Responses to novelty in wild insular birds: comparing breeding populations in ecologically contrasting habitats.

Islands have always provided ideal natural laboratories for assessing ecological parameters influencing behaviour. One hypothesis that lends itself well to testing in island habitats suggests that animals frequenting highly variable environments should be motivated to approach and interact with (i.e. explore) novelty. Intra-species comparisons of populations living in ecologically different island habitats may, thus, help reveal the factors that modulate animals' responses to novelty. In this study, we presented novel objects to two geographically isolated breeding populations of the black-faced sheathbill (Chionis minor), a sedentary land-based bird that frequents remote sub-Antarctic islands. In the first population (Chionis minor ssp. crozettensis), the "Crozet group" (Baie du Marin, Ile de la Possession, Crozet Islands), breeding pairs inhabit a variable habitat close to penguin (Aptenodytes patagonicus) colonies. In the second population (Chionis minor ssp. minor), the "Kerguelen group" (île Verte, Morbihan gulf, Kerguelen Islands) breeding pairs live in penguin-free territories. In this latter population, the environment is less variable due to the presence of a broad intertidal zone which ensures year-round food availability. At both Kerguelen and Crozet, at least one breeding partner in all pairs approached at least one of the novel objects, and we found no significant differences in the latency of approach between the two populations. However, sheathbills at Crozet touched objects significantly more than birds at Kerguelen, and were also faster to touch them. We discuss how environmental variability, along with other potential influencing factors, may favour exploration of novelty in this wild insular bird.

Remote islands as natural laboratories: human-food association increases attraction to humans and novelty exploration in a seabird.

Increased attraction to humans and their objects often arises after repeated and positive human-wildlife encounters (e.g. food provided in tourist settings). The causes of this 'over-attraction', which may result from a learned association between humans and food, are still poorly studied in wild animals. Understanding the influence of humans on animals' responses is yet crucial to prevent negative effects (e.g. aggression). We presented three novel objects to two groups of free-ranging brown skuas (Catharacta antarctica ssp. lonnbergi) in the remote sub-Antarctic, where their habitats show no or minimal human disturbance. Skuas in one group (Verte) had previously participated in repeated food-rewarded behavioural and cognitive tasks with a human experimenter; skuas in the other group (Ratmanoff) had never done so. Objects consisted of (i) one natural-food-resembling object (plastic fish), (ii) one anthropogenic food object (real cake slice), and (iii) one anthropogenic non-food object (yellow glove). Verte group skuas approached the human experimenter and pecked significantly more and sooner at novel objects. Human-food association may have thus resulted in increased attraction to humans and novelty exploration in previously naive brown skuas, making this species a useful model for investigating the consequences of experience with humans on wildlife behaviour.

Assessing sex differences in behavioural flexibility in an endangered bird species: the Southern ground-hornbill (Bucorvus leadbeateri).

Since ecology influences the expression of cognitive traits, intra-specific variation in ecological demands can drive differences in cognition. This is often the case, for instance, when sexes face different ecological challenges. However, so far, most studies have focused on few cognitive domains (i.e., spatial cognition), which limits our understanding of the evolution of sexually dimorphic cognition in animals. Endangered Southern ground-hornbills (Bucorvus leadbeateri), for example, show sex-specific ecological differences in age at dispersal, where females disperse from their natal group earlier than males. Based on this potential sex-specific source of selection, females and males may differ in their capacity to behave flexibly. Here, we used the reversal-learning paradigm in ten Southern ground-hornbills in two conditions: spatial and colour. During the pre-test (learning phase), regardless the sex, all subjects were faster at associating the food reward with spatial rather than with colour cues. Similarly, during the test (reversal-learning phase), both sexes learned the new association quicker with spatial cues. There were no sex differences in learning or reversal learning during both experimental phases. This possibility, however, requires further observation and experimentation. We hope our study will provide the impetus to assess further the cognitive capacities of this still overlooked species.

Wild skuas can follow human-given behavioural cues when objects resemble natural food.

The capacity to follow human cues provides animals with information about the environment and can hence offer obvious adaptive benefits. Most studies carried out so far, however, have been on captive animals with previous experience with humans. Further comparative investigation is needed to properly assess the factors driving the emergence of this capacity under natural conditions, especially in species that do not have longstanding interactions with humans. Wild brown skuas (Catharacta antarctica ssp. lonnbergi) are non-neophobic seabirds that live in human-free habitats. In test 1, we assessed this species' capacity to use human behavioural cues (i.e., pecking at the same object previously picked up and lifted by a human experimenter) when the items presented were food objects: anthropogenic objects (wrapped muffins) and natural-food-resembling objects (plaster eggs). In test 2, we examined the response of another skua population towards non-food objects (sponges). Although all skuas in test 1 pecked at the objects, they pecked significantly more at the same previously handled items when they resembled natural food (plaster eggs). Most skuas in test 2, however, did not approach or peck at the non-food objects presented. Our results lead us to suggest that the use of human behavioural cues may be influenced by skuas' foraging ecology, which paves the way to further field studies assessing whether this capacity is directed specifically towards food objects and/or develops after previous interaction with humans.

