Variable energetic responses to clutch size manipulations in white‐throated dippers Cinclus cinclus

Abstract

We used the doubly‐labelled water technique to measure daily energy expenditure (DEE) of a free‐living uniparental incubator, the white‐throated dipper Cinclus cinclus, in Scotland. DEE was 205±8 (s.e.m.) kJ d−1 for 17 females incubating their natural clutch sizes, equivalent to 3.2±0.1×basal metabolic rate (BMR). To investigate the influence of clutch size on the energy budget, we measured the DEE of 14 females with clutches increased or reduced by a single egg. Birds with reduced clutch sizes had an energy expenditure with a mean and variance that did not differ from those of birds with unmanipulated clutches. Enlarging the clutch led to an increase in energy expenditure to over 4×BMR for some individuals but not for others, resulting in greater variance in energy expenditure for birds with enlarged clutches. Individual variation in energy expenditure could not be fully explained by environmental conditions, by patterns of behaviour or clutch size. Incubating females received a maximum of only 4 kJ d−1 (2% of DEE) from provisioning by the male, and mobilised up to 6 kJ d−1 (3% of DEE) from reserves. Females spent 2.9±0.2 h (n=20) away from the nest each day, so a foraging rate of 95 kJ h−1 was required during incubation recesses to balance DEE. This ‘required foraging rate’ is double previous estimates of the maximum rates of energy acquisition for birds of this size. We suggest that the greater likelihood of a raised energy expenditure associated with larger clutches, combined with the difficulties in maintaining energy supplies, may constitute a constraint on avian clutch size.

A molecular genetic analysis of the communal nesting of the ostrich (Struthio camelus)

“…in press), but there are apparently no data on incubation costs in ostriches. The existence of a ring of ejected, peripheral eggs surrounding the nest may also attract predators to the nest, as these eggs are more visible than the eggs covered by the incubating bird (Bertram 1992). It is possible that the major female's own eggs might have a greater chance of escaping predation due to the dilution effect of risk with a larger number of eggs (Bertram 1992).…”

Female zebra finches compromise clutch temperature in energetically demanding incubation conditions

“…Monaghan & Nager 1997). In line with this, clutch enlargement does not always elevate overall daily energy expenditure during incubation (Moreno & Carlson 1989; Engstrand, Ward & Bryant 2002; de Heij et al. 2008), but may nonetheless elevate the instantaneous metabolic cost of keeping eggs warm (de Heij et al.…”

“…Monaghan & Nager 1997). In line with this, clutch enlargement does not always elevate overall daily energy expenditure during incubation (Moreno & Carlson 1989;Engstrand, Ward & Bryant 2002;de Heij et al 2008), but may nonetheless elevate the instantaneous metabolic cost of keeping eggs warm (de Heij et al 2007) and decrease parental fitness (de Heij, van den Hout & Tinbergen 2006). In addition, results from this work suggests that females do not always pay the full energetic cost of incubating additional eggs, because maintaining equilibrium egg temperatures also when incubating enlarged clutches would presumably require a substantial increase of parental energetic investment.…”

“…Similarly, parents allocate less energy to egg heating when incubation costs are experimentally relieved (Bryan & Bryant 1999;Cresswell et al 2004;Pe´rez et al 2008;Ardia et al 2009; D'Alba, Monaghan & Nager 2009). In line with this, variation in the amount of energy required for incubation has been shown to affect a variety of parental and neonatal fitness components, such as adult survival (Visser & Lessells 2001;de Heij, van den Hout & Tinbergen 2006), future fecundity (Hanssen et al 2005), chick rearing capacity (Heaney & Monaghan 1996;Reid, Monaghan & Ruxton 2000a,b;de Heij, van den Hout & Tinbergen 2006), hatching success (Moreno et al 1991;Siikama¨ki 1995;Reid, Monaghan & Ruxton 2000a,b;, fledging success (Reid, Monaghan & Ruxton 2000a,b;Ilmonen, Taarna & Hasselquist 2002), fledgling mass (Cichon 2000), nestling growth rate (Pe´rez et al 2008;Nilsson, Stjernman & Nilsson 2008) and incubation duration (Coleman & Whittall 1988;Moreno & Carlson 1989;Smith 1989;Siikama¨ki 1995;Wiebe & Martin 2000;Engstrand, Ward & Bryant 2002;Dobbs, Styrsky & Thompson 2006).…”

Comparison of Different Approaches for the Calculation of Energy Expenditure Using Doubly Labeled Water in a Small Mammal

“…Given this evidence, we believe that, at the very least, calculations using both approaches should be made to indicate the effect that such calculations might have on the conclusions being drawn. There is some indication that studies are already adopting this procedure (e.g., Costa and Gales 2003), but at present it is not being universally taken up (e.g., Engstrand et al 2002). We suggest that the availability of high-throughput mass spectrometry methods should make validation work for the DLW method much easier than has hitherto proved possible and that resolving the issues of the most appropriate calculation method should be seen as a priority for this validation work.…”