Factors Affecting Clutch and Brood Size in the Crow, Corvus cornix

Abstract

Positive correlations were found between large clutch size, low predation, and early breeding in a south Swedish population of the hooded crow, Corvus cornix L. Clutches in very dry habitat were smaller than others. Nestlings of above average weight one week before fledging suffered less mortality before independence than did light ones. The probability that a nestling will starve to death is independent of the clutch size. Starvation was most common during the first week of the nestling's life. Body weight one week before fledging was independent of the number of brood mates at that age. There was some evidence that pairs maintained approximately the same clutch size from year to year and it is speculated that the clutch size is in some way correlated to the number of nestlings each pair can expect to raise. It is also speculated that the early starvation of nestlings is a mechanism for late adjustment of the brood to an optimal size.