Social diffusion of new foraging techniques in the Southern ground-hornbill (Bucorvus leadbeateri).

Social learning during foraging has been found in a wide range of animals, including numerous bird species. Still, the mechanisms underlying this cognitive capacity remain largely unstudied and the use of divergent methods limits our understanding of their taxonomic distribution. Using an ecologically relevant design, the open diffusion experiment, we tested whether 11 Southern ground-hornbills (Bucorvus leadbeateri) were able to show imitation on the two-action task. Three experimental groups were created. In the slide and pull group, subjects ('observers') watched a trained conspecific ('demonstrator') opening a box using a specific technique. Naïve individuals from the control group, however, did not receive a social demonstration. All birds of the slide and pull group succeeded in opening the box, whereas all subjects of the control group failed the task. We found consistent inter-individual differences among some observers, with only two birds (one in each group) using the same technique and part of the box contacted by the demonstrator. Our results suggest that at least fine-tune enhancement underlies behavioural diffusion in this novel model species, which provides new research opportunities with direct implications for conservation.

Through the eyes of a hunter: assessing perception and exclusion performance in ground-hornbills.

Logical inference, once strictly associated with spoken language, is now reported in some non-human animals. One aspect of logical inference, reasoning by exclusion, has been traditionally explored through the use of the cups task (cup A and cup B, if not cup A, then exclude cup A and select cup B). However, to fully understand the factors that drove the evolution of logical processes in animals, this latter paradigm needs to cover a taxonomically broader spectrum of species. In this study, we aimed to test the capacity of Southern ground-hornbills (Bucorvus leadbeateri) to show exclusion performance in a two-way object-choice task. First, we determined whether subjects could perceive and choose correctly between two containers (one rewarded, one unrewarded) using visual or acoustic cues (sensory phase). If successful, individuals were then presented with three experimental conditions (test phase): Full information (content of both cups revealed), Exclusion (content of the empty cup revealed), and Control (no content revealed). During the sensory phase, ground-hornbills succeeded in choosing the rewarded container only in the visual modality. Birds were able to select the rewarded container more than would be expected by chance in the Full information condition, but their performances were equal to chance in the Control condition. The without-learning performance of two individuals within the Exclusion condition indicates that this task is not trivial, which invites further investigation on this species' capacity to represent the dependent relationship between the cups (true logical inference).

Wild skuas can use acoustic cues to locate hidden food.

Among animals, the visual acuity of several predatory bird species is probably the most outstanding. This, and the ease with which visually based tasks are administered, has led researchers to predominantly use the visual modality when studying avian cognition. Some wild skua populations routinely use acoustic cues emitted by their prey during foraging. In this study, we thus assessed whether this species was able to locate hidden food using acoustic cues alone (training phase). During the subsequent test phase, we investigated the capacity of successful individuals to choose the correct baited container in four conditions: (i) baited (shaking the baited container), (ii) full information (shaking both containers), (iii) exclusion (shaking the empty container), and (iv) control (shaking neither container). Four out of ten subjects succeeded in locating the baited container in the training phase. During the test phase, most subjects chose the baited container significantly more than the empty container in the baited and full information condition, while their performance was at chance level in the control condition. When no sound emanated from the empty container in the exclusion condition, one out of four skuas chose the baited container with more accuracy than predicted by chance. As this bird chose correctly on the first trial and during the first five trials, its performance is unlikely due to learning processes (learning to exclude the empty container). Although further tests are necessary to draw firm conclusions, our results open the way for assessing further this species' reasoning abilities in the wild.

Wild great tits' alarm calls prompt vigilant behaviours in free-range chickens.

