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Vernasco BJ, Emmerson MG, Gilbert ER, Sewall KB, Watts HE. Migratory state and patterns of steroid hormone regulation in the pectoralis muscle of a nomadic migrant, the pine siskin (Spinus pinus). Gen Comp Endocrinol 2021; 309:113787. [PMID: 33862052 DOI: 10.1016/j.ygcen.2021.113787] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 04/07/2021] [Accepted: 04/10/2021] [Indexed: 10/21/2022]
Abstract
The endocrine system is known to mediate responses to environmental change and transitions between different life stages (e.g., a non-breeding to a breeding life stage). Previous works from the field of environmental endocrinology have primarily focused on changes in circulating hormones, but a comprehensive understanding of endocrine signaling pathways requires studying changes in additional endocrine components (e.g., receptor densities) in a diversity of contexts and life stages. Migratory birds, for instance, can exhibit dramatic changes in their physiology and behavior, and both sex steroids as well as glucocorticoids are proposed mediators of the transition into a migratory state. However, the role of changes in endocrine signaling components within integral target tissues, such as flight muscles, in modulating the transition into a migratory state remains poorly understood. Here, we examined changes in gene expression levels of and correlational patterns (i.e., integration) between 8 endocrine signaling components associated with either glucocorticoids or sex steroid signaling in the pectoralis muscles of a nomadic migratory bird, the pine siskin (Spinus pinus). The pectoralis muscle is essential to migratory flight and undergoes conspicuous changes in preparation for migration, including hypertrophy. We focus on endocrine receptors and enzymes (e.g., 5α-reductase) that modulate the signaling capacity of circulating hormones within target tissues and may influence either catabolic or anabolic functioning within the pectoralis. Endocrine signaling components were compared between captive birds sampled prior to the expression of vernal migratory preparation and during the expression of a vernal migratory state. While birds exhibited differences in the size and color of the flight muscle and behavioral shifts indicative of a migratory state (i.e., zugunruhe), none of the measured endocrine components differed before and after the transition into the migratory state. Patterns of integration amongst all genes did, however, differ between the two life stages, suggesting the contrasting demands of different life stages may shape entire endocrine signaling networks within target tissues rather than individual components. Our work aligns with previous endocrine studies on pine siskins and, viewed together, suggest additional studies are needed to understand the endocrine system's role in mediating the development and progression of the vernal migratory state in this species. Further, the patterns observed in pine siskins, a nomadic migrant, differ from previous studies on obligate migrants and suggest that different mechanisms or interactions between endocrine signaling components may mediate the migratory transition in nomadic migrants.
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Affiliation(s)
- Ben J Vernasco
- School of Biological Sciences, Washington State University, Pullman, WA, USA.
| | | | | | - Kendra B Sewall
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA, USA
| | - Heather E Watts
- School of Biological Sciences, Washington State University, Pullman, WA, USA
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Kimmitt AA, Hardman JW, Stricker CA, Ketterson ED. Migratory strategy explains differences in timing of female reproductive development in seasonally sympatric songbirds. Funct Ecol 2019. [DOI: 10.1111/1365-2435.13386] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
| | - Jack W. Hardman
- Department of Biology Indiana University Bloomington Indiana
| | | | - Ellen D. Ketterson
- Department of Biology Indiana University Bloomington Indiana
- Environmental Resilience Institute Indiana University Bloomington Indiana
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3
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Robart AR, Morado MI, Watts HE. Declining food availability, corticosterone, and migratory response in a nomadic, irruptive migrant. Horm Behav 2019; 110:56-67. [PMID: 30802442 DOI: 10.1016/j.yhbeh.2019.02.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 01/10/2019] [Accepted: 02/08/2019] [Indexed: 11/24/2022]
Abstract
While obligate migrants time their movements to respond to predictable changes in the environment, facultative migration is characterized by more variable movements that are driven by unpredictable changes in resource availability. The proximate cues that trigger facultative migrations and the endocrine mechanisms involved in these responses remain poorly understood, though corticosterone may be a key mediator of facultative migration due to its effects on activity and metabolic processes. We conducted experiments in the fall and spring to examine the response of pine siskins (Spinus pinus), a facultative migrant, to a two-stage food restriction. Our goals were to examine whether declining food availability stimulated behavioral and/or physiological changes consistent with a migratory response, whether anticipatory behavioral and physiological adjustments occurred when birds were initially presented with changing food availability, and if observed changes corresponded to changes in circulating corticosterone levels. We found no evidence of preparatory physiological changes for migration, but food-restricted birds in the spring had increased daytime activity indicative of a migratory response. Corticosterone increased at each stage of the restriction and the change in corticosterone corresponded to the magnitude of decline in body condition. Increased corticosterone was also correlated with larger increases in activity during the initial stage of food restriction, but only during the spring, when birds also displayed higher levels of initial body condition. These results suggest that initial energetic state and corticosterone response may interact to determine an individual's behavioral and physiological response to declining food availability and ultimately the facultative migratory response.
