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PubMed1986

A polyoma-like virus associated with an acute disease of fledgling budgerigars (Melopsittacus undulatus).

A virus previously isolated from fledgling budgerigars (Melopsittacus undulatus) suffering from an acute disease, has been purified and the structural characteristics have been determined. The virions with a buoyant density of 1.34 g/ml are non-enveloped icosahedral particles with a diameter of about 46-48 nm. Their DNA genome has a molecular weight of about 3.3 X 10(6) d, and exists as supericoiled circular, relaxed circular, and linear molecules. There are eight structural proteins, the most abundant of which has a molecular weight of about 42,000 d. Empty capsid shells with buoyant densities of 1.31 g/ml are similar in size and shape, but lack DNA and histone-like polypeptides. Virus replication in chicken embryo cells results in cytopathic changes characterized by rounding and enlargement of the nucleus, and formation of intranuclear inclusion bodies. All these properties justify classification of the virus as polyoma-like.

Animals↗
PubMed2003

The roles of receptor noise and cone oil droplets in the photopic spectral sensitivity of the budgerigar, Melopsittacus undulatus.

Individual budgerigars (Melopsittacus undulatus) were taught to detect narrow bands of wavelengths under ambient illumination of known spectral composition. Because the cone pigments of this species of bird have been identified and data on carotenoid absorbance present in the cone oil droplets are available, predictions of the Vorobyev-Osorio equations can be calculated with reasonable confidence. Based on more than 27,600 individual choices made by several birds at 10 wavelengths, the photopic sensitivity (i.e., color thresholds) of these birds is found to be consistent with the hypothesis that threshold discrimination of colored targets is limited by receptor noise and that high sensitivity to near-ultraviolet wavelengths is in harmony with the relatively small number of ultraviolet cones present in the retina. The pronounced fine structure of the sensitivity spectrum is caused by the absorption of cone oil droplets. Under natural sunlight, containing more energy in the near-ultraviolet than is present in artificial indoor lighting, the birds' peak of sensitivity in the ultraviolet should be much less prominent than it is in laboratory experiments.

Animals↗
PubMed1997

The NADPH-diaphorase-containing system in the brain of the budgerigar (Melopsittacus undulatus).

In the present investigation we studied the presence and distribution of histochemically detected neuronal NADPH-diaphorase (ND) in the brain of the budgerigar, Melopsittacus undulatus. Positive neurons are widely distributed throughout the central nervous system. ND-containing neurons are present in the telencephalon and the paleostriatal-parolfactory lobe complex. Positive cells were observed also in the neostriatum, including the main auditory area (field L), in several nuclei of the archistriatum and in the hyperstriatum (accessory, dorsal, and ventral). In the diencephalon, positive neurons were present both in the lateral hypothalamic and periventricular areas, and in a segregate area at the confluence of the anterior commissure and the lateral prosencephalic bundle. A group of positive perikarya was located lateral to the dorsal part of the IIIrd ventricle, and continued laterally into the thalamus. Weakly stained neurons were observed in the thalamic dorsomedial posterior nucleus. In the mesencephalon, ND-containing neurons were scattered in the reticular formation (pars lateralis and pars medialis) and in the optic tecta. A large population of positive neurons was observed in the substantia nigra, the ventral area of Tsai and the nucleus interpeduncularis. Positive neurons extended through the tegmental nuclei to the locus coeruleus. In the cerebellum, the granular neurons were weakly stained and the internal cerebellar nuclei were surrounded by a wide network of positive fibers. In the medulla the number of positive cells was highly reduced, but stained neurons were observed in the cochlear as well in the vestibular nuclei. The data here presented suggest that the distribution of ND-containing neurons in the brain of the budgerigar is different from those of the chicken and quail. The locations of positive neurons suggest also a possible involvement in sound perception and production pathways, and visual perception.

Animals↗
PubMed1989

Sleep patterns in the parakeet Melopsittacus undulatus.

Electrophysiological and behavioral studies of vigilance states were performed on adult specimens of the parakeet Melopsittacus undulatus. Four states of vigilance were identified: Wakefulness, drownsiness, slow wave sleep and paradoxical sleep. During wakefulness, a low voltage fast EEG pattern was observed. This pattern was progressively increasing in amplitude and decreasing in frequency when passing from drowsiness to slow wave sleep. Sleep spindles were not present. Slow wave sleep was frequently interrupted by paradoxical sleep episodes of short duration (6.4 +/- 3.2 sec), characterized by an EEG pattern similar to that of waking state. During wakefulness there were body and eye movements. This motor activity decreased when animals went into drowsiness and slow wave sleep. Paradoxical sleep was characterized by slight motor automatisms, including sometimes ocular movements.

