Conspecific Cues Research Articles

Consequences of temperature and temperature variability on swimming activity, group structure, and predation of endangered delta smelt

Abstract The effects of water temperature on individual and group movement behaviour in prey fish can affect ecological interactions such as competition and predation, but how variability in temperature influence fish behaviour is less understood. Of particular concern is how increased warming in tidally fluctuating estuaries may impact the native and endangered delta smelt (Hypomesus transpacificus, Osmeridae). To help address this issue, we tested the effects of increased water temperature (fluctuating [17–21°C] and warm [21°C] acclimated treatments) on juvenile delta smelt individual and group behaviour, response to chemical alarm and predator cues, as well as capacity to evade predation. In addition, predation of delta smelt was tested in the presence of a dominant invasive competitor, Mississippi silversides (Menidia beryllina, Atherinopsidae), as well as comparative predation mortality on Mississippi silversides when isolated. After 7 days of increased temperature treatments, delta smelt in the warm treatment increased swimming velocity, decreased turning angle, and altered group structure with larger inter‐individual distances compared to fish in the control (17°C) and fluctuating temperature treatments. Following conspecific and predator chemical alarm cues, delta smelt showed anti‐predator responses. Control and fluctuating treatment fish responded to conspecific cues with increased swimming speeds, decreased inter‐individual distances and near‐neighbour distances, and, after 15 min, fish recovered back to baseline behaviours. In contrast, fish in the warm treatment had not recovered after 15 min, and swimming speeds were maintained at roughly 25 cm/s, close to maximum capabilities. Fish in control and fluctuating treatments showed minimal responses to predator cues, whereas delta smelt exposed to warm conditions significantly increased swimming speeds and decreased turning angle. Predation of delta smelt by largemouth bass (Micropterus salmoides, Centrarchidae) was greatest under the warm treatment, correlating with altered behaviours of delta smelt; however, predation of Mississippi silversides was greater than delta smelt, independent of temperature. This study provides novel insight into the group behaviour of delta smelt, their response to predation, and how prolonged exposure to elevated temperature may induce negative individual and group behaviours causing alterations in predator–prey dynamics. This work highlights the importance of testing ecologically realistic temperature fluctuations in experiments as delta smelt had significantly altered responses to elevated temperature, dependent on variability of warming.

Social attractants, a conservation tool for black‐fronted terns

ABSTRACTSocial attraction techniques for species restoration and conservation projects predominantly target colonial breeding species, which commonly use conspecific cues as indicators of habitat quality. The black‐fronted tern (Chlidonias albostriatus) is a globally endangered species that primarily breeds in transient colonies in New Zealand's braided rivers. Currently, predator control and habitat enhancement are the primary management strategies for improving black‐fronted tern populations. Methods that increase the probability of black‐fronted tern colonies being protected by management through an increase in site fidelity of breeding colonies, both within and among years, may greatly increase effectiveness of management. Social attractants, decoys, and audio playback were deployed at 10 sites within 9 Canterbury braided rivers over the 2016 breeding season (September–December). We found that terns interacted with the social attractants compared with the paired untreated plots absent of social attractants. Nearest locations of tern breeding were recorded for 8 of the 10 sites, with breeding recorded within 300 m of the social attractant experimental plots at 5 of these sites. These results suggest that social attraction has the potential for use in black‐fronted tern conservation by drawing breeding terns into habitat that has added predator or habitat management. © 2019 The Wildlife Society.

The effect of conspecific cues on honey bee foraging behavior

Foraging honey bees (Apis mellifera) seem to use the presence of conspecific foragers as cues for flower quality. However, there is disagreement regarding how a conspecific cue is perceived by other foragers (enhancement or inhibition). Most studies manipulate the total number of bees foraging in an arena or the presence or absence of a bee on a flower and then observe the behavior of one forager in response to a single conspecific, which does not reflect natural foraging. We tested how a range of conspecifics on flowers affected on which flowers foraging honey bees landed. We trained students from a biology class for non-STEM majors to collect data and tested whether the number of conspecifics on flowers influences on which flower foragers land. We found that foragers land more frequently on flowers occupied by more conspecifics, which supports the hypothesis that conspecifics are cues for local enhancement. Our results increase our understanding of how honey bees forage once at a flower patch.

