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PubMed2005

Circadian and seasonal variability and influence of sex and race on eight clinical chemistry parameters in budgerigars (Melopsittacus undulatus, Shaw 1805).

The aim of the study was to investigate if there is a clinically relevant influence of daytime or season and if there are sex-dependant differences in some frequently determined clinical chemistry parameters. The study was performed with 99 1.5- to 2-year old healthy budgerigars of three races. A harmonic regression analysis was performed taking into account linear and cyclic trends over the year. Correlations were investigated by the calculation of Spearman correlation coefficients. Summarizing, it can be said that some circadian, seasonal, as well as sex- and race-dependant influences have been shown. However, although the differences are statistically significant, they were too small to have an impact on clinical decision making. As clinical chemistry results are in practice independent from the influence factors investigated, their meaning and use as a diagnostic tool is further substantiated.

Animals↗
PubMed2006

Differences in bone mineral content and density between male and female budgerigars (Melopsittacus undulatus) during the non-reproductive season.

It is known that female birds increase medullary mineral stores in long bones shortly before egg laying. Here, we present results from two groups of budgerigars, in both of which females had significantly higher bone mineral contents and densities, as measured by peripheral quantitative computed tomography of the tibiotarsus, during a reproductively dormant period. The results could indicate that female birds can accumulate mineral stores outside of the breeding season.

Animals↗
PubMed2004

Development of auditory sensitivity in budgerigars (Melopsittacus undulatus).

Auditory feedback influences the development of vocalizations in songbirds and parrots; however, little is known about the development of hearing in these birds. The auditory brainstem response was used to track the development of auditory sensitivity in budgerigars from hatch to 6 weeks of age. Responses were first obtained from 1-week-old at high stimulation levels at frequencies at or below 2 kHz, showing that budgerigars do not hear well at hatch. Over the next week, thresholds improved markedly, and responses were obtained for almost all test frequencies throughout the range of hearing by 14 days. By 3 weeks posthatch, birds' best sensitivity shifted from 2 to 2.86 kHz, and the shape of the auditory brainstem response (ABR) audiogram became similar to that of adult budgerigars. About a week before leaving the nest, ABR audiograms of young budgerigars are very similar to those of adult birds. These data complement what is known about vocal development in budgerigars and show that hearing is fully developed by the time that vocal learning begins.

Age Factors↗
PubMed2006

Perception of complex sounds in budgerigars (Melopsittacus undulatus) with temporary hearing loss.

Songbirds and parrots deafened as nestlings fail to develop normal vocalizations, while birds deafened as adults show a gradual deterioration in the quality and precision of vocal production. Beyond this, little is known about the effect of hearing loss on the perception of vocalizations. Here, we induced temporary hearing loss in budgerigars with kanamycin and tested several aspects of the hearing, including the perception of complex, species-specific vocalizations. The ability of these birds to discriminate among acoustically distinct vocalizations was not impaired but the ability to make fine-grain discriminations among acoustically similar vocalizations was affected, even weeks after the basilar papilla had been repopulated with new hair cells. Interestingly, these birds were initially unable to recognize previously familiar contact calls in a classification task-suggesting that previously familiar vocalizations sounded unfamiliar with new hair cells. Eventually, in spite of slightly elevated absolute thresholds, the performance of birds on discrimination and perceptual recognition of vocalizations tasks returned to original levels. Thus, even though vocalizations may initially sound different with new hair cells, there are only minimal long-term effects of temporary hearing loss on auditory perception, recognition of species-specific vocalizations, or other aspects of acoustic communication in these birds.

Animals↗
PubMed2005

Influence of outlying values and variations between sampling days on reference ranges for clinical chemistry in budgerigars (Melopsittacus undulatus).

Reference ranges for clinical chemistry variables were established for 99 budgerigars sampled monthly for 12 months. The data from the repeated measurements were compiled to obtain the most reliable population-based reference range defined to be relevant for the population of budgerigars over the whole year. Outlying values were excluded by reference to the population-based reference range and to previously determined values from the same individual, following the guidelines of the International Federation of Clinical Chemistry. The exclusion of outliers significantly reduced the calculated reference ranges.

Animals↗
PubMed2000

Male vocal imitation produces call convergence during pair bonding in budgerigars, Melopsittacus undulatus.

The budgerigar, a small species of parrot, can learn new vocalizations throughout life and is therefore widely used as a model system for studying various aspects of vocal learning. It is not known, however, why parrots imitate sounds. To test the hypothesis that vocal imitation in budgerigars is related to pair bonding, we recorded approximately 100 contact calls from each of nine male and nine female adult budgerigars that were unfamiliar with one another and then placed them into pairs. We sampled their contact call repertoire weekly and conducted twice-weekly behavioural observation sessions. We compared contact calls by sonagram cross-correlation and classified them by means of a hierarchical clustering algorithm. This analysis showed that all pairs developed a shared call within an average of 2.1 weeks. Further analysis revealed that eight of the nine male budgerigars imitated the contact calls of their assigned mates, while none of the females imitated the calls of their males. We conclude that contact call imitation in adult budgerigars probably contributes to pair bond formation and maintenance. Prior studies on budgerigars were limited by the lack of a behavioural paradigm to elicit vocal imitation reliably. Our study remedies this and thereby serves as a foundation for future studies on vocal learning in adult animals. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1996

Testosterone induction of male-like vocalizations in female budgerigars (Melopsittacus undulatus).

