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One key aspect of domain-general thought is the ability to integrate information across different cognitive domains. Here, we tested whether kea ( Nestor notabilis ) can use relative quantities when predicting sampling outcomes, and then integrate both physical information about the presence of a barrier, and social information about the biased sampling of an experimenter, into their predictions. Our results show that kea exhibit three signatures of statistical inference, and therefore can integrate knowledge across different cognitive domains to flexibly adjust their predictions of sampling events. This result provides evidence that true statistical inference is found outside of the great apes, and that aspects of domain-general thinking can convergently evolve in brains with a highly different structure from primates. This has important implications not only for our understanding of how intelligence evolves, but also for research focused on how to create artificial domain-general thought processes. Previously only humans and the great apes have been shown to use probabilities to make predictions about uncertain events, and integrate social and physical information into their predictions. Here, the authors demonstrate these capacities in a parrot species, the kea.

The relationships of passerines (such as the well-studied zebra finch) with non-passerine birds is one of the great enigmas of avian phylogenetic research, because decades of extensive morphological and molecular studies yielded highly inconsistent results between and within data sets. Here we show the first application of the virtually homoplasy-free retroposon insertions to this controversy. Our study examined ~200,000 retroposon-containing loci from various avian genomes and retrieved 51 markers resolving early bird phylogeny. Among these, we obtained statistically significant evidence that parrots are the closest and falcons the second-closest relatives of passerines, together constituting the Psittacopasserae and the Eufalconimorphae, respectively. Our new and robust phylogenetic framework has substantial implications for the interpretation of various conclusions drawn from passerines as model organisms. This includes insights of relevance to human neuroscience, as vocal learning (that is, birdsong) probably evolved in the psittacopasseran ancestor, >30 million years earlier than previously assumed. Zebra finches are passerine birds, but their phylogenetic relationship with non-passerine birds remains controversial. By examining retroposon insertion loci in avian genomes, the authors reveal that parrots are the closest relatives of passerines, which may have implications for understanding the evolution of birdsong.

Grasslands are the world’s most threatened terrestrial biome, with consequences for grassland-dependent species. Many remnant grasslands are threatened by woody plant encroachment (hereafter “encroachment”). Several studies have found that encroachment eliminates grassland species through increased predation rates at the nest. The golden-shouldered parrot Psephotellus chrysopterygius is an Endangered species found on Cape York Peninsula, Australia. Even though this species mainly nests along grassy drainage depressions, a previous study concluded that encroachment improves its nest success. We tested this proposition by assessing the fate of 555 eggs laid in 108 nests. We tested the impact of stem density on the fate of eggs, chicks and adults, and on predation events using linear-by-linear association tests; and on nest success using logistic exposure regression. We then compared the contraction of the parrot’s nesting distribution over three decades with change in canopy foliage cover. We also examined whether nest location was influenced by stem density, and explored the processes driving encroachment across the parrot’s distribution, particularly fire frequency, which has been shown to influence encroachment on Cape York Peninsula. The parrots preferentially nested in areas of low woody vegetation density. In contrast to previous work, we found that encroachment increased the probability of predation, and reduced nest success and survival of nesting adults. Encroachment both drove a decline in fire frequency and was exacerbated by it. The parrots have abandoned areas where encroachment has been most advanced. This study provides an Australian example of the negative effects of encroachment on nesting success that have been demonstrated in many species from North American prairies and other grassland habitats. It supports the current management efforts to reverse encroachment in the parrot’s habitat. We conclude that, wherever woody plant encroachment is occurring, it should be considered as a potential threatening process and managed accordingly.

Theory predicts that contrasting properties of mutualistic and antagonistic networks differentially promote community resilience to species loss. However, the outcome of most ecological interactions falls within a continuum between mutualism and antagonism, and we ignore the extent to which this interactions’ continuum might influence community stability. Using a large data set of interactions, we compared co-extinction cascades that either consider or ignore the mix of beneficial and detrimental actions that parrots exert on plants. When the antagonism–mutualism continuum was considered, a combination of the properties that separately enhance community stability in ecological networks emerged. This combination of properties led to an overall increase of the parrot community robustness to face plant species loss. Our results highlight that the conditional outcomes of interactions can influence the structure of ecological networks, thus affecting our predictions of community stability against eventual changes. Ecological interaction networks may fall on a continuum between mutualism and antagonism. Here, the authors show that community robustness increases when both the beneficial and detrimental effects of parrots feeding on plants is taken into account.

Cerebral lateralization refers to the division of information processing in either hemisphere of the brain and is a ubiquitous trait among vertebrates and invertebrates. Given its widespread occurrence, it is likely that cerebral lateralization confers a fitness advantage. It has been hypothesized that this advantage takes the form of enhanced cognitive function, potentially via a dual processing mechanism whereby each hemisphere can be used to process specific types of information without contralateral interference. Here, we examined the influence of lateralization on problem solving by Australian parrots. The first task, a pebble-seed discrimination test, was designed for small parrot species that feed predominately on small seeds, which do not require any significant manipulation with the foot prior to ingestion. The second task, a string-pull problem, was designed for larger bodied species that regularly use their feet to manipulate food objects. In both cases, strongly lateralized individuals (those showing significant foot and eye biases) outperformed less strongly lateralized individuals, and this relationship was substantially stronger in the more demanding task. These results suggest that cerebral lateralization is a ubiquitous trait among Australian parrots and conveys a significant foraging advantage. Our results provide strong support for the enhanced cognitive function hypothesis.

