Showing papers in "Behaviour in 2023"

High incidence of leg autotomy in urban crickets

Abstract: Predation is an important selection pressure affecting animals. Predation has both consumptive and non-lethal effects. Because it is often difficult to estimate the extent to which non-lethal effects occur, we focused on autotomy as an indicator of non-lethal effects occurring in urban habitats. Autotomy is expected to indicate that individuals have escaped from predators. The incidence of leg autotomy in the cricket Dianemobius nigrofasciatus was compared between urban and rural habitats. The incidence of autotomy was higher in urban than in rural habitats. Failure to moult and conspecific aggressive interactions were not the main factors contributing to the incidence of autotomy in these crickets. The ease of autotomy and risk-taking tendencies did not differ among habitats. These results indicate that the incidence of autotomy reflects predation failure, and the non-lethal effects of predation are more likely to occur in urban habitats.

Shark evacuation from Mo’orea island in 2002

Abstract: Reef sharks, including blackfins (Carcharhinus melanopterus) reside in the lagoons and on the outer slopes of the barrier reefs of Mo’orea Island, French Polynesia. In general the lagoons are shallow enough to permit underwater observation, while dive clubs hold shark dives at different sites in the lagoons and in the ocean. Thus, the presence of blackfin sharks especially, and other species at times, is confirmed daily. Between about 21 July and 2 August 2002, all blackfin reef sharks under observation, and possibly some of the other species, left their lagoon and ocean ranges and disappeared from human view, a unique evacuation for which no explanation was found. The event suggests an unknown pattern or influence at work which was perceived by sharks, but was not apparent to those investigating.

A review of the behaviours of the Chondrichthyes: a multi-species ethogram for the chimaeras, sharks, and rays

Abstract: In this review of the behavioural patterns of chondrichthyan fishes, we have strived to produce a comprehensive catalogue of events and states and develop standardized terminology. Hence, actions that are slightly different, will be pooled under inclusive titles. Those used by different investigators are included in quotations within the textual descriptions of the motor patterns. This standardized ethogram will ideally lead to an increase in inter-observer reliability, giving researchers more confidence when reading colleagues’ papers that report behaviours that appear similar to theirs despite being described for different species. The descriptions are presented under the following categories: (1) maintenance (2) courtship (3) filter feeding (4) scavenging (5) predation (6) sociality (7) aggression and (8) defence. The many actions are illustrated by line drawings and photographs in composite figures with an attempt to provide an example of each action for a chimaera, shark, and ray. The diversity of patterns is evident from this ethogram, consistent with observation that the brain-to-body mass ratios of cartilaginous fishes are greater than a third of the bird species and greater than those for some mammalian species. The major impetus for assembling this ethogram is to demonstrate the diversity of behaviours exhibited by members of the Chondrichthyes and to dispel the apocryphal belief that members of this taxon are ‘simple feeding machines’.

Could convulsive body shuddering of a white shark near a shark cage be an element of a threat display?

Abstract: In this short note, we describe the convulsive body shuddering of a white shark as it approached two large metallic shark cages, each with multiple divers standing within them. When animals feel threatened, they experience conflicting instincts — one is to escape and another is to fight. In this situation, they do not always fight but often perform an agonistic, or aggressive display. Having arrived at the source of an olfactory corridor, this white shark was confronted with highly visible cages made with aluminium bars. The divers use hookah air hoses to breathe, and were therefore releasing bubbles, which reflect light and generate sounds as they oscillate toward the surface. The photographers may also have been taking pictures of the shark with their flash-bulb equipped cameras, which produce a sudden disruptive flash of irradiance. The shark’s behaviour is illustrated with a series of video frames as he approaches the cage. The body of the shark shutters convulsively and he opens his mouth, keeping it open for a prolonged period of 2.8 s as he passes close to the cage, while (1) depressing his pectoral fins, (2) hunching his back, (3) keeping his caudal fin held at right angle to the axis of view to increase his apparent size, and (4) shaking his body with spasmodic oscillations. The shark appears frightened, and hence may perform the display to discourage any aggression directed at him by the cage with humans emitting a panoply of frightening stimuli. Alternative explanations of the motivation behind this behaviour are also discussed. We hope that it will lead other scientists to look for this behaviour when observing the behaviour of white sharks from a cage, so they can provide further evidence shedding light upon the shark’s motivation for performing this conspicuous behaviour.

