Great tits (Parus major) reduce body mass in response to wing area reduction: a field experiment

Risk of feather damage explains fault bar occurrence in a migrant hawk, the Swainson's hawk Buteo swainsoni

“…Thus, feather damage resulting from fault bars may reduce wing-tail surface area for long time periods. All of this is relevant for bird fitness because wing load (body weight/wing area) is crucial for flight performance (Pennycuick 1989), birds being forced to reduce their weight during even slight reductions of wing area # JOURNAL OF AVIAN BIOLOGY JOURNAL OF AVIAN BIOLOGY 37: 29 Á/35, 2006 JOURNAL OF AVIAN BIOLOGY 37:1 (2006) (Swaddle and Witter 1997, Lind and Jakobson 2001, Senar et al 2002. Moreover, experimental reductions of wing area are known to increase the energetic demands of birds, lowering their reproductive success (Mauck andGrubb 1995, Velando 2002).…”

The use of mass and fat reserve measurements from ringing studies to assess body condition

“…Increased mass may allow for more rapid moult, or may be traded off against moult duration and frequency so that there is no direct relationship between mass and fitness (eg Senar et al 1998, Bojarinova et al 1999, or may be reduced during moult to compensate for reduced flying ability (Lind & Jakobsson 2001, Senar et al 2002.…”

Responses to increased costs of activity during incubation in a songbird with female-only incubation: does feather colour signal coping ability?

“…This ability can be influenced by the quality, age and condition of the individual (Fox et al 2001). Individual quality and condition can be signalled to potential mates or rivals by various types of ornaments, including those based on carotenoids (Searcy and Nowicki 2005). Carotenoid-based colouration is widespread in animals, including feathers and bare parts in birds (Olson and Owens 2005).…”

“…Birds can be handicapped by adding weights (Wright and Cuthill 1989;Griggio et al 2005), taping their feathers (Senar et al 2002a) or feather clipping (Slagsvold and Lifjeld 1988;Sanz et al 2000). The last method is particularly suitable because it simulates events that can happen in the wild due to attacks by predators, and hence represents a risk to which birds might have become adapted (Slagsvold and Lifjeld 1990).…”