Fact-checked by Grok 2 weeks ago

Bird intelligence

Bird intelligence encompasses the cognitive capabilities of avian species, which vary widely but reach remarkable levels in groups such as corvids (e.g., crows and ravens) and parrots, where problem-solving, tool use, and social cognition rival those observed in great apes despite much smaller brain sizes of 5–20 grams compared to primate brains of around 400 grams.^[1] These abilities have evolved convergently in birds and mammals, independent of their common ancestor over 300 million years ago, driven by ecological pressures like food caching, omnivory, and complex social structures in modern birds that diversified rapidly after the Cretaceous-Paleogene extinction event 66 million years ago.^[2]^[3] At the neural level, birds achieve such sophistication through exceptionally high neuron densities in the forebrain—up to twice that of primates per unit volume—and specialized regions like the nidopallium caudolaterale, which functions analogously to the mammalian prefrontal cortex in supporting working memory, causal reasoning, and prospection.^[4]^[1] Notable examples include New Caledonian crows crafting hook tools for foraging, ravens planning for future needs by bartering, and African grey parrots demonstrating numerical competence and vocal mimicry equivalent to a young child's understanding.^[2] This intelligence is not uniform across the over 10,000 bird species; while pigeons excel in associative learning and pattern recognition, many others show more limited cognition tied to simpler ecological niches, underscoring the adaptive specialization of avian brains.^[1] Overall, research highlights how avian cognition challenges traditional views of brain size as a sole determinant of intelligence, emphasizing instead neuronal efficiency and evolutionary innovation.^[3]

Anatomical and Evolutionary Foundations

Avian Brain Structure

The avian brain features a pallium that serves as the primary site for higher cognitive functions, structurally distinct from the mammalian neocortex yet functionally analogous in supporting complex behaviors such as learning and problem-solving. Unlike the layered neocortex of mammals, the avian pallium is organized into nuclear clusters, which enable efficient sensory processing and decision-making despite the absence of a laminated cortex. This pallial organization has evolved to facilitate cognitive abilities comparable to those in mammals, with the pallium integrating multimodal sensory inputs and coordinating adaptive responses.^[5]^[6] Within the pallium, key subdivisions include the nidopallium, hyperpallium, mesopallium, and arcopallium, each contributing to sensory integration and executive functions. The nidopallium, often considered analogous to the mammalian neocortex, plays a central role in associative learning, sensory-motor integration, and decision-making, housing neurons that process visual and auditory information for behavioral adaptation. The hyperpallium primarily handles visual processing and spatial cognition, integrating inputs from the optic tectum to support navigation and object recognition. The mesopallium facilitates multisensory convergence and memory formation, while the arcopallium is involved in motor planning and emotional regulation, linking sensory data to action outputs. These structures collectively enable birds to perform tasks requiring foresight and flexibility, underscoring the pallium's role in avian intelligence.^[7] Relative brain size in birds is often assessed using the encephalization quotient (EQ), which measures brain mass relative to body size; intelligent species like corvids and parrots exhibit relatively high EQ values for birds, approaching those of some non-human primates, indicating a high degree of cognitive specialization despite smaller absolute brain volumes. For instance, corvids such as ravens have EQs around 2.5, comparable to chimpanzees, while African grey parrots reach EQs of approximately 1.0–1.3, comparable to some non-primate mammals and supporting advanced problem-solving abilities. These elevated EQs highlight adaptations for intelligence in lineages with compact body plans, prioritizing neural efficiency over sheer size.^[8]^[2] Recent digital endocast studies, leveraging computed tomography scans of skulls from extant and extinct birds, have reconstructed telencephalic and cerebellar volumes to infer historical cognitive capacities, revealing that pallial expansion correlates with behavioral complexity across avian evolution. A 2024 analysis of 136 species across 25 orders demonstrated that endocast-derived estimates accurately predict actual brain volumes, with telencephalon measurements showing less than 10% deviation, allowing researchers to quantify pallial growth in fossil forms like early corvids and parrots. These methods provide evidence that avian brain sizes have scaled with ecological demands, supporting inferences of enhanced cognition in lineages exhibiting tool use and social learning.^[9] Avian brains achieve high cognitive performance through exceptional neuron density, packing more neurons per gram of tissue than mammalian brains, which enables compact structures with primate-level processing power. Seminal work has shown that songbirds and parrots possess forebrain neuron counts rivaling those of similarly sized primate brains, with densities up to twice that of mammals due to smaller, more numerous neurons in the pallium. This pattern of higher neuronal scaling across brain regions in birds compared to mammals and reptiles has been confirmed in recent studies, facilitating efficient cognition in small-bodied species without the metabolic costs of larger brains.^[4]^[10]

Neural Substrates of Cognition

Birds form neural representations of space and objects primarily through the hippocampal formation, which functions analogously to the mammalian hippocampus in encoding cognitive maps. In food-caching species such as the black-capped chickadee, place cells in the hippocampus organize spatial information, accompanied by sharp-wave ripples that consolidate memories of cached locations.^[11] These representations enable birds to navigate complex environments by maintaining mental maps of landmarks and resources. The hyperpallium, a pallial region, further supports visual processing integral to these maps, with neurons in barn owls encoding head direction and allocentric location during flight, facilitating dynamic spatial awareness.^[12] Olfactory associative pathways in birds vary by species, with pronounced development in those reliant on scent for survival. In kiwis, enlarged olfactory bulbs—proportionally larger than in most birds—enhance sensitivity to odors, supporting associative processing for foraging and navigation through projections to the piriform cortex.^[13] Across avian taxa, olfactory bulb size correlates with ecological demands, such as nocturnality or ground-foraging, where larger bulbs facilitate stronger odor-object associations compared to visually dominant species.^[14] These pathways integrate chemosensory inputs to form representations of environmental cues, underscoring olfaction's role in cognitive mapping for scent-dependent species. Sensory integration in birds relies on dual visual pathways: the tectofugal system, which dominates and enables rapid processing of motion, color discrimination, and spatial localization via projections from the optic tectum to the entopallium; and the thalamofugal system, relaying detailed visual information from the thalamus to the hyperpallium for higher-order analysis.^[15]^[16] This parallel architecture allows efficient fusion of visual inputs with other modalities, supporting quick cognitive responses in dynamic settings like predation or flight. In corvids, recent anatomical studies have identified interconnected brain networks linking vocalization centers, such as the HVC (proper name of a nucleus in the avian brain), to cognitive hubs like the nidopallium caudolaterale (NCL), the functional analog of the mammalian prefrontal cortex. These connections, including sparse projections from NCL to the HVC shelf and adjacent song nuclei like the robust nucleus of the arcopallium, suggest shared neural substrates for vocal learning and executive functions such as problem-solving.^[17] Such integration highlights how corvid cognition leverages vocal-motor circuits for flexible, context-dependent behaviors. Neural plasticity in birds is sustained by ongoing neurogenesis in pallial regions, enabling lifelong adaptation and learning. In the song system, new neurons incorporate into pallial nuclei like HVC and the robust nucleus of the arcopallium, allowing seasonal refinements in vocal repertoires and associative memory.^[18] Hippocampal neurogenesis similarly preserves precise spatial hierarchies, countering memory decay and supporting continued environmental learning throughout adulthood.^[19] This regenerative capacity underscores the avian brain's resilience in maintaining cognitive flexibility.

