The effects of molt on the flight performance, body mass, and behavior of European starlings (Sturnus vulgaris): an experimental approach

Abstract

The physiological and energy costs of avian molt are well documented, but indirect consequences such as changes in flight performance have received less attention. Here, we report two experiments that investigated flight performance, body mass regulation, and behavior in captive starlings (Sturnus vulgaris). In the first experiment, we found a U-shaped change in take-off escape performance during natural molt: birds ascended at the shallowest trajectories during midmolt. Birds' body mass was also reduced during molt. In the second experiment, we manipulated the plumage of starlings to simulate different stages of flight-feather molt. This allowed us to separate the aerodynamic costs of feather loss from the physiological costs of feather synthesis normally associated with plumage growth. Through observations of flight (take-off, aerial maneuverability, and level flapping-flight speed) and behavioral parameters, we demonstrated that birds in simulated molt have reduced flight performance and reduced body mass. These birds also decrease the time spent performing energetically costly activities and seek areas of relative protection. In the longer term, some aspects of performance return to pretreatment levels, implying compensation for the plumage manipulations. Our results demonstrate that molt incurs significant functional costs that may play an important role in the adaptive radiation of molt strategies and molt patterns observed in avian species.

Moult strategies of Cory’s Shearwaters Calonectris diomedea borealis: the influence of colony location, sex and individual breeding status

“…Moult is a costly process to birds because feather growth requires a substantial input of nutrients and energy (Rayner and Swaddle 2000) and because flight efficiency is impaired during feather replacement (Swaddle and Witter 1997;Hedenström and Sunada 1999). It is therefore rare for moult to coincide with other energy-demanding annual events, such as reproduction and migration (Payne 1969;Rubolini et al 2002;Bridge 2006;Munro et al 2006;Newton 2008).…”

Patterns of Seasonal Abundance and Social Segregation in Inland and Coastal Plain Swamp Sparrows in a Delaware Tidal Marsh

“…Swamp Sparrows were unusually unresponsive on this date; three individuals observed at close range were color-banded (local breeders), in visibly heavy molt. It is possible that at this time molting Swamp Sparrows are shyer and more difficult to detect than later in the autumn, as has been reported for other passerines (Haukioja 1971, Swaddle andwitter 1997). Coastal Plain Swamp Sparrows were distinctly more conspicuous at the end of September and beginning of October after the completion of molt, and birds were frequently observed singing at this time.…”

Comunidade de aves de sub-bosque em uma área de entorno do Parque Nacional do Itatiaia, Rio de Janeiro, Brasil

“…O período de mudas de penas envolve um grande gasto energético, tanto pela síntese de novas penas quanto pela redução da aerodinãmica e isolamento térmico (CHAI 1997, MERILA 1997, e é desejável que isso ocorra dentro do período de maior disponibilidade de recursos alimentares. Alguns autores observaram que a muda de penas das asas ocorrem em período mais curto que as da cauda, pois aquelas afetam diretamente a eficiência do vôo (GINN & MELVILLE 1995, SWADDLE & WITTER 1997). ciclo, a percentagem de indivíduos com placa de incubação foi maior, seguida por muda de contorno e muda de vôo (Fig.…”