Species interactions and population density mediate the use of social cues for habitat selection

1. The perspective that populations and communities are structured by antagonistic interactions among individuals has dominated much of ecology. Yet how animals use social information to guide decisions, such as habitat selection, may be influenced by both positive and negative interactions among individuals. Recent theory also suggests that the way animals use social information may be substantially influenced by population density, which alters the potential costs and benefits of such behaviours. 2. I manipulated cues of two competitors, the dominant least flycatcher Empidonax minimus (Baird & Baird) and the subordinate American redstart Setophaga ruticilla (Linnaeus), to assess the use of conspecific and heterospecific cues during habitat selection, and if population density influences these strategies. The experiment consisted of surveying birds during a pre-treatment year, which allows for the control and testing the effect of baseline densities, and a treatment year, in which treatments were applied just prior to settlement. Treatments included broadcasting songs of flycatchers and redstarts, and were compared with controls. 3. When controlling for pre-treatment densities, bird densities, and to a lesser extent arrival dates, during the treatment year suggested that flycatchers were attracted to both conspecific and heterospecific cues during settlement. Furthermore, attraction was strongest for flycatchers in plots with moderate pre-treatment densities. American redstarts were rare in the study area but showed apparent attraction to conspecifics and avoidance of heterospecifics. 4. These results provide experimental evidence for the use of multiple social cues in habitat selection and suggest that heterospecific attraction may operate under broader contexts than originally envisioned. In such instances, nontarget effects can potentially occur when manipulating social cues to elicit settlement in conservation strategies. The impact of population density on the use of social cues shown here can also influence our understanding of metapopulation dynamics by causing complex threshold effects on the likelihood of rescue, which may influence metapopulation stability and the likelihood of local extinction.     

Who is in the neighborhood? Conspecific and heterospecific responses to perceived density for breeding habitat selection

Theoretical models of habitat selection often incorporate negative density dependence. Despite strong negative density‐dependent effects on habitat selection, more recent studies indicate that animals settle near members of their own (conspecific) and other species (heterospecific) when selecting habitat with social cues. Social cue use for habitat selection is particularly common among songbirds, but few studies have investigated if songbirds use social cues to assess conspecific or heterospecific density (as opposed to just presence/absence) when making settlement decisions. We conducted a playback experiment to evaluate if yellow warblers (Setophaga petechia) and willow flycatchers (Empidonax traillii), two potential competitors for breeding habitat, use social cues to assess density (conspecific for warblers and heterospecific for flycatchers) when selecting breeding locations at two spatial scales. We simulated yellow warbler density to be high or low at multiple treatment plots (3.14 ha) with song playback and then evaluated settlement decisions by comparing yellow warbler and willow flycatcher abundances across plots (broad‐scale habitat selection) and individual space use within plots (fine‐scale territory establishment). Yellow warbler density treatments did not affect habitat selection by yellow warblers at the broad scale, but caused individuals to cluster territories at high‐density treatments. Willow flycatchers were most abundant at high‐density treatment plots, but yellow warbler density treatments did not affect territory locations. The results indicate that perceived density affects the habitat selection process for both conspecifics and heterospecifics.     

When to use public information for breeding habitat selection? The role of environmental predictability and density dependence

To select their future breeding site, individuals usually have to assess local quality by using environmental cues. One optimal cue may be ‘public information’, the local reproductive success of conspecifics in a breeding patch (patch reproductive success) because it integrates the effect of all environmental factors on breeding success. However, the quality of information conveyed by patch reproductive success is likely to depend on (1) environmental predictability and (2) interactions between individuals. We investigated how these two factors, ignored by previous models, affect the performance of individuals using patch reproductive success for breeding habitat selection compared with other information. We built a two-patch, game-theoretical model to compare the success of a strategy of breeding habitat selection based on patch reproductive success relative to four other strategies: (1) random patch choice; (2) philopatry; (3) choice based on the presence of conspecifics the previous year (conspecific attraction); and (4) choice based on intrinsic patch quality the previous year. The results illustrate how the efficiency of strategies in tracking variations in patch quality depend on environmental predictability and costs linked to density dependence, themselves linked to the dynamics of spatial aggregation of individuals. In particular, strategies based on measures of patch reproductive success perform the best for intermediate and high temporal predictability of patch quality, whereas philopatry and conspecific attraction then perform poorly. The ‘conspecific attraction’ strategy always coexists with other strategies by efficiently parasitizing the information they use. We discuss the implications of a better understanding of breeding habitat selection behaviours for evolutionary and conservation biology. Copyright 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.      