The ‘Mistaken Identity Hypothesis’ for shark bites on humans is an anthropomorphic fallacy

Abstract: The Mistaken Identity Hypothesis (MIH) interprets shark bites on surfers, swimmers and snorkelers as ‘mistakes’ stemming primarily from similarities in the visual appearance of ocean users and the sharks typical prey. MIH is now widely accepted as fact by the general public and some sections of the scientific community despite remaining unproven. This hypothesis assumes that ‘mistaken’ shark bites on humans result primarily from confusing visual cues and ignores the important role of other senses (e.g. hearing) in discriminating potential prey. A far simpler ‘natural exploration’ hypothesis can reasonably explain not only shark bites that have been characterized as ‘mistaken identity’ events but also those that cannot be reasonably explained by MIH (e.g. shark bites that occur in very clear water). Simply stated, sharks don’t make ‘mistakes’ but instead continually explore their environments and routinely investigate novel objects as potential prey by biting them.

Keeping treasure safe: Eurasian red squirrels cache valuable food far from the food source with low canopy cover

Abstract: Scatter-hoarding animals decide their food hoarding location by assessing food quality and pilfering risk. Previous studies have proposed two non-mutually exclusive hypotheses; the optimal density model (ODM) and the habitat structure hypothesis (HSH). The ODM proposes that animals utilize low cache density to protect their valuable caches by transporting food far from food sources. The HSH proposes that animals utilize predation risk to protect their valuable caches by hoarding food in open areas. Here, we investigated the hoarding behaviours in Eurasian red squirrels Sciurus vulgaris by experimentally providing high-quality (walnuts) and low-quality (acorns) food, to examine if they follow ODM or HSH. Compared to acorns, squirrels hoarded walnuts in places further from the area where food was provisioned and in areas with low canopy cover. These results agree with both ODM and HSH, providing the first evidence that hoarding behaviour in Eurasian red squirrels is shaped by multiple factors.

Construction of nest mound and preference for it during relocation in an Indian ant Diacamma indicum

Abstract: Ants living in subterranean nests face the challenge of nest flooding and require to combat this recurring issue. The tropical Ponerine ant species, Diacamma indicum, living in simple nests with a single chamber, was used in the current study to examine mound building in the lab. Upon stimulating rain ( colonies) they built significantly larger nest mounds as compared to controls. Nest mounds proved to be important to colonies that had experienced rain while relocating. Relocating colonies showed significantly higher preference for new nests with mounds (12/13) when choosing between two equidistant, similar quality potential new nests in contrast to control relocations. To the best of our knowledge this study for the first-time documents mound building behaviour in any Ponerine species in laboratory conditions and introduces nest mounds as another architectural feature of interest to relocating colonies.

Female preferences for high vocal effort in singing mice

Abstract: Although vocalizations are essential to mammalian sociosexual behaviours, little is known about female preferences for male vocal displays in non-model mammalian species. Here, we characterized female preferences for the advertisement songs of male Alston’s singing mice (Scotinomys teguina). We developed procedures for inducing oestrus, using vaginal perforation as a morphological indicator of oestrus. We then broadcasted ‘high-effort’ and ‘low-effort’ songs recorded from wild-caught males to virgin laboratory-reared females, using a two-choice experiment. Our results indicate that females spent more time investigating speakers playing high-effort songs; surprisingly, this phonotactic response is independent of oestrus status. In wild singing mice, acoustic characteristics of high-effort male songs positively correlate with body condition. Our data suggest that females could use acoustic cues to select mates in good condition, thus providing preliminary support for adaptive mate choice hypotheses. More generally, our results support the hypothesis that elaborate Scotinomys song may be shaped by female choice.

Behavioural interactions between sika deer and Japanese serows: are larger and gregarious ungulates dominant?

Abstract: In ungulate assemblages, although interspecific differences in body size and gregariousness are thought to have a direct impact on winning or losing in interference competition, this has not been fully investigated. We observed a total of 64 instances of interspecific contact between larger-gregarious sika deer and smaller-solitary Japanese serows over eight years field observations. Deer-to-serow aggression were never observed. Whereas, serows showed antagonistic behaviour, such as walk push and chasing, to deer, but could rarely displace deer. Serows showed higher alertness to deer than deer did to serows. These results suggest that larger-gregarious ungulates do not necessarily exclude smaller-solitary ones and serows are sensitive to the presence of deer. Differences in aggressiveness and alertness between deer and serows may reflect differences in territoriality: serows may be more sensitive to the invasion of deer into their territory. Serows’ sensitivity to deer may have a negative effect on their population.