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Affiliation(s)
- Ashley R Robart
- School of Biological Sciences, Washington State University, Pullman, WA 99164, United States of America; Department of Biology, Loyola Marymount University, Los Angeles, CA 90045, United States of America.
| | - Melissa I Morado
- Department of Biology, Loyola Marymount University, Los Angeles, CA 90045, United States of America
| | - Heather E Watts
- School of Biological Sciences, Washington State University, Pullman, WA 99164, United States of America; Center for Reproductive Biology, Washington State University, Pullman, WA 99164, United States of America; Department of Biology, Loyola Marymount University, Los Angeles, CA 90045, United States of America
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Eikenaar C, Hessler S, Ballstaedt E, Schmaljohann H, Kaiya H. Ghrelin, corticosterone and the resumption of migration from stopover, an automated telemetry study. Physiol Behav 2018; 194:450-455. [DOI: 10.1016/j.physbeh.2018.06.036] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 06/24/2018] [Accepted: 06/25/2018] [Indexed: 01/23/2023]
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Robart AR, McGuire MMK, Watts HE. Increasing photoperiod stimulates the initiation of spring migratory behaviour and physiology in a facultative migrant, the pine siskin. ROYAL SOCIETY OPEN SCIENCE 2018; 5:180876. [PMID: 30225078 PMCID: PMC6124035 DOI: 10.1098/rsos.180876] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 07/06/2018] [Indexed: 05/04/2023]
Abstract
The transition to a migratory state involves coordinated changes in physiology and behaviour. In species with regular, predictable (obligate) migrations, increasing day length triggers the expression of a spring migratory state and androgens play an important role in stimulating its development. By contrast, we know little about the environmental cues and endocrine mechanisms that regulate migration in species with less predictable (facultative) migrations. Here, we tested whether photoperiod stimulates a migratory state in a facultative nomadic migrant, the pine siskin (Spinus pinus). We exposed wintering birds to either a naturally increasing or short-day photoperiod and measured physiological and behavioural changes indicative of a migratory state. We also examined changes in circulating hormones that may play a role in the migratory transition. Natural-day, but not short-day, birds displayed physiological preparations for migration, including increases in fat deposition, and showed increased levels of migratory restlessness. We found no evidence for a role of corticosterone in the migratory transition, but testosterone may be important. This study is the first experimental test of the role of photoperiod in regulating facultative migration and demonstrates that the predictive cue used by many obligate migrants to time spring migration is also important in a facultative migrant.
