Corvid Species Research Articles

Behavioral Responses of Captive Corvids to the Presence of Visitors

Behavioral responses of captive animals to the presence of visitors in zoos and wildlife parks can be interpreted as signs of negative (disturbance), neutral or positive (enrichment) welfare. In the present study, we investigated behavioral responses of captive common ravens, Corvus corax and crows, Corvus corone, to the presence of visitors in general and to the proximity or distance of visitors to the aviary respectively. Duration of affiliative behaviors, feeding and stress-related behaviors did not change when visitors were present compared to control situations without visitors being present. Both corvid species showed less head up behavior when visitors were in sight compared to the control condition. In contrast, preening of crows significantly increased when visitors were within two meters of the aviary compared to the control condition. The same relationship was found in regard to increase in vocalization for common ravens, but not for crows. Our results indicate that corvids, housed in a wildlife park for several years, still show behavioral responses to the presence of human visitors in close proximity to their enclosure. Overall, we did not find clear indications for reduced welfare due to visitor presence, such as increased locomotion or stress-related behaviors. We therefore conclude that the described behavioral changes are not indicative of any negative welfare impacts of visitor presence.

Webcams as a Remote Tool for Eco-ethological Research: A Study on the Alpine Chough

Methods and devices specifically created for remote animal surveys and monitoring are becoming increasingly popular and effective. However, remote devices are also widely used in our societies for different, not scientific, goals. Ski resorts in the European Alps, for instance, use webcams to share panoramic views and promote themselves in the industry of winter recreational activities. We tested preinstalled webcam effectiveness as a remote tool for eco-ethological studies. Our target species was the Alpine ChoughPyrrhocorax graculus, a social and opportunistic corvid species of high mountain environments that attends ski resorts to feed on scraps discarded by high elevation bars and restaurants. We studied the effect of the winter presence of tourists and weather conditions on flocking behaviour at ski resorts. We used flock size and time spent at the ski resort as response variables, and assessed how strongly they were related to the number of tourists and weather conditions. We analysed about 13,500 pictures taken at 10 min intervals at three ski resorts sites in the European Alps in France, Italy and Switzerland. The number of birds was very different among the three study sites. Flock size and time spent were related to the same environmental drivers, but with different effect sizes in the three areas. The daily maximum flock size and the time spent at ski resorts increased with the number of tourists and decreased with temperature at two sites out of three. We also found that the presence of fresh snow caused a decrease in the maximum flock size in all ski resorts. In conclusion, Alpine Choughs modulated their presence at the ski resorts according to human presence and weather conditions, but these responses were context-dependent. Preinstalled webcams, despite a few caveats, can therefore be successfully employed in eco-ethological research. Webcams around the world are increasing in number and represent therefore a large potential resource. If webcam companies could be engaged to make some slight adjustments, without compromising their goals, then this could offer a new way to collect eco-ethological data.

Comparative cognition-Conceptual and methodological advancements.

