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Growth curves were fitted to data collected by L.E. Richdale on Yellow- eyed Penguin (Megadyptes antipodes) chicks during three seasons in the 1930s, and compared statistically with curves fitted to data collected at the same locality over two seasons in the 1980s. Interseasonal variation also was compared across the five decades. Although the variation was similar, chicks from Richdale’s poorest season had higher fledging weights than chicks from two out of the three seasons monitored during the 1980s. Growth rates were significantly different for all comparisons except between the 1939-40 and 1983-84 seasons, with contemporary chicks tending to grow faster at 30 – 50 days of age, i.e. during the period of maximum growth. The slower growth of Richdale’s chicks during this period was not reflected in lower fledging weights. As growth rates are more likely to be affected by diet than by other factors, this difference may be due to a change in the availability or quality of prey items during the chick-rearing period, perhaps in response to long-term commercial fishing pressure in the area.