Evolutionary Origins of Avian Intelligence

Avian intelligence evolved independently from that of mammals, with recent studies revealing convergent expansions in pallial regions that parallel the mammalian neocortex but arose through distinct developmental pathways. Two 2025 investigations published in Science demonstrate that birds developed complex neural circuits in the pallium—responsible for higher cognition—separately from mammals, despite sharing a common amniote ancestor approximately 300 million years ago. These findings highlight innovations in pallial cell types and enhancer-driven gene expression that enabled advanced cognitive abilities in birds without relying on the layered neocortical architecture seen in mammals.^[5] Fossil endocasts provide evidence of early cognitive precursors in avian evolution, tracing back to the Late Jurassic. Endocasts from Archaeopteryx, dating to about 150 million years ago, reveal an enlarged forebrain and expanded regions for visual and spatial processing, resembling those in modern birds and indicating neurological adaptations for flight and perception that laid groundwork for later intelligence. A more recent Cretaceous fossil from Brazil, approximately 80 million years old, fills a key evolutionary gap by showing intermediate brain structures between Archaeopteryx and extant species, with undistorted endocasts confirming progressive pallial development during the Mesozoic.^[20] While intelligence has long been associated with corvids and parrots, recent research indicates a broader distribution across avian lineages, including palaeognaths. A 2025 study in Scientific Reports tested emus, rheas, and ostriches on a novel foraging puzzle requiring mechanical manipulation of a wheel to access food; emus solved it on their first attempt and repeated the task reliably, demonstrating technical innovation in this basal bird group and challenging assumptions of limited cognition outside songbirds. This suggests that cognitive capabilities evolved more widely in birds than previously thought, potentially reflecting shared ancestral traits amplified in diverse ecological contexts.^[21] Selective pressures from ecology and flight likely drove these neural advancements, favoring compact brains with high neuron density. The demands of powered flight imposed constraints on overall brain size, leading to efficient neural packing in the avian pallium—achieving primate-like neuron counts in smaller volumes—which supported cognitive enhancements for navigation, foraging, and social interaction.^[4] Comparatively, birds diverged from reptilian ancestors around 310 million years ago within the archosaur lineage, with major innovations in brain structure and intelligence occurring during the Cretaceous period (145–66 million years ago). This era saw rapid diversification of early birds, coinciding with refined flight capabilities and ecological radiations that selected for enhanced sensory integration and problem-solving, setting the stage for modern avian cognition.

Learning Mechanisms

Associative Learning

Associative learning in birds encompasses both classical (Pavlovian) and operant (Skinnerian) conditioning, enabling individuals to form associations between stimuli and outcomes through trial-and-error processes. In classical conditioning, birds learn to link neutral stimuli with biologically significant events, such as associating a specific color with food availability; for instance, pigeons (Columba livia) rapidly form these associations in laboratory settings, pecking at colored keys that predict food rewards after repeated pairings.^[22] Operant conditioning involves behaviors shaped by consequences, where pigeons in controlled experiments learn to peck levers for reinforcement, demonstrating how actions like key-pecking increase when followed by food delivery.^[23] These mechanisms rely on individual experience rather than observation, with the avian pallium playing a key role in processing these associations.^[4] Reversal learning, a form of associative flexibility, allows birds to adapt when reward contingencies change, such as switching preferences from one stimulus to another after initial training. Corvids exhibit superior reversal learning compared to other birds; for example, species like pinyon jays (Gymnorhinus cyanocephalus), Clark's nutcrackers (Nucifraga columbiana), and scrub-jays (Aphelocoma californica) show progressive improvement across serial reversals of color-based discriminations, outperforming non-corvid species in acquisition speed and error reduction.^[24] In field studies, New Caledonian crows (Corvus moneduloides) demonstrate this adaptability by adjusting foraging responses to altered environmental cues, such as novel object placements near food sources.^[25] Neophobia, an innate caution toward novel objects or foods, modulates associative learning by influencing exploration and risk assessment, with species differences reflecting ecological pressures. Finches display high neophobia, delaying approach to unfamiliar items and slowing conditioning to new stimuli, whereas opportunistic corvids like ravens (Corvus corax) and crows show lower neophobia, facilitating faster associative pairings with novel rewards in both lab and wild contexts.^[26]^[27] Across avian taxa, neophobia varies consistently at individual and species levels, with lower levels in urban-adapted birds enhancing learning efficiency in variable environments.^[26] Several factors modulate associative learning efficacy in birds. Hormones like corticosterone influence stress-response learning; nestlings of western scrub-jays (Aphelocoma californica) exposed to low corticosterone levels during development perform better on adult associative tasks, while elevated levels impair reversal learning.^[28] Diet affects memory consolidation, as high-protein rearing in zebra finches (Taeniopygia guttata) leads to faster mastery of color-food associations compared to low-protein diets, which delay sub-adult growth and learning bouts.^[29] Ecological context shapes adaptations, with urban-adapted birds showing enhanced flexibility in associative learning for novel resources due to human-altered environments. Age contributes to flexibility, as juveniles often exhibit greater plasticity in forming associations than adults.

Observational Learning

Observational learning in birds refers to the acquisition of novel behaviors through the observation of conspecifics or heterospecifics, distinct from individual trial-and-error processes. This form of social learning encompasses mechanisms such as true imitation, where the observer copies the specific actions or sequences performed by a demonstrator, and stimulus enhancement, where observation merely directs attention to a relevant object or location without replicating the exact behavior. In parrots, for instance, true imitation is evident in vocal copying, as demonstrated in studies using the model/rival (M/R) technique, where African grey parrots like Alex learned to label and manipulate objects by observing interactions between a human trainer and a rival model, achieving accurate vocal responses to novel puzzles after demonstrations.^[30] Similarly, corvids exhibit imitation in foraging tasks; Japanese crows (Corvus macrorhynchos) have been observed learning to place walnuts on roads for vehicles to crack, a behavior that spreads socially through observation rather than independent innovation. Evidence from experimental and field studies highlights the role of observational learning in survival-relevant skills. In ravens (Corvus corax), individuals raid food caches made by others by visually observing the caching locations, with captive and wild birds showing higher success rates when visual access is available, indicating tactical use of observed spatial information to pilfer resources without direct confrontation.^[31] This contrasts with associative learning, which relies on solitary cue-response pairings, as observational learning here integrates social cues to interpret demonstrator actions. Developmental aspects are particularly pronounced in juveniles; fledglings often acquire foraging techniques by watching parental behaviors, such as prey capture or food processing, which enhances efficiency during the post-fledging period when direct provisioning decreases.^[32] However, not all birds demonstrate true imitation, with stimulus enhancement being more prevalent in certain taxa. In songbirds, vocal learning typically involves imitation of tutor songs during a sensitive period, but non-vocal behaviors like object manipulation often rely on enhancement, where observing a conspecific near a food item increases the observer's interaction with that item without copying the precise motor actions.^[33] Recent research on corvids further links observational learning to vocal flexibility; a 2024 systematic review of 130 studies found that species exhibiting vocal learning, such as ravens and jackdaws, show greater adaptability in call production through social observation, enabling context-specific communication in dynamic environments.^[34]