This special issue originally placed a Call for Papers that emphasized the importance of "Conceptual and Methodological" advances in the field of Comparative Cognition. Represented here is a collection of 14 papers that helps to display some of the diversity of ideas and approaches within this flourishing research area. The first paper in this issue, by Gazes and Lazareva (2021), discusses transitive inference learning from the perspectives of: identifying the problems of contextual variables in studying different species; whether associative processes can or cannot fully account for the behavior and, if not, what alternative representational mechanisms might be at work; and, finally, how ecological considerations may support comparative research by suggesting novel theoretical and empirical questions. The next paper, by Loy et al. (2021) investigates questions related to the complexity of learning in invertebrate species, single-celled organisms, and plants. The paper by Rawlings et al. (2021) reviews the literature on cumulative cultural evolution, primarily in nonhuman primate species, and critically evaluates the importance of identifying the essential conceptual and methodological issues in what many have deemed to be a uniquely human form of behavior. The paper by Goto and Watanabe (2021) explores whether the mouse visual system is sensitive to Gestalt principles, using operant discrimination learning tasks similar to those used previously to document Gestalt processing in chimpanzees and humans. Qadri and Cook (2021) use the innovative approach of "adaptive genetic algorithms" to assess the relative importance of different features of a stimulus in controlling organisms' discrimination learning performance. Wittek et al. (2021) introduce a novel method for studying the importance of visual accumulation processes in pigeons when information is presented to a single hemisphere at a time. The paper by Cowie et al. (2021) focuses on a misallocation model of two-step sequence learning in young children and explores from a behavioranalytic viewpoint the implications of assuming that reinforcement might be misattributed to a misremembered response at the beginning of the behavioral sequence. The paper by López-Tolsa and Pellón (2021) explores whether the opportunity to display schedule-induced drinking as an early response within a behavioral sequence might alter the accuracy of temporal control in different-length fixed-interval schedule tasks with rats. Crystal (2021) reviews the literature examining episodic memory in nonhuman species and considers a variety of criteria and methods thought to be crucial for establishing empirical evidence for episodic memory in nonhumans, in general, and rats, in particular. Vila et al. (2021) discuss the use a novel 'hide-and-seek' task in preschool age children to study episodic-like memory; their work illustrates how memory dynamics can change over time in a manner not very unlike what has been demonstrated in other nonhuman research paradigms. The paper by Krichbaum et al. (2021) discusses some of the methodological difficulties one faces in studying spatial cognition in canines. The paper by Castro et al. (2021) uses a complex categorization learning task in which different sets of display features are diagnostic, or not, of category mastery depending upon context. The paper by Vernouillet et al. (2021) explores the formation of same/different concept learning in two species of corvids (pinyon jays and California scrub jays). The final paper, by Lazarowski et al. (2021) examines the possibility of abstract same/different learning in canines using a trial-unique training matching-to-sample procedure with olfactory stimuli. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Abstract-concept learning in two species of new world corvids, pinyon jays (Gymnorhinus Cyanocephalus) and California scrub jays (Aphelocoma Californica).

concepts require individuals to identify relationships between novel stimuli. Previous studies have reported that the ability to learn abstract concepts is found in a wide range of species. In regard to a same/different concept, Clark's nutcrackers (Nucifraga columbiana) and black-billed magpies (Pica hudsonia), two corvid species, were shown to outperform other avian and primate species (Wright et al., 2017). Two additional corvid species, pinyon jays (Gymnorhinus cyanocephalus) and California scrub jays (Aphelocoma californica) chosen as they belong to a different clade than nutcrackers and magpies, were examined using the same set-size expansion procedure of the same/different task (the task used with nutcrackers and magpies) to evaluate whether this trait is common across the Corvidae lineage. During this task, concept learning is assessed with novel images after training. Results from the current study showed that when presented with novel stimuli after training with an 8-image set, discrimination accuracy did not differ significantly from chance for pinyon jays and California scrub jays, unlike the magpies and nutcrackers from previous studies that showed partial transfer at that stage. However, concept learning improved with each set-size expansion, and the jays reached full concept learning with a 128-image set. This performance is similar to the other corvids and monkeys tested, all of which outperform pigeons. Results from the current study show a qualitative similarity in full abstract-concept learning in all species tested with a quantitative difference in the set-size functions, highlighting the shared survival importance of mechanisms supporting abstract-concept learning for corvids and primates. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Pre-release training, predator interactions and evidence for persistence of anti-predator behavior in reintroduced `alalā, Hawaiian crow

Animal translocations commonly fail due to predation after release, especially if animals are reared in human care, away from natural predation pressure. Anti-predator training can be a useful tool for combating the predator naivety of released animals, but its effective implementation requires attention to numerous details. We present the step-by-step development of an anti-predator training regime, tailored to the critically endangered `alalā (Corvus hawaiiensis). `Alalā are the last remaining corvid species of the Hawaiian islands, and historically the level of predation they experienced from the Hawaiian hawk, `io (Buteo solitarius) is unclear. However, one factor thought to compromise outcomes of earlier attempts to reintroduce `alalā in the 1990′s was predation by `io, motivating the development of anti-predator training for recent `alalā releases. We documented evidence for what appears to be competent anti-predator behavior in conservation-bred `alalā, with a range of behavioral strategies for coping with `io observed during a series of controlled presentations of `io and `io-related stimuli. These behavioral responses included vigilance, alarm calling, and mobbing during experimental trials conducted in release training aviaries. Our results did not conclusively establish that anti-predator learning occurred as a result of the training, or that the training produced enhanced survival. However, following release, `io-`alalā encounters were observed on more than 35 occasions, and `alalā responses mirrored those observed pre-release, including the first ever recorded mobbing interactions by juvenile flocks of `alalā in the wild. While it is unclear the extent to which training encouraged these species-appropriate anti-predator responses, their occurrence suggests that the `alalā has retained and can express defensive behavioral strategies. By documenting the design process, training execution and behavioral outcomes in `alalā, we highlight details that other reintroduction programs may need to consider when preparing animals for reintroduction alongside natural predators.

