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.     

Grey parrots use inferential reasoning based on acoustic cues alone

Our ability to make logical inferences is considered as one of the cornerstones of human intelligence, fuelling investigations of reasoning abilities in non-human animals. Yet, the evidence to date is equivocal, with apes as the prime candidates to possess these skills. For instance, in a two-choice task, apes can identify the location of hidden food if it is indicated by a rattling noise caused by the shaking of a baited container. More importantly, they also use the absence of noise during the shaking of the empty container to infer that this container is not baited. However, since the inaugural report of apes solving this task, to the best of our knowledge, no comparable evidence could be found in any other tested species such as monkeys and dogs. Here, we report the first successful and instantaneous solution of the shaking task through logical inference by a non-ape species, the African grey parrot. Surprisingly, the performance of the birds was sensitive to the shaking movement: they were successful with containers shaken horizontally, but not with vertical shaking resembling parrot head-bobbing. Thus, grey parrots seem to possess ape-like cross-modal reasoning skills, but their reliance on these abilities is influenced by low-level interferences.     

Spontaneous categorization of vocal imitations in African grey parrots (Psittacus erithacus)

The ability to categorize elements of the environment is a fundamental aspect of information processing. Many experiments demonstrate the ability of birds and non-human primates to classify items according to their perceptual similarities. Few data are available regarding spontaneous classification of items according to a non-perceptual account in non-human animals. Here, we report unexpected results obtained with African grey parrots learning the referential use of French labels. Parrots did not learn the correct labels but they spontaneously produced more labels corresponding to food when a food item was presented to them and more labels corresponding to an object when shown an object item, although they were never rewarded for doing so. These results demonstrate a form of spontaneous categorization by using vocal imitation of the human language.     

Conspecific discrimination in an object-choice task in African grey parrots (Psittacus erithacus)

Living in social groups presents the opportunity to use information provided by other individuals. Several animal species emit specific vocalizations when they find food. Here, we investigate whether African grey parrots (Psittacus erithacus) use vocal and non-vocal information provided by a conspecific in order to find a hidden food source. One subject was attracted by the presence or the vocalizations of a subordinate conspecific, but not of a dominant, which brings us to hypothesize that parrots could be capable of individual vocal discrimination.     

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.     

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.     

Referential learning of French and Czech labels in African grey parrots (Psittacus erithacus): Different methods yield contrasting results

Some African grey parrots (Psittacus erithacus), the most famous being Pepperberg's parrot Alex, are able to imitate human speech and produce labels referentially. In this study, the aim was to teach ten African grey parrots from two laboratories to label items. Training three parrots from the first laboratory for several months with the Model/Rival method, developed by Pepperberg, in which two humans interact in front of the subject to demonstrate the use of a label, led to disappointing results. Similarly, seven parrots from the second laboratory, having been trained with several variants of Model/Rival attained little success. After the informal observation of the efficiency of other methods (i.e. learning to imitate labels either spontaneously or with specific learning methods and use of these labels referentially), four different teaching methods were tested with two birds: the Model/Rival; Repetition/Association which consisted of repeating a label and presenting the item only when the parrot produced the label; Intuitive in which the experimenter handled an item and repeated its name in front of the subject; Diffusion in which labels with either variable or flat intonation were played back daily to parrots. One bird learned three labels, one of which was used referentially, with the Repetition/Association method. He learned one label non-referentially with the Model/Rival but no labels were acquired using the other methods. The second bird did not learn any labels. This study demonstrates that different methods can be efficient to teach labels referentially and it suggests that rearing conditions and interindividual variability are important features when assessing learning ability of African grey parrots.     

Comparative DNA sequence analysis of genetic variation in the African grey parrot, Psittacus erythacus

Comparative genome analysis promises to provide an insight into avian species that have been very little studied. To test the feasibility of this approach, we investigated the use of heterologous primers to generate single nucleotide polymorphisms (SNP) in the African grey parrot, Psittacus erythacus, using primers specific for chicken and turkey DNA fragments. Three of the primers were specific for three expressed sequence tagged sites in the turkey and the fourth for a chicken proteoglycan core protein-like DNA sequence. A total of about 2200 bp of the parrot genome was evaluated for DNA sequence variation. Seven SNPs were identified and confirmed by Mendelian segregation. The frequency distribution of the most common nucleotide at each SNP locus in an unrelated group of parrots ranged from 0.84 to 0.97. The percent similarity of each parrot sequence to the reference sequence was inconsistent and ranged from zero to 100%. The primers as well as the nucleotide variants described represent valuable resources for genetic analysis in the parrot. This revised version was published online in July 2006 with corrections to the Cover Date.     

