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Pectoral Muscle Mass (pectoral + muscle_mass)
Selected AbstractsRuddy turnstones Arenaria interpres rapidly build pectoral muscle after raptor scaresJOURNAL OF AVIAN BIOLOGY, Issue 5 2006Piet J. van den Hout To cope with changes in the environment, organisms not only show behavioural but also phenotypic adjustments. This is well established for the digestive tract. Here we present a first case of birds adjusting their flight machinery in response to predation risk. In an indoor experiment, ruddy turnstones Arenaria interpres were subjected to an unpredictable daily appearance of either a raptor or a small gull (as a control). Ruddy turnstones experiencing threat induced by a flying raptor model, longer than after similar passage by the gull model, refrained from feeding after this disturbance. Pectoral muscle mass, but not lean mass, responded in a course of a few days to changes in the perceived threat of predation. Pectoral muscle mass increased after raptor scares. Taking the small increases in body mass into account, pectoral muscle mass was 3.6% higher than aerodynamically predicted for constant flight performance. This demonstrates that perceived risk factors may directly affect organ size. [source] Intraspecific variation in avian pectoral muscle mass: constraints on maintaining manoeuvrability with increasing body massFUNCTIONAL ECOLOGY, Issue 2 2007MAURINE W. DIETZ Summary 1Within a single year, long-distance migrants undergo a minimum of four cycles of fuel storage and depletion because their migrations have at least one stopover. Each cycle includes an almost twofold change in body mass (mb). Pervasive predation threats beg the question whether escape flight abilities keep up with such large changes in mb. 2We derive aerodynamic predictions how pectoral muscle mass (mpm) should change with mb to maintain constant relative flight power. 3We tested these predictions with data on red knot Calidris canutus, a long-distance migrating wader that breeds in arctic tundra and winters in temperate and tropical coastal areas. We focused on the subspecies C. c. islandica. 4mpm varied with mb in a piecewise manner. In islandica knots with mb , 148 g, the slope (1·06) was indistinguishable from the prediction (1·25). In heavy knots (mb > 148 g) the slope was significantly lower (0·63), yielding a mpm 0·81 times lower than predicted at pre-departure weights (210 g). 5Manoeuvrability tests showed that above 160 g, knots were increasingly unable to make a 90° angle turn. This is consistent with mpm being increasingly smaller than predicted. 6Relatively low mpm enables savings on mass and hence flight costs, and savings on overall energy expenditure. We predict that reduced escape flight ability at high mb will be compensated by behavioural strategies to minimize predation risk. [source] Ruddy turnstones Arenaria interpres rapidly build pectoral muscle after raptor scaresJOURNAL OF AVIAN BIOLOGY, Issue 5 2006Piet J. van den Hout To cope with changes in the environment, organisms not only show behavioural but also phenotypic adjustments. This is well established for the digestive tract. Here we present a first case of birds adjusting their flight machinery in response to predation risk. In an indoor experiment, ruddy turnstones Arenaria interpres were subjected to an unpredictable daily appearance of either a raptor or a small gull (as a control). Ruddy turnstones experiencing threat induced by a flying raptor model, longer than after similar passage by the gull model, refrained from feeding after this disturbance. Pectoral muscle mass, but not lean mass, responded in a course of a few days to changes in the perceived threat of predation. Pectoral muscle mass increased after raptor scares. Taking the small increases in body mass into account, pectoral muscle mass was 3.6% higher than aerodynamically predicted for constant flight performance. This demonstrates that perceived risk factors may directly affect organ size. [source] Changes in body mass and organ size during wing moult in non-breeding greylag geese Anser anserJOURNAL OF AVIAN BIOLOGY, Issue 6 2005Anthony D. Fox The "cost-benefit" hypothesis states that specific body organs show mass changes consistent with a trade-off between the importance of their function and cost of their maintenance. We tested four predictions from this hypothesis using data on non-breeding greylag geese Anser anser during the course of remigial moult: namely that (i) pectoral muscles and heart would atrophy followed by hypertrophy, (ii) leg muscles would hypertrophy followed by atrophy, (iii) that digestive organs and liver would atrophy followed by hypertrophy and (iv) fat depots be depleted. Dissection of geese captured on three different dates during wing moult on the Danish island of Saltholm provided data on locomotory muscles and digestive organ size that confirmed these predictions. Locomotory organs associated with flight showed initial atrophy (a maximum loss of 23% of the initial pectoral muscle mass and 37% heart tissue) followed by hypertrophy as birds regained the powers of flight. Locomotory organs associated with running (leg muscles, since geese habitually run to the safety of water from predator-type stimuli) showed initial hypertrophy (a maximum gain of 37% over initial mass) followed by atrophy. The intestines and liver showed initial atrophy (41% and 37% respectively), consistent with observed reductions in daily time spent feeding during moult, followed by hypertrophy. The majority of the 22% loss in overall body mass (mean 760 g) during the flightless period involved fat utilisation, apparently consumed to meet shortfalls between daily energetic needs and observed rates of exogenous intake. The results support the hypothesis that such phenotypic plasticity in size of fat stores, locomotor and digestive organs can be interpreted as an evolutionary adaptation to meet the conflicting needs of the wing moult. [source] | ||||||||||