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Affiliation(s)
- Ashley R. Robart
- School of Biological Sciences, Washington State University, Pullman, WA 99164, USA
- Department of Biology, Loyola Marymount University, Los Angeles, CA 90045, USA
| | - Mali M. K. McGuire
- Department of Biology, Loyola Marymount University, Los Angeles, CA 90045, USA
| | - Heather E. Watts
- School of Biological Sciences, Washington State University, Pullman, WA 99164, USA
- Center for Reproductive Biology, Washington State University, Pullman, WA 99164, USA
- Department of Biology, Loyola Marymount University, Los Angeles, CA 90045, USA
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Covino KM, Jawor JM, Morris SR, Moore FR. Sex-specific hypothalamic-pituitary-gonadal axis sensitivity in migrating songbirds. Horm Behav 2018; 97:112-120. [PMID: 29128250 DOI: 10.1016/j.yhbeh.2017.11.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 10/13/2017] [Accepted: 11/03/2017] [Indexed: 01/21/2023]
Abstract
In seasonally migratory species, the overlap between the migratory and breeding life history stages is a balance between the physiological and behavioral requirements of each stage. Previous studies investigating the degree to which songbirds prepare for breeding during spring migration have focused on either circulating hormone levels or direct measures of gonadal recrudescence. In this study, we evaluated the phenology of breeding preparation in a long-distance migratory songbird, the Swainson's Thrush (Catharus ustulatus), by assessing hypothalamic-pituitary-gonadal (HPG) axis sensitivity with gonadotropin-releasing hormone (GnRH) bioassays throughout the migratory period. During spring migration both males and females had a significant response to GnRH injections as reflected in elevated testosterone levels. The magnitude of response to GnRH injections, Rpotential, in females stayed consistent throughout spring migration; however, Rpotential in males increased as the migratory season progressed. It is clear that at least some degree of endocrinological breeding development occurs either before or during spring migration in both sexes, however the phenology appears to be sex specific. In males this breeding development continues at a relatively steady pace throughout the migratory period while in females, relatively little endocrine breeding development occurs during migration. These sex-specific differences in the phenology of the endocrine breeding development warrant future investigations for both male and female songbirds. Moreover, research focused on how physiological breeding development is balanced with the expression of migratory traits in long-distance songbird migrants is needed.
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Affiliation(s)
- Kristen M Covino
- Biology Department, Canisius College, 2001 Main St., Buffalo, NY 14208, USA; Department of Biological Sciences, University of Southern Mississippi, Hattiesburg, MS 39406, USA; Shoals Marine Laboratory, 102 Chase Ocean Engineering Lab, 24 Colovos Rd, Durham, NH 03824, USA.
| | - Jodie M Jawor
- Biology Department, Canisius College, 2001 Main St., Buffalo, NY 14208, USA
| | - Sara R Morris
- Department of Biological Sciences, University of Southern Mississippi, Hattiesburg, MS 39406, USA; Shoals Marine Laboratory, 102 Chase Ocean Engineering Lab, 24 Colovos Rd, Durham, NH 03824, USA
| | - Frank R Moore
- Biology Department, Canisius College, 2001 Main St., Buffalo, NY 14208, USA
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Eikenaar C. Endocrine regulation of fueling by hyperphagia in migratory birds. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2017; 203:439-445. [DOI: 10.1007/s00359-017-1152-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 01/05/2017] [Accepted: 01/28/2017] [Indexed: 02/07/2023]
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Ramenofsky M, Campion AW, Pérez JH, Krause JS, Németh Z. Behavioral and physiological traits of migrant and resident White-crowned Sparrows: a common garden approach. J Exp Biol 2017; 220:1330-1340. [DOI: 10.1242/jeb.148171] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 01/25/2017] [Indexed: 12/12/2022]
Abstract
To accommodate a migratory life history, migrants express a greater number of physiological and behavioral stages per annum than residents and are thus considered to have higher finite state diversity (FSD). To investigate the physiological mechanisms and constraints associated with migration, direct comparison of two subspecies of White-crowned Sparrow - migrant, Zonotrichia leucophrys gambelii and resident, Z.l.nuttalli - were made under common garden conditions of photoperiod and housing, as birds progressed from winter through the vernal life history stages. We tested the hypothesis that migrants (higher FSD) respond differently than residents (lower FSD) to the initial predictive cue, photoperiod, to initiate and integrate the progression of vernal stages of prenuptial molt, migration and development of breeding. If differences in vernal phenology were noted then the basis for the distinctions was considered genetic. Results: 1. residents had a lower threshold to vernal photoperiod with elevations of plasma androgen, growth and development of reproductive structures preceeding migrants, 2. only migrants displayed prenuptial molt, preparations for migration and migratory restlessness, 3. neither baseline nor stress-induced plasma corticosterone differed across subspecies suggesting energetic demands of the common garden were insufficient to induce a differential adrenocortical response in either subspecies highlighting the impact of environmental conditions on corticosterone secretion. Thus, in a common garden, Z.l.gambelii responds differently to the initial predictive cue, photoperiod, to initiate and execute the vernal stages of molt, migration and development of breeding in comparisons to the shared stage of breeding with Z.l.nuttalli confirming a genetic basis for the subspecies differences.
