The literature pertaining to a variety of methods for estimating the abundances of songbirds is reviewed, and the use of two of the main methods - mapping and transects - is described and discussed. The mapping method is found to be the most efficient and reliable in the context of the present study, and work elsewhere in the British Isles suggests that the method has wide applicability in the region. Various methods for describing the habitats in which birds occur are discussed. In the present study the method chosen involved measuring various parameters of the vegetation within a limited area at each of several sampling points in five study plots in North-east Fife. It proved a useful method in the habitats studied - dune grassland, commercial and semi-natural coniferous woodlands, and deciduous scrub and mature woodland - and results of the vegetation sampling are discussed in terms of habitat structure and succession, and in the relationship of this structure to the breeding bird communities. The composition of these communities in the study plots is described, as are the changes over the three breeding seasons 1979-1981, which followed on from a meteorologically "hard" winter. Over the study period there was an overall increase in the populations of all five study plots, and this increase was greatest in the poorest habitat - the dune grassland - and least in the richest habitat - the mature deciduous woodland. Using indices to compare the study plots a major difference was found between the grassland plot and all four woodland plots, amongst which the two coniferous ones were most similar. Of the more abundant bird species, Robin, Song Thrush and Coal Tit were more prevalent in coniferous habitats; Willow Warbler and Blue Tit were more prevalent in the deciduous habitats. In relation to habitat structure, the more diverse bird communities were found in the more complex habitats, and there was evidence of succession in the bird communities concomitant with habitat succession. The present study is one of very few in Europe involving woodland habitats especially of a commercial nature near sea-level, and it was found that the four woodland study plots were rich in terms of the diversities and densities of their passerine breeding populations when compared with other European studies.

Thesis (M.S. - Renewable Natural Resources) - University of Arizona. / Includes bibliographical references (leaves 135-148).

Thesis (Ph. D.)--University of Tennessee, 2007. / Title from title page screen (viewed on Nov. 5, 2007). Thesis advisor: David Buehler. Vita. Includes bibliographical references.

In most birds, changing photoperiods from winter to spring and from summer to fall have two consequences: increased feeding followed by migratory activity. To date, the neural system controlling the activation of migratory activity remains unknown, though behavioral observations point to a possible mechanism. During the migration season, diurnal songbirds show extensive disruption of their sleep/wake cycle, sleeping during the day and flying at night. In mammals, similarly altered cycles of activity result from blocking orexin expression in the hypothalamus. It is possible that decreased orexin expression is associated with migratory activity in songbirds. In addition, changes in ingestive behaviors and fuel availability may also be associated with disruptions in the sleep/wake cycles of migratory birds. The studies in my dissertation will address these issues through three main specific aims. First, I will determine that orexin systems are conserved in vertebrate brains. Second, I will test the association between orexin and migratory activity in songbirds. Third, I will confirm the association between fuel availability, orexin expression and migratory activity in songbirds. / text

Patterns of nest attendance behavior by breeding birds represent a parent-offspring trade-off in which adults balance self-maintenance with parental care decisions. Incubation, in particular, is of interest because adults must provide an environment suitable for embryonic development through nest-building and contact-incubation. We evaluated how adult incubation constancy and nest visitation rates varied with life and natural history traits of temperate and tropical bird species. We found that constancy did not differ by latitude or with nest survival rate. A strong negative correlation between incubation constancy and egg mass relative to adult body mass was present. Birds with low constancy tended to have larger relative egg masses and higher basal metabolic rate. Because adult incubation constancy is relatively plastic (i.e., varies with ambient temperature), birds with larger relative eggs may respond to lower cooling rates rather than direct selection for higher or lower constancy. We then assessed if rates of nest visitation (trips to nests by adults during incubation and nestling phases) followed the predictions of the Skutch hypothesis. Skutch suggested that birds nesting in environments with high levels of nest predation would reduce numbers of trips to their nests so as to minimize the risk of visual detection by nest predators. We found support for the basic pattern predicted by Skutch. We also extended his hypothesis to predict other behavior associated with nesting, such as responses of parents to intruders at the nest. Despite apparently early departure from the nest site, adults with higher visitation rates remained conspicuous around the nest site. Thus, while the flight initiation distance from the human observer was earlier than expected, conspicuousness of behavior was associated with nest visitation rate. Finally, we assessed how an environmental variable, photoperiod, might influence rate of embryonic development in a wild songbird, Sylvia atricapilla. We exposed eggs throughout the incubation period to daily photoperiods consisting of 4 hours of light and 20 hours of dark (4L), 12 hours light and 12 hours dark (12L), 20 hours light and 4 hours dark (20L) and a skeleton photoperiod with two 1-hour pulses of light that framed a 20-hour day. We found that the skeleton treatment group differed significantly from our 4L and 12L, but not the 20L treatment groups. The skeleton photoperiod accelerated embryonic development. We suggest that photoperiod may influence incubation period in wild birds and could account for some portion of the widely observed latitudinal variation in incubation period of songbirds. We encourage others to assess how photoperiod interacts with parental attendance patterns to affect embryonic development. / Graduation date: 2013 / Access restricted to the OSU Community at author's request from March 13, 2013 - March 13, 2015

No description available.

