Social Isolation Shortens Telomeres in African Grey Parrots (Psittacus erithacus erithacus)

Telomeres, the caps of eukaryotic chromosomes, control chromosome stability and cellular senescence, but aging and exposure to chronic stress are suspected to cause attrition of telomere length. We investigated the effect of social isolation on telomere length in the highly social and intelligent African Grey parrot (Psittacus erithacus erithacus). Our study population consisted of single-housed (n = 26) and pair-housed (n = 19) captive individuals between 0.75 to 45 years of age. Relative telomere length of erythrocyte DNA was measured by quantitative real-time PCR. We found that telomere length declined with age (p<0.001), and socially isolated parrots had significantly shorter telomeres compared to pair-housed birds (p<0.001) – even among birds of similar ages. Our findings provide the first evidence that social isolation affects telomere length, which supports the hypothesis that telomeres provide a biomarker indicating exposure to chronic stress.     

Possible Levels of Animal Consciousness with Reference to Grey Parrots (Psittacus erithacus)

Researchers often study nonhuman abilities by assuming theirsubjects form representations about perceived stimuli and thenprocess such information; why then would consciousness be required,and, if required, at what level? Arguments about nonhuman consciousnessrange from claims of levels comparable to humans to refutationof any need to study such phenomena. We suggest that (a) speciesexhibit different levels attuned to their ecological niches,and (b) animals, within their maximum possible level, exhibitdifferent extents of awareness appropriate to particular situations,much like humans (presumably conscious) who often act withoutconscious awareness of factors controlling their behavior. Wepropose that, to engage in complex information processing, animalslikely exhibit perceptual consciousness sensu Natsoulas (1978),i.e., are aware of what is being processed. We discuss theseissues and provide examples suggesting perceptual consciousness.     

Functional Vocalizations by an African Grey Parrot (Psittacus erithacus)

An African grey parrot, after 26 months of speech training, has acquired a verbal vocabulary consisting of three color adjectives, two phrases for describing shape, 9 nouns, and functional use of the word “no”. The parrot is capable of correctly combining these vocalizations so as to identify proficiently, request, and/or refuse more than 30 objects by means of verbal labels.     

Context-related vocalizations in African grey parrots (Psittacus erithacus)

A few animal species are capable of vocal learning. Parrots are well known for their vocal imitation abilities. In this study, we investigated whether African grey parrots (Psittacus erithacus) emit specific vocalizations in specific contexts. We first described the vocal repertoire and its ontogenesis of four captive grey parrots. After a comparison with vocalizations emitted by wild and other captive African grey parrots, we observed that only three call categories were shared by all grey parrots populations, suggesting that isolated populations of parrots develop population-specific calls. Then, we artificially provoked ten different contexts and recorded vocalizations of four captive grey parrots in these situations. Parrots predominantly emitted call categories in some contexts: distress, protestation, alarm, asking (i.e. emitted when a bird wanted something from an experimenter) and contact calls. These results suggest that some calls are learned and can be used in specific contexts.     

Functional-morphological and biochemical correlations of the keratinized structures in the African Grey Parrot,Psittacus erithacus (Aves)

Summary Keratinized structures from the African Grey Parrot (feather, down, claw, scale, rhamphotheca, soft lingual epithelium, and lingual nail) were compard by combining biochemical and functional-morphological approaches. At the molecular level, the keratinized structures of Psittacus erithacus are organized essentially like those of other avian species. Correlations were established (or verified) between the mechanical properties of the tissues and the molecular size of the keratin monomers, between the mechanical properties and the x-ray diffraction patterns of the tissues, and between the Polyacrylamide gel electrophoresis (PAGE) patterns of the keratins and certain aspects of growth patterns of the structures. The keratin proteins of the lingual nail, described here for the first time, resemble those of the claw and rhamphotheca. Morphological, biochemical and functional differences between the lingual nail and the rest of the lingual epithelium were established.     

Trade and habitat change virtually eliminate the Grey Parrot Psittacus erithacus from Ghana

The heavily traded Grey Parrot Psittacus erithacus is believed to have undergone rapid population decline, yet there are almost no quantitative data on abundance changes over time from anywhere within its huge range. We reviewed the species’ historical abundance across Ghana, undertook targeted searches during 3‐ to 5‐day visits to 42 100‐km² cells across the country's forest zone, repeated counts at 22 parrot roosts first performed two decades ago and gauged around 900 people's perceptions of the decline and its causes. In over 150 days of fieldwork, just 32 groups (maximum group size = 12) were recorded in 10 cells. Encounter rates averaged 0.15 individuals per hour of targeted search, around 15 times lower than those recorded in the early 1990s. No active roosts were found, and only 18 individuals were recorded in three roost areas that each harboured 700–1200 birds two decades ago. Interviewees stressed the importance of very tall trees of commercially important species such as Terminalia superba and Ceiba pentandra for nesting and roosting, and believed that the felling of large trees on farmland (42% of responses) and trapping for trade (37%) were the two main causes of decline. Ghana has lost 90–99% of its Grey Parrots since 1992, a time when the population had presumably already been seriously reduced by two decades of extremely heavy trade. There is no evidence that, away from one or two localities, declines are less severe anywhere else within the West African range of P. erithacus, or across the entire range of the recently split Timneh Parrot Psittacus timneh.     

