(A. acadicus) in North America. Both species have been shown to exhibit both monogamous and polygamous lifestyles with a focus on bigyny. However, the boreal owl has been show to exhibit biandry as well. Mate choice Vocalizations Mate choice in this genus is largely related to auditory vocalizations (a form of sensory exploitation). A quiet species through most of the year, the northern saw-whet owl male produces a bell-like or “series song” advertisement call. Generally, it can be heard early morning or on bright nights from March – May (the breeding season) to attract females. The calls are believed to be relatively different between individuals, suggesting they may play a role in individual identification by the females. After pairing with a mate, vocalizations are very limited and appear to be related to territory or offspring defence. In contrast, the boreal owl produces a “staccato song” starting around dusk, and ending around midnight in the late winter and early spring. The call serves to attract females and becomes increasingly persistent as time without a mate passes. Some research suggests that unlike the Northern saw-whet owl, a variation of the male call persists after mating throughout the reproductive cycle for defense, aggression, or to convey information about prey. This suggests that vocalization may be used in this species beyond mate attraction and possibly as a contact call. Nest and territory quality Aside from vocalization, females in this genus may choose males based on nest or territory quality. For example, in boreal owls, the number and quality of nest holes or boxes defended by males is a factor in female reproductive effort. The number and quality of nests appear to serve a direct benefit to females (direct benefit hypothesis), as it provides protection from predation, as well as access to food resources, as good nest quality can be indicated by access to prey (i.e. small mammals). Female boreal owls’ reproductive success can decline in polyterritorial polygamous situations, as females are unable to discriminate previously paired and unpaired males (also known as the deception hypothesis). It is also important to note that increasing polygamy levels leads to decreased reproductive success in secondary females. Limited research has been conducted into mate choice of the Northern saw-whet owl in relation to territory quality. Some researchers suggest they follow a similar trend to boreal owls, where the quality of nests is a direct benefit to the female