Eastern oysters use predation risk cues in larval settlement decisions and juvenile inducible morphological defenses

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 621:83-94 (2019) - DOI: https://doi.org/10.3354/meps12998 Eastern oysters use predation risk cues in larval settlement decisions and juvenile inducible morphological defenses Jessica L. Pruett*, Marc J. Weissburg School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA *Corresponding author: jpruett7@gatech.edu ABSTRACT: Predation is an important factor affecting the recruitment of marine benthic populations. Larvae can reduce their risk of predation by avoiding settlement near predators, whereas juveniles can resist predation through induced morphological defenses. We performed a 2 mo field study to understand the nature of the predation risk cues used by settling eastern oyster larvae and developing juveniles to decrease predation threat during recruitment. We found that oyster recruitment was highest on caged tiles near juvenile oysters, but lowest on tiles near active mud crab predators that produce a combination of predator metabolites and crushed conspecific alarm cues. Chemical cues from crushed conspecifics alone did not affect recruitment in the field, yet oyster larvae avoided either mud crab cues or crushed conspecific cues when presented separately in lab behavior experiments. Comparing the field to lab results suggests alarm cues may be unreliable under natural environmental conditions or were not present at high enough concentrations in the relatively high turbulent flow environment of our field site to convey the predation threat necessary to deter oyster settlement. Oyster spat grew most quickly when exposed to crushed conspecifics and may employ different strategies in response to unique risk cues or predation risk levels by avoiding settlement near actively feeding future predators but growing quickly to reach a size refuge in the presence of alarm cues. These non-consumptive predator effects at different life stages may have important demographic consequences for oyster populations that need to be considered in conjunction with predator consumptive effects. KEY WORDS: Alarm cue · Crassostrea virginica · Non-consumptive effect · Panopeus herbstii · Phenotypic plasticity · Predation risk · Settlement cue Full text in pdf format PreviousNextCite this article as: Pruett JL, Weissburg MJ (2019) Eastern oysters use predation risk cues in larval settlement decisions and juvenile inducible morphological defenses. Mar Ecol Prog Ser 621:83-94. https://doi.org/10.3354/meps12998 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 621. Online publication date: July 04, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.

Visual and auditory cues facilitate cache pilferage of Siberian chipmunks (Tamias sibiricus) under indoor conditions.

In the struggle for survival, scatter-hoarding rodents are known to cache food and pilfer the caches of others. The extent to which rodents utilize auditory/visual cues from conspecifics to improve cache-pilfering is unknown. Here, Siberian chipmunks (Tamias sibiricus) were allowed to search for caches of Corylus heterophylla seeds (man-made caches and animal-made caches) after experiencing cues from a conspecific's cache-searching events. For each type of cache, 3 experimental scenarios were presented: (1) alone (control); (2) auditory/visual (hearing and seeing conspecific's cache-searching events); and (3) auditory only (hearing conspecific's cache-searching events only) with random orders. The subjects located man-made caches faster, harvested more caches, and hoarded more seeds both in the auditory/visual and the auditory only treatments compared to the control, while scatter-hoarding more seeds in the auditory/visual treatment but larder-hoarding more seeds in the auditory only treatment. Compared to the control, the animals spent less time locating animal-made caches, harvested more caches, ate fewer seeds, larder-hoarded more seeds and hoarded more seeds in total both in the auditory/visual and the auditory only treatments, while eating more seeds and hoarded fewer seeds in total in the auditory only treatment than in the auditory/visual treatment. The results also show that females spent less time locating the animal-made caches, but they scatter-hoarded fewer seeds than males in the auditory/visual treatment. To the best of our knowledge, this is the first report that visual and/or auditory cues of conspecifics improve cache-pilfering and hoarding in rodents.

Biological Features of Neoseiulus californicus (Acari: Phytoseiidae) Feeding on Schizotetranychus oryzae (Acari: Tetranychidae) Kept on Rice Leaves

Schizotetranychus oryzae Rossi de Simons attains pest level in rice crops. This study aimed to evaluate the biological features of Neoseiulus californicus (McGregor) feeding on S. oryzae on leaves of flooded rice. We also evaluated N. californicus behavior in response to S. oryzae and conspecific cues. Thirty-two eggs were individually placed in arenas on rice leaves and fed on S. oryzae for the biological test. Three cultivars were used to test the behavior of N. californicus in response to S. oryzae and conspecific cues. The intrinsic rate of increase (rm) of the predator feeding on S. oryzae was 0.21 female/female/day. Schizotetranychus oryzae was considered a suitable prey for N. californicus under laboratory conditions. The results obtained in behavioral tests showed that N. californicus preferred laying eggs on leaves uninfested by S. oryzae and it did not show oviposition preference in arenas with conspecific predator cues. This predator was found in all rice cultivation areas in the state of Rio Grande do Sul, Brazil. Neoseiulus californicus proved to be a control agent for S. oryzae.

