Evidence for spring stopover refuelling in migrating silver-haired bats (Lasionycteris noctivagans)

2019 ◽  
Vol 97 (11) ◽  
pp. 961-970 ◽  
Author(s):  
Kristin A. Jonasson ◽  
Christopher G. Guglielmo
Keyword(s):  
Ambient Temperature ◽  
Stopover Site ◽  
Migratory Movement ◽  
Departure Probability ◽  
Radio Transmitters ◽  
Fat Stores ◽  
Stopover Habitat ◽  
Spring Stopover ◽  
Lasionycteris Noctivagans ◽  
Automated Telemetry

Migrating animals must acquire sufficient fuel to sustain migratory movement, but how time is allocated to achieve this can vary greatly. The fuel strategies used by migrating bats are not well understood and have not been investigated during the spring when insectivorous bats face low food abundance. Migrating silver-haired bats (Lasionycteris noctivagans (Le Conte, 1831)) were captured at a stopover site in Long Point, Ontario, Canada, in April and May of 2012–2014. We followed the movements of 40 bats outfitted with radio transmitters using an automated telemetry array and examined the effects of ambient temperature, fat stores, and sex on stopover duration. As seen previously in autumn, most bats departed the evening following capture, but one-third of bats used multiday stopovers. Extended stopover was associated with lower ambient temperature. There was no effect of sex or fat at capture on stopover departure probability. Bats captured closer to dawn had greater fat mass and lean mass than those captured early in the night, a trend indicative of fuel deposition at this site. This is the first study to provide evidence that bats use stopover habitat for refuelling.

Condition-Dependent Nocturnal Hypothermia in Garden WarblersSylvia borinat a Spring Stopover Site

Ardea ◽  
2014 ◽  
Vol 101 (2) ◽  
pp. 113-119 ◽  
Author(s):  
Marco Cianchetti Benedetti ◽  
Leonida Fusani ◽  
Roberto Bonanni ◽  
Massimiliano Cardinale ◽  
Claudio Carere
Keyword(s):  
Stopover Site ◽  
Spring Stopover

Differential migration and body condition in Northern Wheatears (Oenanthe oenanthe) at a Mediterranean spring stopover site

2012 ◽  
Vol 154 (2) ◽  
pp. 321-328 ◽  
Author(s):  
Ivan Maggini ◽  
Fernando Spina ◽  
Christian C. Voigt ◽  
Andrea Ferri ◽  
Franz Bairlein
Keyword(s):  
Body Condition ◽  
Differential Migration ◽  
Stopover Site ◽  
Oenanthe Oenanthe ◽  
Spring Stopover

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.

Effect of forager density on feeding rates in spring-staging Semipalmated Sandpipers (Calidris pusilla) using different foraging modes

2018 ◽  
Vol 96 (9) ◽  
pp. 996-1001 ◽  
Author(s):  
Ivana Novcic ◽  
Guy Beauchamp
Keyword(s):  
Delaware Bay ◽  
Nearest Neighbour ◽  
Feeding Rates ◽  
Stopover Site ◽  
Neighbour Distance ◽  
Short Intervals ◽  
Foraging Modes ◽  
Calidris Pusilla ◽  
Spring Stopover ◽  
Semipalmated Sandpipers

We examined the influence of the density of foragers on feeding rates of Semipalmated Sandpipers (Calidris pusilla (Linnaeus, 1766)) while using different foraging modes at a spring stopover site in Delaware Bay, USA. Using dynamic estimates of interindividual distances obtained at short intervals of time, we explored how forager density affected feeding rates when Semipalmated Sandpipers used visual pecking or tactile probing. Pecking rate significantly increased with interindividual distances, whereas probe rate was not affected by density. Our study also showed that in fast-moving foragers, such as Semipalmated Sandpipers, in which the number of nearby foragers and distance to the nearest neighbour continuously change throughout the foraging bout, pecking rates are more affected by nearest neighbour distance than by the number of foragers in their immediate vicinity. In addition, our study implies that foragers using different foraging modes might be differently affected by nearby competitors perhaps in response to prey disturbance by neighbours.

Alterations in body fat stores and plasma insulin levels with daily intervals of heat exposure in Holtzman rats

1993 ◽  
Vol 265 (5) ◽  
pp. R1109-R1114 ◽  
Author(s):  
C. J. De Souza ◽  
A. H. Meier
Keyword(s):  
Glucose Tolerance ◽  
Ambient Temperature ◽  
Body Fat ◽  
Plasma Glucose ◽  
Plasma Insulin ◽  
Time Of Day ◽  
Light Onset ◽  
Insulin Levels ◽  
Fat Stores ◽  
Plasma Insulin Levels

The ability of timed daily increases in ambient temperature (from 22 +/- 1 degree C to 40 +/- 1 degree C for 2 h) to alter body fat stores, blood lipid levels, and insulin resistance were tested in male Holtzman rats. Of the six times of day tested only temperature pulses administered 16 h after light onset consistently decreased body weights, retroperitoneal fat stores, and plasma insulin levels. Subsequently, temperature pulses were administered either 0 (TP0) or 16 (TP16) h after light onset (light-dark 12:12 h). While no differences were observed between the TP0 group and the constant temperature (22 degrees C) controls, decreases in body weight gain, food consumption, retroperitoneal fat stores, and plasma concentrations of insulin, cholesterol, and triglycerides were consistently observed in the TP16 group. Although changes in plasma glucose during an oral glucose tolerance test were similar when the two treatment groups were compared with their respective controls, glucose tolerance was achieved with less insulin in the TP16 animals than in their respective controls. Insulin effectiveness was greater in the TP16 group as indicated by a decrease in plasma glucose, after insulin injection, that was of greater magnitude and longer duration than in controls. Hence, timed daily increases in ambient temperature may decrease obesity in part by decreasing plasma insulin levels apparently as a consequence of increased tissue sensitivity to insulin (greater glucose tolerance and less insulin intolerance). Because the treatment is effective only at a particular time of day the findings support a role for circadian neuroendocrine interactions in the regulation of these metabolic states.

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