The classical model of sexual differentiation states that genes influence gonadal differentiation, and gonadal hormones then drive sexual differentiation throughout development. This model has been called into question by research, especially in songbirds, providing evidence for alternative mechanisms like direct effect of genes and local production of steroids via de novo synthesis or local metabolism of steroid precursors like DHEA, which can be metabolized to testosterone and E₂. In order to assess the role of local steroid production on sexual differentiation in songbirds, levels of DHEA and E₂ were measured in brachial and jugular plasma, as well as brain and peripheral tissues in zebra finches at critical ages during development and in adulthood. DHEA levels in brachial and jugular plasma peaked at P30 and higher DHEA levels in jugular plasma were found in males relative to females at P30. Also, at P30, higher DHEA levels were found in rostral telencephalon in females relative to males. The findings of this study indicate that DHEA may play a role in sexual differentiation of songbirds. Surprisingly, E₂ was non-detectable in many plasma and tissue samples. Higher E₂ was found in the diencephalon in females relative to males at P3/P4 and higher E₂ was found in gonads in adult females relative to males. There was little evidence to suggest that E₂ is synthesized de novo in the brain, although perhaps E₂ is being rapidly metabolized into another estrogen or E₂ synthesis is more localized in the synapse. The findings of this study support the role of alternative mechanisms like de novo steroid synthesis and local metabolism of steroid precursors and challenge the role of classical mechanisms of sexual differentiation in songbirds. Also, these findings may have important implications for sex differences, which develop independently of gonadal hormones, in other animal species.

Avian point counts were conducted in tall-grass prairie fragments and adjacent grassland and agricultural matrix habitat in southern Manitoba. Bird density/abundance was compared between habitat types, while variables within prairie at local, patch or landscape level were modeled to determin avian habitat selection. Prairies and matrix grassland habitat supported the same number of species in both years, and densities of all focal bird species were the same in non-native grasslands as compared with native tall-grass prairies. Overall species richness in tall-grass prairies was mainly driven by vegetation variables. Variable responses to habitat structure and composition between avian species indicate that managing grasslands to promote heterogeneity is important to sustain a diverse assemblage of avian species. As individual species were affected most strongly by vegetation structure and richness, it follows that management of prairie vegetation through techniques such as grazing and prescribed burning could optimize habitat usability for birds.

Avian point counts were conducted in tall-grass prairie fragments and adjacent grassland and agricultural matrix habitat in southern Manitoba. Bird density/abundance was compared between habitat types, while variables within prairie at local, patch or landscape level were modeled to determin avian habitat selection. Prairies and matrix grassland habitat supported the same number of species in both years, and densities of all focal bird species were the same in non-native grasslands as compared with native tall-grass prairies. Overall species richness in tall-grass prairies was mainly driven by vegetation variables. Variable responses to habitat structure and composition between avian species indicate that managing grasslands to promote heterogeneity is important to sustain a diverse assemblage of avian species. As individual species were affected most strongly by vegetation structure and richness, it follows that management of prairie vegetation through techniques such as grazing and prescribed burning could optimize habitat usability for birds.

<p>The ability of young children to vocally imitate the speech of adults is critical for speech learning. Vocal imitation requires exposure to an external auditory model and the use of auditory feedback to adaptively modify vocal output to match the model. Despite the importance of vocal imitation to human communication and social behavior, it remains unclear how these two types of sensory experience, model exposure and feedback, act on sensorimotor networks controlling the learning and production of learned vocalizations. Using a combination of longitudinal in vivo imaging of neuronal structure and electrophysiological measurements of neuronal function, I addressed the questions of where, when, and how these two types of sensory experience act on sensorimotor neurons important to singing and song learning in zebra finches. The major finding of these experiments is that synaptic inputs onto neurons in HVC, a sensorimotor nucleus important to singing and song learning, are sensitive to tutor song experience and deafening. Thus, these findings for the first time link auditory experiences important to vocal imitation to synaptic reorganization in sensorimotor neurons important to behavior.</p> / Dissertation