Context-dependent dispersal,public information,and heterospecific attraction in newts

Dispersal is one of the main processes that determine community structure. Individuals make dispersal decisions according to environmental and/or social cues that reflect the fitness prospects in a given patch. The presence and abundance of heterospecifics within the same ecological guild, and/or their breeding success, may act as public information that influences movement decisions. To date, most studies investigating the role of heterospecific attraction have focused on habitat choice, using both experimental and correlational approaches. The present study is the first to examine how long-term variation in heterospecific density in breeding patches may affect dispersal patterns in spatially structured populations. We investigate how the dispersal decisions of the great crested newt (Triturus cristatus) are related to the variable density of two other newt species, the alpine newt (Ichthyosaura alpestris) and the palmate newt (Lissotriton helveticus). To examine this issue, we used capture–recapture data collected in an experimental pond network over a 20-year period. The results revealed that the great crested newt’s dispersal is context dependent and is affected by variation in heterospecific density: individuals were less likely to emigrate from ponds with high heterospecific density and were more likely to immigrate to ponds with high heterospecific density. These findings suggest that individuals adjust their dispersal decisions at least partly based on public information provided by heterospecifics. This mechanism may play a critical role in the dynamics of spatially structured populations and community functioning.

     

Lack of species discrimination based on chemical cues by male sailfin mollies, <Emphasis Type="Italic">Poecilia latipinna</Emphasis>

When making mating decisions, individuals may rely on multiple cues from either the same or multiple sensory modalities. Although the use of visual cues in sexual selection is well studied, fewer studies have examined the role of chemical cues in mate choice. In addition, few studies have examined how visual and/or chemical cues affect male mating decisions. Male mate choice is important in systems where males must avoid mating with heterospecific females, as is found in a mating complex of Poecilia. Male sailfin mollies, Poecilia latipinna, are sexually parasitized by gynogenetic Amazon mollies, P. formosa. Little is known about the mechanism by which male sailfin mollies base their mating decisions. Here we tested the hypothesis that male sailfin mollies from an allopatric and a sympatric population with Amazon mollies use multiple cues to distinguish between conspecific and heterospecific females. We found that male sailfin mollies recognized the chemical cues of conspecific females, but we found no support for the hypothesis that chemical cues are by themselves sufficient for species discrimination. Lack of discrimination based on chemical cues alone may be due to the close evolutionary history between P. latipinna and P. formosa. Males from populations sympatric with Amazon mollies did not differentially associate with females of either of the two species when given access to both visual and chemical cues of the females, yet males from the allopatric population did associate more with conspecific females than with heterospecific females in the presence of both chemical and visual cues. The lack of discrimination by males from the sympatric population between conspecific and heterospecific females based on both chemical and visual cues suggests that these males require more complex combinations of cues to distinguish species, possibly due to the close relatedness of these species.     

