses, Labroides dimidiatus and Labroides bicolor. Under competitive scenarios, L. dimidiatus exhibited higher levels of client association compared to L. bicolor, while no differences were observed under non-competitive conditions. These behavioural differences likely facilitate resource partitioning and coexistence, supporting the stability of coexisting mutualistic networks in coral reef ecosystems.

Successful breeding is a critical component of a bird’s life-history, but preferred nesting habitats remain little studied in many Australian species. In southeastern Queensland, a revegetated site shows high bird biodiversity and density, despite being dominated by invasive understory plants. Here, we describe the relative cover of grass species present (Poaceae) at our study site and determine how often Variegated Fairy-wren (Malurus lamberti) nests were built in each species during the 2023 breeding season. We found that the majority of grass cover involved invasive species. Birds used invasive grass species almost exclusively as construction substrate, and as material to build their nests. Our results suggest that invasive grass species may not have had a negative impact on the breeding habits of fairy-wrens.

Sexually-selected ornaments typically confer reproductive benefits, but ornamented and unornamented male phenotypes often co-occur in the same population. Reduced social costs are one potential compensatory benefit of unornamented male phenotypes, but few studies have tested this hypothesis in a natural context. Here we present a field-based experiment testing whether ornamented plumage carries social costs in the red-backed fairywren (Malurus melanocephalus), a small Australian songbird that exhibits delayed but flexible plumage maturation. Only one-quarter of 1-yr-old male red-backed fairywrens acquire ornamented plumage, but young ornamented males obtain greater reproductive success than males that retain brown, female-like plumage. We experimentally tested whether ornamented plumage is associated with social costs by implanting brown 1-yr-old males with testosterone to induce molt into ornamented plumage, then recorded the resulting social interactions. Testosterone-implanted males developed ornamentation and were chased and attacked more often by conspecific males than were control-implanted males without ornamentation, supporting the hypothesis that molt into ornamented plumage is socially costly. However, despite these apparent costs, some 1-yr-old males naturally acquired ornamented plumage after pairing with a female. Paired 1-yr-olds who naturally acquired ornamented plumage exhibited smaller home ranges than the unpaired, implanted males in their natal groups. Post-hoc simulations suggested that smaller home ranges could result in fewer interactions with neighbors, meaning smaller home ranges may reduce the social costs associated with acquiring ornamentation. We discuss the aspects of manipulating ornamentation with testosterone and suggest that our results add to growing evidence that social costs can enforce the honesty of sexually-selected ornaments. Some male songbirds exhibit dull, female-like plumages in their first year instead of the ornamented plumage the species is known for. To test if ornamentation carries social costs, we used hormone treatment to force one-year-old male Red-backed Fairywrens to acquire the breeding plumage typical of older males. Testosterone-implanted males acquired ornamented plumage and received more aggression from neighboring males than did control-implanted males, suggesting delayed acquisition of mating signals may help young males avoid aggression.

Documenting the diversity of nest construction behaviours is essential for understanding a species’ life-history. The Variegated Fairy-wren Malurus lamberti is a socially complex species whose nest building habits remain poorly described. Here, we report three nest construction behaviors that were observed during the 2024 breeding season at our study site in south-east Queensland, which have not been reported in Variegated Fairy-wren. In one instance, a female began constructing two nests simultaneously to then only finish one. Another involved the building of a nest before abandoning it to build another with no apparent signs of predation or reason for failure at the initial nest. Finally, a female was observed repairing then laying eggs in a nest that was previously damaged following depredation. These observations provide insight into the flexibility of nest building behaviors in this species.

Recording soundscapes in coral reef ecosystems provides an efficient, non-invasive method for ecosystem monitoring and conservation. This study assesses the ecological relevance of coral reef soundscapes, validating their utility for conservation decision-making. Using the Soundscape Code—a method that summarizes soundscape amplitude, impulsiveness, periodicity, and uniformity—we analyzed habitat differentiation across 25 simultaneous recordings from back, flat, and fore reef zones. Benthic composition analysis identified two distinct healthy habitat types: one dominated by branching corals and another without a dominant coral growth form. Acoustic analysis revealed these habitats also had unique nighttime soundscapes, driven by amplitude (loudness) and uniformity (sound diversity) differences linked to fish and invertebrate activity. This alignment between benthic structure and nocturnal soundscape patterns suggests that reef soundscapes reflect both benthic composition and the associated biological communities, including cryptic invertebrates and nocturnal fish. Our findings underscore the potential of nighttime soundscapes and the Soundscape Code as valuable tools for coral reef monitoring and management, with practical applications for ecosystem assessment and restoration planning.

