The article presents the results of a comparative analysis of post-juvenile molt in two widespread passerine species – the Willow Warbler (Phylloscopus trochilus) and the Reed Bunting (Schoeniclus schoeniclus) – in the conditions of the extreme North (Pasvik Nature Reserve, Murmansk region). The study was conducted at the Varlam Island research station in 2022–2024. Birds were captured using mist nets, followed by in vivo description. The stages of post-juvenile and post-breeding molt were assessed based on plumage condition in individual pteryla using standard methods, separately for young and adult individuals. In fi rst-year birds, feather replacement was evaluated according to stages described in the literature. In adults, stages were distinguished based on the degree of flight feather replacement. The study revealed signifi cant interspecifi c diff erences in molt dynamics and duration, linked to their migratory strategies. The Willow Warbler exhibited a synchronous and concentrated pattern of feather replacement (peak activity August 6–11, duration ~15 days), whereas the Reed Bunting underwent a more prolonged process (July 28 – August 29, ~25–30 days) with signs of bifi dity. It was found that northern populations of both species display specifi c adaptations: reduced molt completeness, earlier onset of the process, and partial overlap with the fi nal stages of nesting. The Reed Bunting’s status as a short-distance migrant and granivorous diet allows for more fl exible regulation of pre-migratory preparation, whereas the Willow Warbler, being a long-distance migrant, replaces its plumage more rapidly under the constraints of the waning polar summer. The obtained data enhance the understanding of avian phenological adaptations to extreme latitudes and are relevant for predicting their responses to climate change.