Safe as a cave? Intraspecific aggressiveness rises in predator-devoid and resource-depleted environments

Intraspecific aggressiveness can be affected by multiple environmental pressures. In several cases, aggressiveness can grade into full-scale cannibalism, particularly when resources are scarce. However, limited information exists on how intraspecific aggressiveness varies among populations experiencing different environmental pressures, and on the role intraspecific predation plays for the exploitation of harsh habitats. The fire salamander, Salamandra salamandra, is an excellent model species to study factors affecting intraspecific aggressiveness, because of its ability to breed in habitats with contrasting food resources and predation pressure. Here, we evaluated the influence of predation risk and habitat of origin on aggressive interactions. To this extent, we reared larvae from cave (scarce resources; nearly-absent predators) and surface (abundant resources and predators) populations under different risk conditions and measured aggressive behavior towards conspecifics. During behavioral trials, larvae were exposed to different combinations of predator and wounded conspecific chemical cues. Intraspecific aggressiveness increased in large and late-development larvae. Larvae from all the populations significantly reduced aggressiveness under both typologies of risk experienced during rearing (constant presence of predator; pulses of high predation risk), and also when stimulated by predator cues. However, larvae from cave populations exhibited a more pronounced aggressiveness, especially when exposed to wounded conspecific cues. Intraspecific aggressiveness can be modulated by the complex interaction between multiple variables, and both behavioral plasticity and local adaptations can determine its variation across populations. Our findings reveal that aggressive interactions are favored in cave environment, suggesting intraspecific predation can play a key role in the exploitation of resource-depleted habitats. In this study, we investigated how intraspecific aggressiveness of salamander larvae is shaped under predation risk in populations originating from contrasting environments, such as cave and surface habitats. Larvae experiencing predator presence during their development or exposed to predator cues significantly reduced their aggressive interactions, both in cave and surface populations. Interestingly, cave-originating individuals reacted to wounded conspecific cues by increasing the frequency of their aggressive displays, suggesting cannibalistic behavior is locally enhanced in populations from resource-depleted habitats. The present study offers new insights on the importance of intraspecific aggressiveness for the adaptation to harsh environments.

Baseline activity and shoal type determine antipredator behaviors in bluegill from a southern Ontario lake

Shoaling is an evolved behavior in fishes that has several adaptive advantages, including allowing individuals to avoid predation through risk dilution. However, factors such as size disparity and the presence of heterospecifics may influence the behavior of individual fish within shoals following exposure to elevated predation risk. Using bluegill Lepomis macrochirus as a model species, we measured changes in area use, shoaling index, and movement of a focal individual in isolation, in single-species shoals with two conspecifics, or in mixed-species shoals with two congeneric pumpkinseed L. gibbosus. The experimental shoals were exposed to one of three chemical cues selected to present graded levels of risk: lakewater controls (lowest risk), Northern pike Esox lucius predator odor (kairomones; intermediate risk), or conspecific chemical alarm cues (highest risk). Within the individual bluegill, we found that the multivariate response of area use and post-stimulus activity (line crosses) of the focal fish was significantly influenced by pre-stimulus activity, but not by cue type or fish size. As univariate responses, post-stimulus activity varied positively with pre-stimulus activity. Post-stimulus activity was greater in single-species shoals compared to mixed-species shoals, and again varied positively with pre-stimulus activity. Contrary to predictions, bluegill did not demonstrate graded antipredator responses to the chemical cues. Our findings suggest that prey fish may alter their risk-aversive behaviors in response to chemical stimuli based on shoal composition and provide further insight into the role of intra-prey guild interactions in response to predators in co-occurring prey species. When faced with predation, individuals in groups may experience lower levels of risk than solitary individuals. Using bluegill as a model organism, we examined how antipredator behaviors, in response to chemical cues indicating different levels of risk, varied between focal individuals as singletons and in single- and mixed-species shoals. Contrary to our prediction of graded stepwise responses indicative of differing levels of risk posed by the cues, we found that individuals with greater baseline activity levels demonstrated weaker antipredator responses independent of cue type, while fish in single-species shoals had higher post-stimulus activity levels than fish in mixed-species shoals. Our results suggest that studies examining changes in antipredator and shoaling behaviors will benefit from including ecologically relevant scenarios involving sympatric prey guild members.

