Christopher A. Lepczyk, William H. Karasov
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We tested for the presence of compensatory growth (i.e. faster age-specific growth) following ephemeral periods of food restriction in altricial nestlings using the House Sparrow (Passer domesticus) as a model species. To simulate periods of poor food conditions, we raised nestlings in captivity, fed them a synthetic diet, and held them at constant body mass for 48 h beginning on either day 3 or 6 of life. Controls were fed according to an age-specific feeding schedule that yielded normal growth curves. During realimentation, restricted nestlings did not achieve a faster rate of growth than that of controls. Instead, these nestlings either died (all controls lived) or gained mass at a rate similar to that of controls. Consequently, restricted nestlings reached asymptotic mass two days later than control nestlings. Growth of culmen and tarsus was not affected, but growth of the eighth primary was reduced for several days in nestlings restricted at day 6 (i.e. late restricted), although this difference disappeared by the age of fledging. Because surviving nestlings achieved only a 15.9% increase in food consumption compared with unrestricted controls and were unable to translate it into a faster rate of growth, the nestlings may have been growing at a maximum rate. We found no differences between late-restricted and unrestricted nestlings in % water, % protein, % lipid, and % ash. The two groups were of similar maturity as measured by % body water and the water index. Our results are consistent with current theory in that periods of food restriction delayed the schedule of mass accretion by the length of the restriction period. Although House Sparrows have a labile growth rate and developmental time, our results did not support the hypothesis of compensatory growth. Based on this and one other study, compensatory growth does not appear to occur in altricial birds.

Christopher A. Lepczyk and William H. Karasov "EFFECT OF EPHEMERAL FOOD RESTRICTION ON GROWTH OF HOUSE SPARROWS," The Auk 117(1), 164-174, (1 January 2000). https://doi.org/10.1642/0004-8038(2000)117[0164:EOEFRO]2.0.CO;2
Received: 6 May 1998; Accepted: 1 June 1999; Published: 1 January 2000
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