Does High Fecundity Reduce Survival in Song Sparrows?

Several life history models (reviewed by Stearns, 1976) incorporate the intuitively attractive assumption that animals forego maximum annual fecundity to increase their subsequent survival. Birds are among the most convenient animals to test this assumption, since fecundity and survival can be measured readily. Descriptive studies by Kluyver (1963) and Campbell (Lack, 1966, p. 109), and a recent experimental study by De Steven (1980), do not support the assumption. On the other hand, a descriptive study by Bryant (1979) and experimental studies by Kluyver (1971) and Askenmo (1979) do support the assumption. Further empirical information is needed to establish how often, and under what circumstances, survival and fecundity are negatively associated. In this paper I report on a positive association between reproductive performance and female survival in the song sparrow, Melospiza melodia. This study of an island population provided detailed life history information because individuals were sedentary and immigration rates low. I addressed the following questions: (1) Did females which disappeared between breeding seasons differ in fecundity and reproductive success from surviving females? (2) Are fecundity and reproductive success of individual females similar in successive years? (3) Are differences in fecundity and reproductive success heritable? (4) Is the probability that an individual will be recruited to the breeding population influenced by the size of clutch in which it was raised, or by the total fecundity of its mother in the year it was hatched?