FLIGHT-FEATHER MOLT PATTERNS AND AGE IN NORTH AMERICAN WOODPECKERS

--Specimens of 1399 North American woodpeckers were examined to assess flightfeather replacement patterns and their use in aging. The primaries and rectrices are fully replaced during the first prebasic molt in most species, but fully retained in two species. In contrast, all species typically retain secondaries and primary coverts during the first prebasic molt, and the regular retention of up to six secondaries during definitive prebasic molts is found in some birds of most species. Replacement of the primary coverts during the second prebasic molt is incomplete, 0-5 consecutive outer coverts typically being renewed. This delayed replacement pattern of primary coverts, not corresponding to the replacement of the primaries, may be unique in woodpeckers (and perhaps certain kingfishers) among birds. By combining retention patterns with differences in color pattern and relative wear between juvenal and adult feathers, many woodpeckers can be reliably aged through their third or fourth year of life. PATRON DE MUDA DE LAS PLUMAS DE VUELO Y EDAD EN PJ•JAROS CARPINTEROS DE NORTE •CA Sinopsis. --Se examinaron 1399 especimenes de p•jaros carpinteros de Norte Am6rica para determinar el patr6n de reemplazo de las plumas de vuelo y su utilidad para determinar la edad. Durante la primera muda preb•sica las primarias y las rectrices son reemplazadas en su totalidad en la gran mayoria de las especies y retenidas en dos de 6stas. En contraste, todas las especies tipicamente retienen las secundarias y las cobijas primarias durante la primera muda preb•sica y algunos individuos de la mayoria de las especies retienen de forma regular hasta seis de las secundarias. El reemplazo de las cobijas primarias durante la segunda muda preb•sica es incompleto, remplaz•ndose consecutivamente de 0-5 cobijas exteriores. Este retraso en el reemplazo de las cobijas primarias, el cual no corresponde al reemplazo de las primarias, puede set 6nico en los carpinteros (y quiz•s en algunos martin pescadores). Combinando el patr6n de retenci6n de algunas plumas, las diferencias en los patrones de coloraci6n y desgaste ntre el plumaje de juvenil y el de los adultos, se podria determinar la edad de p•jaros carpinteros en su tercer y cuarto afio de vida. Woodpeckers have long interested North American ornithologists researching systematics, behavioral ecology and other topics of life history (e.g., Howell 1952; Koenig and Mumme 1987; Morrison and With 1987; Selander and Giller 1966; Short 1965, 1971, 1982). It is thus surprising that so little attention has focused on molt in this group. Differences in the timing and extent of molts can lead to accurate aging of woodpeckers, a vital component to increasingly important studies on reproductive success, population ecology and conservation-related management. Historically, a complete annual prebasic molt was assumed to occur in both juveniles and adults of most species of North American woodpeckers (Bent 1939, Forbush 1927, Howell 1952, Oberholser 1974, Stone 1896). Test (1945), Stresemann and Stresemann (1966), and George (1972) were the first to point out that the secondaries are not replaced during the first prebasic molt in certain species. George (1972) further indicated