Conspecific Chemical Cues Modulate Reproductive Physiology and Behavior in a Live‐Bearing Fish

Chemical communication in aquatic environments plays a crucial role in mating by facilitating conspecific recognition, mate selection, and coordination of reproduction. Aquatic chemical communication is well‐understood in a handful of model species; moreover, none of the models are live‐bearing fish. We studied chemical communication in a live‐bearing fish, Poecilia latipinna, using behavior and physiology to identify potential cues and mating responses. We hypothesized that this species uses chemical communication to coordinate reproduction. We tested male behavioral response to conspecific cues using a two‐choice arena, with water‐borne steroid extracts from mature females and a control solution on either side. To quantify physiological response, males and females were individually placed in tanks containing 5 L of water for 4 hrs, and exposed to a control or water‐borne extracts of mature individuals of the opposite sex. At 0, 0.5, 1.5, and 4 hrs, we took 1 L water samples from each tank and extracted them for steroid analysis via solid‐phase extraction. We quantified estradiol (E2), progesterone, and prostaglandin F2α (PGF2α) in females, and testosterone (T) and 11‐ketotestosterone (11‐KT) in males using enzyme‐linked immunosorbent assays. At the end of the experiment, we sacrificed the fish, collected gonads, and fixed them in Bouin for histology. Gonads were serially cut at 7 μm, then stained with hematoxylin‐eosin to quantify maturation stages and with specific antibodies for main steroidogenic enzymes (3β‐hydroxysteroid‐dehydrogenase, 11 β‐hydroxylase, aromatase, and 17,20‐lyase) to localize steroidogenic sites.We found that male P. latipinna can detect female chemical cues, as males spent 178.4% more time on the side where female cues were released. However, males exposed to female cues showed no physiological response. Neither T nor 11‐KT was differentially released by males after being exposed to female cues. In females, we found that control fish had a cyclical pattern of hormone release rates, and these cyclical patterns were altered in treatment females. Progesterone and PGF2α show opposite cycling patterns in treatment females (i.e. when control females increased release, treatment females decreased). While the physiological cause for these cycles has not yet been investigated, the mirrored cycling between treatment and control females suggests that male cues alter hormone release cycles. Control females also have cyclical release of E2, but in treatment females cycling is suppressed. Estradiol decreases prior to ovulation in many teleost species, thus our results indicate that male cues alter female physiology to coordinate reproduction. Preliminary analysis of gonadal tissue for both males and females indicate differences in steroid synthesis between control and treatment fish. These results suggest that water‐borne steroids are acting as a chemical cue, and modulate hormone release and production in conspecifics. This study demonstrates some of the effects of chemical cues on behavior and reproductive physiology in this species, indicating that chemical communication plays a role in the coordination of reproduction in P. latipinna, and provides new insights into the potential mechanisms and origins of chemical cues in live‐bearing fish.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Preferential settling at sites with higher conspecific density does not protect Yellow Warblers (Setophaga petechia) from brood parasitism

Conspecific attraction has been found in many songbird species, but the benefit of settling near conspecifics is generally unknown. Previous research indicates that Yellow Warblers (Setophaga petechia) use conspecific cues to select breeding habitat, and cluster territories more closely around experimental playbacks mimicking high conspecific density. We were interested if Yellow Warblers at sites treated with playback of high conspecific density would be more likely to detect and aggressively interact with Brown-headed Cowbirds (Molothrus ater), a brood parasite that often reduces the reproductive success of warblers. We found that at sites treated with playbacks of high conspecific density, more Yellow Warblers approached and alarm-called toward models of Brown-headed Cowbirds early in the season. There were fewer cowbirds at high-density treatments, but overall brood parasitism rates did not vary across density treatments.

Farm Animal Cognition-Linking Behavior, Welfare and Ethics.