Perceptual and Physical Cognition

Spatial and Temporal Abilities

Birds demonstrate sophisticated spatial cognition, particularly in food-caching species reliant on hippocampal-dependent memory for relocating stored resources. Clark's nutcrackers (Nucifraga columbiana), for instance, cache up to 30,000 pine seeds across vast areas and accurately recover approximately 70-90% of them months later, relying on a cognitive map of spatial locations rather than olfactory or visual cues alone.^[35] This ability is linked to an enlarged hippocampus relative to body size, which supports the formation and retrieval of detailed spatial representations in these corvids.^[36] Navigation in migratory and homing birds integrates multiple strategies, including sun compasses, geomagnetic field detection, and visual landmarks. Homing pigeons (Columba livia), a classic model, use the sun's position as a time-compensated compass for orientation, while magnetite-based magnetoreception in their beaks provides directional information from Earth's magnetic field.^[37] They also incorporate familiar landmarks near home lofts to refine routes, allowing precise returns from unfamiliar release sites up to hundreds of kilometers away.^[38] Temporal abilities in birds encompass interval timing and episodic-like memory, enabling adaptive responses to changing environmental schedules. European starlings (Sturnus vulgaris) adjust pecking rates in foraging tasks to optimize wait times between food rewards, demonstrating scalar timing where variability scales with interval duration, as predicted by optimal foraging models.^[39] Western scrub-jays (Aphelocoma californica) exhibit what-where-when memory, recovering perishable items like waxworms before non-perishables from the same locations, indicating integrated recall of event specifics over time delays of hours to days.^[40] Certain birds perceive and synchronize to external rhythms, a form of beat induction tied to vocal-muscular entrainment. The Eleonora cockatoo Snowball spontaneously adjusted head-bobbing movements to the tempo of music, synchronizing within 15-20% of the beat across varying speeds, as shown in controlled experiments.^[41] Subsequent studies from 2009 to 2024 on vocal-learning species like parrots and songbirds reveal that rhythmic entrainment involves motor coordination with auditory beats, facilitated by neural circuits for vocal production and mimicry.^[42]^[43] The neural basis of these abilities involves avian analogs to mammalian entorhinal-hippocampal systems. In food-caching birds like chickadees, a dorsomedial hyperpallium region projects to the hippocampus in patterns resembling mammalian entorhinal inputs, supporting spatial mapping.^[44] Place and head-direction cells in the avian hippocampus encode location and orientation independently of sensory cues, providing a foundation for grid-like representations of space.00542-X)

Object Permanence

Object permanence in birds refers to the cognitive ability to understand that objects continue to exist even when they are out of sight, a foundational aspect of physical cognition adapted from Jean Piaget's sensorimotor stages in human infants. In avian species, this capacity is assessed through progressive tasks involving visible and invisible displacements, where birds must track hidden items like food rewards. Early stages involve simple visual pursuit and partial occlusion (Stages 3-4), while advanced levels require inferring object locations after full occlusion and movement without direct visibility (Stages 5-6). Young birds often exhibit the A-not-B error, perseverating in searches at previously rewarded but incorrect sites, akin to human infants, whereas adults in intelligent lineages demonstrate representational understanding.^[45] Evidence of object permanence varies across species, with pigeons (Columba livia) typically failing advanced tasks despite training. In rotational beam experiments, pigeons achieved low accuracy on invisible displacements (around 50-60% correct), performing only slightly above chance without delays, and showing little spontaneous retrieval in visible displacements. In contrast, parrots such as the African grey (Psittacus erithacus) succeed in invisible displacement tests, reaching Stage 6 by tracking objects hidden under barriers or in successive occlusions. Corvids like rooks (Corvus frugilegus) also master Stage 6, with individuals correctly inferring worm locations after invisible movements behind barriers (up to 11/12 trials correct), though some show individual variation and A-not-B errors early on.^[46]^[47]^[45] Species differences in object permanence align with ecological demands, particularly foraging strategies; corvids and psittacines exhibit advanced abilities linked to food-caching and manipulative behaviors requiring mental representation of hidden resources. Food-storing corvids, such as Western scrub-jays (Aphelocoma californica), develop Stage 4 by 35 days post-hatch, preceding caching onset, enabling them to retrieve buried items without visual cues. Psittacines, with similar manipulative foraging, show comparable proficiency, as seen in New Zealand parakeets (Cyanoliseus patagonus) evidencing A-not-B errors but progressing to full displacements. This variation underscores how evolutionary pressures for tracking ephemeral food sources enhance permanence in these taxa.^[48]^[49] Experimental paradigms, such as rotation tasks, probe these abilities by requiring birds to follow hidden objects through unseen trajectories. In invisible rotational displacements, subjects track a container's movement under a screen or beam rotation; corvids like carrion crows (Corvus corone) master these by 6-9 months, overcoming initial A-not-B perseveration. Pigeons, however, require delays to improve accuracy, suggesting reliance on memory cues rather than true representation. These tasks integrate with spatial cognition, aiding location memory in natural environments.^[50]^[46] Developmental progression in birds transitions from sensorimotor tracking to representational permanence during the nestling phase. Newborn chicks (Gallus gallus domesticus) demonstrate innate object permanence, succeeding in invisible displacement tasks (7/8 correct) without prior occlusion experience, indicating prenatal origins. In corvids, carrion crow nestlings show A-not-B errors in early visible rotations but achieve Stage 6 by fledging age (around 40-50 days). Psittacine nestlings, like African greys, progress rapidly: Stage 3 at 9 weeks, Stage 5 at 18-20 weeks, and Stage 6 at 22 weeks, following moving objects through arcs as eyes open at 2-3 weeks. This ontogeny supports foraging independence, with social and environmental factors accelerating higher stages in some species.^[51]^[50]^[47]