Budgerigars possess a complex learned vocal repertoire that includes a long rambling song called warble. While both males and females can warble, there are marked sex differences in the amount of song produced. Males generally warble daily at a high rate, while females rarely sing. Both the quantity and the quality of male warble are influenced by circulating levels of testosterone. Males have higher circulating levels of testosterone than females. In this study we asked whether administering testosterone to adult female budgerigars would activate male-like vocal behavior. Four females were implanted with 8-mm Silastic implants filled with testosterone and recorded before and after implantation. Within 10-14 days, all four birds showed: (1) changes in there color to the male-like condition (blue), (2) male-typical patterns of precopulatory behavior, and (3) an increase in their rate of warbling to male-like levels. Sound analysis revealed that the acoustic structure of the testosterone-induced female warble is similar to the male warble. These data indicate that sex differences in budgerigar vocal behavior are not based on early organizational effects of steroid hormones, but rather are probably the result of adult sex differences in circulating testosterone levels.

Animals↗
PubMed1995

Effect of syringeal denervation in the budgerigar (Melopsittacus undulatus): the role of the syrinx in call production.

In the budgerigar, the left and right tracheosyringeal nerves (ts) were sectioned both above and below the common anastomosis in order to assess the roles of the hypoglossal nuclei and syringeal muscle halves in the control of call production. Signal processing software was used to quantify changes in contact call fundamental frequency and duration, and similarity analysis for pre- and postsurgical contact calls was performed by means of spectrogram cross-correlation. After resecting a portion of either the right or left ts nerve above the anastomosis (thereby eliminating the input from the ipsilateral half of the brainstem), contact call fundamental frequency decreased 40-50% on Day 1 postsurgery, while call structure and duration remained largely unaffected. Fundamental frequency returned to normal within 4-7 days after surgery. In contrast, nerve sectioning below the anastomosis on either side of the syrinx (thereby eliminating input to the ipsilateral half of the syringeal muscles) resulted in moderately noisy harsh-sounding calls with little change in temporal characteristics. Thus, budgerigars differ from many oscines studied to date in that they do not demonstrate laterality in vocal control at the level of the syrinx. Vocalizations produced by birds after bilateral syringeal denervation were abnormal, consisting entirely of broadband harmonic sounds with very low fundamental frequencies (i.e., less than 900 Hz) and poor frequency modulation. In contrast, individual call durations, as well as the rhythm and patterning of vocalizations resembling warble song, were remarkably similar to presurgical recordings after both unilateral and bilateral ts nerve resection.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Communication↗
PubMed2000

Effects of lesions of the central nucleus of the anterior archistriatum on contact call and warble song production in the budgerigar (Melopsittacus undulatus).

We studied the effects of both unilateral and bilateral lesions of the central nucleus of the anterior archistriatum (AAc) on the production of contact calls and warble song in adult male and female budgerigars. Birds were sorted into three experimental groups based on the percentage of AAc destroyed and whether lesions were unilateral or bilateral. The experimental groups were Unilateral Lesion (N = 8), Partial Bilateral Lesion (N = 5), and Bilateral Lesion birds (N = 12). Each group contained both sexes. Unilateral lesions had no demonstrable effects on contact call or warble song production. Bilateral lesions resulted in immediate and permanent disruption of all learned temporal and spectral characteristics of contact calls, although call initiation was not dependent on the AAc. Partial bilateral lesion effects varied with lesion size and location. At least 20-30% sparing of the AAc, including sparing portions of both the dorsal (AAcd) and ventral (AAcv) subdivisions on the same side of the brain, is necessary for production of prelesion contact call patterns. Warble song was absent in birds with complete bilateral destruction. Two birds with large yet incomplete lesions of the AAc sang after surgery, although the warble song of these birds was extremely impoverished and contained only a few of the typical warble song elements. Lesion results indicate that the AAc mediates the production of learned vocal features in male and female budgerigars, with each hemisphere capable of supporting a normal vocal repertoire.

Animal Communication↗
PubMed1975

The differentiation of the acrosome in the spermatid of the budgerigar (Melopsittacus undulatus).

The development of the acrosome of the budgerigar spermatid was studied under the electronmicroscope. The acrosome arises from a granule derived from the Golgi apparatus which interacts with the nucleus to form a cone shaped acrosomal cap and a perforatorium. A quanity of cytoplasm and plasma membrane is captured from the cell periphery and incorporated into the substance of the acrosome. The possible significance of the developmental phases and comparative avian spermatology is discussed.

Animals↗