Individually variable energy management strategies in relation to energetic costs of egg production

Francois Vezina, John Roger Speakman, Tony D. Williams

Research output: Contribution to journalArticle

44 Citations (Scopus)


Marked interindividual variation in metabolic rate suggests considerable complexity in energy management strategies, but attempts to further our understanding of the relationship between resting metabolic rate (RMR), daily energy expenditure (DEE), and reproductive effort have been hampered by the complexity of studying this system in the field. Here, we describe energy management strategies in a captive-breeding system, using Zebra Finches (Taeniopygia guttata), to demonstrate the high-level of complexity and interindividual variability in energy expenditure, food intake, locomotor activity, and reproductive effort. In particular, we investigated whether the increase in RMR associated with egg production is additive, resulting in higher DEE and a need for elevated food intake, or whether this cost is compensated by reduced expenditure in nonreproductive components of the energy budget. We found high levels of intra-individual variation in energy expenditure associated with egg production in female Zebra Finches, e.g., comparing nonbreeding stage with the one-egg stage, change in RMR varied from 4.0% and 41.3%, and change in DEE varied from -33.3% to +46.4%. This variation was systematically related to aspects of locomotor activity and reproductive effort. Females with the largest increase in RMR during egg production decreased locomotor activity the most but still had increased DEE at the one-egg stage, and females with high DEE at the one-egg stage produced larger clutches. Our study suggests that females minimize increases in DEE during egg production through behavioral energy reallocation (reduced locomotor activity) but that individuals differ in their use of this strategy, which, in turn, is related to the absolute level of reproductive investment. This suggests a very complex, individually variable system of energy management to meet the demands of egg production.

Original languageEnglish
Pages (from-to)2447-2458
Number of pages12
Issue number10
Publication statusPublished - Oct 2006


  • basal metabolic rate (BMR)
  • daily energy expenditure (DEE)
  • egg production costs
  • energy reallocation
  • reproduction
  • resting metabolic rate (RMR)
  • Taeniopygia guttata
  • Zebra Finch
  • finch taeniopygia guttata
  • starling sturnus vulgaris
  • labeled water technique
  • zebra finches
  • body water
  • intraspecific variation
  • respiratory quotient
  • indirect calorimetry
  • savannah sparrows


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