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Scholarly Works (3 results)

  • Thesis
  • Peer Reviewed
UC Berkeley Electronic Theses and Dissertations (2012)

The prevalence of female-biased affiliations in group living mammalian species suggests that same-sex relationships are of particular importance for females. However, little is known about the influence of environmental and physiological factors on same-sex social bonds. Female meadow voles present an interesting opportunity for the investigation of these questions because free-living females display seasonal variations in same-sex affiliation. From summer to winter, females transition from an aggressive, territorial phenotype to an affiliative, group living phenotype. The thermoregulatory advantages of huddling have been offered as an explanation for winter sociality in meadow voles; thus, I designed a study to assess the effects of ambient temperature, day length, food availability, and frequency of handling on same-sex affiliative behavior and several potential physiological correlates. Adult female pairs were housed in varying combinations of day length (short (SDs) or long days (LDs)), temperature (21¢ªC or 10¢ªC), and food availability (ad libitum or restricted) and regularly assessed for food intake and body mass. After seven weeks of treatment, females were evaluated for same-sex huddling behavior using 3 h partner preference tests. Uterine mass and serum concentrations of corticosterone and estradiol were assessed for all focal voles. In another study, group size and social preferences were evaluated in male and female meadow voles. Voles were housed in same-sex trios at weaning and behavior tested at 70-100 days of age. During behavior tests, focal voles were presented with the options of huddling with one familiar individual (a member of their trio) or a trio of strangers. My findings suggest that:

1) Day length, food availability, and ambient temperature interact to regulate same-sex affiliative behavior in female meadow voles.

2) Low temperature exposure can modify social preferences without increasing huddling behavior.

3) In SDs, lower ambient temperature augments the propensity to interact with strangers without interfering with existing social bonds, whereas lower temperature in LDs disrupts the retention of bonds.

4) Food restriction enhances affiliative behavior in SDs without causing significant body mass decline.

5) Differences in handling modulate uterine mass, plasma corticosterone, and plasma estradiol without modifying same-sex affiliation.

6) Under certain environmental conditions, variations in same-sex affiliative behavior are correlated with plasma corticosterone and estradiol.

7) The propensity to join a group consisting of novel individuals varies by day length and sex.

Collectively, the results described in this dissertation suggest that conditions associated with winter (food scarcity, low temperatures, and short day lengths) increase social tolerance and promote aggregation of females into groups. Corticosterone secretion and the reproductive axis are also responsive to the environmental factors examined; however, current concentrations of blood plasma corticosterone and estradiol do not fully account for the behavioral responses observed.

    Cover page: Environmental modulation and physiological correlates of same-sex affiliative behavior in female meadow voles
    • Article
    • Peer Reviewed
    UC Davis Previously Published Works (2017)
    Urban-dwelling birds have the potential to serve as powerful biomonitors that reveal the impact of environmental change due to urbanization. Specifically, urban bird populations can be used to survey cities for factors that may pose both public and wildlife health concerns. Here, we review evidence supporting the use of avian biomonitors to identify threats associated with urbanization, including bioaccumulation of toxicants and the dysregulation of behavior and physiology by related stressors. In addition, we consider the use of birds to examine how factors in the urban environment can impact immunity against communicable pathogens. By studying the behavior, physiology, and ecology of urban bird populations, we can elucidate not only how avian populations are responding to environmental change, but also how unintended consequences of urbanization affect the well-being of human and non-human inhabitants.
      Cover page: Urban health and ecology: the promise of an avian biomonitoring tool
      • Article
      • Peer Reviewed
      UC Davis Previously Published Works (2018)
      Collective behaviors, including flocking and group vocalizing, are readily observable across a diversity of free-living avian populations, yet we know little about how neural and ecological factors interactively regulate these behaviors. Because of their involvement in mediating a variety of social behaviors, including avian flocking, nonapeptides are likely mediators of collective behaviors. To advance the neuroecological study of collective behaviors in birds, we sought to map the neuroanatomical distributions of nonapeptide receptors in three promising avian models that are found across a diversity of environments and widely ranging ecological conditions: European starlings, house sparrows, and rock doves. We performed receptor autoradiography using the commercially available nonapeptide receptor radioligands, 125I-ornithine vasotocin analog and 125I-linear vasopressin antagonist, on brain tissue sections from wild-caught individuals from each species. Because there is known pharmacological cross-reactivity between nonapeptide receptor subtypes, we also performed a novel, competitive-binding experiment to examine the composition of receptor populations. We detected binding in numerous regions throughout the brains of each species, with several similarities and differences worth noting. Specifically, we report that all three species exhibit binding in the lateral septum, a key brain area known to regulate avian flocking. In addition, sparrows and starlings show dense binding in the dorsal arcopallium, an area that has received scant attention in the study of social grouping. Furthermore, our competitive binding results suggest that receptor populations in sparrows and starlings differ in the lateral septum versus the dorsal arcopallium. By providing the first comprehensive maps of nonapeptide receptors in European starlings, house sparrows, and rock doves, our work supports the future use of these species as avian models for neuroecological studies of collective behaviors in wild birds.
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