Animals↗
PubMed1986

Memory formation in birds: 1. Avoidance conditioning of the budgerigar (Melopsittacus undulatus) to sound stimuli.

A system is described for avoidance conditioning of the budgerigar (Melopsittacus undulatus), for sound patterns consisting of one or two sequential subunits and to discriminate between two closely resembling sounds. Electric shock was used as the unconditioned stimulus. Simple conditioning was accomplished in about 300-400 trials. After a given sound pattern was firmly fixed by conditioning, discrimination between this and a new sound pattern was established relatively rapidly by using several consecutive sessions in which the two patterns were mixed. Discrimination was reinforced by associating the two signals by opposing electric shocks. An overnight rest period after the first few sessions improved the rate of conditioning during the following experimental period. A temporary, partial or complete extinction of conditioning was produced by longer rest intervals, but the original conditioning was reestablished by subjecting the animal to a few trials of reconditioning. Short intercalations of a new conditioned stimulus had no effect on the retention of the original conditioning whereas a random mixing of the first conditioned stimulus with a second produced a temporary decay in the original conditioning. The experimental system described here is useful for studying physiological and biochemical changes accompanying a memory process based on a linear sequence of sound patterns.

Animals↗
PubMed2003

Experimental infection of budgerigars (Melopsittacus undulatus) with a low virulent K21 strain of Toxoplasma gondii.

In total 53 budgerigars (Melopsittacus undulatus) were divided into six groups and orally infected with a suspension of oocysts of low virulent Toxoplasma gondii K21 strain in the doses of 10(2), 10(3), 10(4), 10(5) and 10(6), respectively. Blood was collected from the birds prior to the inoculation and then on days 10, 20 and 30 post infection. Latex-agglutination test (LAT) was used for the detection of antibodies in the inoculated birds. The infected birds showed no apparent signs of disease. The antibodies were found in all but two birds inoculated a dose of 10(2) oocysts. Haematological values remained unchanged after infection. T. gondii was isolated by bioassay in mice from all 37 birds fed 10(3) or more oocysts and 6 of 9 fed 10(2) oocysts. The results demonstrate that budgerigars are resistant to T. gondii infection.

Animals↗
PubMed1997

The rod and green cone opsins of two avian species, the budgerigar, Melopsittacus undulatus, and the mallard duck, Anas platyrhynchus.

The genes for the rod and rod-like green cone opsins in two avian species, the budgerigar, Melopsittacus undulatus, and the mallard duck, Anas platyrhynchus, are identified on the basis of amino acid identity with the equivalent chicken sequences and their placement into a single phylogenetic clade with the rod and rod-like green cone opsin genes from other vertebrate species. Since the two bird species studied are taxonomically quite distinct, this would indicate that this rod-like green cone opsin gene, although absent in mammals, is common in the Aves. The two avian pigments differ consistently at site 122, consistent with the reported role of this site in determining the rate of metarhodopsin II formation and decay in rod and cone pigments. Candidate sites are identified to compensate for the known spectral effects of substitution at this site.

Amino Acid Sequence↗
PubMed1991

Perception of distance calls by budgerigars (Melopsittacus undulatus) and zebra finches (Poephila guttata): assessing species-specific advantages.

Budgerigars (Melopsittacus undulatus) and zebra finches (Poephila guttata) share a common functional class of vocalizations called distance calls. The perception of species-specific distance calls by both species was measured with a habituation-dishabituation operant paradigm. Changes in discrimination performance were noted as listening conditions were modified or stimulus properties were altered. Both species showed better performance for calls of their own species. For zebra finches this tendency increased slightly when a background noise was added to the testing environment. Shifting the frequency region of the calls affected the discrimination performance of male budgerigars but not females or zebra finches. Reversing the temporal order of the calls affected the perceptual advantage for conspecific vocalizations in zebra finches but not in budgerigars. These results highlight species differences in perceiving acoustic communication signals.

Animals↗
PubMed1992

Perception of conspecific faces by budgerigars (Melopsittacus undulatus): I. Natural faces.

Perception of faces by 4 budgerigars (Melopsittacus undulatus), a species of small parrot, was studied with a same-different discrimination task. Reaction times were taken as a measure of the similarity between pairs of faces and analyzed with multidimensional scaling to reveal patterns of similarity among the faces. The perception of natural faces was tested to determine which characteristics were perceptually salient. Color, patterns of markings, darkness of the iris, and size of the pupil corresponded to the observed patterns of similarity among the faces. Differences among budgerigar faces were more salient than differences among zebra finch faces, and budgerigar faces were perceptually distinct from the faces of other avian species. The results from these experiments provide a basis for understanding the ways in which these signals function in the coordination of social behaviors.