Ethogram for blacktip reef sharks (Carcharhinus melanopterus)

Abstract: The chondrichthyan lineage diverged from the osteichthyan line around 440 million years ago, resulting in a vast evolutionary gulf between modern elasmobranchs and other vertebrates. Though this has supported the assumption that as an ancient line, elasmobranchs are dangerously stupid, intelligent actions including social interactions have been noted in the field, while laboratory studies have confirmed a variety of cognitive capacities. Yet, due to fear of sharks and the difficulties of observing them in their aquatic environments, few ethological studies have been done, so their natural behaviour remains little known. On noting that the blacktip reef shark, Carcharhinus melanopterus, displayed complex actions during incidental meetings, a long-term ethological study of the species was carried out on the north shore of Mo’orea Island, French Polynesia. During the 6.5 years of the study, new behaviours continued to present. The 35 context-specific actions identified as comprising the behavioural repertoire of C. melanopterus are described.

Effects of chronic social defeat on social interaction and partner preference in mandarin voles

Abstract: Different types of stress produce different effects on social relationships between partners. Chronic social defeat has been found to alter the emotional and social behaviours, whether it affects partner preference remains unclear. Using monogamous mandarin voles (Microtus mandarinus), the present study found that 14 days of social defeat to male vole could increase social avoidance in sociality test, and reduced attacking, intimate, sniffing and exploratory behaviours, but increased avoidance defensive, immobile behaviours in social interaction test. In addition, this treatment significantly reduced side-by-side contact with partner throughout cohabitation period, and reduced the attacking behaviour to strangers after 11 days’ cohabitation. Furthermore, in mandarin vole with chronic social defeat, partner preference was abolished on 5 and 7 days’ cohabitation indicating that pair bonding stability was impaired by chronic social defeat. Moreover, although mandarin voles spent longer time rescuing partner than stranger in both groups, chronic social defeat did not affect rescuing significantly. Impairment of pair bonding may be due to abnormalities in social interaction induced by chronic social defeat. This finding provides some insights into mechanisms underlying effects of prolong social stress on social relationships between partners.

Opposing effects of vigilance and foraging on escape behaviour in hooded crows

Abstract: Escape represents an important component of animals’ antipredator behaviour entailing both benefits and costs dependent on a moment an animal flees upon predator’s approach. In this study, I examined how the level of vigilance and foraging activity affected escape decision in the urban hooded crow Corvus cornix, predicting that alert distance (AD) and flight initiation distance (FID) should be positively affected by the level of vigilance and negatively affected by foraging activity, whereas buffer distance (BD) should be negatively affected by the level of vigilance and positively affected by foraging activity. Using LMMs it was shown that percent of time crows allocated to vigilance was positively correlated with AD and FID, whereas foraging activity of crows had negative impact on AD and FID. In addition, both AD and FID were positively related to starting distance (SD), while AD was also positively influenced by tree coverage. BD was positively affected by foraging activity and AD. This study demonstrated that more vigilant birds detected predators earlier, which is in accordance with the major function of vigilance. Also, it was shown that foraging crows delayed their escape, once the predator has been detected, as benefits of delayed flight, such as feeding on a profitable food item or within a profitable patch, may outweigh costs, which is consistent with the optimal escape theory.

Ring a bell? Variable recognition of a multicomponent auditory stimulus associated with predation risk by zebrafish responding to full and partial matches

Abstract: Many fishes learn to recognize correlates of predation risk by pairing novel stimuli with injury-released chemical cues released from damaged epidermal tissues. Here, zebrafish were conditioned to associate predation risk with a three-note auditory stimulus C5 (523.25 Hz) + E5 (659.25 Hz) + G5 (783.99 Hz), then tested for responses to either only one tone (C), two of the components (C + G) or the full three-note chord (C + E + G). Zebrafish conditioned with alarm cues and C + E + G responded significantly more intensely to the full C + E + G stimulus or to partial representation of the original mix (C + G) than they did to the single element (C) of the original C + E + G conditioning stimulus. The lack of a response to the single component alone may be a failure to recognize the stimulus or an interpretation that the partial component is an indicator of low risk.