Abstract Blue-and-yellow Macaws in Três Lagoas City (State of Mato Grosso do Sul, Brazil) have utilized Terminalia catappa seeds increasingly, after rarely eating this resource fifteen years ago. Consequently, to improve our understanding of the importance of this novel food in urban areas (center and peri-urban), I once again documented the feeding habits and diet breadth of Blue-and-yellow Macaws in Três Lagoas City and analyzed their responses to resource availability. Blue-and-yellow Macaws foraged on 16 plant species (10 native and 6 exotic), with T. catappa dominating their diet (43.6%), particularly in sites in the city center (up to 81%). Overall, exotic items comprise 50.9% of the Blue-and-Yellow Macaw’s current diet, compared to only 5.4% fifteen years before (from April 2007 to March 2008). Due to the extensive consumption of T. catappa seeds, macaws generally exhibited low diet breadth, especially in the city center. In contrast, in the peri-urban areas, the diet was varied, exhibiting intermediate values of diet breadth. Paralleling the increased presence of exotic species in the Blue-and-yellow Macaw’s diet, the native food resources, especially Cerrado fruits, have been reduced by the expansion of urban areas and eucalyptus plantations. As a result, in just a few years, T. catappa has become the primary food for the Blue-and-yellow Macaw, displaying extreme dietary flexibility to survive in a rapidly changing urban environment. To mitigate such impacts, it is suggested that native species, which once dominated the macaw diet, be used for afforestation throughout the city to encourage a more similar species-rich diet that this macaw eats in the Cerrado. The extensive use of the urban area by Blue-and-yellow Macaws underscores the need for management practices to improve their population growth, as they, unfortunately, are declining along with the Cerrado. Resumo Há quinze anos, as araras Canindé virtualmente não consumiam sementes de Terminalia catappa. No entanto, após alguns anos esse item se tornou comum em sua dieta. Face ao desproporcional uso de alimentos exóticos, novamente, documentei os hábitos alimentares e amplitude de nicho alimentar das araras Canindé, tanto na área central quanto na periferia da cidade de Três Lagoas (Mato Grosso do Sul, Brasil). Também, analisei a relação entre o número de araras se alimentando e a disponibilidade de recursos alimentares. As araras Canindé exploraram 16 espécies de plantas (10 nativas e 6 exóticas), das quais T. catappa teve preponderância (43,6% da dieta), principalmente nas áreas centrais em que constituiu até 81% da dieta. Nesse sentido, atualmente 50,9% da dieta das Canindé resulta de itens exóticos, enquanto que 15 anos atrás representavam apenas 5,4%. Devido ao intenso consumo de sementes de T. catappa, as araras frequentemente apresentaram baixa amplitude de nicho alimentar, principalmente nas áreas centrais. Já na periferia, por utilizarem alimentos mais variados os valores de amplitude de nicho foram maiores. A crescente expansão tanto da área urbana, quanto das plantações de eucalipto tem reduzido cada vez mais as fontes nativas de alimento. Em meio a tais mudanças, como T. catappa se tornou o principal alimento para as Canindé, fica evidente sua acentuada flexibilidade alimentar ao permanecer em um ambiente em transformação. Para atenuar a atual restrição alimentar, as espécies nativas, que até poucos anos dominavam sua dieta, deveriam ser empregadas na arborização em toda a cidade. Isso promoveria uma oferta mais diversificada de alimentos e dieta semelhante a observada no Cerrado. O uso extensivo da área urbana pelas araras Canindé enfatiza a necessidade de práticas de manejo para favorecer seu crescimento populacional, pois infelizmente estão declinando junto com o Cerrado.

Imitation of cultural practices is ubiquitous in humans and often involves faithful copying of intransitive (i.e., non-object directed) gestures and societal norms which play a crucial role in human cumulative cultural evolution. Apart from learning these directly from a tutor, humans often learn passively as third-party observers from the interactions of two or more individuals. Whether third-party imitation has evolved outside humans remains unknown. In the current study, we investigated whether undomesticated blue-throated macaws ( Ara glaucogularis ) could imitate in a third-party setting. A naïve test group ( N  = 6) passively observed a conspecific demonstrator performing rare intransitive actions in response to specific human gestural commands. Directly afterwards, the observer received the same gestural commands and performance-contingent rewards. An equally naïve control group ( N  = 5) was tested correspondingly, in the absence of third-party demonstrations. The test group learned more target actions (mean = 4.16 versus mean = 2.2) in response to the specific commands, significantly faster and performed them more accurately than the control group. The test group also spontaneously imitated some of the actions even before they received any gestural commands or rewards. Our findings show that third-party imitation, even for intransitive actions, exists outside humans, allowing for rapid adaption to group specific behaviours and possibly cultural conventions in parrots.

