Maternal glucocorticoids are known to affect offspring phenotype in numerous vertebrate taxa. In birds, the maternal transfer of corticosterone to eggs was recently proposed as a hormonal mechanism by which offspring phenotype is matched to the relative quality of the maternal environment. However, current hypotheses lack supporting information on both intra- and inter-clutch variation in yolk ...

Various layer traits were recorded on 1082 pullets at 29 generation of selection to evaluate the variability for egg production. Oviposition time of each egg was recorded at hourly and half an hour intervals under 16L: 8D cycle, up to 40 weeks of age and for 15 days period respectively, to study the distribution pattern of oviposition time. Early (06-11h) and late (11-17 h) pattern of ovipositi...

It is poorly understood whether female morphological and behavioural traits can be used as 'signals'. In particular, experimental tests of the hypothesis that female ornaments reflect quality are scarce. Here, we experimentally examine whether female plumage coloration might signal maternal quality in the blue tit, Cyanistes caeruleus by forcing half of the females breeding in our population to...

Understanding the variation in selection pressure on key life-history traits is crucial in our rapidly changing world. Density is rarely considered as a selective agent. To study its importance, we partition phenotypic selection in fluctuating environments into components representing the population growth rate at low densities and the strength of density dependence, using a new stochastic mode...

Phenotypic plasticity is an important mechanism via which populations can respond to changing environmental conditions, but we know very little about how natural populations vary with respect to plasticity. Here we use random-regression animal models to understand the multivariate phenotypic and genetic patterns of plasticity variation in two key life-history traits, laying date and clutch size...

A male zebra finch, Taeniopygia guttata, kept with its father until adulthood develops an imitation of its father's song motif. We report here that the completeness of this imitation was sensitive to the social or auditory context in which the bird grew up: the greater the number of male siblings in a clutch, the shorter the mean duration of the song motif and the fewer the mean number of song ...

In this research, we focus on development of a new configuration magneto-rheological fluid (MRF) based clutch (MRC) featuring tooth-shaped disc with multiple teeth acting as magnetic poles the clutch. The is placed in housing composed left and right housing. inner face also has tooth shaped features mating through working MRF. Excitation coils are directly stationary winding cores both side An ...

Field studies were conducted with "three species of passerine, in order to investigate the possibility that an energetic constraint limits reproduction during incubation. Swallows (Hirundo rustiea), Dippers (Cinelus einelus) and Great Tits (Parus nlajor) were studied at sites in Central Scotland. All three species exhibit gynelateral intermittent incubation, so time and energy must be allocated...

During the mode transition from the pure electric propulsion mode to the hybrid propulsion mode, clutch-based pre-transmission parallel hybrid electric vehicles are subject to drivability issues. These issues originate from the fact that in the clutch-based pre-transmission parallel hybrid powertrain (CPPHP) configuration, the clutch connects the engine and the motor. Without a carefully design...