Annual changes in body mass and resting metabolism in captive barnacle geese (Branta leucopsis): the importance of wing moult

Abstract

SUMMARY Many different physiological changes have been observed in wild waterfowl during the flightless stage of wing moult, including a loss of body mass. We aimed to determine whether captive barnacle geese (Branta leucopsis)would show the characteristic decrease in body mass during their wing moult,even though they had unlimited and unrestricted access to food. Fourteen captive geese were weighed at 1–2-week intervals for two complete years. During the flightless period of the moult, body mass decreased by approximately 25% from the pre-moult value. To understand the basis of this change, the rate of oxygen consumption was measured during daytime and nighttime at six points in the second year, and at three points (before,during and after wing moult) behavioural observations were made. Measurements of the rate of oxygen consumption showed an 80% increase above that of the nonmoulting periods of the year. We propose that metabolism was increased during moult because of the cost of feather synthesis. Although food was available, the captive birds chose not to forage and instead increased the proportion of time spent resting. It is likely that this behaviour in response to wing moult is a strategy to avoid predation in the wild. Thus, the innate nature of this behaviour has potential survival value for wild birds of this species. We conclude that the increase in metabolism led to the use of endogenous energy reserves because the birds reduced rather than increased their food intake rates, and as a result, the barnacle geese lost body mass during wing moult.

Predicting the rate of oxygen consumption from heart rate in barnacle geeseBranta leucopsis: effects of captivity and annual changes in body condition

“…Training consisted of walking the birds at previously determined speeds for 2-3 h a week (see Ward et al, 2002). Sampling periods were selected based on year round body mass data, collected from the same captive flock of barnacle geese the previous year (see Portugal et al, 2007). Points chosen included the maximum and minimum body masses recorded in the year, and periods of body mass increase and decrease, in particular, those associated with wing moult.…”

“…Recent work on captive barnacle geese has demonstrated that they undergo changes in body mass, body composition and abdominal temperature similar to those of wild geese (Portugal et al, 2007;Portugal, 2008;Portugal et al, 2009). For example, despite ad libitum access to food, captive geese lost approximately 25% of their body mass during their annual wing moult, while simultaneously experiencing an increase in the resting rate of metabolism of approximately 80% (Portugal et al, 2007). These findings are comparable with those found for wild moulting waterfowl (see Hohman et al, 1992).…”

Leukocyte profiles indicate nutritional, but not moulting stress in a migratory shorebird, the Common Snipe (Gallinago gallinago)

“…Alerstam and Lindström 1990;Hemborg and Lundberg 1998). Nutritional costs of moult are primarily associated with increased amino acid metabolism necessary for renewal of feathers, as well as with increased heat loss caused by reduced insulation (Lindström et al 1993;Klaassen 1995;Portugal et al 2007). Feather production results in a deposition of proteins that constitute up to 25% of lean body mass (Murphy and Taruscio 1995), and this process is associated with substantial increase of metabolic rate (Croxall 1982;Guillemette et al 2007).…”

Understanding the energetic costs of living in saline environments: effects of salinity on basal metabolic rate, body mass and daily energy consumption of a long-distance migratory shorebird

“…In birds, body mass loss has been considered a strategy to reduce maintenance cost during energy-costly activities such as reproduction (Freed, 1981;Norberg, 1981;Cavitt and Thomson, 1997;Bech et al, 2002), locomotion (Deerenberg et al, 1998;Elliott et al, 2008) and moulting (Portugal et al, 2007). Several studies have reported body mass losses in different species of aquatic birds during the adjustment period to saltwater (e.g.…”