The Experts below are selected from a list of 213 Experts worldwide ranked by ideXlab platform
Lesley P Bulluck - One of the best experts on this subject based on the ideXlab platform.
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vector contact rates on Eastern Bluebird nestlings do not indicate west nile virus transmission in henrico county virginia usa
International Journal of Environmental Research and Public Health, 2013Co-Authors: Kevin A Caillouet, Charles W Robertson, David C Wheeler, Nicholas Komar, Lesley P BulluckAbstract:Sensitive indicators of spatial and temporal variation in vector-host contact rates are critical to understanding the transmission and eventual prevention of arboviruses such as West Nile virus (WNV). Monitoring vector contact rates on particularly susceptible and perhaps more exposed avian nestlings may provide an advanced indication of local WNV amplification. To test this hypothesis we monitored WNV infection and vector contact rates among nestlings occupying nest boxes (primarily Eastern Bluebirds; Sialia sialis, Turdidae) across Henrico County, Virginia, USA, from May to August 2012. Observed host-seeking rates were temporally variable and associated with absolute vector and host abundances. Despite substantial effort to monitor WNV among nestlings and mosquitoes, we did not detect the presence of WNV in these populations. Generally low vector-nestling host contact rates combined with the negative WNV infection data suggest that monitoring transmission parameters among nestling Eastern Bluebirds in Henrico County, Virginia, USA may not be a sensitive indicator of WNV activity.
Michael D Kern - One of the best experts on this subject based on the ideXlab platform.
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interactions of body temperature and nutritional status on hypothalamo pituitary adrenal axis activity in pre thermoregulatory Eastern Bluebird chicks sialia sialis
General and Comparative Endocrinology, 2018Co-Authors: Sharon E Lynn, Michael D KernAbstract:Abstract Early life experiences can affect the function of the hypothalamo-pituitary-adrenal (HPA) axis of vertebrates, with potential fitness consequences later in life. In altricial species, for example, variation in parental behavior, e.g. brooding or feeding, can modify the activity of the HPA axis of the young by altering their exposure to noxious stimuli as the young develop in the nest. We have shown that a drop in the body temperature of Eastern Bluebird (Sialia sialis) chicks, such as occurs when females are away from the nest, elevates their blood corticosterone levels. If repeated during the early days of their development, cooling bouts also reduce the chicks’ later corticosterone secretion in response to handling. Thus, variation in maternal behavior has the capacity to shape the function of the chicks’ HPA axis. To better understand how maternal absence from the nest activates the HPA axis of Bluebird chicks, we experimentally mimicked the cooling that occurs when the female is away from the nest, and investigated a) the age at which the HPA axis becomes capable of responding to cooling by increasing corticosterone secretion, b) whether corticosterone secretion remains elevated throughout long periods of cooling, and c) whether fasting (also potentially associated with maternal absence) interacts with cooling to affect corticosterone secretion. Cooling for 18 min significantly elevated circulating corticosterone levels of chicks as young as 4 days post-hatch, indicating that their HPA axis is sensitive to cooling very early in life. Corticosterone levels remained elevated throughout longer bouts of cooling. However, a 1-hr period of fasting had no effect on corticosterone secretion, regardless of whether chicks were cooled or not. Collectively, these data demonstrate that variation in maternal brooding behavior can substantially modify the corticosterone profiles of chicks during early postnatal development, and that chick temperature is likely the main driver of this.