Social phenotype extended to communities: Expanded multilevel social selection analysis reveals fitness consequences of interspecific interactions

In social species, fitness consequences are associated with both individual and social phenotypes. Social selection analysis has quantified the contribution of conspecific social traits to individual fitness. There has been no attempt, however, to apply a social selection approach to quantify the fitness implications of heterospecific social phenotypes. Here, we propose a novel social selection based approach integrating the role of all social interactions at the community level. We extended multilevel selection analysis by including a term accounting for the group phenotype of heterospecifics. We analyzed nest activity as a model social trait common to two species, the lesser kestrel (Falco naumanni) and jackdaw (Corvus monedula), nesting in either single‐ or mixed‐species colonies. By recording reproductive outcome as a measure of relative fitness, our results reveal an asymmetric system wherein only jackdaw breeding performance was affected by the activity phenotypes of both conspecific and heterospecific neighbors. Our model incorporating heterospecific social phenotypes is applicable to animal communities where interacting species share a common social trait, thus allowing an assessment of the selection pressure imposed by interspecific interactions in nature. Finally, we discuss the potential role of ecological limitations accounting for random or preferential assortments among interspecific social phenotypes, and the implications of such processes to community evolution.     

Nonideal nest box selection by tree swallows breeding in farmlands: Evidence for an ecological trap?

Animals are expected to select a breeding habitat using cues that should reflect, directly or not, the fitness outcome of the different habitat options. However, human‐induced environmental changes can alter the relationships between habitat characteristics and their fitness consequences, leading to maladaptive habitat choices. The most severe case of such nonideal habitat selection is the ecological trap, which occurs when individuals prefer to settle in poor‐quality habitats while better ones are available. Here, we studied the adaptiveness of nest box selection in a tree swallow (Tachycineta bicolor) population breeding over a 10‐year period in a network of 400 nest boxes distributed along a gradient of agricultural intensification in southern Québec, Canada. We first examined the effects of multiple environmental and social habitat characteristics on nest box preference to identify potential settlement cues. We then assessed the links between those cues and habitat quality as defined by the reproductive performance of individuals that settled early or late in nest boxes. We found that tree swallows preferred nesting in open habitats with high cover of perennial forage crops, high spring insect biomass, and high density of house sparrows (Passer domesticus), their main competitors for nest sites. They also preferred nesting where the density of breeders and their mean number of fledglings during the previous year were high. However, we detected mismatches between preference and habitat quality for several environmental variables. The density of competitors and conspecific social information showed severe mismatches, as their relationships to preference and breeding success went in opposite direction under certain circumstances. Spring food availability and agricultural landscape context, while related to preferences, were not related to breeding success. Overall, our study emphasizes the complexity of habitat selection behavior and provides evidence that multiple mechanisms may potentially lead to an ecological trap in farmlands.     

Phenotypic modifications to conspecific density arising from predation risk assessment

Organisms often perceive predation risk through visual, auditory, or chemical cues that accompany or persist after an attack on other prey individuals. In this paper an argument is developed that suggests that it is adaptive for species that use such indirect cues to include conspecific density in the assessment of predation risk, and to respond to conspecific density by modifying phenotype (e.g. behavior, morphology of life history). A model based on this argument predicts that at equivalent (including negligible) indirect cue levels an organism should adopt less vulnerable phenotypes at lower conspecific density. Further, the phenotypic modifications to differences in conspecific density are predicted to be on the same order of magnitude as phenotypic responses to differences in predator density, to be more pronounced at higher indirect cue levels, and can be extended to responses to differences in the density of heterospecific species that share predators. This "risk assessment" mechanism is qualitatively different from other mechanisms, such as the dilution and "many eyes" effects that predict behavioral responses to conspecific density. If species use conspecific or heterospecific density to assess predation risk as predicted, there may be implications for the role and evolution of traits used to perceive conspecific and heterospecific densities, species aggregation, and population dynamics, and should be considered in the design of experiments of nonlethal effects of predators.     