Tool Use and Innovation

Bird tool use refers to the active manipulation of external objects to achieve a goal, such as foraging, often distinguishing between rote application—repeating learned actions without comprehension—and causal understanding, where birds modify tools based on physical properties to solve novel problems. New Caledonian crows (Corvus moneduloides) exemplify causal understanding by bending straight pieces of wire into hooked tools to retrieve food from tubes, demonstrating insight into material pliability rather than mere imitation.^[52] This contrasts with rote use seen in some species that apply unmodified sticks without adaptation.^[53] Several bird species employ tools for insect extraction, highlighting adaptive foraging strategies. The woodpecker finch (Camarhynchus pallidus) of the Galápagos Islands selects and modifies twigs or cactus spines to probe crevices and dislodge arthropods, with tool use comprising up to 30% of its foraging efforts in certain habitats.^[54] Recent studies on palaeognath birds, including emus (Dromaius novaehollandiae), reveal unexpected innovation; in controlled experiments, emus spontaneously fashioned leaf strips into tools to extract food from narrow apertures, marking the first documented technical innovation in this ancient avian lineage.^[55] Birds also demonstrate spontaneous innovation by devising novel tools without prior exposure. Common ravens (Corvus corax), for instance, have been observed pulling rakes—improvised from sticks or debris—to access out-of-reach food rewards, adapting the tool's design to the task's geometry in real-time.^[56] Such behaviors underscore birds' capacity for flexible problem-solving beyond habitual actions. Advanced tool use in birds requires metatool selection—choosing one tool to retrieve or modify another—and future planning. New Caledonian crows excel here, spontaneously using a short stick to obtain a longer one for food extraction, mentally representing out-of-sight tool locations and sequences.^[57] They further plan specific tool applications, caching appropriate implements in advance for anticipated foraging scenarios.30088-0) Tool-using traditions in birds often involve cultural transmission through observation, where techniques propagate across generations without genetic inheritance. In New Caledonian crow populations, regional variations in tool design, such as pandanus leaf strips, are maintained via social learning, with juveniles acquiring designs by watching adults, suggesting mental templates guide replication.^[58] This observational process enables the spread of innovations within groups.^[59]

Abstract and Conceptual Cognition

Conceptual Abilities

Birds demonstrate conceptual abilities through their capacity to form abstract categories, process numerical information, infer causal relationships, and engage in rudimentary analogical reasoning, abilities that extend beyond simple associative learning to reveal higher-order cognitive processing. These skills are particularly evident in corvids and parrots, species known for their enlarged forebrains relative to body size. Such conceptual thinking allows birds to generalize learned rules to novel situations, suggesting a level of abstraction comparable to some mammalian cognition, though with species-specific variations and limitations. Categorization in birds is exemplified by pigeons' ability to distinguish novel images based on trained concepts, such as identifying trees versus non-trees in photographs. In seminal experiments, pigeons were trained to peck at keys corresponding to positive exemplars (e.g., trees) among distractors, achieving high accuracy on novel stimuli that shared conceptual features rather than superficial traits like color or texture. This transfer indicates that pigeons form abstract representations of natural categories, generalizing beyond specific training examples to unseen instances. Numerical cognition in birds includes counting small quantities, understanding zero as an absence, and grasping ordinal sequences. African grey parrots, such as the renowned subject Alex, could accurately label the number of items up to six or eight, distinguishing quantities like three versus six toys regardless of size or type, and even performing basic addition (e.g., two plus four). Furthermore, these parrots demonstrated comprehension of zero by responding to "none" when no items were present and understood ordinality by labeling positions in sequences (e.g., first, second). These abilities suggest symbolic numerical representation, with the parrot treating numbers as abstract concepts rather than mere perceptual aggregates. Causal reasoning enables birds to infer hidden mechanisms affecting outcomes, as seen in Eurasian jays' performance on tasks requiring understanding of physical support and connectivity. In support intuition experiments, juvenile jays learned to discriminate stable from unstable configurations and inferred the presence of hidden supports or connections that prevented object collapse, outperforming random chance even when visual cues were absent.^[60] Similarly, in water displacement tasks akin to Aesop's fable paradigms, Eurasian jays demonstrated causal understanding by selectively dropping stones into tubes to raise water levels, avoiding non-functional configurations and indicating reasoning about invisible causal relations rather than relying solely on trial-and-error.^[61] This causal understanding serves as a prerequisite for innovative tool use in these species. Preliminary evidence for analogical reasoning appears in Amazon parrots, capable of solving relational match-to-sample tasks. Amazon parrots have shown success in selecting comparison stimuli that match the relation (e.g., same color or shape) between sample pairs, rather than absolute features, transferring this relational rule to novel combinations.^[62] This suggests an ability to map structural similarities across contexts, a core component of analogy, though further studies are needed to confirm robustness beyond basic relations. Despite these advances, bird conceptual abilities have notable limits, with no conclusive evidence for syntax-like recursion involving nested hierarchies, as seen in human language. While songbirds like European starlings exhibit advanced pattern recognition by distinguishing recursive acoustic sequences in lab settings, this appears driven by statistical learning rather than generative syntactic rules, failing to generalize to deeply embedded structures without extensive training. Corvids show promise in recursive sequence processing, but overall, avian cognition excels in linear patterns and simple abstractions over complex hierarchical syntax.^[63]

Conservation

Birds demonstrate varying degrees of understanding conservation principles, the cognitive recognition that a quantity of objects or substance remains constant despite changes in spatial arrangement, shape, or appearance. This ability is tested using adapted versions of Piagetian tasks, which assess whether birds can inhibit responses to perceptual transformations and maintain an accurate representation of quantity. In studies with pigeons (Columba livia), birds typically fail standard liquid conservation tasks, where the amount of liquid is poured from one container to another of different shape, leading them to choose the taller or wider container as containing more.^[64] However, with training, pigeons can succeed in solid displacement tasks, where the quantity of solid items (such as food pieces) is rearranged or spread out, allowing them to select the original quantity after transformation.^[65] Corvids, such as crows and ravens, show evidence of number conservation in behavioral tasks involving rotated or rearranged arrays. For example, in numerical discrimination experiments, corvids accurately select arrays with the same number of tokens even after the arrangement is rotated or spread, indicating they track numerical invariance rather than relying solely on spatial cues.^[66] Parrots, particularly grey parrots (Psittacus erithacus), exhibit partial success in conservation tasks involving length and volume. In Piagetian liquid conservation tests, grey parrots choose the container with the equal amount of liquid after pouring into a different-shaped vessel, performing at levels comparable to human children over 7 years old, though success is less consistent in more complex volume displacement scenarios without verbal labeling support.^[67] These abilities are closely linked to object permanence, as birds must first track hidden or moved objects, but conservation requires additional inhibitory control to override misleading perceptual changes, such as apparent increases in height or spread. Experimental designs often involve pre-transformation familiarization followed by post-transformation choices, where birds select between food quantities in transformed versus unchanged configurations to measure reliance on invariant quantity over appearance. This builds briefly on broader numerical understanding in conceptual abilities.

