Observation of Plectrophenax hyperboreus (McKay’s Bunting) mating in late July on St. Matthew and Hall Islands (Alaska)

Plectrophenax hyperboreus (McKay’s Bunting), an Arctic passerine endemic to Alaska (United States of America), breeds primarily on St. Matthew and Hall Islands. Despite its restricted range and conservation concern, key aspects of its breeding ecology remain poorly understood. The typical breeding season spans late May to mid-August, a narrow window shaped by harsh environmental conditions. Understanding variation in reproductive timing is critical, particularly in the context of rapid environmental change. During a field observation on St. Matthew Island in late July, we documented mating behaviour well beyond the expected peak breeding period. Using direct behavioural observations, we assessed the timing of reproductive activity relative to the known breeding phenology of the species. Our findings suggest the possibility of either a second brood or a replacement clutch within a single season. This extended reproductive effort may represent an adaptive response to variable conditions and could have important implications for population persistence. These results highlight the need for further study of reproductive strategies in Arctic endemic species under changing climatic regimes.