We measured the energy requirements during postnatal development of six hand-reared Common Loon (Gavia immer) chicks using continuous feeding trials and doubly labeled water. At fledging, the mean (?? SE) body mass of chicks was 3,246 ?? 51 g. They reached asymptotic body mass in ???66 days and had a mean growth rate constant of 0.089 ?? 0.002 day-1, which was greater than growth rate constants of other, similar-sized precocial birds. Between hatch and day 66, chicks allocated 16.5% of their metabolizable energy to new tissue, lower than the average for other bird species (20%), which might be expected considering their precocial mode of development. There was a developmental change in the assimilation efficiency of food (metabolizable energy coefficient), with a mean of 0.64 ?? 0.03 in chicks aged 21 days, rising to 0.83 ?? 0.07 in chicks aged 35 days. ?? The American Ornithologists' Union, 2007.
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Growth and energy requirements of captive-reared Common Loon (Gavia immer) chicks