Self-Awareness and Theory of Mind

Self-awareness in birds has been primarily investigated through the mirror self-recognition (MSR) test, where an animal must recognize its reflection to remove a mark visible only in the mirror. In a seminal study, Eurasian magpies (Pica pica) demonstrated this ability: two out of five individuals repeatedly removed stickers from their feathers after observing them in a mirror, while ignoring marks on their bodies not visible without reflection, indicating self-directed behavior. This marked the first evidence of MSR in a non-mammalian species, suggesting that self-recognition may arise independently of mammalian brain structures. However, replication efforts have shown variability, with a 2020 study using a larger sample failing to provide evidence of self-recognition, suggesting the ability may not be robust across individuals or conditions.^[68] In parrots, results remain debated and inconclusive, with no robust evidence of full MSR. African grey parrots (Psittacus erithacus) and common hill mynas (Gracula religiosa) failed to exhibit self-directed behaviors in mark tests, instead treating mirrors as social stimuli or tools for object location. Some studies suggest a gradualist interpretation, where parrots show partial understanding, such as using mirrors for spatial tasks without clear self-recognition, but critics argue this reflects associative learning rather than metacognition. Theory of mind (ToM), the ability to attribute mental states to others, is evidenced in corvids through tasks analogous to human false-belief tests. Ravens (Corvus corax) anticipate conspecifics' actions by inferring visual access: when caching food, they adjust behavior based on whether a competitor could have seen the cache, even if the competitor is out of sight, suggesting attribution of knowledge states. This performance implies a basic ToM, as ravens protect caches more vigilantly from observers with prior visual access, akin to understanding false beliefs about location. Precursors to empathy, such as consolation, appear in corvids following conflicts. In ravens, bystanders initiate affiliative contacts—like preening or proximity—with victims of aggression, particularly those with strong social bonds, reducing the victims' stress more than self-directed calming. Similarly, carrion crows (Corvus corone) engage in post-conflict reconciliation and third-party affiliation, with aggressors preening victims after fights, indicating efforts to repair relationships and alleviate distress. Evidence for self-awareness and ToM is strongest in corvids, particularly ravens and magpies, with convergent findings across behavioral paradigms. In parrots, evidence is emerging but weaker, limited to indirect social inferences rather than explicit MSR. Recent multi-species comparisons, including 2022 tests on ravens, azure-winged magpies, and Eurasian jays, confirm corvid variability but reinforce magpie success, while 2025 reviews highlight corvids' multidimensional consciousness, including self-experience tied to social cognition.^[69] Neural correlates involve the nidopallium caudolaterale (NCL), the avian analog of the mammalian prefrontal cortex, which supports executive functions underlying perspective-taking. In corvids, NCL neurons encode social variables during caching tasks requiring inferred mental states, linking brain activity to ToM-like behaviors. This pallial region's connectivity facilitates the cognitive flexibility observed in self-awareness and empathy precursors. Birds exhibit a range of complex social behaviors that underpin group dynamics and survival strategies, including cooperation, deception, hierarchical structures, and cultural transmission. In species like the Florida scrub-jay (Aphelocoma coerulescens), cooperative breeding is prominent, where non-breeding helpers assist breeders in raising offspring by provisioning food to nestlings and participating in mobbing displays against predators such as hawks and snakes to defend the territory.^[70] This cooperation enhances reproductive success, with helpers gaining indirect fitness benefits through kin selection, though direct reciprocity—such as coordinated vigilance during foraging—also plays a role in pair and group interactions.^[71] Deception emerges as a strategic behavior in corvids, particularly common ravens (Corvus corax), which mislead competitors about food cache locations to protect resources. During caching episodes, ravens observe onlookers and later feign interest in empty sites or delay caching until unobserved, demonstrating tactical deception. Such actions may involve rudimentary theory of mind, allowing ravens to attribute knowledge states to others based on visual access.^[72] Social hierarchies in birds often stabilize group interactions and resource access. In domestic chicken (Gallus gallus domesticus) flocks, individuals form linear dominance hierarchies, or "pecking orders," where higher-ranking birds gain priority access to food and mates, with stability maintained through consistent agonistic interactions over weeks or months.^[73] Among corvids, hierarchies are more fluid, with individuals forming temporary coalitions or alliances to challenge dominants; for instance, carrion crows (Corvus corone) engage in coordinated chases and attacks against intruders, where subordinates recruit allies to shift power dynamics and improve their rank.^[74] Cultural behaviors in songbirds are transmitted socially across generations, fostering group cohesion and local adaptations. In species like the white-crowned sparrow (Zonotrichia leucophrys), song dialects—distinct regional variants—emerge through vocal imitation of tutors during a sensitive learning period, persisting stably due to conformity biases that favor local traditions over innovations.^[75] These culturally inherited repertoires influence mate choice and territory defense, with transmission fidelity exceeding 90% in some populations, highlighting birdsong as a model for cumulative cultural evolution.^[76] Recent research in 2025 has linked the evolution of aggression in cavity-nesting birds to social complexity, showing how resource pulses like insect outbreaks modulate territorial behaviors. In black-capped chickadees (Poecile atricapillus) and red-breasted nuthatches (Sitta canadensis), increased food availability heightens conspecific aggression while reducing interspecific conflicts, suggesting flexible social strategies that balance competition and cooperation in shared nesting environments.^[77] This plasticity underscores how ecological pressures drive repeated evolutionary convergence in aggressive traits among cavity-nesters, enhancing group-level resilience.