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environmentally relevant bouts of cooling stimulate corticosterone secretion in free living Eastern Bluebird sialia sialis nestlings potential links between maternal behavior and corticosterone exposure in offspring
General and Comparative Endocrinology, 2014Co-Authors: Sharon E Lynn, Michael D KernAbstract:In vertebrates, exposure to stressful stimuli or to elevated glucocorticoids early in development can contribute to phenotypic variation that may have significant fitness consequences. In species with altricial young, offspring may be partially buffered from elevations in glucocorticoids by a period of low glucocorticoid responsiveness to stressors coupled with high levels of parental care. Because altricial young depend heavily on their parents for warmth, parental brooding behavior could buffer offspring from glucocorticoid exposure associated with cooling. We studied Eastern Bluebirds (Sialia sialis) with two goals: (1) to determine whether an experimental drop in body temperature such as that which might occur when a brooding female is off the nest was sufficient to stimulate glucocorticoid secretion in young chicks, and (2) to examine the extent to which chicks experienced such bouts of cooling in the field. We subjected chicks to treatments simulating nest temperatures while females were brooding or absent from the nest. We also recorded chick surface temperatures and ambient temperatures at nests during the first week of the brood period. Reductions of surface temperature of less than 10 °C significantly elevated corticosterone secretion in chicks as young as 5 days old, and thermal and hormonal responses of chicks to cooling increased in an age-dependent manner. One quarter of broods experienced repeated, natural bouts of cooling of this magnitude or greater in the nest. Our data suggest that natural variations in maternal brooding patterns can result in differential exposure of offspring to glucocorticoids, and this may have important phenotypic consequences later in life.
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neonatal handling alters the development of the adrenocortical response to stress in a wild songbird Eastern Bluebird sialia sialis
General and Comparative Endocrinology, 2013Co-Authors: Sharon E Lynn, Michael D Kern, Megan M PhillipsAbstract:Abstract Neonatal handling of captive vertebrates can shape the development of their hypothalamo–pituitary–adrenal (HPA) axis and alter their ability to respond to stressful stimuli later in life. However, the long-term effects of such handling on this endocrine axis in free-living species are not well understood. We investigated the effects of age and neonatal handling on corticosterone secretion in response to restraint in Eastern Bluebird ( Sialia sialis ) chicks. We found that unhandled (“naive”) and handled (“experienced”) chicks exhibited no corticosterone response to handling early in development. Thereafter, naive individuals exhibited the progressive development of a corticosterone response with age, and by day 12 post-hatch, the response resembled that of adult Bluebirds. Experienced nestlings, which were handled every other day from the day of hatch, showed a similar pattern of HPA development until day 12 post-hatch, when their corticosterone response was significantly reduced compared to that of naive nestlings. In contrast, chicks that were handled only once, when 10 days old, did not show a reduced corticosterone response at 12 days old. Taken together, our data suggest that a certain threshold of accumulated neonatal handling episodes is necessary to depress corticosterone secretion, and/or that the cumulative effects of several handling episodes only manifest themselves once the HPA axis is fully developed. Our findings, in concert with studies on two other wild species, indicate that routine handling of nestlings in the field can alter their responses to stress in a species-specific manner, potentially leading to important fitness consequences.
Sharon E Lynn - One of the best experts on this subject based on the ideXlab platform.
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interactions of body temperature and nutritional status on hypothalamo pituitary adrenal axis activity in pre thermoregulatory Eastern Bluebird chicks sialia sialis
General and Comparative Endocrinology, 2018Co-Authors: Sharon E Lynn, Michael D KernAbstract:Abstract Early life experiences can affect the function of the hypothalamo-pituitary-adrenal (HPA) axis of vertebrates, with potential fitness consequences later in life. In altricial species, for example, variation in parental behavior, e.g. brooding or feeding, can modify the activity of the HPA axis of the young by altering their exposure to noxious stimuli as the young develop in the nest. We have shown that a drop in the body temperature of Eastern Bluebird (Sialia sialis) chicks, such as occurs when females are away from the nest, elevates their blood corticosterone levels. If repeated during the early days of their development, cooling bouts also reduce the chicks’ later corticosterone secretion in response to handling. Thus, variation in maternal behavior has the capacity to shape the function of the chicks’ HPA axis. To better understand how maternal absence from the nest activates the HPA axis of Bluebird chicks, we experimentally mimicked the cooling that occurs when the female is away from the nest, and investigated a) the age at which the HPA axis becomes capable of responding to cooling by increasing corticosterone secretion, b) whether corticosterone secretion remains elevated throughout long periods of cooling, and c) whether fasting (also potentially associated with maternal absence) interacts with cooling to affect corticosterone secretion. Cooling for 18 min significantly elevated circulating corticosterone levels of chicks as young as 4 days post-hatch, indicating that their HPA axis is sensitive to cooling very early in life. Corticosterone levels remained elevated throughout longer bouts of cooling. However, a 1-hr period of fasting had no effect on corticosterone secretion, regardless of whether chicks were cooled or not. Collectively, these data demonstrate that variation in maternal brooding behavior can substantially modify the corticosterone profiles of chicks during early postnatal development, and that chick temperature is likely the main driver of this.
