VARIATIONS IN GROWTH OF ROSEATE TERN CHICKS - II - EARLY GROWTH AS ANINDEX OF PARENTAL QUALITY

We measured growth of Roseate Tern (Sterna dougallii) chicks at a colo ny in Connecticut in 10 successive years, 1987-1996. Data on body mass during the first 3-4 days of life were fitted to a quadratic regressi on model, yielding three parameters of early growth for each of 1,551 chicks: mass at hatching, linear growth, and quadratic growth. First c hicks in each brood (A-chicks) exceeded second chicks (B-chicks) in ea ch of the three growth parameters; A-chicks from broods of two grew fa ster during the first 3 days than single chicks. The three parameters of early growth depended upon egg mass, hatch order, hatch date, and y ear, but not on parental age after controlling for effects of the othe r variables. The linear and quadratic growth parameters were negativel y correlated. Subsequent growth and survival of chicks were predicted by all three parameters of early growth. After controlling for effects of early growth, none of the other variables measured (hatch date, eg g mass, parental age, hatching asynchrony, female-female pairing, or t rapping) contributed significantly to explaining later growth or survi val. Year effects were substantial in only 2 of the 10 years of study. Individual pairs were consistent in performance (as indexed by early growth) in successive years. These results suggest that growth and sur vival of Roseate Tern chicks are determined primarily by parental qual ity; much of the information about parental quality is expressed by th e time the eggs are laid, and most of it is expressed by the time the chicks are three days old.