Animals↗
PubMed1993

Perception of conspecific faces by budgerigars (Melopsittacus undulatus): II. Synthetic models.

Perception of faces by budgerigars (Melopsittacus undulatus) was studied with computerized images modeled after natural faces. Individual facial characteristics were varied with all others held constant; then relative importance among several features was determined by varying each within a single experiment. Characteristics with the potential to signal important biological information (e.g., age or sex) were perceptually salient, whereas characteristics that vary among faces but have limited potential to signal important information were not. Model faces were also presented in a normal or an altered configuration. Birds discriminated among faces in a normal configuration more easily than among models with an altered configuration even when the facial features on which the discrimination was based differed in the same way; this suggests that configurational cues play an important role in face perception by budgerigars.

Animals↗
PubMed1994

Vocal plasticity in budgerigars (Melopsittacus undulatus): evidence for social factors in the learning of contact calls.

Distance or contact calls of 6 unrelated adult male budgerigars (Melopsittacus undulatus) were recorded before and during 8 weeks of social contact. The 6 birds were housed in 2 separate groups of 3 each in adjoining cages. Birds in each cage could hear but not see the birds in the neighboring cage. At the beginning of the study, none of the birds shared any contact call types. The first appearance of 1 bird's imitation of a cagemate's contact call type occurred after 1 week. Call type repertoires continued to change; some call types dropped out of the repertoires, and others were modified over time. Birds in the same cage shared the same dominant call type 8 weeks later, and the dominant call types differed between the 2 cages. Thus, budgerigars can learn calls as adults, and call type convergence is achieved through mutual vocal imitation of social companions. In the absence of social but not aural contact, vocal imitation was greatly reduced.

Animal Communication↗
PubMed1998

Hearing and vocalizations of wild-caught Australian budgerigars (Melopsittacus undulatus).

This study examined the hearing and contact calls of wild-caught Australian budgerigars (Melopsittacus undulatus) and compared these data to hearing and vocalizations in the much more extensively studied domesticated budgerigar. The spectral energy in the contact calls of both wild-caught and domesticated budgerigars falls almost exclusively in the frequency of 2-4 kHz. Absolute and masked thresholds were similar in both groups of birds. Similar to the results found in domesticated birds, critical ratio functions for the wild-caught budgerigars decreased at frequencies of 1.0 kHz-2.86 kHz and then increased again dramatically at frequencies above 2.86 kHz.

Animals↗
PubMed1999

Effects of deafening on the development of nestling and juvenile vocalizations in budgerigars (Melopsittacus undulatus).

The effects of complete and partial cochlear extirpation at ages 9-11 days posthatch were assessed in 5 nestling budgerigars (Melopsittacus undulatus) to determine if auditory feedback is necessary for the production of nestling vocalizations. Although early deafening had no effect on the production of food-begging calls produced during the first 2 weeks posthatch, deafening did disrupt the expected transition from these early calls to the longer and more complex frequency-modulated, patterned food-begging calls normally appearing 3-4 weeks posthatch. All birds sustaining either complete or partial cochlear extirpation failed to develop stereotyped contact calls around the time of fledging at 5 weeks. These results are consistent with previous research showing that deafened nestlings do not develop normal contact calls (R. J. Dooling, B. F. Gephart, P. H. Price, C. McHale, & S. E. Brauth, 1987) and also indicate that a form of sensorimotor learning is involved in the production of mature, patterned food-begging calls in budgerigars.

Animals↗
PubMed2003

Budgerigars (Melopsittacus undulatus) copy virtual demonstrators in a two-action test.

Juvenile budgerigars (Melopsittacus undulatus) observed thin film transistor video playback of a virtual conspecific demonstrator using its beak to remove a stopper from a food box, either by pulling the object upward or by pushing it downward. Simultaneously (Experiment 1) or subsequently (Experiment 2), the observers were offered a similar stopper box and rewarded with access to food for each removal response, regardless of its direction. Observers of upward movement made a greater proportion of up responses in total and showed a stronger tendency to increase the proportion of up responses over test trials than observers of downward movement. These findings provide the first demonstration of which the authors are aware that birds are able not only to detect and respond to a moving video image but also to copy its movements.

Animals↗
PubMed1998

The molecular basis for UV vision in birds: spectral characteristics, cDNA sequence and retinal localization of the UV-sensitive visual pigment of the budgerigar (Melopsittacus undulatus).