Intestinal Histopathology due to an Acanthocephalan in Two Corvid Species from Northern Italy.

Carnivorous birds maintain parasites in the sylvatic cycle and have a role in their diffusion. The histopathology and ultrastructure of the intestine of 29 Hooded Crows (Corvus corone cornix) and 51 Eurasian Magpies (Pica pica), from the Province of Ferrara (Northern Italy), naturally infected with Sphaerirostris picae (Acanthocephala), were investigated. In both bird species, the prevalence of infection was around 10%, and the intensity of the infection in the Hooded Crows ranged from two to 12 acanthocephalans per host, whereas in the Eurasian Magpies it ranged from one to nine worms per bird. Previous records on the histopathology of acanthocephalans in birds do not provide information on the type of cells involved in the host's reaction. We aimed to gain information on the effects of acanthocephalans on the structural integrity of the birds' intestine and to describe the type of immune cells in the hosts against the parasite. Our results showed that S. picae disrupted the intestinal wall at the site of attachment by means of its neck and proboscis, and three main types of bird intestinal reactions were noticed. The most severe response of the hosts was against the proboscis because of the action of its hooks with recruitment of macrophages, giant cells, eosinophils, and heterophils. Sphaerirostris picae perforated the birds' entire intestinal wall, reaching the peritoneal visceral serosa, but it did not provoke a diffuse peritonitis.

Population dynamics and habitat preference of two urbanized Columbidae species and their nest predator in two settlement types

Abstract Since urbanization is a worldwide phenomenon, numerous species have gained the advantage of urban ecosystems. The Eurasian Collared Doves (Streptopelia decaocto) has become widespread all across Europe along with human-altered habitats. In general, population levels are stable but numbers have locally decreased in the past few decades. In parallel, a new wave of urbanization came forward, so Wood Pigeons (Columba palumbus) entered urban ecosystems alongside with other Columbidae species. In this paper, our primary goal was to find any connection between habitat availability factors such as coniferous tree density and the population dynamics of two urbanized species. A locally emerging corvid species, the Hooded Crow (Corvus cornix) was also taken into consideration in influencing tree-nesting doves and pigeons as a primary nest predator. During the research period, we aimed to express the differences in habitat structure of two urban ecotypes by nesting tree availability and structure and to prove the power of predator presence in sampling sites. Our results showed that residential areas have a higher proportion of coniferous trees, as well as the high preference of residential areas by Wood Pigeons and Eurasian Collared Doves.

Replication of the mirror mark test experiment in the magpie (Pica pica) does not provide evidence of self-recognition.

Self-recognition in animals is demonstrated when individuals pass the mark test. Formerly, it was thought that self-recognition was restricted to humans, great apes, and certain mammals with large brains and highly evolved social cognition. However, 1 study showed that 2 out of 5 magpies (Pica pica) passed the mark test, suggesting that magpies have a similar level of cognitive abilities to great apes. The scientific advancement depends on confidence in published science, and this confidence can be reached only after rigorous replication of published studies. Here, we present a close replication of the magpie study but using a larger sample size while following a very similar experimental protocol. Like the previous study, in our experiment, magpies showed both social and self-directed behavior more frequently in front of the mirror versus a control cardboard stimulus. However, during the mark test, self-directed behavior proved more frequent in front of the cardboard than in the mirror. Thus, our replication failed to confirm the previous results. Close replications, while not disproving an earlier study, identify results that should be considered with caution. Therefore, more replication studies and additional experimental work is needed to unambiguously demonstrate that magpies are consistently able to pass the mark test. The existence of compelling evidence of self-recognition in other corvid species is discussed in depth. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Task Aspects Triggering Observational Learning in Jackdaws (Corvus monedula)