Communication Systems

Birds exhibit sophisticated communication systems that reveal underlying cognitive processes, including the ability to convey specific information about predators, coordinate social interactions, and manipulate receivers through deception. These systems often involve vocalizations that are learned and context-dependent, distinguishing birds like songbirds and parrots from non-vocal learners. Referential signaling, where calls denote particular external referents, exemplifies this precision, while multimodal displays integrate auditory and visual cues to enhance message efficacy during courtship. Recent research on corvids further links vocal flexibility to broader cognitive traits, suggesting potential precursors to more complex linguistic structures.^[78] Referential signaling in birds allows for the transmission of predator-specific information, akin to semantic communication in primates. Black-capped chickadees (Poecile atricapillus) produce distinct alarm calls that encode details about predator size and type; for instance, higher-pitched "seet" calls signal small, agile flying predators like hawks, prompting evasive flight responses, while descending "chick-a-dee" calls indicate larger, perched threats like owls, eliciting mobbing behaviors.^[79] This allometric variation in call structure—where call frequency inversely correlates with predator size—enables conspecifics and heterospecifics to respond adaptively without visual confirmation of the threat. Neurogenomic studies confirm that chickadee auditory forebrains process these calls equivalently to their referents, underscoring the cognitive basis of referential meaning.^[80] Vocal learning underpins much of avian communication, enabling songbirds and parrots to imitate environmental sounds and develop structured repertoires. In songbirds, juveniles acquire songs through auditory templating from tutors, refining output via feedback to match species-typical patterns, a process shared with human speech acquisition. Parrots demonstrate similar imitative prowess, often mimicking non-avian sounds with high fidelity, which supports social bonding and individual recognition. Some species exhibit syntactic elements, where call sequences follow rule-based orders conveying relational information; for example, nightingales (Luscinia megarhynchos) engage in antiphonal duets during territorial disputes, alternating song phrases with precise timing and matching to signal partnership strength and deter rivals. These duets require cognitive coordination, as juveniles learn interaction rules by participating with adults, gradually increasing fidelity to duet codes.^[78]^[81] Multimodal communication enhances signal reliability by combining vocalizations with visual displays, particularly in courtship contexts where coordination maximizes mate attraction. In species like the golden-collared manakin (Manacus vitellinus), males perform synchronized song-and-dance routines, tapping feet rhythmically while vocalizing to court females, with multimodal signals outperforming unimodal ones in eliciting female approaches. Similarly, in socially monogamous songbirds such as the white-shouldered fairywren (Malurus alboscapulatus), both sexes escalate multimodal displays—integrating bow-calls with postural bows—in the presence of audiences, promoting pair bonding and territory defense. This integration exploits sensory biases, as receivers integrate auditory and visual cues to assess signaler quality more accurately than from either modality alone.^[82]^[83]^[84] Deception in bird signals demonstrates strategic manipulation of communication systems for self-interest, often involving false alarm calls to usurp resources. Fork-tailed drongos (Dicrurus adsimilis) are notorious kleptoparasites, producing mimicked heterospecific alarm calls—such as those of pied babblers—to flush foraging birds from food sources, successfully deceiving victims in over 75% of attempts despite repeated exposure. To sustain deception, drongos vary call types and contexts, avoiding habituation by receivers who otherwise ignore frequent fakers. In great tits (Parus major), individuals emit false alarm calls near feeding heterospecifics to drive them away, securing food without genuine threats, a tactic that exploits the referential reliability of alarm systems for competitive gain. Such behaviors highlight the cognitive demands of assessing receiver knowledge and timing deceptive signals appropriately. Recent 2025 research on corvids underscores connections between vocal control and cognitive flexibility, positioning these birds as models for proto-language evolution. Studies reveal that corvids like crows (Corvus corone) exhibit voluntary vocal modulation, linking forebrain networks for vocalization to those for problem-solving and social cognition, with flexible mimicry enabling context-specific signaling. This integration suggests proto-linguistic elements, where vocal sequences convey abstract intentions, bridging avian communication with human language precursors.^[85]^[86]