Farm animal welfare is a major concern for society and food production. To more accurately evaluate animal farming in general and to avoid exposing farm animals to poor welfare situations, it is necessary to understand not only their behavioral but also their cognitive needs and capacities. Thus, general knowledge of how farm animals perceive and interact with their environment is of major importance for a range of stakeholders, from citizens to politicians to cognitive ethologists to philosophers. This review aims to outline the current state of farm animal cognition research and focuses on ungulate livestock species, such as cattle, horses, pigs and small ruminants, and reflects upon a defined set of cognitive capacities (physical cognition: categorization, numerical ability, object permanence, reasoning, tool use; social cognition: individual discrimination and recognition, communication with humans, social learning, attribution of attention, prosociality, fairness). We identify a lack of information on certain aspects of physico-cognitive capacities in most farm animal species, such as numerosity discrimination and object permanence. This leads to further questions on how livestock comprehend their physical environment and understand causal relationships. Increasing our knowledge in this area will facilitate efforts to adjust husbandry systems and enrichment items to meet the needs and preferences of farm animals. Research in the socio-cognitive domain indicates that ungulate livestock possess sophisticated mental capacities, such as the discrimination between, and recognition of, conspecifics as well as human handlers using multiple modalities. Livestock also react to very subtle behavioral cues of conspecifics and humans. These socio-cognitive capacities can impact human-animal interactions during management practices and introduce ethical considerations on how to treat livestock in general. We emphasize the importance of gaining a better understanding of how livestock species interact with their physical and social environments, as this information can improve housing and management conditions and can be used to evaluate the use and treatment of animals during production.

Immuno-modulation of settlement cues in the barnacle, Amphibalanus amphitrite: significance of circulating haemocytes

Gregarious settlement in barnacles has been attributed to chemical cues originating from the associated microorganisms, lectins, and settlement-inducing protein complex from arthropodin, a glycoprotein present in their conspecifics/adults. In this study, we explored the influence of haemolymph haemocytes on the metamorphosis of barnacle, Amphibalanus amphitrite cyprids. The barnacle haemocytes were also characterized for the first time using flow cytometry. Cyprid metamorphosis was significantly higher in the presence of surface-bound haemocytes compared to water-borne cues from haemolymph or adult glycoprotein, a known settlement inducer. The flow cytometry-assisted haemocyte characterization, sorting and their subsequent microscopic evaluation indicated the presence of hyalinocytes and granulocytes. Tagging of these haemocytes with lectins revealed that a significant number of haemocytes had d-glucose/d-mannose and N-acetyl-d-galactosamine, which are important settlement cues. These glycoconjugates were also detected in the cyprid larva pointing out the origin of conspecific cues. The retention of these glycoconjugates in the adult haemocytes and their occurrence in adult leachants indicate pelago-benthic coupling in sessile barnacles wherein these glycoconjugates play a significant role in their gregarious settlement. Characterization of such a coupling process in other sessile benthic invertebrates will pave the way to the understanding of complexities in their population dynamics.

Predatory developmental environments shape loser behaviour in animal contests

Abstract High predation risk during development induces phenotypic changes in animals. However, little is known about how these plastic responses affect signalling and competitiveness during contests. Herein, we have studied the consequences of anti-predator plasticity during the intra-sexual competition of Pelvicachromis taeniatus, a cichlid fish with mutual mate choice. We staged contests between adult size-matched siblings of the same sex derived from different environments: one fish was regularly exposed to conspecific alarm cues since the larval stage (simulating predator presence), the other fish to control conditions. Rearing environment did not affect the winner of contests or total aggression within a fight. However, contest behaviour differed between treatments. The effects were especially pronounced in alarm cue-exposed fish that lost a contest: they generally displayed lower aggression than winners but also lower aggression than losers of the control treatment. Thus, perceived predator presence modulates intra-sexual competition behaviour by increasing the costs associated with fighting.

Necessary Conditions for Social Transmission of Food Preference Through Feces in the House Mouse, Mus musculus domesticus.