Complex novel tasks are often used in animal cognition research to allow discrimination between various learning mechanisms. Successful performance relies on the capacity to identify informational cues from features in the environment. Additionally, observational learning is often considered more beneficial for survival than individual learning. Despite the importance of controlling task complexity, it can often be challenging to operationalize. This study investigated whether jackdaws, a highly social corvid species, can learn to drop stones inside a tube to release a reward after observing a trained conspecific. Additionally, it aimed to identify the underlying learning mechanisms and to detect the informational cues triggering learning. A research design was developed to highlight different aspects of the required action sequence. Experimental conditions included a conspecific model demonstrating the full sequence, parts of the sequence, consuming the reward without solving the task, and consuming the reward after the solution was demonstrated without a visible model. None of the 12 naïve jackdaws solved the task in pretests. Two subjects started solving in test sessions and they developed modified versions of the demonstrated action. Observing the full action sequence performed by a conspecific seemed to trigger learning. The majority of the subjects exhibited changes in their stone-oriented behavior, most likely due to stimulus and/or local enhancement. As predicted, jackdaws were influenced by conspecific model demonstrations when manipulating a complex novel foraging task. Factors contributing to the apparent task difficulty and directions for future studies are discussed within a tri-dimensional framework including the task, setup, and individuals.

Sex-specific effects of cooperative breeding and colonial nesting on prosociality in corvids.

The investigation of prosocial behavior is of particular interest from an evolutionary perspective. Comparisons of prosociality across non-human animal species have, however, so far largely focused on primates, and their interpretation is hampered by the diversity of paradigms and procedures used. Here, we present the first systematic comparison of prosocial behavior across multiple species in a taxonomic group outside the primate order, namely the bird family Corvidae. We measured prosociality in eight corvid species, which vary in the expression of cooperative breeding and colonial nesting. We show that cooperative breeding is positively associated with prosocial behavior across species. Also, colonial nesting is associated with a stronger propensity for prosocial behavior, but only in males. The combined results of our study strongly suggest that both cooperative breeding and colonial nesting, which may both rely on heightened social tolerance at the nest, are likely evolutionary pathways to prosocial behavior in corvids.

Precise cache detection by olfaction in a scatter-hoarder bird

The sense of olfaction has been traditionally considered of low relevance in bird biology. In particular, the location of cached seeds by scatter-hoarder corvids is assumed to depend on spatial memory, whereas no study has demonstrated the use of olfaction to detect these seeds. In this study we tested whether olfaction might play a role in the precise location of cached nuts by magpies, Pica pica , a scatter-hoarder corvid species. We conducted an experiment under natural conditions where nuts belonging to four treatments were buried, simulating natural caches, and we monitored the rate of nut detection by magpies. Three of the treatments included nuts with natural odour or odour of a strong-smelling substance (untreated nuts, nutshells filled with soil and nuts soaked in diesel), whereas the fourth treatment consisted of 3D-printed fake nuts made of polypropylene. The experiment was replicated in two sites and in several breeding territories, using a total of 624 nuts. Motion-activated cameras were installed to identify the animals foraging in the plots. The results show that magpies detected untreated nuts, nutshells or nuts soaked in diesel ca. three times more than 3D-printed fake nuts. Among detected and unburied nuts, the 3D-printed nuts were largely abandoned on site, followed by nutshells without a kernel, natural nuts and nuts soaked in diesel. All this strongly supports the hypothesis that magpies use olfaction to pinpoint cached nuts, either for nut recovery or pilfering, but once a nut is detected they may use other senses such as vision or touch for selection. Given the strong changes in landscape features that may occur under natural conditions between the time of nut caching and nut retrieval, we suggest that the use of olfaction might be crucial to help spatial memory in determining the location of cached nuts in corvids. • Olfaction has been neglected in studies of seed retrieval in scatter-hoarder birds. • We experimentally studied the role of smell in buried seed detection in magpies. • Magpies detected buried natural nuts and discarded 3D-printed fake nuts. • Results suggest that magpies make use of olfaction to pinpoint cached nuts. • Olfaction might help spatial memory in the location of cached nuts in corvids.

Extended parenting and the evolution of cognition.

