From Tragedy to Triumph: Renesting in Ring-Billed Gulls

Abstract

ABsTAcT.-When animals that provide parental care to offspring are faced with actual or potential failure during a breeding bout, the option to continue breeding is countered by the option to cut losses and forego reproduction until the next breeding season. In 1990, we recorded laying date and laying order of eggs in 51 Ring-billed Gull (Larus delawarensis) clutches prior to their total loss by flooding. Pairs remained on territory and produced new clutches following a refractory period of 11.6 ? SD of 1.9 days. Post-loss clutches were initiated synchronously (n = 51 clutches in four days; 89% of all clutches marked in the 7 x 7 m study plot) but mostly contained significantly fewer and lighter eggs than first clutches. We contrast incubation, hatching and chick survival patterns of these storm-delayed pairs in 1990 with patterns of early-, peak- and late-nesting pairs at the same colony in 1992. The incubation and within-clutch hatching patterns of post-loss clutches 1990 were most similar to those of late nesting pairs in 1992, yet these storm-delayed pairs realized a fledging success similar to that of early-and peak-nesting pairs in 1992. We discuss larid reproductive strategies in the context of conditions that favor successful renesting. Received 22 August 1994, accepted 27 January 1995.