The rapid development of artificial, man-made environments may unintentionally produce evolutionary traps, where the cues that organisms rely on to indicate high-fitness resources are mismatched with novel resources that deliver low fitness outcomes. In this study, we identify urban sports fields as a new source of ecological trap surfaces, which globe skimmers (Pantala flavascens) lay their eggs on. We found that dragonflies preferred to lay eggs on green and blue sports field surfaces, but rarely did so on red surfaces. In this attraction both colour and polarization can play an important role, because dragonflies are colour- and polarization-sensitive. Reflectance spectrum analysis showed that red was most distinct from the other colors, highlighting the importance of sensory preferences for determining where eggs were laid. Given that we did not measure the polarized reflection of the field, our conclusions were derived in the context of a presumed polarized background. Future research is needed to investigate the interaction between dragonfly polarization vision and color vision. These results identify sports fields as an evolutionary trap enticing dragonflies to oviposit on unsuitable substrates. There is an urgent need to further evaluate the potential impact of this phenomenon on dragonfly populations in urban environments. By optimizing the substrate and color design of sports fields, it might mitigate threats to dragonfly populations and provide support for the conservation of insect biodiversity in urban ecosystems.

Settlement patterns of juvenile fish shape coral reef communities. During the recruitment process, predation rates are extremely high. However, the role that parental care plays in reducing mortality, especially by cryptic natural enemies such as parasites, remains largely unstudied. We investigated whether parental care in the spiny chromis damselfish ( Acanthochromis polyacanthus ) protects juveniles from parasite-induced mortality by gnathiid isopods ( Gnathia aureamaculosa ). Using laboratory experiments, we found that survival of recently hatched juveniles when exposed to gnathiids was higher when parents were present (77%) than when parents were absent (25%). Investigation of their faeces in the field and laboratory indicates that adults consume gnathiids. Together, our data suggest that parental care plays a key role in reducing parasite-induced mortality of juvenile spiny chromis via parental consumption of gnathiids. This highlights the overlooked role of parasites as a source of high mortality in juvenile coral reef fishes and the composition of coral reef fish communities.

Seaweed farming comprises over half of global coastal and marine aquaculture production by mass; however, the future of the industry is increasingly threatened by disease outbreaks. Nature-based solutions provided by enhancing functions of coinciding species or ecosystems offer an opportunity to increase yields by reducing disease outbreaks while conserving biodiversity. Seagrass ecosystems can reduce the abundance of marine bacterial pathogens, although it remains unknown whether this service can extend to reducing disease risk in a marine resource. Using a meta-analysis of articles published over the past 40 y, we find that 17 known diseases of seaweeds are attributed to bacteria that have been previously shown to be lower when associated with seagrass ecosystems. Next, we surveyed over 8,000 individual seaweeds among farms in Indonesia and found that disease risk is reduced by 75% when seaweeds are co-cultivated directly within seagrass ecosystems, compared to when seagrass ecosystems were removed. Finally, we estimate that farming seaweed with seagrass ecosystems could increase annual revenue by $292,470 - $1,015,990 USD per km2 from yield loss due to disease reduction and that similar to 20.7 million km(2) in 107 countries and 34 territories have suitable environmental conditions for farming seaweeds with seagrass ecosystems. These results highlight the global utility for nature-based solutions as an ecologically and economically sustainable management strategy.