Traditional attempts to understand the evolution of human cognition compare humans with other primates. This research showed that relative brain size covaries with cognitive skills, while adaptations that buffer the developmental and energetic costs of large brains (e.g. allomaternal care), and ecological or social benefits of cognitive abilities, are critical for their evolution. To understand the drivers of cognitive adaptations, it is profitable to consider distant lineages with convergently evolved cognitions. Here, we examine the facilitators of cognitive evolution in corvid birds, where some species display cultural learning, with an emphasis on family life. We propose that extended parenting (protracted parent-offspring association) is pivotal in the evolution of cognition: it combines critical life-history, social and ecological conditions allowing for the development and maintenance of cognitive skillsets that confer fitness benefits to individuals. This novel hypothesis complements the extended childhood idea by considering the parents' role in juvenile development. Using phylogenetic comparative analyses, we show that corvids have larger body sizes, longer development times, extended parenting and larger relative brain sizes than other passerines. Case studies from two corvid species with different ecologies and social systems highlight the critical role of life-history features on juveniles' cognitive development: extended parenting provides a safe haven, access to tolerant role models, reliable learning opportunities and food, resulting in higher survival. The benefits of extended juvenile learning periods, over evolutionary time, lead to selection for expanded cognitive skillsets. Similarly, in our ancestors, cooperative breeding and increased group sizes facilitated learning and teaching. Our analyses highlight the critical role of life-history, ecological and social factors that underlie both extended parenting and expanded cognitive skillsets. This article is part of the theme issue 'Life history and learning: how childhood, caregiving and old age shape cognition and culture in humans and other animals'.

Azure-winged magpies fail to understand the principle of mirror imaging

Mirror self-recognition (MSR) is considered a crucial step in the emergence of self-cognition. The MSR paradigm has become a standard method for evaluating self-cognition in several species. For example, Eurasian magpies and Indian house crows have passed the mark test for self-cognition, whereas efforts to find MSR in other corvid species have failed. However, no literature has conducted MSR tests on azure-winged magpies, a species of corvids. Therefore, the current research aimed to investigate the MSR behaviours of azure-winged magpies upon looking into a mirror for the first time. The study included four tests: (1) mirror preference and standardised mirror exploration, (2) single vertical mirror test, (3) mark test and (4) mirror-triggered search test. The azure-winged magpies displayed immense curiosity towards the mirror and their images in the mirror in Test 1&2. In the subsequent mark tests, they failed to recognise themselves in the mirror and regarded their images as conspecifics. Behaviour analysis showed no significant difference between marked and unmarked behaviours. Finally they seemed to infer the presence of bait from the image in the mirror, but were found to fail to understand that the location of the bait in the mirror was the same as that in the real world. For a better insight into the MSR behaviour of azure-winged magpies, research studies involving prolonged mirror exposure and training are recommended.

Ravens respond to unfamiliar corvid alarm calls

Eavesdropping on heterospecific alarm calls is a crucial source of information for many species (including corvids) and it is effective especially if these species form mixed-species flocks, have a similar spectrum of predators, and share habitat. Previous research on wild common ravens (Corvus corax) has shown that they react to the jackdaws’ alarm call. We tested their responses to the heterospecific alarm calls of various bird species differing in familiarity and taxonomical relatedness to ravens. Two other corvid species (the blue jay Cyanocitta cristata and the European jay Garrulus glandarius) and two non-corvids (the black-headed gull Chroicocephalus ridibundus and the laughing gull Leucophaeus atricilla) were presented. We played back the tested alarm calls to free-ranging ravens at a feeding site and observed the ravens’ responses to particular stimuli. We observed three behavioural responses made by the tested ravens: flying away, freezing (ceasing to move and crouching on the ground), and vigilance (observing the surroundings). The ravens responded to the Eurasian jay alarm call by freezing and flying away and to the blue jay alarm call by freezing and vigilance. The laughing gull alarm call induced mostly vigilance and the black-headed gull alarm call did not elicit any reaction. The responses to the alarm calls of both jays were similar to the responses to the playbacks of conspecific alarm calls, used as control (as well as to the response to a jackdaw alarm call from the previous study), which may point to the existence of a specific corvid characteristic in their alarm calls. The response to the alarm calls of both American species included vigilance, which suggests an uncertainty about the meaning of the call.

Crows (Corvus corone ssp.) check contingency in a mirror yet fail the mirror-mark test.