Eyes over stomach: companion dogs choose the larger quantity by sight, irrespective of the actual reward eaten

Abstract: Domestic dogs tested in a free-choice task between two sets of food prefer that of a larger quantity. A recent study pointed out the critical role of the first trial. Dogs succeeded only after being allowed at least once to eat the selected food. Here we explore the importance of the actual experience of consuming the selected reward on dogs’ capability to redirect their choice to solve numerical discriminations. Dogs tested in the 2 vs 4 and 1 vs 8 comparisons could never consume the quantity selected but always obtained a single dogs’ treat. Despite never experiencing a difference in the eaten quantity, dogs discriminated between the two sets, preferring the larger. Whereas they behaved at chance at first choice, they successfully redirected their preference toward the larger set already on their second trial. We discuss our results in terms of motivational biases toward the larger quantity that can bear relevant ecological value.

A historical approach to describing the complex behaviour of a large species of carnivorous shark. Case study No. 1: the scalloped hammerhead, Sphyrna lewini

Abstract: A historical example, case study No. 1, is given illustrating the complexity of interactions between sharks in their natural environment. Scalloped hammerhead sharks, Sphyrna lewini, form polarized schools at offshore islands and seamounts. Females perform a display while inside a school to force smaller individuals to the periphery. The Corkscrew consists of a rapid burst of swimming into a tight looping trajectory, with the shark rotating its torso almost 360° on its longitudinal axis. This conveys a shark’s intent to contact the recipient with a Hit. This is competition for a position at the centre of the school. Males dash into the schools, directing emphatic tail beats to one side with a Torso Thrust, propelling the shark‘s anterior torso laterally, to pair with a dominant female. The pair then moves outside the school to copulate in midwater with the male biting the female’s body and inserting his clasper within her uterus.

Tongue-flicking: an idiosyncratic displacement behaviour in a free-ranging and urban-dwelling population of Balinese long-tailed macaques

Abstract: This brief report describes the occurrence of an idiosyncratic behaviour, labelled tongue-flicking, that was performed by one subadult male long-tailed macaque living in a free-ranging population in Bali, Indonesia. Tongue-flicking may serve a similar purpose as a displacement behaviour in which the subject sticks his tongue out of his mouth and moves it either slightly up and down or in and out without bringing it all the way back into the mouth. Additionally, while abnormal behaviours in non-human animals are almost exclusively reported in captive individuals, the investigation of idiosyncratic behaviours such as tongue-flicking allows us to explore the potential occurrence of abnormal behaviours in free-ranging populations. This preliminary descriptive analysis of tongue-flicking aims to highlight the need for understanding the motivational bases and affective implications (e.g., welfare) of abnormal behaviours in captive and free-living animals.

Effects of snow leopards (Panthera uncia) on olfactory communication of Pallas’s cats (Otocolobus manul) in the Altai Mountains, Mongolia

Abstract: Olfactory communication is important for many solitary carnivores to delineate territories and communicate with potential mates and competitors. Pallas’s cats (Otocolobus manul) are small felids with little published research on their ecology and behaviour, including if they avoid or change behaviours due to dominant carnivores. We studied their olfactory communication and visitation at scent-marking sites using camera traps in two study areas in Mongolia. We documented four types of olfactory communication behaviours, and olfaction (sniffing) was the most frequent. Pallas’s cats used olfactory communication most frequently at sites that were not visited by snow leopards (Panthera uncia) and when they used communal scent-marking sites, they were more likely to use olfactory communication when a longer time had elapsed since the last visit by a snow leopard. This suggests that Pallas’s cats may reduce advertising their presence in response to occurrence of snow leopards, possibly to limit predation risk.

The link between animal personality and habitat selection in males of the Neotropical poison frog Allobates femoralis

Abstract: Environmental variation plays a key role in the evolution and maintenance of animal personality. Individuals with different personality types might exhibit different habitat preferences. Alternatively, variation in individual behaviour across space could arise as a plastic adaptation to distinct habitats. Our study aims to investigate if habitat choice is influenced by an individual’s personality. We assessed individual levels of activity, boldness, and exploration in male poison frogs, and performed a habitat choice test under controlled laboratory conditions. Individuals were consistent in their behaviours, but all tested frogs chose the complex over the simple habitat. Individuals that were characterized as bold and very explorative also showed more movements between the two different habitats in the choice test. These results indicate that personality measured in a highly standardized artificial setup, such as a novel environment test, indeed can reflect boldness and exploration related behaviours measured in a more naturalistic setup.

