Re-expression of songs deleted during vocal development in white-crowned sparrows, Zonotrichia leucophrys

White-crowned sparrows learn and produce multiple song types as juveniles, but most individuals stop singing all except one by the end of the first si nging season. This single song type is generally maintained throughout adul thood. We demonstrate that, at the start of the second and subsequent singi ng seasons, this species can recall songs that had been deleted during the first singing season. The re-expression of song occurred in both the oriant ha and the gambelii subspecies. Although all our males recrystallized the o riginal song in the second year, our results indicate a mechanism for seaso nal song change without new song memorization. The traditional dichotomy of closed-ended versus open-ended learning is inadequate for birds that learn early in life but can change their song output seasonally We suggest that species can exhibit a closed sensitive period for song memorization and fir st production, with the ability to recall deleted songs later in life. This type of learning, selective attrition followed by subsequent re-expression , may be used by some species currently considered open-ended learners. (C) 2000 The Association for the Study of Animal Behaviour.