African grey parrots (Psittacus erithacus) use inference by exclusion to find hidden food

Exclusion allows the detection of hidden food when confronted with the choice between an empty and a potentially baited food location. However, exclusion may be based on avoidance of the empty location without drawing inferences about the presence of the food in the baited location. So far, such inferences have been demonstrated in the great apes only: after seeing an experimenter eating one of two food types, which both had been hidden previously in two boxes, the apes were able to choose the box that still contained the other food type. African grey parrots are capable of exclusion, and we here assessed if they are capable of inference by exclusion. In our task, two different but equally preferred food items were hidden in full view of the birds under two opaque cups. Then, an experimenter secretly removed one food type and showed it to the bird. Similarly to the apes, one out of seven parrots significantly preferred the baited cup; control conditions rule out that its choice was based on associative learning or the use of olfactory cues. Thus, we conclude that-like the apes-some grey parrots are able to infer the location of a hidden food reward.     

Characterization of 12 microsatellite primer pairs for the African grey parrot,Psittacus erithacus and their conservation across the Psittaciformes

This study describes 12 microsatellite loci identified in the African grey parrot Psittacus erithacus. Eleven were polymorphic, with observed heterozygosities 42–94% (average 68) and exclusion powers of P_E1 = 0.996 and P_E2 = 0.999. Microsatellites have previously been developed for a number of other parrots but showed limited cross‐species polymorphism. Here high levels of cross‐species amplification were observed: 71% of 32 Psittacines (22 genera). At least seven loci, 58%, were polymorphic in other African parrots as well as Neotropical and Australasian parrots, which diverged from the African parrots c30.6 and over 41.4 million years ago, respectively.     

Vocal Imitation in Parrots Allows Addressing of Specific Individuals in a Dynamic Communication Network

Parrots in captivity are known for their ability to vocally imitate humans and recently it has been shown that wild-living orange-fronted conures are able to immediately imitate other individuals’ contact calls. The function of this exceptional ability to imitate remains unclear. However, orange–fronted conures live in fission-fusion flocks where they encounter many different individuals every day, and it is possible that their vocal imitation ability is a flexible means to address a specific individual within a flock. We tested this via playback to short-term captive wild conures. Test birds were placed together in pairs in outdoor aviaries to form simple flocks. To simulate imitation of a specific individual these pairs received playback of contact calls that primarily imitate one of the two birds. Overall, individuals that received simulated vocal imitations of its calls responded more frequently and faster than the other individual. This suggests that orange-fronted conures can use imitations of contact calls to address specific individuals of a flock. In the discussion we argue that the fission-fusion flock dynamics of many parrot species has been an important factor in evolving conures’ and other parrots’ exceptional ability to imitate.     

Loss of the gene for the alpha subunit of ATP synthase (ATP5A1) from the W chromosome in the African grey parrot (Psittacus erithacus)

This study describes the results of an analysis using Southern blotting, the polymerase chain reaction, and sequencing which shows that the African grey parrot (Psittacus erithacus) lacks the W-chromosomal gene for the alpha subunit of mitochondrial ATP synthase (ATP5A1W). Additional evidence shows that in other psittacines a fragment of the ATP5A1W gene contains five times as many nonsynonymous nucleotide replacements as the homologous fragment of the Z gene. Therefore, whereas in these other psittacines the corresponding ATP5A1Z protein fragment is highly conserved and varies by only a few, moderately conservative amino acid substitutions, the homologous ATP5A1W fragments contain a considerable number of, sometimes highly nonconservative, amino acid replacements. In one of these species, the ringneck parakeet (Psittacula krameri), the ATP5A1W gene is present in an inactive form because of the presence of a nonsense codon. Other changes, possibly leading to an inactive ATP5A1W gene product, involve the substitution of arginine residues by cysteine in the ATP5A1W protein of the mitred conure (Aratinga mitrata) and the blue and gold macaw (Ara ararauna). The data suggest also that although the divergence of the psittacine ATP5A1W and ATP5A1Z genes preceeded the origin of the psittacidae, this divergence occurred independently of a similar process in the myna (Gracula religiosa), the outgroup used in this study. Received: 6 September 2000 / Accepted: 7 March 2001     