Good fences make good neighbours: territorial male Cape fur seals use spatial acoustic map of neighbours

Abstract: In territorial species, individual recognition among neighbouring males is likely to reduce energy expenses and risk of injury associated with the costly period of maintaining territory during the breeding season. This study explored neighbour–stranger vocal recognition in male Cape fur seals, one of the most colonial and polygynous mammals. Playback experiments revealed that territorial males were able to recognise the calls of their neighbours, in combination with their relative spatial position to their own harem. No ‘dear-enemy’ nor ‘nasty neighbour’ effects were detected. However, the strongest responses observed were towards the calls of familiar neighbours played back from an incongruent location, simulating a situation in which a neighbour is outside its own territory. The colony structure and movements of the seals across the day could explain such results. This study has implications for understanding how vocal signals regulate interactions among males in polygynous mammals, particularly during the competitive mating period.

Twig-assisted masturbation in Balinese long-tailed macaques

Abstract: We documented evidence of idiosyncratic but repeated twig-assisted genital stimulation by Balinese long-tailed macaques (Macaca fascicularis), living in Ubud, Indonesia. This population is known to customarily engage in genital stone-tapping/-rubbing, a behaviour expressed by males and females of different age classes as part of a broader cultural repertoire of stone-directed and overall playful actions known as stone handling. However, genital stimulation using other objects has never been reported in this population and species. We observed repeated and extensive twig-assisted genital stimulation in one adult female and one adult male. We also recorded three instances of twig-assisted genital stimulation in three additional individuals. Our results indicate that this behaviour is not accidental and may be sexually motivated; that is, it may be another form of tool-assisted masturbation in this primate population. This report provides a valuable addition to the increasing literature on tool-assisted behavioural innovations pertaining to self-care and possibly pleasure.

Predator and duck behaviours at depredated nests in wetlands of Great Salt Lake, Utah

Abstract: Nest depredation is one of the greatest threats posed to ground-nesting ducks. We employed cameras to monitor 164 duck nests (71 cinnamon teal, Spatula cyanoptera, 44 gadwall, Mareca strepera, 38 mallard, Anas platyrhynchos, and 11 nests of unknown species) in the wetlands surrounding Great Salt Lake, from 2015–2021. Of the 164 nests, 21% were successful, 73% were depredated and 7% were abandoned. We observed predators at 99 of the 119 depredated nests; predators at 20 nests went undetected. Raccoons (Procyon lotor, depredated nests) and striped skunks (Mephitis mephitis, ) were the most common of the 99 nest predators recorded. Other predators that depredated nests included long-tailed weasels (Mustela frenata), northern harriers (Circus hudsonius), California gulls (Larus californicus), Sandhill cranes (Antigone canadensis), common ravens (Corvus corax), coyotes (Canis latrans) and red foxes (Vulpes vulpes). Neither the number of eggs removed per depredation event nor the number of eggs remaining varied by predator species. Depredated nests were easier for predators to find than undisturbed, incubated nests, resulting in 68% of depredated nests being visited by multiple predators. All hens detected the approach of a predator and flushed before the predator reached the nest; no hens attempted to defend their nest or attack the predator. Only 21% of hens returned to their depredated nest, and those that did remained off their nest an average of 33 h and 23 h after their nest was depredated by a raccoon or skunk, respectively. Seventeen percent of hens resumed incubation of their depredated nest, but only 1 nest to which a hen returned successfully hatched an egg. Depredation events of raccoons and skunks were not distributed randomly during the 24-hour day, but rather occurred most often during the night and nautical twilight, and rarely during the day. Depredation events of avian predators occurred during the day, rarely during twilight, and none during the night. Depredation events during the night were more likely when the wind was calm but temperature, humidity, and actual moon illumination had no impact. Depredation events by skunks and raccoons occurred more often during the 1st and 4th phases of the moon (new moon) than in the 2nd or 3rd phase.