The ability to use heterospecific alarm calls is adaptive in the wild, as it provides an opportunity to avoid predators. We now know that several species are able to respond to alarm calls intended for others. However, this capacity has never been investigated in domestic animals. The capacity to use heterospecific alarm calls may be relevant for free-range domestic species, especially when they share predators with wild signallers. Using playback experiments, we investigated the vigilance behaviour of free-range naked neck chickens (Gallus gallus domesticus) when confronted with alarm calls (test playbacks) and songs (control playbacks) of a commonly occurring wild passerine, the great tit (Parus major). We found that subjects exhibited an increased vigilance to alarm calls compared to songs, therefore, showing that chickens respond to heterospecific signals as wild birds do. Recently, there has been an increased interest for free-range poultry production, notably because of the benefits of this farming method for chicken welfare. Although future studies are required to address this question, mortality due to predation may be reduced through the implementation of structures in areas frequented by wild heterospecific signallers.

Exclusion in the field: wild brown skuas find hidden food in the absence of visual information.

Inferential reasoning by exclusion allows responding adaptively to various environmental stimuli when confronted with inconsistent or partial information. In the experimental context, this mechanism involves selecting correctly between an empty option and a potentially rewarded one. Recently, the increasing reports of this capacity in phylogenetically distant species have led to the assumption that reasoning by exclusion is the result of convergent evolution. Within one largely unstudied avian order, i.e. the Charadriiformes, brown skuas (Catharacta antarctica ssp lonnbergi) are highly flexible and opportunistic predators. Behavioural flexibility, along with specific aspects of skuas' feeding ecology, may act as influencing factors in their ability to show exclusion performance. Our study aims to test whether skuas are able to choose by exclusion in a visual two-way object-choice task. Twenty-six wild birds were presented with two opaque cups, one covering a food reward. Three conditions were used: 'full information' (showing the content of both cups), 'exclusion' (showing the content of the empty cup), and 'control' (not showing any content). Skuas preferentially selected the rewarded cup in the full information and exclusion condition. The use of olfactory cues was excluded by results in the control condition. Our study opens new field investigations for testing further the cognition of this predatory seabird.

Social learning in great white pelicans (Pelecanus onocrotalus): A preliminary study.

Great white pelicans (Pelecanus onocrotalus) exhibit life-history parameters and ecological traits thought to be associated with social learning, and advanced cognitive processing more generally. In this study we investigated whether this species can acquire novel behavior socially in a foraging context. Birds from the test group watched a trained conspecific opening an opaque box containing a food reward by using its beak, whereas the control group had no demonstrator but saw the box for an equivalent time span. Individuals from both groups were subsequently allowed access to the box. Subjects of the test group performed significantly better than the control group. This is the first experimental evidence of social learning in a cooperatively hunting bird. Further studies are needed in order to shed light on the factors favoring the evolution of this capacity, by testing different pelican species that vary in their ecology.

Responses of wild skuas (Catharacta antarctica ssp. lonnbergi) to human cues in cooperative and competitive social contexts.

Many animals respond to and use social cues emitted by other species (e.g., head direction). In the context of human-animal communication, these capacities have been attributed to regular and longstanding exposure to humans. We presented wild brown skuas (Catharacta antarctica ssp. lonnbergi) with two versions of an object-choice paradigm. In the cooperative version (Experiment 1), one human experimenter provided a simple and salient cue indicating which of two containers covered a food reward. The cues administered consisted of touching, looking at, pointing at, or pointing and looking at the container hiding food. In Experiment 1, skuas could thus cooperate with an experimenter by using the cues provided to locate the rewarded container. In the competitive version (Experiment 2), two human experimenters presented a platform with a visible food reward. In six experimental conditions, we varied experimenters' body orientation, head orientation, eye-gaze direction, face occlusion, and mouth occlusion, as well as the platform's location, ensuring that in each case only one experimenter had visual access to the rewarded platform. Here, birds could compete with the experimenters by robbing the human who does not see the food. Skuas failed to use human-given cues spontaneously in Experiment 1, and took the reward regardless of whether the experimenters could see in Experiment 2. Our results contrast with those obtained on other wild birds with pre-experience with humans. Hopefully, our findings will stimulate further research in order to illuminate the potential role of such experience in the capacity to respond to and use human-given cues. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Exclusion by donkey's ears: Donkeys (Equus asinus) use acoustic information to find hidden food in a two-way object-choice task.

