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  1. Article ; Online: Sex steroids modulate circadian behavioral rhythms in captive animals, but does this matter in the wild?

    Elderbrock, Emily K / Hau, Michaela / Greives, Timothy J

    Hormones and behavior

    2020  Volume 128, Page(s) 104900

    Abstract: Nearly all organisms alter physiological and behavioral activities across the twenty-four-hour day. Endogenous timekeeping mechanisms, which are responsive to environmental and internal cues, allow organisms to anticipate predictable environmental ... ...

    Abstract Nearly all organisms alter physiological and behavioral activities across the twenty-four-hour day. Endogenous timekeeping mechanisms, which are responsive to environmental and internal cues, allow organisms to anticipate predictable environmental changes and time their daily activities. Among-individual variation in the chronotype, or phenotypic output of these timekeeping mechanisms (i.e. timing of daily behaviors), is often observed in organisms studied under naturalistic environmental conditions. The neuroendocrine system, including sex steroids, has been implicated in the regulation and modulation of endogenous clocks and their behavioral outputs. Numerous studies have found clear evidence that sex steroids modulate circadian and daily timing of activities in captive animals under controlled conditions. However, little is known about how sex steroids influence daily behavioral rhythms in wild organisms or what, if any, implication this may have for survival and reproductive fitness. Here we review the evidence that sex steroids modulate daily timing in vertebrates under controlled conditions. We then discuss how this relationship may be relevant for the reproductive success and fitness of wild organisms and discuss the limited evidence that sex steroids modulate circadian rhythms in wild organisms.
    MeSH term(s) Animals ; Circadian Rhythm ; Gonadal Steroid Hormones ; Neurosecretory Systems ; Steroids ; Time
    Chemical Substances Gonadal Steroid Hormones ; Steroids
    Language English
    Publishing date 2020-11-29
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S. ; Review
    ZDB-ID 214409-8
    ISSN 1095-6867 ; 0018-506X
    ISSN (online) 1095-6867
    ISSN 0018-506X
    DOI 10.1016/j.yhbeh.2020.104900
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

    Zs.A 693: Show issues Location:
    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
    bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
    Jg. 1995 - 2021: Lesesall (1.OG)
    ab Jg. 2022: Lesesaal (EG)

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  2. Article ; Online: Adult Provisioning Influences Nestling Corticosterone Levels in Florida Scrub Jays (Aphelocoma coerulescens).

    Elderbrock, Emily K / Small, Thomas W / Schoech, Stephan J

    Physiological and biochemical zoology : PBZ

    2018  Volume 91, Issue 6, Page(s) 1083–1090

    Abstract: We studied Florida scrub jay (Aphelocoma coerulescens) nestlings to examine the relationship between parental feeding rates and levels of corticosterone (CORT), a metabolic and stress-related steroid hormone hypothesized to play a role in mediating ... ...

    Abstract We studied Florida scrub jay (Aphelocoma coerulescens) nestlings to examine the relationship between parental feeding rates and levels of corticosterone (CORT), a metabolic and stress-related steroid hormone hypothesized to play a role in mediating begging behavior. It has been documented that nutritional deficiency results in increased glucocorticoid levels in nestling birds. Further, previous studies have found that CORT levels of Florida scrub jay nestlings are negatively correlated with parental nest attendance and provisioning rates; however, the behavioral observations were made several days before the collection of samples to assess CORT levels. Few studies have investigated whether experience immediately before sampling impacts nestling glucocorticoid levels, especially in a free-living species. By monitoring parental activity at the nest before sample collection, we found that nestling CORT levels varied as a function of parental provisioning rate and the time since their last feed. However, counter to our predictions, higher provisioning rates and more recent feedings were associated with higher CORT levels in nestlings rather than lower CORT levels. These results suggest that some aspect of parental provisioning results in increased CORT levels in nestling Florida scrub jays.
    MeSH term(s) Animals ; Corticosterone/blood ; Female ; Maternal Behavior ; Nesting Behavior ; Songbirds/physiology
    Chemical Substances Corticosterone (W980KJ009P)
    Language English
    Publishing date 2018-09-26
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 1473845-4
    ISSN 1537-5293 ; 1522-2152
    ISSN (online) 1537-5293
    ISSN 1522-2152
    DOI 10.1086/700258
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Influence of corticosterone treatment on nestling begging in Florida scrub-jays (Aphelocoma coerulescens).

    Elderbrock, Emily K / Small, Thomas W / Schoech, Stephan J

    General and comparative endocrinology

    2018  Volume 259, Page(s) 213–222

    Abstract: Altricial young are dependent on adults for protection and food, and they display nutritional need by begging to elicit feeding from parents. Begging at high levels can be energetically expensive and attract predators; thus, an individual must balance ... ...