A simulation of evasive mimicry in the wild

The hypothesis of evasive mimicry proposes that: (a) the conspicuous coloration of some animals has evolved to warn predators that they are good at avoiding capture; and (b) this conspicuous coloration is mimicked by other, less evasive species which thus gain protection from predation. We have tested these ideas with wild birds as the predators and red and yellow pastry 'baits' as the prey. We used a specially constructed bird table to make one of the colours good at 'escaping': when a bird was about to eat a bait the observer pulled a cord which activated a mechanism that made the baits of one colour (but not the other) drop out of the bird's reach. We first measured the overall selection by the naive birds by presenting, for one day, a 'control' of equal numbers of non-evasive red and non-evasive yellow baits. The birds were then trained for 20 days on equal numbers of evasive yellow and non-evasive red baits, and were then again given a second control (in which the yellows were now non-evasive 'mimics'). The training was repeated for 18 days but with red as the evasive colour, and a third control was then presented (with reds now as the mimics). The proportions attacked daily in the two training sessions suggested that the birds were learning to ignore yellows in the first and reds in the second. In comparison with the first control, fewer yellows were eaten after they had been trained to ignore escaping yellows, and more were eaten after they had been trained on escaping reds. We conclude that the results are further evidence for the hypothesis of evasive mimicry.     

Vocal mimicry in spotted bowerbirds is associated with an alarming context

Although the presence of vocal mimicry in songbirds is well documented, the function of such impressive copying is poorly understood. One explanation for mimicry in species that predominantly mimic alarm calls and predator vocal isations is that these birds use mimicry to confuse or deter potential threats or intruders, so these vocalisations should therefore be produced when the mimic is alarmed and be uncommon in other contexts. Male bowerbirds construct bowers to display to females and anecdotal reports from the Ptilonorhynchus genus suggest that males mimic alarm sounds when disturbed at their bowers. We quantified and compared the rate of mimicry during disturbance to the bower by a human and in naturally occurring social contexts in a population of spotted bowerbirds Ptilonorhynchus maculatus. Male bowerbirds produced mimicry more than thirty times more frequently in response to bower disturbance than they did in any other context. Neither conspecifics nor heterospecifics were attracted to the bower area by mimicry. These data are consistent with the hypothesis that the production of mimicry is associated with a response to an alarming situation. Additionally, the predominance of alarm mimicry by spotted bowerbirds raises the possibility that the birds learn these sounds when they experience alarming situations and they reproduce them in subsequent alarming situations.     

Measurement of grey parrot (Psittacus erithacus) trachea via magnetic resonance imaging,dissection, and electron beam computed tomography

To produce a model to explain the acoustic properties of human speech sounds produced by Grey parrots (Psittacus erithacus) and to compare these properties across species (e.g., with humans, other psittacine and nonpsittacine mimics), researchers need adequate measurements of the chambers that constitute the parrot vocal tract. Various methods can provide such data. Here we compare results for tracheal measurements provided by a) magnetic resonance imaging (MRI) of a live bird, b) caliper measurements of four preserved specimens, and c) electron beam computed tomography (EBCT) of three of these preserved specimens. We find that EBCT scans provide data that correspond to the inner area of the dissected trachea, whereas MRI results correspond to area measurements that include tracheal ring thickness. We briefly discuss how these data may predict formant values for Grey parrot reproduction of human vowels. Our results suggest how noninvasive techniques can be used for cross-species comparisons, including the coevolution of structure and function in avian mimicry. J. Morphol. 238:81–91, 1998. © 1998 Wiley-Liss, Inc.     

环境丰容对圈养灰鹦鹉日常行为的影响

于2008年1、2、6、7月通过改变食物投喂方式、给予玩具、在环境中增加带皮的树干等方式,对两只饲养于成都动物园的灰鹦鹉实施了丰容试验,观察了丰容前、后及丰容期间的行为.结果表明,灰鹦鹉的日常行为有10多种,其中发生最多的行为是休息行为,其次为观望行为以及梳理行为.统计分析表明,灰鹦鹉丰容试验中鸣叫、啃树皮的行为显著高于丰容前、后(P<0.05);丰容期间休息行为显著低于丰容前、后阶段(P<0.01).环境丰容增加了灰鹦鹉行为活动,同时还减少了咬毛、咬脚趾等不良刻板行为的发生,提高了展出效果.     

Lack of canonical E6 and E7 open reading frames in bird papillomaviruses: Fringilla coelebs papillomavirus and Psittacus erithacus timneh papillomavirus

Determination and analyses of the complete sequence of Fringilla coelebs papillomavirus and Psittacus erithacus timneh papillomavirus indicate that they represent a distinct and distant lineage of papillomaviruses. The lack of canonical E6-E7 open reading frames suggests that they serve adaptive functions during papillomavirus evolution.