Photoperiodic Synchronization of Circannual Rhythms in Gonadal Activity, Migratory Restlessness, Body Weight, and Molt in the Garden Warbler (Sylvia borin)

2015 ◽  
pp. 30-44 ◽  
Author(s):  
Eberhard Gwinner
Keyword(s):  
Body Weight ◽  
Migratory Restlessness ◽  
Garden Warbler ◽  
Gonadal Activity ◽  
Sylvia Borin

scholarly journals Energy Stores, Oxidative Balance, and Sleep in Migratory Garden Warblers (Sylvia borin) and Whitethroats (Sylvia communis) at a Spring Stopover Site

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Andrea Ferretti ◽  
Scott R McWilliams ◽  
Niels C Rattenborg ◽  
Ivan Maggini ◽  
Massimiliano Cardinale ◽  
...  
Keyword(s):  
Food Intake ◽  
High Energy ◽  
Oxidative Status ◽  
Energy Reserves ◽  
Stopover Site ◽  
Garden Warbler ◽  
Oxidative Balance ◽  
Energy Stores ◽  
Sylvia Borin ◽  
Sylvia Communis

Synopsis Little is known about how songbirds modulate sleep during migratory periods. Due to the alternation of nocturnal endurance flights and diurnal refueling stopovers, sleep is likely to be a major constraint for many migratory passerine species. Sleep may help to increase the endogenous antioxidant capacity that counteracts free radicals produced during endurance flight and reduces energy expenditure. Here, we investigated the relationship between sleep behavior, food intake, and two markers of physiological condition—the amount of energy reserves and oxidative status—in two migratory songbird species, the garden warbler (Sylvia borin) and the whitethroat (Sylvia communis). In garden warblers, birds with high energy stores were more prone to sleep during the day, while this condition-dependent sleep pattern was not present in whitethroats. In both species, birds with low energy stores were more likely to sleep with their head tucked in the feathers during nocturnal sleep. Moreover, we found a positive correlation between food intake and the extent of energy reserves in garden warblers, but not in whitethroats. Finally, we did not find significant correlations between oxidative status and sleep, or oxidative status and energy stores. Despite our study was not comparative, it suggests that different species might use different strategies to manage their energy during stopover and, additionally, it raises the possibility that migrants have evolved physiological adaptations to deal with oxidative damage produced during migration.

scholarly journals Ghrelin affects stopover decisions and food intake in a long-distance migrant

2017 ◽  
Vol 114 (8) ◽  
pp. 1946-1951 ◽  
Author(s):  
Wolfgang Goymann ◽  
Sara Lupi ◽  
Hiroyuki Kaiya ◽  
Massimiliano Cardinale ◽  
Leonida Fusani
Keyword(s):  
Food Intake ◽  
Peptide Hormone ◽  
Migratory Behavior ◽  
Migratory Restlessness ◽  
Long Distance ◽  
Stopover Site ◽  
Blood Concentrations ◽  
Timing Of Migration ◽  
Fat Stores ◽  
Sylvia Borin

Billions of birds migrate long distances to either reach breeding areas or to spend the winter at more benign places. On migration, most passerines frequently stop over to rest and replenish their fuel reserves. To date, we know little regarding how they decide that they are ready to continue their journey. What physiological signals tell a bird’s brain that its fuel reserves are sufficient to resume migration? A network of hormones regulates food intake and body mass in vertebrates, including the recently discovered peptide hormone, ghrelin. Here, we show that ghrelin reflects body condition and influences migratory behavior of wild birds. We measured ghrelin levels of wild garden warblers (Sylvia borin) captured at a stopover site. Further, we manipulated blood concentrations of ghrelin to test its effects on food intake and migratory restlessness. We found that acylated ghrelin concentrations of garden warblers with larger fat scores were higher than those of birds without fat stores. Further, injections of unacylated ghrelin decreased food intake and increased migratory restlessness. These results represent experimental evidence that appetite-regulating hormones control migratory behavior. Our study lays a milestone in migration physiology because it provides the missing link between ecologically dependent factors such as condition and timing of migration. In addition, it offers insights in the regulation of the hormonal system controlling food intake and energy stores in vertebrates, whose disruption causes eating disorders and obesity.

Variation in hypothalamic gonadotrophin-releasing hormone content, plasma and pituitary LH, and in-vitro testosterone release in a long-distance migratory bird, the garden warbler (Sylvia borin), under constant photoperiods

1991 ◽  
Vol 128 (3) ◽  
pp. 339-345 ◽  
Author(s):  
C. K. Bluhm ◽  
H. Schwabl ◽  
I. Schwabl ◽  
A. Perera ◽  
B. K. Follett ◽  
...  
Keyword(s):  
Body Mass ◽  
In Vitro Release ◽  
Gradual Change ◽  
Long Distance ◽  
Garden Warbler ◽  
Releasing Hormone ◽  
Testicular Mass ◽  
Gonadotrophin Releasing Hormone ◽  
Sylvia Borin

ABSTRACT Changes in concentrations of hypothalamic gonadotrophin-releasing hormone (GnRH), pituitary and plasma LH, testicular mass, in-vitro release of testosterone, body mass and migratory activity were measured in male garden warblers (Sylvia borin) kept from November to June under a constant photoperiod of 12·8 h. Under such conditions garden warblers gradually change from the photorefractory to the photosensitive state and gonadal recrudescence then occurs. Hypothalamic GnRH content was low from December to March, but increased in April to reach the highest levels in June. The spontaneous increase in GnRH was paralleled by increases in pituitary LH content, testicular mass and in-vitro testosterone release. Body mass decreased 1 month and nocturnal activity 2 months before the spontaneous increase in GnRH. Ovine LH increased in-vitro testosterone release over basal release at all times. The results suggest that in garden warblers (1) changes in hypothalamic GnRH content can occur under constant photoperiodic condition, (2) the gradual change from the photorefractory to the photosensitive state is not characterized by a gradual increase in hypothalamic content of GnRH (cf. starlings), and (3) Leydig cells are capable of testosterone release even during the photorefractory state. Journal of Endocrinology (1991) 128, 339–345

Food availability affects migratory restlessness in caged garden warblers (Sylvia borin)

1985 ◽  
Vol 72 (1) ◽  
pp. 51-52 ◽  
Author(s):  
E. Gwinner ◽  
H. Biebach ◽  
I. v. Kries
Keyword(s):  
Food Availability ◽  
Migratory Restlessness ◽  
Sylvia Borin
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