Testing the heterospecific attraction hypothesis with time-series data on species co-occurrence

The distributional patterns of actively moving animals are influenced by the cues that the individuals use for choosing sites into which they settle. Individuals may gather information about habitat quality using two types of strategies, either directly assessing the relevant environmental factors, or using the presence of conspecifics or heterospecifics as an indirect measure of habitat quality. We examined patterns of heterospecific attraction with observational time-series data on a community of seven waterbird species breeding in artificial irrigation ponds. We fitted to the data a multivariate logistic regression model, which attributes the presence–absence of each species to a set of environmental and spatial covariates, to the presence of con- and heterospecifics in the previous year and to the presence of heterospecifics in the same year. All species showed a clear tendency to continue breeding in the same sites where they were observed in the previous year. Additionally, the presence of heterospecifics, both in the previous year and in the same year, generally increased the probability that the focal species was found breeding on a given pond. Our data thus give support for the heterospecific attraction hypothesis, though causal inference should be confirmed with manipulative experiments.     

Conspecific and heterospecific information use in bumblebees

Heterospecific social learning has been understudied in comparison to interactions between members of the same species. However, the learning mechanisms behind such information use can allow animals to be flexible in the cues that are used. This raises the question of whether conspecific cues are inherently more influential than cues provided by heterospecifics, or whether animals can simply use any cue that predicts fitness enhancing conditions, including those provided by heterospecifics. To determine how freely social information travels across species boundaries, we trained bumblebees (Bombus terrestris) to learn to use cues provided by conspecifics and heterospecific honey bees (Apis mellifera) to locate valuable floral resources. We found that heterospecific demonstrators did not differ from conspecifics in the extent to which they guided observers'' choices, whereas various types of inorganic visual cues were consistently less effective than conspecifics. This was also true in a transfer test where bees were confronted with a novel flower type. However, in the transfer test, conspecifics were slightly more effective than heterospecific demonstrators. We then repeated the experiment with entirely naïve bees that had never foraged alongside conspecifics before. In this case, heterospecific demonstrators were equally efficient as conspecifics both in the initial learning task and the transfer test. Our findings demonstrate that social learning is not a unique process limited to conspecifics and that through associative learning, interspecifically sourced information can be just as valuable as that provided by conspecific individuals. Furthermore the results of this study highlight potential implications for understanding competition within natural pollinator communities.     

Socially flexible female choice and premating isolation in field crickets (Teleogryllus spp.)

Social influences on mate choice are predicted to influence evolutionary divergence of closely related taxa, because of the key role mate choice plays in reproductive isolation. However, it is unclear whether females choosing between heterospecific and conspecific male signals use previously experienced social information in the same manner or to the same extent that they do when discriminating among conspecific mates only. We tested this using two field cricket sister species (Teleogryllus oceanicus and Teleogryllus commodus), in which considerable information is known about the role of male calling song in premating isolation, in addition to the influence of acoustic experience on the development of reproductive traits. We manipulated the acoustic experience of replicate populations of both species and found, unexpectedly, that experience of male calling song during rearing did not change how accurate females were in choosing a conspecific over a heterospecific male song during playback trials. However, females with acoustic experience were considerably less responsive to male song compared with naïve females. Our results suggest that variation in the acoustic environment affects mate choice in both species, but that it may have a limited impact on premating isolation. The fact that social flexibility during interspecific mate discrimination does not appear to operate identically to that which occurs during conspecific mate discrimination highlights the importance of considering the context in which animals exercise socially flexible mating behaviours. We suggest an explanation for why social flexibility might be context dependent and discuss the consequences of such flexibility for the evolution of reproductive isolation.     

Social structure modulates the evolutionary consequences of social plasticity: A social network perspective on interacting phenotypes

Organisms express phenotypic plasticity during social interactions. Interacting phenotype theory has explored the consequences of social plasticity for evolution, but it is unclear how this theory applies to complex social structures. We adapt interacting phenotype models to general social structures to explore how the number of social connections between individuals and preference for phenotypically similar social partners affect phenotypic variation and evolution. We derive an analytical model that ignores phenotypic feedback and use simulations to test the predictions of this model. We find that adapting previous models to more general social structures does not alter their general conclusions but generates insights into the effect of social plasticity and social structure on the maintenance of phenotypic variation and evolution. Contribution of indirect genetic effects to phenotypic variance is highest when interactions occur at intermediate densities and decrease at higher densities, when individuals approach interacting with all group members, homogenizing the social environment across individuals. However, evolutionary response to selection tends to increase at greater network densities as the effects of an individual's genes are amplified through increasing effects on other group members. Preferential associations among similar individuals (homophily) increase both phenotypic variance within groups and evolutionary response to selection. Our results represent a first step in relating social network structure to the expression of social plasticity and evolutionary responses to selection.     