Microspectrophotometric (msp) studies have shown that the colour-vision system of many bird species is based on four pigments with absorption peaks in the red, green, blue and UV regions of the spectrum. The existence of a fourth pigment (UV) is the major difference between the trichromacy of humans and the tetrachromacy of such birds, and recent studies have shown that it may play a determining role in such diverse aspects of behaviour as mate selection and detection of food. Avian visual pigments are composed of an opsin protein covalently bound via a Schiff-base linkage to the chromophore 11-cis-retinal. Here we report the cDNA sequence of a UV opsin isolated from an avian species, Melopsittacus undulatus (budgerigar or small parakeet). This sequence has been expressed using the recombinant baculovirus system; the pigment generated from the expressed protein on addition of 11-cis-retinal yielded an absorption spectrum typical of a UV photopigment, with lambdamax 365+/-3 nm. This is the first UV opsin from an avian species to be sequenced and expressed in a heterologous system. In situ hybridization of this sequence to budgerigar retinas selectively labelled a sub-set of UV cones, representing approx. 9% of the total cone population, that are distributed in a semi-regular pattern across the entire retina.

Amino Acid Sequence↗
PubMed2002

Morphometry of the heart of budgerigars (Melopsittacus undulatus), Alisterus parrots (Alisterus s scapularis) and common buzzards (Buteo buteo).

In order to establish data and reference values for the thickness of the myocardium and the length of the left and the right ventricle of the avian heart, the hearts of 14 budgerigars (Melopsittacus undulatus), five Alisterus parrots (Alisterus s scapularis) (also known as Australian king parrot) and 10 common buzzards (Buteo buteo) of both sexes were examined according to a standard protocol. In order to compare the results of birds of different sizes all data were related to the size of the bird's body (length of the sternum) and the results of the measurements of the myocardial thickness in relation to the length of the heart. Results of different zones were compared by means of statistical methods within one species. Besides that a comparison between the different species was performed. Only minor significant differences were noted.

Animals↗
PubMed1991

The nutrition of the budgerigar (Melopsittacus undulatus).

Growing interest in the nutrition of the budgerigar (Melopsittacus undulatus) has highlighted the paucity of knowledge in this area. The aims of this study were to review the available literature on their individual nutrient requirements and relate this to the nutrient content of their predominantly seed-based diet and to investigate the effect of the bird's daily energy requirement on the fluctuations in body weight. Studies were conducted at the Waltham Centre to measure the relationship between daily metabolizable energy intake (kJ/kg BW) and body weight change (g/d) for groups of adult budgerigars. The birds were found to require daily 48-128 kJ/bird depending on their body mass (birds in our colony typically weigh 30-80 g). During a series of breeding trials the daily energy intake for a breeding pair plus their three chicks, at peak energy intake, was found to be 483-505 kJ (at pairing, the mean daily energy intake of the breeding pairs was 231 kJ). Apparent metabolizability of the major nutrients from a seed diet were generally found to be greater than 80%, which allows these birds to assimilate the high levels of energy needed for their basal metabolism. In summary, the nutrient requirements of the budgerigar (where known) were found to be similar to those of other avian species, however, further work is needed, especially in the area of availability of key nutrients. Further developments in the dietary management of these birds will only be possible if researchers can overcome the birds' poor acceptance of novel foods and satisfy their high basal energy requirements before establishing their requirements for individual nutrients.

Animal Nutritional Physiological Phenomena↗
PubMed2001

Ultraviolet vision, fluorescence and mate choice in a parrot, the budgerigar Melopsittacus undulatus.

As in many parrots, the plumage of the budgerigar Melopsittacus undulatus reflects near-ultraviolet (UVA) wavelengths (300-400 nm) and exhibits UVA-induced fluorescence. However, there have, to our knowledge, been no tests of whether the yellow fluorescence observed under intense UVA illumination has any role in signalling. Four experiments were carried out on wild-type budgerigars, where the presence and absence of UV reflectance and fluorescence were manipulated using filters. Few studies have attempted to separate the contribution of UV reflectance to plumage hue as opposed to brightness or distinguish between a role in sexual as opposed to social preferences. However, our first experiments show that not only do females consistently prefer UV-reflecting males, but also that the observed preferences are due to removal of UV affecting the perceived hue rather than brightness. Furthermore, we found no effect of the light environment on male response to females, suggesting that the female preferences relate to plumage colour per se. Whilst UV reflectance appears important in heterosexual choice by females, it has no detectable influence on same-sex association preferences. The results from the second series of experiments suggest that enhancement of the budgerigar's yellow coloration through fluorescence has no effect on male attractiveness. However, the fluorescent plumage may play a role in signalling by virtue of the fact that it absorbs UVA and so increases contrast with nearby UV-reflecting plumage. Our study provides convincing evidence that UV reflectances can play a role in mate choice in non-passerines, but no evidence that the yellow fluorescence observed under UVA illumination is itself important as a signal.

Animals↗