Mirror reflections can elicit various behavioral responses ranging from social behavior, which suggests that an animal treats its own reflection as a conspecific, to mirror-guided self-directed behaviors, which appears to be an indication for mirror self-recognition (MSR). MSR is scarcely spread in the animal kingdom. Until recently, only great apes, dolphins, and elephants had successfully passed this test. The range of convergence was, however, expanded by an avian species, the Eurasian magpie (Pica pica). Efforts to find MSR in other corvid species have so far failed, and with only a few studies conducted, the cause of these discrepancies is difficult to identify. In the present study, we examined the responses to mirrors and the ability of MSR in hitherto untested species: the carrion and hooded crows (Corvus corone ssp.). These crows showed a pronounced and lasting interest in the mirror; unlike many species, they did not exhibit social behaviors on their first encounters but immediately started investigating the mirror. Some crows showed contingent behaviors in front of the mirror, but none of the crows showed significant mirror-guided self-directed behaviors nor mark-directed behavior during the subsequent mark test. This lack of mark-directed behavior could not be explained by a lack of interest in the mirror nor in the mark. These findings could indicate that crows lack a concept of self, or the need for other means of investigating self-recognition and self-awareness in avian species. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Epidemiologic Survey on Toxoplasma gondii and Trichinella pseudospiralis Infection in Corvids from Central Italy.

Free-ranging corvids—678 magpies (Pica pica) and 120 hooded crows (Corvus cornix) from nine protected areas of the Pisa province (central Italy)—were examined for Toxoplasma gondii and Trichinella pseudospiralis. The intracardiac blood clots from 651 magpies and 120 hooded crows were serologically examined for T. gondii. The DNA extracted from the hearts of seropositive birds was then used to perform a nested PCR for the amplification of the T. gondii B1 gene and for genotyping for SAG genetic markers. Breast muscle samples from 678 magpies and 91 hooded crows were tested by an artificial digestion method for Trichinella. Data were statistically analyzed. Forty-five (5.8%—41 magpies and four hooded crows) out of the 771 examined animals scored seropositive for T. gondii, with titers ranging from 1:25 to 1:100. T. gondii DNA was detected in 15 of the 45 positive birds and T. gondii genotypes II and III were identified. No positivity for T. pseudospiralis was found. No significant differences between the two species of corvids and among the different areas of origin were observed for seropositivity to T. gondii. This is the first extensive study on both T. gondii and T. pseudospiralis in magpies and hooded crows, as well as the first detection of T. gondii SAG genotypes in magpies.

Individual exploratory responses are not repeatable across time or context for four species of food-storing corvid

Exploration is among one of the most studied of animal personality traits (i.e., individual-level behavioural responses repeatable across time and contexts). However, not all species show clear evidence of this personality trait, and this is particularly so for members of the Corvidae family. We assessed the exploratory behaviour of four food-caching corvid species: pinyon jays (Gymnorhinus cyanocephalus), Clark’s nutcrackers (Nucifraga columbiana), California scrub jays (Aphelocoma californica), and black-billed magpies (Pica hudsonia). Contextual repeatability was assessed through examining behavioural measures during the Novel Environment task and the Novel Object task, whereas temporal repeatability was assessed by examining changes in these measures over repeated trials. Our results suggest that, for corvids, an individual’s exploratory behaviour was not repeatable across contexts or over time. Hence, we found no evidence that exploration constitutes a personality trait for these species of corvid. We did find differences in exploratory behaviour, at a species level, that may be explained by relative reliance on cached food.

Late Pleistocene and Earliest Holocene avifauna from the Loutra Almopias Cave (Macedonia, Greece)