Examining causes and characteristics of egg ejection behaviour in the American robin (Turdus migratorius)

Abstract: American robins (Turdus migratorius) are among few hosts of parasitic brown-headed cowbirds (Molothrus ater) that frequently eject foreign eggs from their nests. However, we know little about some characteristics of the robins’ egg ejection process including its distance and direction. We used a novel technique (i.e., radio transmitters inserted into 3D-printed eggshells) to examine egg rejection in female robins as a function of model egg coloration (i.e., robin-mimetic blue, non-mimetic deep blue, and non-mimetic beige). Based on prior work, we predicted that female robins’ egg ejection decisions would be dependent on egg coloration. Accordingly, we found a significant effect of female identity (using nest identity as a proxy) and model egg colour on egg ejection, but neither predicted ejection distance or direction. Deep blue model eggs had shorter ejection latencies than beige eggs. Fully characterizing the egg ejection process will allow us to further understand the mechanisms and outcomes of egg ejection behaviours in host-parasite interactions.

Sex and reproductive status affect sheltering and exploratory behaviours with high intra-individual variability in crayfish

Abstract: The contexts in which individuals demonstrate behavioural consistency or variability have been the subject of research focus. We studied exploratory and sheltering behaviour in the crayfish F. virilis to understand how these behaviours vary by sex and reproductive readiness and to quantify the repeatability of these behaviours. Crayfish were tested in two sets of three rounds, one in the summer non-reproductive season and another in the autumn reproductive season. Reproductive crayfish spent more time outside the shelter and were more likely to accept a food item than non-reproductive crayfish. In the non-reproductive season, females spent more time outside the shelter than males, and over both seasons, females were more likely to seek and accept a food item. Repeatability estimates were low, indicating high intra-individual variability in these behaviours. Sheltering and exploratory behaviours were not correlated. This indicates sex or reproductive readiness have strong effects on both sheltering and exploratory behaviours.

Effects of cross-fostering experience on emotion in adolescent Kunming mice

Abstract: Parent–infant bonds are critical early postnatal environment in mammals. Unstable parent–infant bonds, such as maternal separation, paternal deprivation, and neonatal social isolation have negative effects on emotion, cognition, addiction, and social behaviours in the animal’s whole lifespan. Another unstable parent–infant bond, cross-fostering, in which pups were randomly exchanged to other parents has mostly focused on kin recognition and anxiety-like behavioural changes in adult. But its effects on adolescence, particularly on autism spectrum disorder, are poorly understood. Whole cross-fostering model was used in the present study. The results showed that with cross-fostering, adolescent Kunming mice buried more marbles, expressed higher levels of anxiety and depression. Cross-fostering attenuated prosocial behaviours and reduced the activity of adolescence when encountering another individual in social interaction test. Taken together, our results demonstrate that experiencing whole cross-fostering in early life is more likely to induce autism-, anxiety-, and depression- like behaviours in adolescence.

Invader’s success: behavioural and reproductive plasticity of interacting exotic dung beetles

Abstract: Dung beetles have been introduced to non-native sites to perform dung removal function in cattle pastures. Despite some species becoming invasive, their behavioural and reproductive strategies remain to be elucidated in detail. Here we evaluated the shift in behaviour and reproduction of two species of dung beetles, Euoniticellus intermedius and Digitonthophagus gazella, when they interact with the same or other species out of their native range. Under natural conditions, E. intermedius brood masses were lighter in traps (i.e., field enclosures) with more total brood masses. In the laboratory, D. gazella induced faster dung colonization by E. intermedius and conspecifics. The presence of conspecifics or heterospecifics reduced reproductive success in D. gazella, revealing intense competition for dung. In the offspring, E. intermedius females emerged larger in the presence of D. gazella, revealing differential maternal investment triggered by competitors. In conclusion, behavioural and reproductive plasticity are fundamental for dung beetles to become successful invaders.

Sharing your snack: unusual observation of a chick–chick feeding occurrence in colonial king penguin (Aptenodytes patagonicus)

Abstract: King penguins (Aptenodytes patagonicus) are colonial seabirds presenting an extraordinary breeding cycle. Parents take over 14 months to raise a single chick to independence, upon which fledglings depart at sea for more than a year. Juveniles often return to the colony within the three austral summers following departure, and before the age of first reproduction (around 5–6 years old), possibly to acquire the essential skills involved in breeding. Little to nothing is known on the acquisition of parental behaviour. Here, we report an anecdotal, yet highly unusual, observation of chick–chick feeding behaviour in this species. The behaviour is highly unusual in that two non-sibling chicks, not yet independent, and hatched at different times (early and late) of the same breeding season were observed, the older chick feeding the younger one. Whereas alloparental feeding is known to occur in this species, this is the first reported observation of a chick–chick feeding event. This unusual behaviour raises the question of whether the early social environment plays a role in the acquisition of essential parenting skills in this species.