The heterospecific habitat copying hypothesis: can competitors indicate habitat quality?

According to the "habitat copying" hypothesis, animals use thereproductive performance of conspecifics to assess habitat suitabilityand choose their future breeding site. This is because conspecificsshare ecological needs and thus indicate habitat suitability.Here, we propose the "heterospecific habitat copying" hypothesis,which states that animals should use public information (i.e.,information derived from the performance of others) from con-and heterospecifics sharing ecological needs. In a correlationalapproach we test some assumptions and predictions of this hypothesiswith a data set from two sympatric bird populations, rollers(Coracias garrulus) and kestrels (Falco tinnunculus), usingthe same nest-boxes and exploiting similar food resources. Sincekestrels are residents and breed earlier, we assumed that theyare dominant over rollers for nest-box acquisition. The environmentappears to be patchy for both species and temporally predictablefor kestrels only. Two results suggest that the use of heterospecificpublic information in breeding habitat selection may be at work:(1) an increase in the reoccupancy probability by kestrels ofprevious roller nests with increasing nest success, and (2)an increase in roller breeding population with increasing localkestrel success. Most of the other observed patterns could beexplained by alternative mechanisms such as natal philopatry,breeding fidelity, conspecific attraction, intraspecific habitatcopying, and the effect of interspecific competition.     

Relationships between the floral neighborhood and individual pollen limitation in two self-incompatible herbs

Local flower density can affect pollen limitation and plant reproductive success through changes in pollinator visitation and availability of compatible pollen. Many studies have investigated the relationship between conspecific density and pollen limitation among populations, but less is known about within-population relationships and the effect of heterospecific flower density. In addition, few studies have explicitly assessed how the spatial scales at which flowers are monitored affect relationships. We investigated the effect of floral neighborhood on pollen limitation at four spatial scales in the self-incompatible herbs Armeria maritima spp. maritima and Ranunculus acris spp. acris. Moreover, we measured pollen deposition in Armeria and pollinator visits to Ranunculus. There was substantial variation in pollen limitation among Armeria individuals, and 25% of this variation was explained by the density of compatible and heterospecific flowers within a 3 m circle. Deposition of compatible pollen was affected by the density of compatible and incompatible inflorescences within a 0.5 m circle, and deposition of heterospecific pollen was affected by the density of heterospecific flowers within a 2 m circle. In Ranunculus, the number of pollinator visits was affected by both conspecific and heterospecific flower densities. This did not, however, result in effects of the floral neighborhood on pollen limitation, probably due to an absence of pollen limitation at the population level. Our study shows that considerable variation in pollen limitation may occur among individuals of a population, and that this variation is partly explained by floral neighborhood density. Such individual-based measures provide an important link between pollen limitation theory, which predicts ecological and evolutionary causes and consequences for individual plants, and studies of the effects of landscape fragmentation on plant species persistence. Our study also highlights the importance of considering multiple spatial scales to understand the spatial extent of pollination processes within a population.     