    Abstract Altricial young are dependent on adults for protection and food, and they display nutritional need by begging to elicit feeding from parents. Begging at high levels can be energetically expensive and attract predators; thus, an individual must balance its nutritional needs with these potential costs. Further, because a parent is limited in the amount of food it can provide, begging can contribute to both parent-offspring conflict and sibling-sibling competition. Many extrinsic and intrinsic factors may contribute to begging behavior. One intrinsic factor of interest is corticosterone (CORT), a metabolic hormone hypothesized to play a role in regulating a nestling's begging behavior. We investigated the hypothesis that increased exposure to CORT influences nestling begging behavior in an altricial species, the Florida scrub-jay (Aphelocoma coerulescens). We treated one nestling per treatment nest with a twice-daily dose of exogenous hormone via a CORT-injected waxworm, whereas a second individual received a vehicle-injected waxworm. We monitored individual nestling and adult behavior at all nests with the use of high-definition video cameras on several days during treatment. We found no difference in begging rate between CORT fed and vehicle fed nestlings within a treatment nest. Further, to determine whether CORT treatment had indirect effects on the entire brood, we monitored additional nests, in which nestlings were not manipulated. When treatment and controls were compared, overall begging rates of nestlings in treatment nests were greater than those in control nests. This result suggests that CORT treatment of an individual altered its behavior, as well as that of its siblings.
    MeSH term(s) Animals ; Birds ; Corticosterone/pharmacology ; Corticosterone/therapeutic use ; Female ; Nesting Behavior/physiology
    Chemical Substances Corticosterone (W980KJ009P)
    Language English
    Publishing date 2018--01
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 1851-x
    ISSN 1095-6840 ; 0016-6480
    ISSN (online) 1095-6840
    ISSN 0016-6480
    DOI 10.1016/j.ygcen.2017.12.003
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

    Zs.A 164: Show issues Location:
    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
    bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
    Jg. 1995 - 2021: Lesesall (1.OG)
    ab Jg. 2022: Lesesaal (EG)

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  4. Article ; Online: Stress-responsiveness influences baseline glucocorticoid levels: Revisiting the under 3min sampling rule.

    Small, Thomas W / Bebus, Sara E / Bridge, Eli S / Elderbrock, Emily K / Ferguson, Stephen M / Jones, Blake C / Schoech, Stephan J

    General and comparative endocrinology

    2017  Volume 247, Page(s) 152–165

    Abstract: Plasma glucocorticoid (CORT) levels collected within 3min of capture are commonly believed to reflect pre-stressor, baseline CORT levels. Differences in these "baseline" values are often interpreted as reflecting differences in health, or the amount of ... ...

    Abstract Plasma glucocorticoid (CORT) levels collected within 3min of capture are commonly believed to reflect pre-stressor, baseline CORT levels. Differences in these "baseline" values are often interpreted as reflecting differences in health, or the amount of social and environmental stress recently experienced by an individual. When interpreting "baseline" values it is generally assumed that any effect of capture-and-handling during the initial sampling period is small enough and consistent enough among individuals to not obscure pre-capture differences in CORT levels. However, plasma CORT increases in less than 3min post-capture in many free-living, endothermic species in which timing has been assessed. In addition, the rate of CORT secretion and the maximum level attained (i.e., the degree of stress-responsiveness) during a severe stressor often differs among individuals of the same species. In Florida scrub-jays (Aphelocoma coerulescens), an individual's stress-responsiveness during a 30min post-capture stressor is correlated with CORT levels in samples collected within 1.5min of capture, suggesting there is an intrinsic connection between stress-responsiveness and pre-capture CORT levels. Although differences in stress-responsiveness accounted for just 11% of the variance in these samples, on average, higher stress-responsive jays (top third of individuals) had baseline values twice that of lower stress-responsive jays (bottom third). Further, plasma CORT levels begin to increase around 2min post-capture in this species, but the rate of increase between 2 and 3min differs markedly with CORT increasing more rapidly in jays with higher stress-responsiveness. Together, these data indicate that baseline CORT values can be influenced by an individual's stress response phenotype and the differences due to stress-responsiveness can be exaggerated during sample collection. In some cases, the effects of differences in stress-responsiveness and the increase in CORT during sample collection could obscure, or supersede, differences in pre-capture plasma CORT levels that are caused by extrinsic factors.
    MeSH term(s) Animals ; Corticosterone/blood ; Female ; Glucocorticoids/pharmacology ; Linear Models ; Male ; Models, Biological ; Passeriformes/blood ; Passeriformes/physiology ; Phenotype ; Statistics, Nonparametric ; Stress, Physiological/drug effects ; Stress, Physiological/physiology
    Chemical Substances Glucocorticoids ; Corticosterone (W980KJ009P)
    Language English
    Publishing date 2017-06-01
    Publishing country United States
    Document type Journal Article
    ZDB-ID 1851-x
    ISSN 1095-6840 ; 0016-6480
    ISSN (online) 1095-6840
    ISSN 0016-6480
    DOI 10.1016/j.ygcen.2017.01.028
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