The effect of individual personality on novel food preference in a social context in the cinereous tit (Parus cinereus)

Abstract: Exploratory behaviour is one of the best-investigated behavioural traits. However, little is known about the influence of personality on novel food preferences in the social context, i.e., whether knowledge and previous experience can influence individual preference or if the presence of conspecifics can alter their choice. In the present study, we examined in cinereous tit (Parus cinereus) whether individuals with different personality types in the social context will prefer their own previously chosen novel food or change their preference in the presence of conspecifics. Second, we studied how the presence and behaviour of conspecifics may mediate individual personality. We conducted a standardized personality assay (exploratory behaviour) to analyse the individual personality. Birds were trained and provided with three different types of novel human-derived materials in both asocial and social contexts (with a conspecific). We recorded the latency to feed, time spent at the feeder, and the number of visits by fast and slow explorers in the two contexts, i.e., asocial and social. After the analyses of experimental data, we found that fast-exploring cinereous tits preferred peanuts in an asocial context, while slow explorers consumed a greater amount of sunflower seeds. In the social context, individuals of both personality types preferred peanuts to sunflower seeds. Additionally, individuals took less latency to eat food, made more visits to the feeder, and spent more time at the feeder in the social context than in the asocial context. Our findings show that foraging success may be determined by personality and social context. However, personality traits may be subject to constraints arising from correlations with other behavioural traits, and it remains a major challenge to understand the functional significance of individual foraging strategies.

Functional traits including interspecific sociality affect mobbing behaviour in a bird community of southern China

Abstract: Mobbing is a prevalent anti-predatory behaviour in birds where prey actively engage in harassing predators. Functional traits have been shown to affect prey species’ tendency to engage in mobbing, but empirical studies have largely neglected to assess the influence of some other potentially important functional traits, such as intraspecific and interspecific sociality, on mobbing or measured different aspects of the behaviour. In this study, we performed playback experiments that elicited mobbing responses from a forest bird community in southern China, to investigate the influence of body mass, foraging strata, as well as intra- and interspecific sociality, on the prevalence of mobbing, as well as the intensity of aggression and vocalness. We found that species with small body masses engaged in more frequent and intense mobbing behaviours. Notably, interspecific sociality was negatively associated with birds’ mobbing prevalence and tended to be negatively associated with vocalness.

Facultative male investment in prolonged mate-guarding in a butterfly

Abstract: Sexual conflict over mating may induce male mate-guarding prolonged in time in the absence of males, via devices such as mating plugs, widespread in insects. In most Lepidoptera, internal plugs are common, while in some butterfly families large external devices, called sphragides, evolved independently. Lack of, or incomplete sphragis in a few individuals were reported in sphragis-bearing species. Previous studies focused on typifying species-specific devices in a few specimens of many species. In contrast, we investigated alternative mate-guarding devices in detail of a sphragis-bearing butterfly. We conducted a six-year observational field study in a Clouded Apollo Parnassius mnemosyne population. Inspecting 492 females, we identified 3 different devices, filament, stopple and shield (i.e., sphragis) increasing in size and structure complexity, implying differential male investment and effectiveness in securing paternity. Shield dimensions, colour and all devices’ shapes varied considerably. Shields were far more frequent than other devices. Some devices were lost, and a few were video-recorded when removed by males, showing the role of different parts of male external genitalia. We discuss potential causes of device variation and the role of removal attempts, and assess potential costs and benefits for both sexes.

Western Australian magpies respond to urgency information contained in conspecific alarm calls

Abstract: Many animals provide information about predator proximity in their alarm calls. In response to predators further away, Western Australian magpies (Gymnorhina tibicen dorsalis) produce alarm calls containing fewer notes compared to those produced when predators are closer. Since the ability to make fine-scale adjustments to antipredator responses by being sensitive to the level of urgency in calls may be beneficial, receivers are expected to be able to appropriately decipher and respond to this information. We conducted playbacks to test whether magpies can respond to urgency information in conspecific alarm calls. Magpies were exposed to low-urgency calls (calls with one note), high-urgency calls (calls with four notes), and one- and four-note control calls. Receivers showed greater levels of responsiveness following playbacks of high-urgency calls compared to playbacks of low-urgency and control calls, providing evidence that magpies can respond to information about the urgency of a predator threat from conspecific alarm calls.