Energy Utilization by Free‐Ranging Jackass Penguins, Spheniscus Demersus

Abstract

Rates of C02 production by breeding Jackass Penguins (mean mass, 3170 g) were measured by using doubly labeled water. Time budgets were estimated from behavioral observations, and energy budgets were calculated for a typical 2-d period of 24 h sitting on a nest and 24 hoff the nest (which includes 9 h foraging at sea). Distances traveled at sea were determined by using speed/ time meters harnessed to five birds containing doubly labeled water, and these measurements were used to calculate the energetic costs of swimming.Field metabolic rates (as C02 production) averaged 0.991 mL· g·L h-1 , or (in energy units) 3890 kJ·penguin-1.2 d-1 • Energy expenditures were 1.7 times the standard metabolic rate (SMR) while brooding, 6.6 x SMR while foraging, 9.8 x SMR while swimming underwater, and 2.6 x SMR integrated over a 2-d period. Penguins spent :::::48% of their energy budget and 19% of their time budget to obtain food. Foraging efficiency (the metabolizable energy gained while foraging + the energy used during foraging) was 2.

Metabolic rates of swimming Humboldt penguins

“…This discrepancy can be attributed to the methodology employed by Hui (1988) -a test cage pushed through the water by a boat -and the stress imposed on the birds because of the involuntary nature of the exercise. Nagy et al (1984), using doubly labelled water and a speed meter attached to free-ranging African penguins Spheniscus demersus, and RMR-values derived from allometric equations, determined a mean COT of 15.5 J (kg m) , or 55% higher than our measurement at the same speed. Besides additional COT imposed on the device-equipped birds by the frictional drag of the speed meters (cf.…”

“…Minimum power input (P cor ) and cost of transport (COT) calculated by assuming only one acceleration and subsequent sustained swimming speeds (Culik et al 1994a), and aerobic dive limits (ADL) of penguins calculated from energy requirements during swimming. Sources: (1) Bethge et al (1997), (2) Culik et al (1994a), (3) Nagy et al (1984), (4) Hui (1988), (5) Butler & Woakes (1984), and (6) this study…”

“…Besides additional COT imposed on the device-equipped birds by the frictional drag of the speed meters (cf. Culik et al 1994b), the use of an allometric equation as opposed to actually measured values of RMR water may have led to the high estimate of swimming metabolism by Nagy et al (1984).…”

Validation of Water Flux and Body Composition in Glaucous Gulls (Larus hyperboreus)

“…The turnover rate of isotopically labeled water (e.g., 3 H 2 O) has widely been used to evaluate net water flux, overall water bal ance, and food or water consumption in free-ranging animals (e.g., Nagy and Costa 1980;Hui 1981;Nagy et al 1984;Williams and Nagy 1985;Adams et al 1986;Costa 1987;Nagy and Pe terson 1988;Lea et al 2002). Despite its widespread application (see Nagy and Peterson 1988), only a modicum of validation studies have quantified the errors in water turnover measured isotopically compared with direct measures of water intake (Nagy and Costa 1980;Degen et al 1981;Costa 1987;Gales 1989;Robertson and Newgrain 1992;Lea et al 2002;Salatas et al 2002;Gessaman et al 2004).…”

Annual energy budget and food requirements of breeding wandering albatrosses ( Diomedea exulans )

“…Food consumption can also be estimated from energy budget models (e.g. Furness 1978) and from direct measures of metabolism (Nagy et al 1984;Gabrielsen et al 1987;Nagy 1987). Overall, these estimates may be critical for evaluating how individuals or populations respond to variability in the supply and demand of energy resources (Nagy 1989), and they may provide information about the role that seabirds play as top predators in the marine environment.…”