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     

Great apes use weight as a cue to find hidden food

Bonobos (Pan paniscus; n = 5), orangutans (Pongo pygmaeus abelii; n = 6), and a gorilla (Gorilla gorilla gorilla; n = 1) were presented with two opaque cups, one empty and one baited (containing two bananas). Subjects had to independently gain weight information about the contents of the cups to find the hidden food. Six apes attained above chance level within a total of 16 trials. Successful subjects spontaneously adopted the method of successively lifting the cups and thus comparing their weight before making a choice. Prior to testing, these apes had participated in a weight discrimination task. To rule out that a subject's good performance was influenced by previous experience in weight experiments, we ran a second test in which the same task was presented to a group of chimpanzees (Pan troglodytes; n = 9) who were naïve to weight experiments. These subjects also participated in an additional test condition in which the same problem was presented based on learning to associate arbitrary visual stimuli. The results show that experience did not affect performance because the nine naïve subjects were equally able to find the food when the task stimuli held a causal relation (i.e. weight indicates the hidden food). Interestingly, only one of the naïve subjects solved the task when the task elements held an arbitrary relation (i.e. certain visual pattern indicates food). Our results confirm previous findings that apes perform better in problems grounded on causal compared to arbitrary relations. Am. J. Primatol. 73:323–334, 2011. © 2010 Wiley‐Liss, Inc.     

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.     

Assessment of microsatellite and SNP markers for parentage assignment in ex situ African Penguin (Spheniscus demersus) populations

Captive management of ex situ populations of endangered species is traditionally based on pedigree information derived from studbook data. However, molecular methods could provide a powerful set of complementary tools to verify studbook records and also contribute to improving the understanding of the genetic status of captive populations. Here, we compare the utility of single nucleotide polymorphisms (SNPs) and microsatellites (MS) and two analytical methods for assigning parentage in ten families of captive African penguins held in South African facilities. We found that SNPs performed better than microsatellites under both analytical frameworks, but a combination of all markers was most informative. A subset of combined SNP (n = 14) and MS loci (n = 10) provided robust assessments of parentage. Captive or supportive breeding programs will play an important role in future African penguin conservation efforts as a source of individuals for reintroduction. Cooperation among these captive facilities is essential to facilitate this process and improve management. This study provided us with a useful set of SNP and MS markers for parentage and relatedness testing among these captive populations. Further assessment of the utility of these markers over multiple (>3) generations and the incorporation of a larger variety of relationships among individuals (e.g., half‐siblings or cousins) is strongly suggested.     

Geographic variation of the major histocompatibility complex in Eastern Atlantic grey seals (Halichoerus grypus)

Pathogen-driven balancing selection maintains high genetic diversity in many vertebrates, particularly in the major histocompatibility complex (MHC) immune system gene family, which is often associated with disease susceptibility. In large natural populations where subpopulations face different pathogen pressures, the MHC should show greater genetic differentiation within a species than neutral markers. We examined genetic diversity at the MHC-DQB locus and nine putatively neutral microsatellite markers in grey seals (Halichoerus grypus) from eight United Kingdom (UK) colonies, the Faeroe Islands and Sable Island, Canada. Five DQB alleles were identified in grey seals, which varied in prevalence across the grey seal range. Among the seal colonies, significant differences in DQB allele and haplotype frequencies and in average DQB heterozygosity were observed. Additionally, the DQB gene exhibited greater differentiation among colonies compared with neutral markers, yet a weaker pattern of isolation by distance (IBD). After correcting for the underlying IBD pattern, subpopulations breeding in similar habitats were more similar to one another in DQB allele frequencies than populations breeding in different habitats, but the same did not hold true for microsatellites, suggesting that habitat-specific pathogen pressure influences MHC evolution. Overall, the data are consistent with selection at MHC-DQB loci in grey seals with both varying selective pressures and geographic population structure appearing to influence the DQB genetic composition of breeding colonies.     

Characterization of high-yield pulp (HYP) by the solute exclusion technique

By following the solute exclusion technique, we determined the pore characteristics of 3 hardwood high-yield pulps (aspen, birch, maple). The fiber saturation point (FSP) was 1.40, 1.36 and 1.19 g water/g pulp, for aspen, birch, maple, respectively, which is lower than that of chemical pulps. Different fractions obtained from the Bauer–McNett classifier showed that the HYP fines have much more pore volume than their long fiber counterparts. The effects of beating, drying and re-wetting on the pore characteristics of HYP were also studied. Beating led to increased total pore volumes. Upon drying and re-wetting, much of the small pores from the HYP underwent permanent closure while the big pores were only slightly affected. Finally, the relationship between the water retention value (WRV) and FSP for HYP was examined.     