Three families of probe-foraging birds, Scolopacidae (sandpipers and snipes), Apterygidae (kiwi), and Threskiornithidae (ibises, including spoonbills) have independently evolved long, narrow bills containing clusters of vibration-sensitive mechanoreceptors (Herbst corpuscles) within pits in the bill-tip. These 'bill-tip organs' allow birds to detect buried or submerged prey via substrate-borne vibrations and/or interstitial pressure gradients. Shorebirds, kiwi and ibises are only distantly related, with the phylogenetic divide between kiwi and the other two taxa being particularly deep. We compared the bill-tip structure and associated somatosensory regions in the brains of kiwi and shorebirds to understand the degree of convergence of these systems between the two taxa. For comparison, we also included data from other taxa including waterfowl (Anatidae) and parrots (Psittaculidae and Cacatuidae), non-apterygid ratites, and other probe-foraging and non probe-foraging birds including non-scolopacid shorebirds (Charadriidae, Haematopodidae, Recurvirostridae and Sternidae). We show that the bill-tip organ structure was broadly similar between the Apterygidae and Scolopacidae, however some inter-specific variation was found in the number, shape and orientation of sensory pits between the two groups. Kiwi, scolopacid shorebirds, waterfowl and parrots all shared hypertrophy or near-hypertrophy of the principal sensory trigeminal nucleus. Hypertrophy of the nucleus basorostralis, however, occurred only in waterfowl, kiwi, three of the scolopacid species examined and a species of oystercatcher (Charadriiformes: Haematopodidae). Hypertrophy of the principal sensory trigeminal nucleus in kiwi, Scolopacidae, and other tactile specialists appears to have co-evolved alongside bill-tip specializations, whereas hypertrophy of nucleus basorostralis may be influenced to a greater extent by other sensory inputs. We suggest that similarities between kiwi and scolopacid bill-tip organs and associated somatosensory brain regions are likely a result of similar ecological selective pressures, with inter-specific variations reflecting finer-scale niche differentiation.

The ability to imitate complex sounds is rare, and among birds has been found only in parrots, songbirds, and hummingbirds. Parrots exhibit the most advanced vocal mimicry among non-human animals. A few studies have noted differences in connectivity, brain position and shape in the vocal learning systems of parrots relative to songbirds and hummingbirds. However, only one parrot species, the budgerigar, has been examined and no differences in the presence of song system structures were found with other avian vocal learners. Motivated by questions of whether there are important differences in the vocal systems of parrots relative to other vocal learners, we used specialized constitutive gene expression, singing-driven gene expression, and neural connectivity tracing experiments to further characterize the song system of budgerigars and/or other parrots. We found that the parrot brain uniquely contains a song system within a song system. The parrot \"core\" song system is similar to the song systems of songbirds and hummingbirds, whereas the \"shell\" song system is unique to parrots. The core with only rudimentary shell regions were found in the New Zealand kea, representing one of the only living species at a basal divergence with all other parrots, implying that parrots evolved vocal learning systems at least 29 million years ago. Relative size differences in the core and shell regions occur among species, which we suggest could be related to species differences in vocal and cognitive abilities.

A case control study was conducted to estimate the prevalence of feather-damaging behavior and evaluate the correlation with risk factors among pet psittacine birds in Japan. Although feather-damaging behavior among pet parrots is frequently observed in Japan, its prevalence and potential risk factors have not been investigated. Therefore, we conducted an online questionnaire survey on parrot owners throughout Japan to examine regional differences in feather-damaging behavior and associated risk factors. In total, 2,331 valid responses were obtained. The prevalence of feather-damaging behavior was 11.7%, in general agreement with prior studies. The highest prevalence was among Cockatoos ( Cacatua spp., etc.; 30.6%), followed by Lovebirds ( Agapornis spp.; 24.5%) and African grey parrots ( Psittacus erithacus ; 23.7%). Multivariate logistic regression was carried out to calculate the adjusted odds ratio (OR adj ) for potential risk factors and adjust the confounding of the variables. The odds of feather-damaging behavior were significantly higher for Conures ( Aratinga spp., Pyrrhura spp., Thectocercus acuticaudatus , Cyanoliseus patagonus ) (OR adj = 2.55, P = 0.005), Pacific parrotlets ( Forpus coelestis ) (OR adj = 3.96, P < 0.001), African grey parrots (OR adj = 6.74, P < 0.001), Lovebirds (OR adj = 6.79, P < 0.001) and Cockatoos (OR adj = 9.46, P < 0.001) than Budgerigars ( Melopsittacus undulatus ), and for young adults (OR adj = 1.81, P = 0.038) and adults (OR adj = 3.17, P < 0.001) than young birds, and for signs of separation anxiety (OR adj = 1.81, P < 0.001). Species, bird age and signs of separation anxiety were significantly higher risk factors for feather-damaging behavior than any other potential risk factors. Our findings, which include broad species diversity, are a good source of data for predicting risk factors for feather-damaging behavior and could be useful in preventing declines in welfare.