    Zs.A 164: Show issues Location:
    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
    bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
    Jg. 1995 - 2021: Lesesall (1.OG)
    ab Jg. 2022: Lesesaal (EG)

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  5. Article: Problems with Using Ptilochronology to Measure the Growth and Nutritional Status of Nestling Bluebirds

    Elderbrock, Emily K / Kern Michael D / Lynn Sharon E

    Condor. 2012 Nov., v. 114, no. 4

    2012  

    Abstract: Variation in habitat quality can influence birds' survival and reproduction profoundly, but many methods for assessing it are logistically difficult. Ptilochronology is a method of determining the nutritional state of a bird by measuring the width of the ...

    Abstract Variation in habitat quality can influence birds' survival and reproduction profoundly, but many methods for assessing it are logistically difficult. Ptilochronology is a method of determining the nutritional state of a bird by measuring the width of the growth bars on its feathers and may be a useful proxy for assessing habitat quality. Since each growth bar is thought to represent 24 hr of feather growth, the average size of growth bars provides a record of the bird's nutritional state during feather growth. Ptilochronology has been validated in adult birds but may not be reliable when applied to nestlings. We compared the growth rate of remiges and the average width of the growth bars on them in Eastern Bluebird (Sialia sialis) chicks. On average, the width of growth bars was slightly less than 50% of that expected if each bar corresponded to the daily growth of the feather. The average width of the growth bars also failed to correlate with the concurrent growth rates of the wing and the remiges themselves, although growth rates of the latter were significantly related. Growth bars on nestlings' feathers were also narrower than those of adult bluebirds and their size varied considerably. These data suggest that nestlings' feathers undergo daily pulses of growth that are variable in duration and number, and consequently ptilochronology may not be a reliable method for determining the growth rate of the feathers and hence determining the nutritional status of nestling birds.
    Keywords Sialia sialis ; adults ; birds ; chicks ; feathers ; habitats ; nestlings ; nutritional status ; reproduction ; Eastern Bluebird ; growth bars ; ptilochronology
    Language English
    Dates of publication 2012-11
    Size p. 823-830.
    Publishing place University of California Press
    Document type Article
    ISSN 1938-5422
    DOI 10.1525%2Fcond.2012.110191
    Database NAL-Catalogue (AGRICOLA)

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  6. Article: Problems with Using Ptilochronology to Measure the Growth and Nutritional Status of Nestling Bluebirds

    Elderbrock, Emily K. / Kern Michael D. / Lynn Sharon E.

    Condor

    Volume v. 114,, Issue no. 4

    Abstract: Variation in habitat quality can influence birds' survival and reproduction profoundly, but many methods for assessing it are logistically difficult. Ptilochronology is a method of determining the nutritional state of a bird by measuring the width of the ...

    Abstract Variation in habitat quality can influence birds' survival and reproduction profoundly, but many methods for assessing it are logistically difficult. Ptilochronology is a method of determining the nutritional state of a bird by measuring the width of the growth bars on its feathers and may be a useful proxy for assessing habitat quality. Since each growth bar is thought to represent 24 hr of feather growth, the average size of growth bars provides a record of the bird's nutritional state during feather growth. Ptilochronology has been validated in adult birds but may not be reliable when applied to nestlings. We compared the growth rate of remiges and the average width of the growth bars on them in Eastern Bluebird (Sialia sialis) chicks. On average, the width of growth bars was slightly less than 50% of that expected if each bar corresponded to the daily growth of the feather. The average width of the growth bars also failed to correlate with the concurrent growth rates of the wing and the remiges themselves, although growth rates of the latter were significantly related. Growth bars on nestlings' feathers were also narrower than those of adult bluebirds and their size varied considerably. These data suggest that nestlings' feathers undergo daily pulses of growth that are variable in duration and number, and consequently ptilochronology may not be a reliable method for determining the growth rate of the feathers and hence determining the nutritional status of nestling birds.
    Language English
    Document type Article
    ISSN 1938-5422
    Database AGRIS - International Information System for the Agricultural Sciences and Technology

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