Metabolism and Solar Radiation in Dark and White Herons Nesting in Hot Climates

Metabolism, body temperature (Tb), and feather reflectance was measured for dark Louisiana herons (LOU), little blue herons (LB), snowy egrets (SE), and cattle egrets (CE); only LOU nest preferentiallyin shade. The reflectance of LOU and adult LB was 13%-15%; it was 80%-82% for SE, CE, and immature (white) LB. Tb for all four species approximated 40 C; hypothermy was never observed. Basal metabolism (HJb) was 107% of the expected level for LOU, 85% for SE and CE, and 66% for LB. Minimal thermal conductance (C) was calculated as approximately 131% of the expected value for LOU, 115% for SE and CE, and 110% for LB. Metabolism and solar radiation may combine to produce heat stress in hot climates, particularly in dark birds; reduced Hb allows LB and other dark birds to nest in exposed sites. High values for C suggest a heat dissipation function; the relatively lower values are found in species with relatively lower Hb\u27S, thus preventing or reducing increases in T1, the lower limit of thermoneutrality. White plumage is thermally advantageous in tropical/subtropical birds nesting in open habitat, but dark coloration is not; other evolutionary explanations must be sought to explain the occurrence of dark birds in hot climates

Daily energy expenditure of Florida Scrub-Jays (Aphelocoma coerulescens) in suburban and wildland landscapes

Urbanization alters ecological systems, disturbance regimes, food webs, and a variety of other processes that can influence local flora and fauna. In birds, most studies have focused on behavioral or demographic responses to altered conditions; however, the physiological mechanisms associated with these responses have been understudied. We have previously documented shifts in foraging behavior because of the availability of human-provided food; we sought to see if this was driven by or associated with a change in field metabolic rates. We measured field metabolic rates (FMR), a measure of daily energy expenditure (DEE), of Florida Scrub-Jays (Aphelocoma coerulescens) in 2 habitats using doubly labeled water (DLW). One population of jays lived in wildland habitat, the other in a suburban area where the habitat was badly degraded. During the breeding season FMR of suburban males exceeded that of wildland males by over 100%. Female FMR did not differ between sites but increased following incubation. In the wildlands, FMRs of females were barely lower than those of males, but in the suburban landscape, female FMRs were much lower than in males. For both sexes in the wildlands, FMRs were about 3.53 basal rates of metabolism (BMR) during breeding; in the suburbs female FMR exceeded BMR by 43 but did not differ from that of wildland females. Suburban male FMRs exceeded BMR by 7.13. During the nonbreeding seasons of fall and winter, FMR did not differ between habitats, ranging from 1.73 to 2.13 BMR, thus it is the breeding season that separated wildland and suburban jays energetically. In both habitats, a low water economy index (mL/kJ) and low water fluxes indicated that these jays are well adapted to their xeric habitat, but their FMRs distinguished them from desert birds. The very high energetic cost associated with breeding for suburban males may help explain why in the metapopulation of Florida Scrub-Jays, suburban jay populations are sinks. This study underscores the value of physiology in the conservation of listed species

Total Body Water and Body Composition in Phalaropes and Other Birds

Contrary to some reviews, total body water (TBW) may fall below the expected value of about 65% in birds if measured as a percentage of total body mass. However, water constitutes a relatively stable proportion (659%-70%) of body composition when measured as a percentage of lean body mass (LBM). We demonstrate this by using data from two migratory phalaropes (Phalaropus tricolor and Phalaropus lobatus), which exhibit inverse relationships between TBW and body mass and between TBW and fat content. As the phalaropes fatten before migration, lipids increase but not at the expense of water, which also increases with gains in lean tissue. The gain in lean dry mass with body size is also correlated with migration. Because absolute water increases with body mass, TBW is a poor measure of hydration; however, because of the inverse relationship between TBW and fat, TBW can predict body fat accurately if a calibration curve is first generated. We provide equations that predict fat content in both species of phalaropes suggest that water normally be reported not as TBW (a percentage of total body mass) but preferably as lean body water (LBW, a percentage of lean body mass). In the absence of quantitative estimates off at, we suggest that water be communicated in absolute amount, preferably with some estimate of condition (fat)