Microsatellite analysis of genetic diversity in African buffalo (Syncerus caffer) populations throughout Africa

Genetic diversity in nine African buffalo (Syncerus caffer) populations throughout Africa was analysed with 14 microsatellites to study the effects of rinderpest epidemics and habitat fragmentation during the 20th century. A gradient of declining expected heterozygosity was observed among populations in Save Valley Conservancy (Zimbabwe), and northern and southern Kruger National Park (South Africa). This was explained by a high mortality in northern Kruger National Park during the rinderpest pandemic at the end of the 19th century followed by recolonization from neighbouring populations, resulting in intermediate heterozygosity levels in northern Kruger National Park. In other populations expected heterozygosity was very high, indicating that rinderpest and recent habitat fragmentation had a limited effect on genetic diversity. From expected heterozygosity, estimates of long-term effective population size were derived. Migration rates among populations in eastern and southern Africa were very high, as shown by a weak isolation by distance and significant correlation in allele frequencies between populations. However, there were indications that dry habitats could limit migration. Genetic distances within buffalo in central Africa were relatively large, supporting their status as distinct subspecies. Finally, it was observed that the higher polymorphic microsatellites were less sensitive at detecting isolation by distance and differences in Ne, which may be a result of the high mutation pressure at these loci.     

The use of low-frequency vocalizations in African elephant(Loxodonta africana) reproductive strategies

Fertility-advertisement calls in females are predicted to occur in nonmonogamous species where males and females are widely separated in space. In African elephants, low-frequency vocalizations have thus been suggested as a reproductive strategy used by fertile females to attract mates. This study examined the use of low-frequency vocalizations with respect to different phases of the estrous cycle in African elephants by simultaneously monitoring vocalizations, behavior, and hormonal profiles. Subjects were one male and six female African elephants housed at Disney's Animal Kingdom. No acoustically distinct vocalizations were restricted to the ovulatory follicular phase. However, overall rate of low-frequency vocalization as well as the rate of one acoustically distinct vocalization changed over the estrous cycle, with highest rates of calling related to the first period of follicular growth, or anovulatory follicular phase. Elevated rates of vocalization thus were not restricted to behavioral estrus and occurred much earlier in the estrous cycle than in most species that produce fertility-advertisement calls. Both herd composition and elephant identity also affected rates of vocalization. Vocalizations therefore may not be reliable signals of actual fertility. However, the increase in vocalizations in advance of estrus may attract males to the herd prior to ovulation, facilitating both male-male competition and female choice. Once present in the herd, males may then switch strategies to use more reliable chemical and visual cues to detect ovulating females.     

The biology and use of the African brush-tailed porcupine (Atherurus africanus, Gray, 1842)as a food animal. A review

The brush-tailed porcupine (Atherurus africanus) is a hystricomorph rodent, which frequents the forests of West and Central Africa. With an average weight of 3 kg, it is a favourite source of meat for urban and rural populations of Gabon, Nigeria, Cameroon or Congo. Hunted in large quantities, its price is often higher than that of other game or domestic animals. Although its current productivity in captivity is limited to a single young per birth and two to three births per year per female, this species could be a good candidate for minilivestock programmes in African forest areas if its current reproductive potential in captivity could be improved. Further research should be encouraged on its biology and reproduction since the current level of hunting for this species is probably not sustainable. Captive breeding programmes could play a role in assessing a better knowledge of the species' biology, and in reducing the effects of intensive hunting in areas where this activi ty is no longer sustainable.     

Captive cotton‐top tamarins' (Saguinus oedipus oedipus) use of landmarks to localize hidden food items

Seventeen captive cotton‐top tamarins (Saguinus oedipus oedipus) were individually tested on their use of spatial relationships between landmarks to locate multiple hidden food items. In two experiments, the tamarins were presented with a spatial‐foraging task in which positions of hidden food rewards were fixed in relation to an array of visual cues. In Experiment 1, the cues+hidden food configuration was rotated 90° and the tamarins were successful in locating the food items significantly above chance levels (P<0.01). In Experiment 2 the cues+hidden food configuration was translated (up, down or sideways) from the previously learned configuration, and the monkeys successfully localized the hidden food items (P<0.001). Results indicate that the tamarins relied on the spatial relationship between the multiple landmarks to locate hidden food items rather than on an associative or beacon strategy. The results of these experiments support the contention that when contextually appropriate these captive New World monkeys have the capacity to rely on the spatial relationship or positions of several cues as an array to localize points in their environment. Am. J. Primatol. 71:316–323, 2009. © 2009 Wiley‐Liss, Inc.     

Regulation of antiviral immune response by African swine fever virus (ASFV)

African swine fever (ASF) is a highly contagious and acute hemorrhagic viral disease with a high mortality approaching 100% in domestic pigs. ASF is an endemic in countries in sub-Saharan Africa. Now, it has been spreading to many countries, especially in Asia and Europe. Due to the fact that there is no commercial vaccine available for ASF to provide sustainable prevention, the disease has spread rapidly worldwide and caused great economic losses in swine industry. The knowledge gap of ASF virus (ASFV) pathogenesis and immune evasion is the main factor to limit the development of safe and effective ASF vaccines. Here, we will summarize the molecular mechanisms of how ASFV interferes with the host innate and adaptive immune responses. An in-depth understanding of ASFV immune evasion strategies will provide us with rational design of ASF vaccines.