Mice can obtain information about a new food source through olfactory cues of conspecifics and consequently develop an attraction for this diet. The social transmission of food preference (STFP) takes place directly, during an encounter with a conspecific or indirectly, via feces. In indirect STFP, the digestive process can degrade odorant compounds characterizing the food, impairing the matching between feces and food. In a previous study, indirect STFP was efficient when the information support was a composite odorant. We, thus, hypothesized that the acquisition of indirect STFP depends on the multiplicity of the odorant compounds present in diets. Tested in female house mice (Mus musculus domesticus) our results showed that a single odorant compound as information support was not sufficient to induce an indirect STFP. Chemical analysis did not reveal the presence of the compounds in feces suggesting that the degradation of diet cues during the digestive process prevented the pairing between feces and food. By using a process that limits the degradation of molecules, we performed indirect STFP when the pertinent information was represented by a single odorant compound and multiple odorant compounds. Unlike with multiple odorant compounds, our results did not show a clear indirect STFP with single odorant compound, despite their presence in feces confirmed by chemical analysis. We conclude that constraints associated to indirect STFP can be removed by the multiplicity of information characterizing the diet both by reducing the degradation risk during the digestive process and by allowing an accurate assessment of diet consumed by the conspecific.

Male attraction to female airborne cues by the net-casting spider, Deinopis spinosa

For many animals, finding a mate can be a difficult task. For males, it often involves actively searching for conspecific females, sometimes over great distances. This mate-searching can be aided through chemical or visual signals or cues produced by sexually receptive females. Here, we investigate the roles of olfaction and vision in mate-searching in a strictly nocturnal net-casting spider, Deinopis spinosa. First, we used an olfactometer assay to determine if mature male D. spinosa respond to conspecific airborne cues. We found that mature males, but not mature females, were attracted to airborne cues of mature female conspecifics. We next investigated the relative importance of olfaction and vision in male mate-searching. While manipulating airflow and light levels in screened enclosures in the laboratory, we tested freely moving mature males for mate-searching success. We found no effect of our airflow treatment on mate-searching success. Light levels, however, affected mate-searching in an unexpected way - males were more likely to locate females in complete darkness when compared to dim-light conditions. Our results suggest that visual cues are not necessary for successful male mate-searching in D. spinosa, but that the visual environment can nonetheless influence male behavior. In summary, we provide evidence suggesting that airborne cues, but not visual cues, are important in D. spinosa male mate-searching efforts, though the source of these chemical airborne cues remains unknown.

Conspecific mortality cues mediate associative learning in crickets, Acheta domesticus (Orthoptera: Gryllidae)

Many terrestrial and aquatic animals learn associations between environmental features and chemical cues of mortality risk (e.g. conspecific alarm pheromones or predator-derived cues), but the chemical nature of the cues that mediate this type of learning are rarely considered. Fatty acid necromones (particularly oleic and linoleic acids) are well established as cues associated with dead or injured conspecifics. Necromones elicit risk aversive behavior across diverse arthropod phylogenies, yet they have not been linked to associative learning. Here, we provide evidence that necromones can mediate associative olfactory learning in an insect by acting as an aversive reinforcement. When house crickets (Achetadomesticus) were forced to inhabit an environment containing an initially attractive odor along with a necromone cue, they subsequently avoided the previously attractive odor and displayed tolerance for an initially unattractive odor. This occurred when crickets were conditioned with linoleic acid but not when they were conditioned with oleic acid. Similar aversive learning occurred when crickets were conditioned with ethanol body extracts composed of male and female corpses combined, as well as extracts composed of female corpses alone. Conditioning with male body extract did not elicit learned aversion in either sex, even though we detected no notable differences in fatty acid composition between male and female body extracts. We suggest that necromone-mediated learning responses might vary depending on synergistic or antagonistic interactions with sex or species-specific recognition cues.

Cue hierarchy in the foraging behaviour of the brackish cladoceran Daphniopsis australis

Zooplankton communities are an essential component of marine and freshwater food webs. However, there is still a relative lack of information on how these organisms behaviourally respond to a range of abiotic and biotic stressors. Specifically, the behaviour of the cladoceran Daphniopsis australis, a species endemic to South-eastern Australian saline lakes and ponds, is still unknown despite its potential role in the structure and function of inland water ecosystems. The swimming behaviour of males, parthenogenetic females and epiphial females was investigated under various conditions and combinations of food and conspecific cues. In the absence of cues, males displayed the most extensive swimming behaviour, exploring all areas of the container, and swimming in a series of relatively straight trajectories. In contrast, females typically exhibited a hop-and-sink motion characterised by the alternation between short bursts of swimming and sinking phases. Both females spent long periods near the bottom of the container, but epiphial females appeared to be more active than parthenogenetic ones that rarely made an excursion in the water column. In the presence of cues, males and females showed abilities to detect infochemicals from food and conspecifics, but exhibited specific behavioural strategies. Males essentially increased their swimming speed in the presence of food and/or conspecific infochemicals, and this increase was independent on the source of the cues, i.e. food, conspecific or a mixture of food and conspecifics. In contrast, females exhibited cue hierarchies that were related to their sexual status. Parthenogenetic females swam faster in the presence of food and a mixture of food and conspecific infochemicals than in the presence of cue from the opposite sex, which did not significantly differ from control observations conducted in the absence of cues. Epiphial females decreased their swimming speed in the presence of cues, with the most significant behavioural answers being driven by sex-related cues.