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Affiliation(s)
- Marilyn Ramenofsky
- Department of Neurobiology Physiology Behavior, Univ. of California, Davis CA, 95616, USA
| | - Andrew W. Campion
- Department of Neurobiology Physiology Behavior, Univ. of California, Davis CA, 95616, USA
- David Geffen School of Medicine, University of California, Los Angeles, CA, 90095, USA
| | - Jonathan H. Pérez
- Department of Neurobiology Physiology Behavior, Univ. of California, Davis CA, 95616, USA
| | - Jesse S. Krause
- Department of Neurobiology Physiology Behavior, Univ. of California, Davis CA, 95616, USA
| | - Zoltán Németh
- Department of Neurobiology Physiology Behavior, Univ. of California, Davis CA, 95616, USA
- MTA-DE “Lendület” Behavioral Ecology Research Group, Department of Evolutionary Zoology, University of Debrecen, Debrecen, Egyetem tér 1., 4032, Hungary
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9
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Seasonal expression of migratory behavior in a facultative migrant, the pine siskin. Behav Ecol Sociobiol 2016. [DOI: 10.1007/s00265-016-2248-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Bauer CM, Needham KB, Le CN, Stewart EC, Graham JL, Ketterson ED, Greives TJ. Hypothalamic-pituitary-adrenal axis activity is not elevated in a songbird (Junco hyemalis) preparing for migration. Gen Comp Endocrinol 2016; 232:60-6. [PMID: 26718082 DOI: 10.1016/j.ygcen.2015.12.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 12/01/2015] [Accepted: 12/19/2015] [Indexed: 11/23/2022]
Abstract
During spring, increasing daylengths stimulate gonadal development in migratory birds. However, late-stage reproductive development is typically postponed until migration has been completed. The hypothalamic-pituitary-adrenal (HPA) axis regulates the secretion of glucocorticoids, which have been associated with pre-migratory hyperphagia and fattening. The HPA-axis is also known to suppress the hypothalamic-pituitary-gonadal (HPG) axis, suggesting the possibility that final transition into the breeding life history stage may be slowed by glucocorticoids. We hypothesized that greater HPA-axis activity in individuals preparing for migration may foster preparation for migration while simultaneously acting as a "brake" on the development of the HPG-axis. To test this hypothesis, we sampled baseline corticosterone (CORT), stress-induced CORT, and negative feedback efficacy of Dark-eyed Juncos (Junco hyemalis) in an overwintering population that included both migratory (J.h. hyemalis) and resident (J.h. carolinensis) individuals. We predicted that compared to residents, migrants would have higher baseline CORT, higher stress-induced CORT, and weaker negative feedback. Juncos were sampled in western Virginia in early March, which was about 2-4wk before migratory departure for migrants and 4-5wk before first clutch initiation for residents. Contrary to our predictions, we found that migrants had lower baseline and stress-induced CORT and similar negative feedback efficacy compared with residents, which suggests that delayed breeding in migrants is influenced by other physiological mechanisms. Our findings also suggest that baseline CORT is not elevated during pre-migratory fattening, as migrants had lower baseline CORT and were fatter than residents.
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Affiliation(s)
- Carolyn M Bauer
- Department of Biological Sciences, North Dakota State University, Fargo, ND, USA.
