UMD Theses and Dissertations

Permanent URI for this collectionhttp://hdl.handle.net/1903/3

New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.

More information is available at Theses and Dissertations at University of Maryland Libraries.

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    The structure and perception of budgerigar (Melopsittacus undulatus) warble songs
    (2009) Tu, Hsiao-Wei; Dooling, Robert J; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The warble song of male budgerigars (Melopsittacus undulatus) is an extraordinarily complex, multi-syllabic, learned vocalization that is produced continuously in streams lasting from a few seconds to a few minutes without obvious repetition of particular patterns. As a follow-up of the warble analysis of Farabaugh et al. (1992), an automatic categorization program based on neural networks was developed and used to efficiently and reliably classify more than 25,000 warble elements from 4 budgerigars. The relative proportion of the resultant seven basic acoustic groups and one compound group is similar across individuals. Budgerigars showed higher discriminability of warble elements drawn from different acoustic categories and lower discriminability of warble elements drawn from the same category psychophysically, suggesting that they form seven perceptual categories corresponding to those established acoustically. Budgerigars also perceive individual voice characteristics in addition to the acoustic measures delineating categories. Acoustic analyses of long sequences of natural warble revealed that the elements were not randomly arranged and that warble has at least a 5th-order Markovian structure. Perceptual experiments provided convergent evidence that budgerigars are able to master a novel sequence between 4 and 7 elements in length. Through gradual training with chunking (about 5 elements), birds are able to master sequences up to 50 elements. The ability of budgerigars to detect inserted targets taken in a long, running background of natural warble sequences appears to be species-specific and related to the acoustic structure of warble sounds.
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    Personality Traits in the Budgerigar, Melopsittacus undulatus
    (2008) Callicrate, Taylor; Estevez, Inmaculada; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    This study investigated bold-shy personality in the budgerigar, Melopsittacus undulatus . Adult budgerigars (14 females, 9 males) fed either a control diet, or one supplemented with docosahexaenoic acid (DHA), were subjected to seven behavioral tests and two immunocompetence assays. Behavioral responses were categorized by context: fear, feeding, or activity. Correlations were obtained within contexts and among immunocompetence variables and all behavioral variables. Kruskal-Wallis analysis was used to investigate effects of gender and DHA on all variables. Budgerigars behaved consistently within activity and feeding contexts. Males had higher feeding rates, and their feeding responses were negatively correlated with a measure of innate immunity. Cluster analysis characterized birds by activity levels; bold birds were highly active and shy birds were less active. The results of this study suggest that budgerigars exhibit consistent behaviors in two contexts, feeding and activity, which are unrelated to each other, and that activity is the predominant personality trait.