Copy if dissatisfied, innovate if not: contrasting egg-laying decision making in an insect.

The use of conspecific cues as social information in decision making is widespread among animals; but, because this social information is indirect, it is error-prone. During resource acquisition, conspecific cues also indicate the presence of competitors; therefore, decision makers are expected to utilize direct information from resources and modify their responses to social information accordingly. Here, we show that, in a non-social insect, unattractive egg-laying resources alter the behavioural response to conspecific cues from avoidance to preference, leading to resource sharing. Females of the adzuki bean beetle Callosobruchus chinensis avoid laying eggs onto beans that already have conspecific eggs. However, when we provided females with bean-sized clean glass beads with and without conspecific eggs, the females preferred to add their eggs onto the beads with eggs. The glass beads, once coated with water extracts of adzuki beans, enabled the females to behave as if they were provided with the beans: the females preferred bean-odoured glass beads to clean glass beads and they avoided the substrates with eggs. When females are provided with unattractive egg-laying substrates only, joining behaviour (i.e. copying) might be advantageous, as it takes advantage of information about positive attributes of the substrate that the focal animal might have missed. Our results suggest that given only unsatisfactory options, the benefits of copying outweigh the costs of resource competition. Our study highlights the importance of integrating multiple information sources in animal decision making.

Transmission of food preference between unfamiliar house mice (Mus musculus domesticus) is dependent on social context.

Rodents obtain information about a new food source through olfactory cues of conspecifics and consequently develop an attraction for this diet. Generally, physical contact between an observer and a demonstrator that has recently consumed a novel food item is required to allow the social transmission of food preference (STFP). However, in natural populations of house mice, social encounters between unfamiliar individuals usually turn into a fight. Thus, social intolerance between the individuals involved could prevent STFP. It has been shown that the feces of rodents can act as a social stimulus and promote STFP in mice, which could reduce the social constraints associated with an encounter. Here, we examined the acquisition of the STFP in female house mice of wild origin (Mus musculus domesticus) after a direct encounter with a familiar and unfamiliar female, and after the presentation of olfactory marks of an unfamiliar female. Unlike in encounters between familiar females, our results did not provide significant support for the existence of STFP after encounters between two unfamiliar females, independently of the occurrence or absence of offensive agonistic behavior. However, STFP through olfactory marks of an unfamiliar female was effective. We suggest that the social context might strongly impair direct STFP, not necessarily via the unfamiliarity of the information provider but rather via its physical presence. (PsycINFO Database Record

Early singers attend to conspecific but not heterospecific behavioural cues at dawn

During the dawn chorus songbirds initiate singing activities just prior to sunrise. Environmental factors affect the timing of the dawn chorus, but relatively little is known about how behavioural cues influence chorus timing. We assessed whether early playback of conspecific and heterospecific song influenced chorus start times in two early‐singing temperate species, hermit thrush Catharus guttatus and veery C. fuscescens. We used arrays of GPS time‐synchronized recorders to record the dawn chorus at 30 locations. In each location, thirty minutes prior to natural chorus initiation, we broadcast: 1) an early singing species (hermit thrush or veery), 2) a late singing species (black‐throated green warbler Setophaga virens or Nashville warbler Oreothlypis ruficapilla), 3) a noise control, and 4) also recorded without playback (silent control). Playback treatments were separated by two‐three days at each location. Both hermit thrush and veery sang significantly earlier in response to conspecific playback compared to noise or silent controls. Both species also sang earlier in response to conspecific playback compared to the day before or the day after playback. Neither species sang earlier in response to heterospecific playback (regardless of whether the broadcast species was a naturally early or late song initiator) compared to noise or silent controls. Our results support the theory that the dawn chorus is a communication network where individuals attend primarily to conspecific cues; heterospecific song appears to have minimal impacts on the chorus start times of the two early‐singing species we investigated.