| | - Katie B Needham
- Department of Biological Sciences, North Dakota State University, Fargo, ND, USA
| | - Chuong N Le
- Department of Biological Sciences, North Dakota State University, Fargo, ND, USA
| | - Emily C Stewart
- Department of Biological Sciences, North Dakota State University, Fargo, ND, USA
| | - Jessica L Graham
- Department of Biological Sciences, North Dakota State University, Fargo, ND, USA
| | | | - Timothy J Greives
- Department of Biological Sciences, North Dakota State University, Fargo, ND, USA
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Covino KM, Morris SR, Moore FR. Patterns of testosterone in three Nearctic-Neotropical migratory songbirds during spring passage. Gen Comp Endocrinol 2015; 224:186-93. [PMID: 26315385 DOI: 10.1016/j.ygcen.2015.08.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Revised: 08/11/2015] [Accepted: 08/22/2015] [Indexed: 11/19/2022]
Abstract
Preparation for breeding may overlap extensively with vernal migration in long-distance migratory songbirds. Testosterone plays a central role in mediating this transition into breeding condition by facilitating changes to physiology and behavior. While changes in testosterone levels are well studied in captive migrants, these changes are less well known in free-living birds. We examined testosterone levels in free-living Nearctic-Neotropical migrants of three species during their vernal migration. Testosterone levels increased during the migratory period in males of all three species but significantly so in only two. Testosterone levels in females remained the same throughout their migration. Our results support the extensive overlap between vernal migration and breeding preparation in male songbirds. The pattern of testosterone changes during vernal migration is far from clear in females.
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Affiliation(s)
- Kristen M Covino
- Department of Biological Sciences, University of Southern Mississippi, 118 College Drive Box 5018, Hattiesburg, MS 39406, USA; Shoals Marine Laboratory, 102 Chase Ocean Engineering Lab, 24 Colovos Rd, Durham, NH 03824, USA.
| | - Sara R Morris
- Shoals Marine Laboratory, 102 Chase Ocean Engineering Lab, 24 Colovos Rd, Durham, NH 03824, USA; Biology Department, Canisius College, 2001 Main St., Buffalo, NY 14208, USA
| | - Frank R Moore
- Department of Biological Sciences, University of Southern Mississippi, 118 College Drive Box 5018, Hattiesburg, MS 39406, USA
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12
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Ketterson ED, Fudickar AM, Atwell JW, Greives TJ. Seasonal timing and population divergence: when to breed, when to migrate. Curr Opin Behav Sci 2015. [DOI: 10.1016/j.cobeha.2015.09.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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13
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Ramenofsky M, Németh Z. Regulatory mechanisms for the development of the migratory phenotype: roles for photoperiod and the gonad. Horm Behav 2014; 66:148-58. [PMID: 24780144 DOI: 10.1016/j.yhbeh.2014.04.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2013] [Revised: 04/21/2014] [Accepted: 04/22/2014] [Indexed: 12/15/2022]
Abstract
This article is part of a Special Issue "Energy Balance". Male white-crowned sparrows, Zonotrichia leucophrys gambelii, were studied to investigate roles of natural day length and the testes in regulating development and expression of the vernal migration phenotype. Previous work suggested that a pulse of androgen during winter months followed by the vernal increase in photoperiod promotes fueling (fat deposition) to support long distance flight; however, other traits required for successful migration remain untested. To investigate these points, birds were captured on their wintering grounds and castrated prior to winter solstice following Mattocks (1976). A subset of the castrates received 8mm Silastic implants of testosterone (T-castrates) and others blank implants (Blank-castrates) for 16 days in February. Shams were surgical controls. Migratory traits measured were as follows: 24h locomotor activity, prenuptial molt, body mass, fat score, flight muscle profile, cloacal protuberance (CPL) and plasma androgens measured over 28 weeks divided into 3 experimental periods (pre-implant, implant, and post-implant). Under short day lengths, castration increased diurnal locomotor activity over Shams. Testosterone implants temporarily enhanced CPL, plasma androgens and flight muscle enlargement, but failed to induce migratory restlessness. Whereas all groups exhibited seasonal increases in mass, fat score and muscle profile, only Shams showed timely onset and completion of prenuptial molt and migratory restlessness. Thus, for castrated males exposed to naturally increasing day lengths, the organizational effects of a transient testosterone surge were not sufficient to actuate a timely spring molt and migratory behavior. A fully functional testis that can organize central processes is required for the entire expression of the spring migratory phenotype.
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Affiliation(s)
- Marilyn Ramenofsky
- University of California Davis, Department of Neurobiology Physiology and Behavior, Davis, CA 95616, USA.
| | - Zoltán Németh
- University of California Davis, Department of Neurobiology Physiology and Behavior, Davis, CA 95616, USA
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