Urban greening offers an opportunity to reinforce food security and safety. Seagrass ecosystems can reduce human bacterial pathogens from coastal sources, but it remains unknown whether this service is conferred to associated food fish. We find a 65% reduction in human bacterial pathogens from marine bivalves experimentally deployed across coastal urban locations with seagrass present compared with locations with seagrass absent. Our model estimates that 1.1 billion people reside in urban areas within 50 km of a seagrass ecosystem. These results highlight the global opportunity to support human health and biodiversity sustainability targets. Seagrass ecosystems often co-occur with urbanized coastal regions, providing important filtration services that reduce human bacterial pathogens from coastal sources. This study examines whether such filtration function is transferred to food fish such as marine bivalves, and its global applicability.

Lay summary Research on elaborate animal coloration overwhelmingly focuses on how males dress to impress potential mates or how color wards off potential rivals. In reality, female animals do this too, but it is less clear how competitive behavior varies among females that are pair-bonded with the prettiest males. In two closely-related songbird species, we did not find evidence that behavior varies in this context, showcasing how coloration may not be the most important variable females consider. While the impacts of male phenotypic quality on female mating decisions are well-studied, less is known about how male attributes may influence female aggressive behavior. To address this, we evaluated the degree to which females mated to more attractive males may behave more aggressively toward simulated female rivals, as might be predicted if intrasexual competition exists over access to mates. We studied two sister taxa of fairywren (Maluridae) with distinct life-history strategies: white-shouldered fairywrens ( Malurus alboscapulatus moretoni ) in Papua New Guinea, a species with year-round territoriality and female-limited plumage polymorphisms, and red-backed fairywrens ( M. melanocephalus melanocephalus ) in temperate Australia, a species with seasonal breeding and one in which females do not exhibit any plumage ornamentation. We characterized male quality by assessing the plumage coloration alongside three morphological characteristics that are known to be important in Malurus fairywrens: body mass, cloacal protuberance volume, and tail length. We quantified female aggression using mirror image stimulations, finding that female white-shouldered fairywrens were more aggressive on average than female red-backed fairywrens. There was a non-significant tendency for more aggressive white-shouldered fairywren females to have heavier mates with longer tails, but male phenotype did not predict female behavior in the red-backed fairywrens. Overall, our results are consistent with the idea that variation in mating system and life-history help shape female aggressive behaviors between divergent species. In socially monogamous species that form long, multiyear bonds with their mates, phenotypic quality may not be the best predictor of mate choice as has historically been emphasized.

The use of Ocean Sound to describe ecosystems and address ecological questions has increased remarkably during the last decades. The current capacity of recording, storing, and analyzing large amounts of data urges efforts toward developing standards and guidelines to advance underwater soundscape analyses. The development and use of metrics to summarize soundscape attributes have become widespread, but further field-testing and validation are still necessary to identify their ecological relevance resolution. We explore a combination of approaches to determine the performance of ecoacoustic indices and the recently proposed “Soundscape Code” in combination with ecological metrics (habitat and fish assemblage composition) for discrimination between coral reef microhabitats. We collected ecological and acoustic data from Lizard Island (Great Barrier Reef), where we established five transects each with five sampling stations, covering a range of microhabitats from the reef flat zone to the forereef zone, and from high live coral cover to rubble-dominated areas. Conspicuous differences were observed between the soundscapes of the live coral cover and the rubble-dominated areas, demonstrating the potential value of using soundscapes to discriminate between and monitor changes in coral reefs. [Work supported by the BHP-AIMS Australian Coral Reef Resilience Initiative.]

Cooperatively breeding species vary widely in degree of social complexity, and disentangling relationships among group members can reveal the costs and benefits of cooperation. Here, we explore the social system of a relatively unstudied cooperatively breeding bird, the Variegated Fairywren ( Malurus lamberti ), and explore how social complexity and group dynamics may affect cooperation and conflict. We used a combination of field-based population monitoring and detailed social association observations to determine group membership annually across four breeding seasons (2014 – 2017), and used a ddRAD-seq genotyping method to determine genetic relationships within social groups. Social groups ranged in size from 2 – 8 individuals and nearly half of all social groups had multiple adult individuals of both sexes. Approximately two-thirds of those groups exhibited plural breeding, in which multiple females within the same social group nested individually on the same territory. Genetic relationships were diverse across social groups, and many consisted of a combination of relatives and non-relatives of each sex. Notably, although related females often were present within a social group, co-breeding females in the same social group were never closely related to each other. Given extensive variation in relatedness among group members, cooperation in the Variegated Fairywren is likely maintained by a combination of direct and indirect fitness benefits.