Once believed uniquely human, the capacity to reason is now investigated in a wide range of species. One component of this ability, inference by exclusion, has been traditionally explored through the cups task, where 2 containers are presented but only 1 covers a food reward (if Cup A is empty, then choose Cup B). Often based on low-level cognitive mechanisms (learning), performance on this task can also reflect reasoning processes in some individuals. Limited taxonomic investigation, however, has hindered our understanding of the factors that contribute to the evolution of reasoning in animals. Using the cups task, we first investigated the ability of 14 semiwild donkeys to locate a food reward by using visual or acoustic cues alone (pretest phase). Although all subjects failed the task when provided with visual cues, 7 donkeys succeeded in the acoustic modality. We thus tested the capacity of donkeys to make choices by exclusion in the acoustic modality (test phase). Three conditions were presented, where subjects received information about either both containers (full information condition), solely the empty container (exclusion condition), or no information (control condition). Most subjects chose the correct container in the full information condition, whereas they chose randomly in the control condition. Except for 1 individual, donkeys improved their performance across trials in the exclusion condition. Our study contributes to the very small body of literature on exclusion based on acoustic cues in animals and paves the way to further experiments on the cognitive processes underlying exclusion performance in donkeys. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Assessing the spontaneous use of human-given cues in ground-hornbills.

A wide range of species relies on heterospecific visual cues to detect the location of resources like food. Although different hypotheses have been suggested to explain the emergence of this capacity in animals, results are often difficult to interpret due to the influence of other factors, such as close contact with humans. In this study, we presented eight Southern ground-hornbills (Bucorvus leadbeateri) with a two-way object-choice paradigm. The human experimenter provided a static and salient cue indicating which of the two containers was baited in four experimental conditions: (a) Touch, (b) Head, (c) Point + Head, and (d) Point. In an additional control condition (no cues given), we assessed whether subjects relied on olfactory cues to solve the task. Overall, our subjects did not spontaneously use human-given cues and their performance fluctuated near chance during the control condition. Noteworthy, most birds exhibited a side bias towards one container. We do not exclude the possibility that this species may be capable of using other cue types, or learning to use cues, after long interaction with humans is provided.

First description of nest-decoration behaviour in a wild sub-Antarctic shorebird.

A wide range of animal species accumulate objects in, on, and/or around structures they build. Sometimes, these accumulations serve specific functions (e.g. structural or isolating features) or are purely incidental, while in other cases the materials are deliberately displayed to serve signalling purposes (extended phenotype signals). In this pilot study, we employed systematic in situ observations and camera trapping to describe for the first time that both partners of a territorial shorebird, the black-faced sheathbill (Chionis minor ssp minor) collect, carry, and arrange colourful marine shells and dry twigs within and around their nest cavity. Our observations expand the taxonomic breadth of avian extended phenotype signals, by showing that at least one species within a largely understudied group i.e., Charadriiformes, exhibits nest-decoration behaviour. Multiple manipulative experiments are needed to explore further the signalling function of these decorations, which opens new exciting avenues for animal communication and cognition research.

Complex nests but no use of tools: An investigation of problem solving in weaverbirds (Ploceidae).

Few avian species use tools in the wild. Yet, several birds build nests of great complexity and many aspects of tool use may also apply to nest building. It has long been hypothesised that tool use may select for specialised cognitive adaptations or even general cognitive skills. This might similarly pertain to species that build complex nests. In this study, we investigated the problem-solving capacity of a complex nest builder, a weaverbird species, in a foraging context that either required or did not require the use of tools. First, we tested the capacity of yellow-crowned bishops (Euplectes afer ssp. afer) to use a tool for retrieving an out-of-reach reward during three problem-solving tasks offering different nest/non-nest materials (Experiment 1). Next, subjects were confronted with two problem-solving tasks that required no tools (Experiment 2). No subject was able to use a tool in Experiment 1. However, 11 out of 12 subjects succeeded in using their beak in the first problem-solving task, and 9 in the second problem-solving task of Experiment 2. These results suggest that weaverbirds showed flexible problem-solving if the use of tools was not required.

From the Age of 5 Humans Decide Economically, Whereas Crows Exhibit Individual Preferences.

Human societies greatly depend on tools, which spare us considerable time and effort. Humans might have evolved a bias to employ tools, using them even when they are unnecessary. This study aimed to investigate whether adult humans and a distantly related habitually tool-using vertebrate species, the New Caledonian crow (Corvus moneduloides), use tools depending on their necessity. In addition, children aged 3 to 5 years were examined to investigate the developmental pattern. The task involved choosing between using a body part (i.e. crows: beak; humans: hand) or a tool for retrieving a reward from a box. All subjects were tested in two conditions. In the Body+/Tool- condition, using the body was more efficient than using the tool, and conversely in the Body-/Tool+ condition. Our results suggest that the capacity to employ tools economically develops late in humans. Crows, however, failed to choose economically. At the individual level, some subjects exhibited striking individual preferences for either using a tool or their beak throughout the task. Whether such biases depend on individual experience or whether they are genetically determined remains to be investigated. Our findings provide new insights about tool use and its cognitive implementation in two outstanding tool-using taxa.