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environmentally relevant bouts of cooling stimulate corticosterone secretion in free living Eastern Bluebird sialia sialis nestlings potential links between maternal behavior and corticosterone exposure in offspring
General and Comparative Endocrinology, 2014Co-Authors: Sharon E Lynn, Michael D KernAbstract:In vertebrates, exposure to stressful stimuli or to elevated glucocorticoids early in development can contribute to phenotypic variation that may have significant fitness consequences. In species with altricial young, offspring may be partially buffered from elevations in glucocorticoids by a period of low glucocorticoid responsiveness to stressors coupled with high levels of parental care. Because altricial young depend heavily on their parents for warmth, parental brooding behavior could buffer offspring from glucocorticoid exposure associated with cooling. We studied Eastern Bluebirds (Sialia sialis) with two goals: (1) to determine whether an experimental drop in body temperature such as that which might occur when a brooding female is off the nest was sufficient to stimulate glucocorticoid secretion in young chicks, and (2) to examine the extent to which chicks experienced such bouts of cooling in the field. We subjected chicks to treatments simulating nest temperatures while females were brooding or absent from the nest. We also recorded chick surface temperatures and ambient temperatures at nests during the first week of the brood period. Reductions of surface temperature of less than 10 °C significantly elevated corticosterone secretion in chicks as young as 5 days old, and thermal and hormonal responses of chicks to cooling increased in an age-dependent manner. One quarter of broods experienced repeated, natural bouts of cooling of this magnitude or greater in the nest. Our data suggest that natural variations in maternal brooding patterns can result in differential exposure of offspring to glucocorticoids, and this may have important phenotypic consequences later in life.
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neonatal handling alters the development of the adrenocortical response to stress in a wild songbird Eastern Bluebird sialia sialis
General and Comparative Endocrinology, 2013Co-Authors: Sharon E Lynn, Michael D Kern, Megan M PhillipsAbstract:Abstract Neonatal handling of captive vertebrates can shape the development of their hypothalamo–pituitary–adrenal (HPA) axis and alter their ability to respond to stressful stimuli later in life. However, the long-term effects of such handling on this endocrine axis in free-living species are not well understood. We investigated the effects of age and neonatal handling on corticosterone secretion in response to restraint in Eastern Bluebird ( Sialia sialis ) chicks. We found that unhandled (“naive”) and handled (“experienced”) chicks exhibited no corticosterone response to handling early in development. Thereafter, naive individuals exhibited the progressive development of a corticosterone response with age, and by day 12 post-hatch, the response resembled that of adult Bluebirds. Experienced nestlings, which were handled every other day from the day of hatch, showed a similar pattern of HPA development until day 12 post-hatch, when their corticosterone response was significantly reduced compared to that of naive nestlings. In contrast, chicks that were handled only once, when 10 days old, did not show a reduced corticosterone response at 12 days old. Taken together, our data suggest that a certain threshold of accumulated neonatal handling episodes is necessary to depress corticosterone secretion, and/or that the cumulative effects of several handling episodes only manifest themselves once the HPA axis is fully developed. Our findings, in concert with studies on two other wild species, indicate that routine handling of nestlings in the field can alter their responses to stress in a species-specific manner, potentially leading to important fitness consequences.
Kevin A Caillouet - One of the best experts on this subject based on the ideXlab platform.
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vector contact rates on Eastern Bluebird nestlings do not indicate west nile virus transmission in henrico county virginia usa
International Journal of Environmental Research and Public Health, 2013Co-Authors: Kevin A Caillouet, Charles W Robertson, David C Wheeler, Nicholas Komar, Lesley P BulluckAbstract:Sensitive indicators of spatial and temporal variation in vector-host contact rates are critical to understanding the transmission and eventual prevention of arboviruses such as West Nile virus (WNV). Monitoring vector contact rates on particularly susceptible and perhaps more exposed avian nestlings may provide an advanced indication of local WNV amplification. To test this hypothesis we monitored WNV infection and vector contact rates among nestlings occupying nest boxes (primarily Eastern Bluebirds; Sialia sialis, Turdidae) across Henrico County, Virginia, USA, from May to August 2012. Observed host-seeking rates were temporally variable and associated with absolute vector and host abundances. Despite substantial effort to monitor WNV among nestlings and mosquitoes, we did not detect the presence of WNV in these populations. Generally low vector-nestling host contact rates combined with the negative WNV infection data suggest that monitoring transmission parameters among nestling Eastern Bluebirds in Henrico County, Virginia, USA may not be a sensitive indicator of WNV activity.