Indo-Pacific lionfishes generally exhibit cryptic behaviours and so can be missed when conducting non-targeted surveys. Here, the authors report the results from targeted surveys of lionfish at Moorea, French Polynesia. Lionfish from three species (Pterois antennata, Pterois radiata, Dendrochirus biocellatus) were observed at a mean density of 267 individuals ha(-1). This is substantially higher than previous estimates from the same area (Moorea) and represents the highest reported density of lionfishes from their Pacific range. Overall, this study highlights the importance of targeted survey techniques for detecting cryptic species on coral reefs.

We studied a brood parasite–host system (the cuckoo finch Anomalospiza imberbis and its host, the tawny-flanked prinia Prinia subflava ) to test (1) the fundamental hypothesis that deceptive mimics evolve to resemble models, selecting in turn for models to evolve away from mimics (‘chase-away evolution’) and (2) whether such reciprocal evolution maintains imperfect mimicry over time. Over only 50 years, parasites evolved towards hosts and hosts evolved away from parasites, resulting in no detectible increase in mimetic fidelity. Our results reflect rapid adaptive evolution in wild populations of models and mimics and show that chase-away evolution in models can counteract even rapid evolution of mimics, resulting in the persistence of imperfect mimicry.

Abstract Brood parasitism by cuckoos relies on manipulating hosts to raise their offspring and has evolved stunning adaptations to aid in their deception. The fact that cuckoos usually but not always, remove one or two host eggs while laying their eggs has been a longstanding focus of intensive research. However, the benefit of this behavior remains elusive. Moreover, the recently proposed help delivery hypothesis, predicting that egg removal by cuckoos may decrease the egg‐laying duration in the parasitism process caused by biting action, lacks experimental verification. Therefore, in this study, we examined the effects of egg removal/biting on the egg‐laying speed in the common cuckoo (Cuculus canorus) to experimentally test this hypothesis. We compared the duration of cuckoo egg‐laying in empty nests, nests with host eggs, and nests with artificial blue stick models to test whether cuckoos biting an egg/stick can significantly hasten the egg‐laying speed than no biting action. Our results showed that biting an egg or an object is associated with cuckoos laying approximately 37% faster than when they do not bite an egg or an object. This study provides the first experimental evidence for the help delivery hypothesis and demonstrates that when cuckoos bite eggs or other objects in the nest, they lay eggs more quickly and thereby avoid suffering the hosts' injurious attack.

In marine environments, mutualisms such as those between corals or sea anemones and their algal symbionts (Symbiodiniaceae) play a key role for supporting surrounding biodiversity. However, as the breakdown of the mutualism between corals and/or anemones and Symbiodiniaceae (i.e. bleaching) become increasingly frequent and severe, the risk of losing the additional species that rely on them may also increase. While the effects of anemone bleaching on the biology and ecology of anemone-associated fishes have been the subject of recent research, relatively little is known about the impacts that anemone bleaching might have on the recruitment of larval fish. Here, we report that climate change-induced anemone bleaching impairs a secondary mutualism between anemones and an anemone-associated fish species, the threespot dascyllus (Dascyllus trimaculatus). Field-based monitoring over a 1-year period showed anemones that bleached experienced decreased recruitment of larval D. trimaculatus compared to those that did not bleach, with abundances of newly settled D. trimaculatus three times lower in bleached versus unbleached anemones. A visual choice experiment showed that this pattern is associated with fish being less attracted to bleached anemones, and a predation experiment demonstrated that fish associated with bleached anemones experienced higher mortality compared to those associated with unbleached anemones. These results suggests that the decreased recruitment of D. trimaculatus observed in bleached anemones may be driven by hampered pre-settlement (habitat selection) and post-settlement (survival to predation) processes for larval D. trimaculatus in bleached hosts. This study highlights the risk of cascading mutualism breakdowns in coral reefs as conditions deteriorate and stresses the importance of protecting these mutualisms for the maintenance of coral reef biodiversity.