AGE-RELATED TIMING AND PATTERNS OF PREBASIC BODY MOLT IN WOOD WARBLERS (PARULIDAE)

Abstract

We compared timing and patterns of prebasic body molt between hatch-year (HY) and after-hatch-year (AHY) American Redstarts (Setophaga ruticilla) and Yellow Warblers (Dendroica petechia) in Ontario, Canada. In each body region of both species, there was no age-related difference in the proportion of individuals undergoing molt. Furthermore, there was no difference between HY and AHY American Redstarts in the overall timing of body molt; molt started in early July and lasted until early September. In contrast, HY Yellow Warblers started body molt in late June to early July, while adults began body molt in mid-July. Both American Redstarts and Yellow Warblers displayed age-class differences in the intensity and timing of molt among specific body regions. External factors (e.g., food availability and geographical distribution), and internal factors (e.g., physiological status) may contribute to variations in body molt timing observed in these two species.