Temperature Regulation and the Constraints of Climate in the Eared Grebe

Eared Grebes (Podiceps nigricollis) encounter a variety of climatic regimes in their annual cycle. The most dramatic occur while on staging areas in autumn. We investigated the thermoregulatory abilities of the Eared Grebe to determine how they coped with these climate changes during staging. The basal metabolic rate (BMR) was higher than predicted. Mass-specific BMR was 1.212 mL O2/g·h for birds averaging 317 g. The thermoneutral zone is wide and extended from 15°C to 38°C. Minimal thermal conductance and average body temperature were not unusual. We conclude that Eared Grebes live most of the year under thermoneutral conditions and that food availability, not temperature extremes, determines the timing of their winter migration

Conceptualisations of 'the community' and 'community knowledge' among community radio volunteers in Katutura, Namibia

Community radio typically relies on volunteers to produce and present stations’ programming. Volunteers are generally drawn from stations’ target communities and are seen as “representatives” of those communities. It is with such volunteers and their role as representatives of stations’ target communities that this study is concerned. It poses the question: “what are the central concepts that typically inform volunteers’ knowledge of their target community, and how do these concepts impact on their perception of how they have gained this knowledge, and how they justify their role as representatives of this community?” The dissertation teases out the implications of these conceptualisations for a volunteer team’s ability to contribute to the establishment of a media environment that operates as a Habermasian ‘critical public sphere’. It argues that this can only be achieved if volunteers have detailed and in-depth knowledge of their target community. In order to acquire this knowledge, volunteers should make use of systematic ways of learning about the community, rather than relying solely on knowledge obtained by living there. In a case study of Katutura Community Radio (KCR), one of the bestknown community radio stations in Namibia, the study identifies key differences in the way in which different groups of volunteers conceptualise “the community”. The study focuses, in particular, on such difference as it applies to those who are volunteers in their personal capacity and those who represent non-governmental and community-based organisations at the station. It is argued that two strategies would lead to significant improvement in such a station’s ability to serve as a public sphere. Firstly, the station would benefit from an approach in which different sections of the volunteer team share knowledge of the target community with each other. Secondly, volunteers should undertake further systematic research into their target community. It is also argued that in order to facilitate such processes, radio stations such as KCR should recognise the inevitability of differences between different versions of “community knowledge”

How Is Stress Reduced by a Workplace Mindfulness Intervention? A Qualitative Study Conceptualising Experiences of Change

Mindfulness-based interventions are effective as curative and preventative approaches to psychological health. However, the mechanisms by which outcomes are secured from such interventions when delivered in the workplace, and to a stressed workforce, are not well understood. The aim of the present study was to elicit and analyse accounts from past participants of a workplace mindfulness intervention in order to generate a preliminary model of how positive benefits appear to be secured. In-depth, semi-structured interviews were completed with 21 employees of a higher education institution who had completed an eight-week intervention based on Mindfulness-Based Stress Reduction, adapted for the workplace. Interviews invited participants to recount their experiences of the intervention and its impact, if any, on their work life. Aspects of the interview data that pertained to intervention experience and positive benefits were analysed using a version of grounded theory, leading to the generation of a provisional model of how positive change occurred. The model suggests that discrete, temporal experiences build on each other to generate multiple, positive benefits. As anticipated in mindfulness-based interventions, enhanced attentional capacity was important, but our provisional model also suggests that resonance, self-care, detection of stress markers, perceiving choice, recovering self-agency and upward spiralling may be central mechanisms that lead to positive outcomes. Understanding mechanisms of change may help support participant engagement and trust in work-based mindfulness programmes, and enhance participants’ ability to apply mindfulness in their work life

Incubation Energetics of the Laysan Albatross

The energy expenditure of incubating and foraging Laysan Albatross (Diomedea immutabilis, mean body weight 3.07 kg) was estimated by means of the doubly-la- belled water technique. During incubation, the energy expenditure was similar to that of resting birds that were not incubating an egg. The energy expenditure of foraging albatross (2072 kJ/day) was 2.6 times that of resting birds. It was concluded that the energy expenditure of the tropical Laysan Albatross was not less than that of species foraging over cold, high-latitude oceans. An energy budget compiled for an incubating pair of albatross revealed that the energy expenditure of the female was greater than that of the male bird, during the incubation perio