Kimberly A Rosvall - One of the best experts on this subject based on the ideXlab platform.
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nesting strategy shapes territorial aggression but not testosterone a comparative approach in female and male birds
Hormones and Behavior, 2021Co-Authors: Sara E Lipshutz, Kimberly A RosvallAbstract:Our understanding of the proximate and ultimate mechanisms shaping competitive reproductive phenotypes primarily stems from research on male-male competition for mates, even though competition is widespread in both sexes. We evaluate the hypothesis that the restricted nature of a resource required for reproduction, i.e. nest site, is a key variable driving territorial competition and testosterone secretion in female and male birds. Obligate secondary cavity-nesting has evolved repeatedly across avian lineages, providing a useful comparative context to explore how competition over limited nest cavities shapes aggression and its underlying mechanisms across species. Although evidence from one or another cavity-nesting species suggests that territorial aggression is adaptive in both females and males, this has not yet been tested in a comparative framework. We predicted that cavity-nesting generates more robust territorial aggression, in comparison to close relatives with less restrictive nesting strategies. Our focal species were two obligate secondary cavity-nesting species and two related species with more flexible nesting strategies in the same avian family: tree swallow (Tachycineta bicolor) vs. barn swallow (Hirundo rustica); Eastern Bluebird (Sialia sialis) vs. American robin (Turdus migratorius). We assayed conspecific aggression using simulated territorial intrusion and found that cavity-nesting species displayed greater territorial aggression than their close relatives. This pattern held for both females and males. Because territorial aggression is often associated with elevated testosterone, we also hypothesized that cavity-nesting species would exhibit higher testosterone levels in circulation. However, cavity-nesting species did not have higher testosterone in circulation for either sex, despite some correlative evidence that testosterone is associated with higher rates of physical attack in female tree swallows. Our focus on a context that is relevant to both sexes - competition over essential breeding resources - provides a useful framework for co-consideration of proximate and ultimate drivers of reproductive competition in females and males.
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nesting strategy shapes territorial aggression but not testosterone a comparative approach in female and male birds
bioRxiv, 2020Co-Authors: Sara E Lipshutz, Kimberly A RosvallAbstract:Our understanding of the proximate and ultimate mechanisms shaping competitive phenotypes primarily stems from research on male-male competition for mates, even though female-female competition is also widespread. Obligate secondary cavity-nesting has evolved repeatedly across avian lineages, providing a useful comparative context to explore how competition over limited nest cavities shapes aggression and its underlying mechanisms across species. Although evidence from one or another cavity-nesting species suggests that territorial aggression is adaptive in both females and males, this has not yet been tested in a comparative framework. We tested the hypothesis that cavity-nesting generates more robust territorial aggression, in comparison to close relatives with less restrictive nesting strategies. Our focal species were two obligate secondary cavity-nesting species and two related species with more flexible nesting strategies in the same avian family: tree swallow (Tachycineta bicolor) vs. barn swallow (Hirundo rustica); Eastern Bluebird (Sialia sialis) vs. American robin (Turdus migratorius). We assayed conspecific territorial aggression, and found that cavity-nesting species physically attacked a simulated intruder more often than their close relatives. This pattern held for both females and males. Because territorial aggression is often associated with elevated testosterone, we also hypothesized that cavity-nesting species would exhibit higher testosterone levels in circulation. However, cavity-nesting species did not have higher testosterone in circulation for either sex, despite some correlative evidence that testosterone is associated with higher rates of physical attack in female tree swallows. Our focus on a competitive context that is relevant to both sexes - competition over essential breeding resources - provides a useful comparative framework for co-consideration of proximate and ultimate drivers of reproductive competition in females and males.