Social effects of territorial neighbours on the timing of spring breeding in North American red squirrels

Organisms can affect one another's phenotypes when they socially interact. Indirect genetic effects occur when an individual's phenotype is affected by genes expressed in another individual. These heritable effects can enhance or reduce adaptive potential, thereby accelerating or reversing evolutionary change. Quantifying these social effects is therefore crucial for our understanding of evolution, yet estimates of indirect genetic effects in wild animals are limited to dyadic interactions. We estimated indirect phenotypic and genetic effects, and their covariance with direct effects, for the date of spring breeding in North American red squirrels (Tamiasciurus hudsonicus) living in an array of territories of varying spatial proximity. Additionally, we estimated indirect effects and the strength of selection at low and high population densities. Social effects of neighbours on the date of spring breeding were different from zero at high population densities but not at low population densities. Indirect phenotypic effects accounted for a larger amount of variation in the date of breeding than differences attributable to the among‐individual variance, suggesting social interactions are important for determining breeding dates. The genetic component to these indirect effects was however not statistically significant. We therefore showcase a powerful and flexible method that will allow researchers working in organisms with a range of social systems to estimate indirect phenotypic and genetic effects, and demonstrate the degree to which social interactions can influence phenotypes, even in a solitary species.     

Pollen competition between two sympatric Orchis species (Orchidaceae): the overtaking of conspecific of heterospecific pollen as a reproductive barrier

The frequency of hybrid formation in angiosperms depends on how and when heterospecific pollen is transferred to the stigma, and on the success of that heterospecific pollen at fertilising ovules. We applied pollen mixtures to stigmas to determine how pollen interactions affect siring success and the frequency of hybrid formation between two species of Mediterranean deceptive orchid. Plants of Orchis italica and O. anthropophora were pollinated with conspecific and heterospecific pollen (first conspecific pollen then heterospecific pollen and vice versa) and molecular analysis was used to check the paternity of the seeds produced. In this pair of Mediterranean orchids, competition between conspecific and heterospecific pollen functions as a post‐pollination pre‐zygotic barrier limiting the frequency of the formation of hybrids in nature. Flowers pollinated with heterospecific pollen can remain receptive for the arrival of conspecific pollen for a long time. There is always an advantage of conspecific pollen for fruit formation, whether it comes before or after heterospecific pollen, because it overtakes the heterospecific pollen. The conspecific pollen advantage exhibited in O. italica and O. anthropophora is likely to result from the reduced germination of heterospecific pollen or retarded growth of heterospecific pollen tubes in the stigma and ovary. Overall, the results indicate that our hybrid zone represents a phenomenon of little evolutionary consequence, and the conspecific pollen advantage maintains the genetic integrity of the parental species.     

Mechanisms and reproductive consequences of breeding dispersal in a specialist predator under temporally varying food conditions

Individual variation in breeding dispersal has extensive ecological and evolutionary consequences, but the factors driving individual dispersal behaviour and their fitness consequences remain poorly understood. Our data on dispersal events of a rodent‐specialist predator, the Eurasian kestrel Falco tinnunculus, over 20 years in western Finland offers a unique opportunity to explore the mechanisms underlying breeding dispersal behaviour and its reproductive consequences in a wild bird population. Sex, age, body condition and previous breeding success affected breeding dispersal. Dispersal distances were longer in females than in males as well as longer in yearlings than in older individuals. Body condition was positively correlated to breeding dispersal distances, particularly for females. The lowest dispersal distances were recorded for intermediate brood sizes in the year preceding dispersal. Our results highlight sex‐ and environment‐specific consequences of breeding dispersal on reproductive performance. During increase phases of the three‐year vole cycles, males dispersing further had lower reproductive performance after dispersal, whereas in females, long breeding dispersal distances were associated with increased breeding success under all environmental conditions. These results suggest benefits associated to breeding dispersal in females, potentially related to large spatio‐temporal variation in main food abundance and intensity of intra‐specific competition. Breeding dispersal of males was costly during increasing food abundance, indicating the potential fitness benefits of environmental familiarity in this migratory species. Overall, our results indicate that both individual traits and environmental factors interact to shape breeding dispersal strategies in wide‐ranging predator populations under fluctuating food conditions.     