The bird fauna of the Loutra Almopias Cave comprised eight orders, 22 families, 41 genera and at least 47 species (68 different taxa) established based on 551 avian bone finds. The Loutra Almopias Cave is a new (26th) Pleistocene avian locality in Greece. About 92.5% of the material was dated to the Earliest Holocene (11.230 ± 110 y. BP), coming from the upper chamber of the cave, whereas an older assemblage was dated to the Late Pleistocene (37,880 y. ± 370/360 BP), coming from the floor chambers of the cave. Here is provided the first fossil record of 13 species in Greece (Buteo lagopus, Francolinus francolinus, Lagopus lagopus, Bonasa bonasia, Dryocopus martius, Lulula arborea, Bombicylla garrulus, Cinclus cinclus, Sylvia borin, Carduelis carduelis, Loxia curvirostra, Plectrophenax nivalis, and Emberiza cirlus). Three genera (Francolinus, Anthus and Riparia/Ptyonoprogne) were established for the first time in Pleistocene deposits in the country. The record of Fr. francolinus was the first one for the Balkans and Eastern Europe. At both sites inside the cave, regardless of their different age, the habitat preferences of the identified bird species indicated that the surrounding paleoenvironment included both grassy openlands (dominated by gramineans) and woodland (coniferous or mixed woods). In addition, rocky habitats were represented in the surroundings of the locality. The presence of small species of Perdicinae (26%) and corvids (34%) indicated the former existence and prevelance of open grassy fields and rocky environments. The Alpine chough was the most abundant species at both localities. In the Earliest Holocene it comprised 29.5%, whereas in the Late Pleistocene it reached 25.6% of the material. Such a representation suggests a natural non-human accumulation of the material, probably due to the feeding behavior of Bubo bubo. The Late Pleistocene record (19 taxa; 41 finds) included Falco sp. cf. F. peregrinus, Perdix perdix, Perdix sp., Alectoris graeca, Alectoris sp., Lagopus cf. lagopus, cf. Bonasa bonasia, Columba livia, Columba palumbus, Bubo bubo, Melanocorhypha calandra, Anthus sp., Turdus sp., Pica pica, Pyrrhocorax graculus, Loxia curvirostra, Coccothraustes coccothraustes, Pyrrhula pyrrhula, Fringillidae gen. indet., non-Passeriformes indet. and also suggests the site has been used by the eagle owl. The climate probably used to be drier and cooler than in the Earliest Holocene. The record of 17 woodland species from the Earliest Holocene that were absent in the Late Pleistocene could be explained by the more humid and moderate climate at the very end of the Pleistocene.

Corvids exhibit dynamic risk assessment during escape

It is widely accepted that stationary prey are able to carefully assess the risk levels associated with an approaching predator to make informative decisions on when to escape. However, little is known about subsequent decision-making process. We set out to compare whether escape durations of three species of corvids differ depending on how a human observer (in the role of a predator) behaves after the escape has begun. When birds were being followed during escape, escape durations were the longest, escape trajectory was modified the most during escape, and a larger proportion of individuals changed from terrestrial to aerial escape strategy compared to observations where birds were not followed. Mean horizontal escape angle of ca 120° was also a potential indication that monitoring the threat is taken into account when deciding on the escape trajectory. While there were some differences between the behaviour of these three closely related species, the general patterns supported the notion that birds dynamically assess risk during escape to find an optimal balance between getting caught and spending too much time and energy on escaping. Further research using different predator-prey combinations or making comparisons between habitats could help understand the generality of our results.

Warm temperatures during cold season can negatively affect adult survival in an alpine bird.

Climate seasonality is a predominant constraint on the lifecycles of species in alpine and polar biomes. Assessing the response of these species to climate change thus requires taking into account seasonal constraints on populations. However, interactions between seasonality, weather fluctuations, and population parameters remain poorly explored as they require long‐term studies with high sampling frequency. This study investigated the influence of environmental covariates on the demography of a corvid species, the alpine chough Pyrrhocorax graculus, in the highly seasonal environment of the Mont Blanc region. In two steps, we estimated: (1) the seasonal survival of categories of individuals based on their age, sex, etc., (2) the effect of environmental covariates on seasonal survival. We hypothesized that the cold season—and more specifically, the end of the cold season (spring)—would be a critical period for individuals, and we expected that weather and individual covariates would influence survival variation during critical periods. We found that while spring was a critical season for adult female survival, it was not for males. This is likely because females are dominated by males at feeding sites during snowy seasons (winter and spring), and additionally must invest energy in egg production. When conditions were not favorable, which seemed to happen when the cold season was warmer than usual, females probably reached their physiological limits. Surprisingly, adult survival was higher at the beginning of the cold season than in summer, which may result from adaptation to harsh weather in alpine and polar vertebrates. This hypothesis could be confirmed by testing it with larger sets of populations. This first seasonal analysis of individual survival over the full life cycle in a sedentary alpine bird shows that including seasonality in demographic investigations is crucial to better understand the potential impacts of climate change on cold ecosystems.