References

[1]
https://www.cell.com/trends/cognitive-sciences/fulltext/S1364-6613(23)00281-4
[2]
Cognitive ornithology: the evolution of avian intelligence - PMC
In reviewing the evidence for avian intelligence, corvids and parrots appear to be cognitively superior to other birds and in many cases even apes.
[3]
Bird Brain Evolution | American Scientist
Birds are the only vertebrates whose brains have expanded over the course of evolution at levels that approach those seen in mammals, particularly in primates.
[4]
Birds have primate-like numbers of neurons in the forebrain - PNAS
Jun 13, 2016 · Many birds have cognitive abilities that match or surpass those of mammals (1). Corvids and parrots appear to be cognitively superior to other ...
[5]
Developmental origins and evolution of pallial cell types ... - Science
Feb 14, 2025 · Innovations in the pallium likely facilitated the evolution of advanced cognitive abilities in birds. We therefore scrutinized its cellular ...
[6]
Avian brains and a new understanding of vertebrate brain evolution
Although the avian pallium is nuclear, and the mammalian cortex is laminar in organization, the avian pallium supports cognitive abilities similar to, and for ...
[7]
High associative neuron numbers could drive cognitive performance ...
Jan 8, 2022 · These findings support our hypothesis that large absolute numbers of associative pallial neurons contribute to cognitive flexibility and complexity.3 Results · 3.1 Corvid Brains Have High... · 4 Discussion
[8]
Birds have primate-like numbers of neurons in the forebrain - PMC
Jun 13, 2016 · Thus, large-brained parrots and corvids have forebrain neuron counts equal to or greater than primates with much larger brains. We suggest that ...
[9]
Avian telencephalon and cerebellum volumes can be accurately ...
Jan 22, 2025 · We here use the largest dataset of histology and digital endocasts to date, including 136 species from 25 avian orders, to compare digital endocast surface ...
[10]
Neural representations of space in the hippocampus of a food ...
Jul 16, 2021 · We found mammalian-like neural activity in the titmouse hippocampus, including sharp-wave ripples and anatomically organized place cells.Missing: mental | Show results with:mental
[11]
Spatial coding in the hippocampus and hyperpallium of flying owls
Jan 24, 2023 · We found neurons that code the direction of flight and the location of the owl in-flight. These results provide unique comparative and evolutionary insights.Missing: mental | Show results with:mental
[12]
Anatomical specializations for enhanced olfactory sensitivity in kiwi ...
Nov 5, 2014 · In this study, we examine the size of the olfactory bulbs in kiwi and compare them with 55 other bird species, including emus, ostriches, rheas, tinamous, and ...
[13]
Diversity in olfactory bulb size in birds reflects allometry, ecology ...
In this study, we use the relative size of OBs as a neuroanatomical proxy for olfactory capabilities in 135 species of birds, representing 21 orders.
[14]
Mapping the avian visual tectofugal pathway using 3D reconstruction
Dec 4, 2023 · The tectofugal system dominates with functions such as color and motion processing, spatial orientation, stimulus identification, and localization.
[15]
A histological and diceCT-derived 3D reconstruction of the avian ...
Apr 11, 2024 · Amniotes feature two principal visual processing systems: the tectofugal and thalamofugal pathways. In most mammals, the thalamofugal ...
[16]
Exploring Anatomical Links Between the Crow's Nidopallium ...
Feb 8, 2025 · Crows are corvid songbirds that exhibit remarkable cognitive control, including their ability to vocalize on command. The activity of single ...
[17]
Neurogenesis in the Adult Avian Song-Control System - PMC - NIH
Song behavior in oscine birds is regulated by a network of pallial and striatal nuclei. The song-control system shows extensive plasticity in adults, including ...Missing: lifelong | Show results with:lifelong
[18]
Adult Neurogenesis Is Associated with the Maintenance of a ...
May 16, 2012 · Adult neurogenesis is thought to provide neural plasticity used in forming and storing new memories. Here we show a novel relationship ...Missing: pallium lifelong
[19]
Cretaceous bird from Brazil informs the evolution of the avian skull ...
Nov 13, 2024 · Virtually no well-preserved skulls bearing undistorted endocasts are known from taxa phylogenetically intermediate between Archaeopteryx (the ...
[20]
https://www.nature.com/articles/s41586-024-08114-4
[21]
CLASSICAL CONDITIONING IN ANIMALSl - Annual Reviews
This process is responsible for organisms learning about relationships between events, enabling them to build up an associative representation of the causal.
[22]
Pigeons acquire multiple categories in parallel via associative learning
The present study sought to develop an associative learning task for pigeons that requires a mapping between many visual exemplars and many categories, a ...
[23]
Serial reversal learning and the evolution of behavioral flexibility in ...
In serial reversal learning, subjects learn to respond differentially to 2 stimuli. When the task is fully acquired, reward contingencies are reversed, ...
[24]
New Caledonian Crows Learn the Functional Properties of Novel ...
Associative learning is driven by correlations between initially neutral stimuli and unconditioned stimuli or primary reinforcers (here, access to food). It ...Missing: field | Show results with:field
[25]
A large-scale study across the avian clade identifies ecological ...
We first demonstrated that consistent differences in neophobia existed among individuals, among species, and among other taxonomic levels in our dataset, ...
[26]
Socio-ecological correlates of neophobia in corvids - ScienceDirect
Jan 10, 2022 · Neophobia, ie, fear of novel stimuli, impacts adaptability, and survival. Individual and species-level variation found in object and food neophobia in corvids.
[27]
Associative learning is inversely related to reversal ... - ResearchGate
Aug 8, 2025 · Scrub-jays with low levels of corticosterone as 11-day-old nestlings performed better on an associative learning test as adults, and there was ...
[28]
Getting a head start: diet, sub-adult growth, and associative learning ...
High-diet birds mastered an associative learning task in fewer bouts than those reared on the low-protein diet. In both diet treatments, amount of sub-adult ...Missing: influence | Show results with:influence
[29]
Enhanced problem-solving ability as an adaptation to urban ... - NIH
Our results are in line with findings in various bird species showing that populations living in human-altered areas show enhanced problem-solving performances ...<|separator|>
[30]
Cognitive flexibility and memory in pigeons, human children, and ...
This work examines cognitive flexibility using a comparative approach. Pigeons (Experiment 1), human children (Experiment 2a), and human adults (Experiment ...
[31]
The economics of brain size evolution in vertebrates - ScienceDirect
Jun 20, 2022 · The second pathway to meet the costs of increased brain size is to reduce energy allocation to other body functions and shunt it to the brain.<|separator|>
[32]
A Review of the Model/Rival (M/R) Technique for Training ...
Aug 24, 2021 · In this paper, I will review the Model/Rival (M/R) technique that has been used to establish interspecies communication with Grey parrots (Psittacus erithacus).
[33]
Animal behavior: Innovation in the city - ScienceDirect.com
Oct 11, 2021 · (2001), pp. 1901-1905. View in Scopus Google Scholar. 3. Y. Nihei, H. Higuchi. When and where did crows learn to use automobiles as nutcrackers.
[34]
Observational learning and the raiding of food caches in ravens ...
Group-foraging ravens scatter-hoard when they are competing for food and, to some extent, also raid the caches made by others.
[35]
Social learning in birds and its role in shaping a foraging niche - NIH
Social learning of foraging may take place early in life, using parents as role models [8,40,45], and later in life by observing others [20,43,46]. The ...Missing: fledglings observational
[36]
Biological Mechanisms for Observational Learning - PMC - NIH
In birds, vocal imitation is the best documented form of social learning [48,49]. Juvenile songbirds such as zebra finches sequentially acquire their father's ...
[37]
Vocal communication in corvids: a systematic review - ScienceDirect
The ability to vocally learn shows enhanced vocal flexibility in corvids. The fact that evidence for vocal learning is only described in nine species does ...
[38]
Cache recovery and spatial memory in Clark's nutcrackers ...
Clark's nutcrackers cache pine seeds and recover them months later. Four experiments with 5 nutcrackers tested their ability to relocate their caches when ...Missing: hippocampal | Show results with:hippocampal
[39]
The Cognition of Caching and Recovery in Food-Storing Birds
Many food-hoarding birds use memory to relocate their caches. The hippocampus plays an important role in spatial memory.
[40]
Homing pigeons as a model for avian navigation? - Wiltschko - 2017
Feb 10, 2017 · Birds have a magnetic compass that uses the vector of the geomagnetic field for direction finding, and celestial compass mechanisms; here, the ...
[41]
The role of visual landmarks in the avian familiar area map
Jun 1, 2003 · We know that homing pigeons and other birds can use visual landmarks both with a compass and independently to locate a goal in small-scale ...
[42]
[PDF] Interval Timing and Optimal Foraging
Without the scalar timing model, we would not have understood why the starlings' giving-in times are a fixed proportion of the interval between food items.
[43]
Episodic-like memory during cache recovery by scrub jays - Nature
Sep 17, 1998 · Here we show that scrub jays (Aphelocoma coerulescens) remember 'when' food items are stored by allowing them to recover perishable 'wax worms' ...Abstract · Main · Methods · References