Conspecific and Heterospecific Cues Override Resource Quality to Influence Offspring Production

Animals live in an uncertain world. To reduce uncertainty, animals use cues that can encode diverse information regarding habitat quality, including both non-social and social cues. While it is increasingly appreciated that the sources of potential information are vast, our understanding of how individuals integrate different types of cues to guide decision-making remains limited. We experimentally manipulated both resource quality (presence/absence of cactus fruit) and social cues (conspecific juveniles, heterospecific juveniles, no juveniles) for a cactus-feeding insect, Narnia femorata (Hemiptera: Coreidae), to ask how individuals responded to resource quality in the presence or absence of social cues. Cactus with fruit is a high-quality environment for juvenile development, and indeed we found that females laid 56% more eggs when cactus fruit was present versus when it was absent. However, when conspecific or heterospecific juveniles were present, the effects of resource quality on egg numbers vanished. Overall, N . femorata laid approximately twice as many eggs in the presence of heterospecifics than alone or in the presence of conspecifics. Our results suggest that the presence of both conspecific and heterospecific social cues can disrupt responses of individuals to environmental gradients in resource quality.     

Prospectors combine social and environmental information to improve habitat selection and breeding success in the subsequent year

1.?Because habitats have profound effects on individual fitness, there is strong selection for improving the choice of breeding habitat. One possible mechanism is for individuals to use public information when prospecting future breeding sites; however, to our knowledge, no study has shown prospecting behaviour to be directly linked to subsequent choice of breeding site and future reproductive success. 2.?We collected long-term data on territory-specific prospecting behaviour and subsequent breeding in the short-lived northern wheatear (Oenanthe oenanthe). Non-breeders established prospecting territories (<2 ha) that overlapped the breeding territories of conspecifics. We tested whether: (i) prospectors used social and environmental cues that predicted territory-specific breeding success in the following year, and (ii) the prospecting territory was tightly linked to the subsequent breeding territory of the prospector, and whether this link would be weakened by intraspecific competition with original territory owners if they also survived. 3.?As expected, prospectors were attracted to a combination of site-specific cues that predicted future breeding success, i.e. short ground vegetation, a successfully breeding focal pair and successful close neighbours. 4.?Prospecting behaviour was directly linked to the choice of the following year's breeding territory: 79% of surviving prospectors established a breeding territory at their prospecting site in the following year, with their breeding success being higher than other individuals of the same age. As predicted, fidelity to the prospected site was strongly dependent on whether the original territory owner of the same sex had died or moved. 5.?Our findings suggest that the use of multiple cues reduces the negative impact of stochasticity on the reliability of social cues at small spatial scales (e.g. territories) and hence increases the probability of breeding success in the next year. Also, the use of conspecific attraction (i.e. the preference for breeding aggregations) is selectively advantageous because individuals are more likely to find a vacancy in an aggregation as compared to a solitary site. By extension, we hypothesize that species life-history traits may influence the spatial scale of prospecting behaviour and habitat selection strategies.     

Anemonefishes rely on visual and chemical cues to correctly identify conspecifics

Organisms rely on sensory cues to interpret their environment and make important life-history decisions. Accurate recognition is of particular importance in diverse reef environments. Most evidence on the use of sensory cues focuses on those used in predator avoidance or habitat recognition, with little information on their role in conspecific recognition. Yet conspecific recognition is essential for life-history decisions including settlement, mate choice, and dominance interactions. Using a sensory manipulated tank and a two-chamber choice flume, anemonefish conspecific response was measured in the presence and absence of chemical and/or visual cues. Experiments were then repeated in the presence or absence of two heterospecific species to evaluate whether a heterospecific fish altered the conspecific response. Anemonefishes responded to both the visual and chemical cues of conspecifics, but relied on the combination of the two cues to recognize conspecifics inside the sensory manipulated tank. These results contrast previous studies focusing on predator detection where anemonefishes were found to compensate for the loss of one sensory cue (chemical) by utilizing a second cue (visual). This lack of sensory compensation may impact the ability of anemonefishes to acclimate to changing reef environments in the future.