[44]
Experimental evidence for synchronization to a musical beat in a ...
May 26, 2009 · Here we report experimental evidence for synchronization to a beat in a sulphur-crested cockatoo (Cacatua galerita eleonora).
[45]
Spontaneous Motor Entrainment to Music in Multiple Vocal ...
Apr 30, 2009 · Here we provide comparative data demonstrating the existence of two proficient vocal mimicking nonhuman animals (parrots) that entrain to music.Missing: muscular | Show results with:muscular
[46]
Beat-based dancing to music has evolutionary foundations in ...
Nov 6, 2024 · This paper proposes that human-parrot similarities in movement to music and in the neurobiology of advanced vocal learning hold clues to the evolutionary ...
[47]
An entorhinal-like region in food-caching birds - ScienceDirect.com
Jun 19, 2023 · We mapped extrinsic hippocampal connections in chickadees, whose hippocampi are used for remembering numerous food caches.
[48]
Object permanence in rooks (Corvus frugilegus) - PubMed Central
Sep 3, 2024 · In birds, the greatest variation is in Stage 6 (invisible displacements) and in “A-not-B” errors—incorrectly persevering in searching an empty ...
[49]
Object permanence in the pigeon (Columba livia): Insertion of a ...
We tested pigeons' accuracy on both visible and invisible displacement using a rotational beam with a container at either end.
[50]
[PDF] Development of Piagetian Object Permanence in a Grey Parrot ...
The authors evaluated the ontogenetic performance of a grey parrot (Psittacus erithacus) on object permanence tasks designed for human infants.
[51]
The Development of Caching and Object Permanence in Western ...
Piagetian object permanence is the understanding that objects continue to exist even when they are no longer visible. Here, the authors focus on Piagetian ...
[52]
Development of object permanence in the New Zealand parakeet ...
The birds successfully completed all tasks in this scale, and many aspects of their testing were similar to human results, such as evidencing the A-not-B error.
[53]
Ontogeny of object permanence and object tracking in the carrion ...
Object permanence is a component of physical cognition and refers to the knowledge that an object still exists when out of sight or displaced.
[54]
[PDF] Object Permanence in Newborn Chicks (arXiv) - OpenReview
(A) Newborn chicks were hatched in darkness, raised in impoverished worlds with no object occlusion events, then tested on object permanence tasks. (B) In the ...
[55]
Tool bending in New Caledonian crows | Royal Society Open Science
Aug 1, 2016 · ... bent straight pieces of garden wire into hooked foraging tools. ... Activity profiles and hook-tool use of New Caledonian crows recorded by bird- ...
[56]
Was Betty the crow a genius—or a robot? | Science | AAAS
Aug 9, 2016 · "We now think that they bend their tools to get them ready to use; bending is thus part of their natural repertoire." A follow-up experiment ...Missing: paper | Show results with:paper
[57]
The ecology of tool‐use in the woodpecker finch (Cactospiza pallida)
Sep 12, 2002 · Insects, mammals and birds are known to use tools, but empirical evidence of the ecological importance of tool-use is scarce.
[58]
(PDF) Palaeognath birds innovate to solve a novel foraging problem
... use tools, and ravens have sophisticated insights in social relationships. This volume describes the full range of avian cognitive abilities, the mechanisms ...
[59]
Tool use and tooling in ravens (Corvus corax): A review and novel ...
Dec 20, 2022 · Pulling a pre-positioned rake to get food that is out of reach or ... Raven using a stick as a reach or insert and probe tool. The tube ...INTRODUCTION · LITERATURE REVIEW · OBSERVATIONS · DISCUSSION
[60]
Animal Cognition: Crows Spontaneously Solve a Metatool Task
Oct 23, 2007 · A recent study found that tool-manufacturing New Caledonian crows spontaneously solved a metatool task in which the birds used a tool to obtain a second, ...
[61]
Mental template matching is a potential cultural transmission ...
Jun 28, 2018 · We provide the first evidence supporting this hypothesis, by demonstrating that New Caledonian crows have the cognitive capacity for mental template matching.
[62]
How New Caledonian crows solve novel foraging problems and ...
Aug 15, 2015 · New Caledonian crows make and use tools, and tool types vary over geographic landscapes. Social learning may explain the variation in tool design.
[63]
The development of support intuitions and object causality ... - Nature
Jan 5, 2017 · In order to raise the water level, rooks prefer to drop large (more efficient) stones instead of small stones, and Eurasian jays drop sinking ( ...
[64]
Using the Aesop's Fable Paradigm to Investigate Causal ...
Mar 26, 2014 · Second, errors made by animals on a key transfer task, the inverted trap-tube ... Eurasian jays and human children – have confirmed that ...
[65]
Simple rules can explain discrimination of putative recursive ... - PNAS
Dec 1, 2009 · So we conclude that seven out of eight birds were unable to generalize the discrimination of the stimuli to novel ones using structure cues only ...Abstract · Sign Up For Pnas Alerts · Results
[66]
Birds' Judgments of Number and Quantity
This chapter looks mainly at how birds perform on a variety of number-related tasks in which visual stimuli have been used.
[67]
Neurons selective to the number of visual items in the corvid ... - NIH
Birds are known for their advanced numerical competence, although a six-layered neocortex that is thought to enable primates with the highest levels of ...
[68]
Piagetian liquid conservation in grey parrots (Psittacus erithacus).
An understanding of Piagetian liquid conservation was investigated in four Grey parrots (Psittacus erithacus), their ages ranging from initially less than 1 ...Missing: tasks | Show results with:tasks
[69]
On mark-test replication and mirror self-recognition in magpies.
... magpie, Pica pica. Over 10 years ago, a study revealed evidence of two magpies (out of five tested) passing the mark-test (Prior, Schwarz, & Güntürkün, 2008) ...
[70]
Helper Response to Experimentally Manipulated Predation Risk in ...
We conclude that predation risk reduces helper food intake, but despite this effect, helpers were more willing to support the breeders, supporting PS.
[71]
Coordinated vigilance provides evidence for direct reciprocity in ...
Sep 25, 2015 · Although limited to observational data, we provide strong evidence for a clear coordination of foraging and vigilance behaviour in pairs and ...
[72]
Ravens attribute visual access to unseen competitors - Nature
Feb 2, 2016 · Observational learning and the raiding of food caches in ravens, Corvus corax: is it 'tactical' deception? Anim. Behav. 64, 185–195 (2002) ...
[73]
Finding hens in a haystack: Consistency of movement patterns ...
Aug 17, 2018 · Dominant hens would be more likely to access the nest earlier or with less consideration of current nestbox users, whereas less dominant hens ...
[74]
Dominance relationships and coalitionary aggression against ...
Nov 4, 2019 · We here characterize coalitionary aggression behaviour in a group of female carrion crows consisting of recruitment, coordinated chase, and attack.
[75]
Cultural conformity generates extremely stable traditions in bird song
Jun 20, 2018 · To produce species-typical songs, young birds must memorise songs heard early in life, and later develop imitations of those songs.
[76]
Cumulative cultural evolution and mechanisms for cultural selection ...
Jul 11, 2022 · Cultural evolution occurs when variation in a behaviour is followed by social learning of the new behaviour, and that new form of the ...
[77]
Cavity nesting birds show behavioural plasticity to simulated ...
Mar 18, 2025 · We investigated the impact of two natural pulses (food and nesting resources) on intra- and inter-specific territorial behaviour of species ...
[78]
The multi-dimensional nature of vocal learning - Journals
Sep 6, 2021 · The classical view of vocal production learning is based on studies of humans and songbirds. In this process, the animal uses auditory input ...
[79]
Functional neurogenomic responses to acoustic threats, including a ...
Jan 25, 2024 · The auditory forebrain in at least one songbird species, the black-capped chickadee Poecile atricapillus, responds similarly to threat calls and their referent ...
[80]
Early development of vocal interaction rules in a duetting songbird
Feb 21, 2018 · Results show that juveniles acquire a duet code by singing with a mated pair of adults and that juveniles gradually increase their fidelity to ...Missing: parrots | Show results with:parrots
[81]
Tap dancing birds: the multimodal mutual courtship display of males ...
Nov 19, 2015 · According to classical sexual selection theory, complex multimodal courtship displays have evolved in males through female choice.
[82]
Couples showing off: Audience promotes both male and female ...
Oct 3, 2018 · We found that in both sexes, multimodal courtship displays (song accompanied by dance) were promoted in the presence of an audience, especially if it was the ...
[83]
Evolution and function of multimodal courtship displays - Mitoyen
May 10, 2019 · Courtship displays are behaviours aimed to facilitate attraction and mating with the opposite sex and are very common across the animal kingdom.
[84]
Bridging the fields of cognition and birdsong with corvids - PubMed
Jan 3, 2025 · We suggest corvids with their flexible vocal control as promising model species to study the links between brain networks for cognition and vocalization.Missing: HVC NCL
[85]
Vocal mimicry in corvids - bioRxiv
Mar 29, 2025 · This study explores vocal mimicry in corvids, a family of intelligent birds including crows and jays. Researchers investigated the prevalence of ...