and therefore a determining factor. Northern saw-whet owls' nest locations appear less linked to the availability of small mammals, as they have a greater variety of prey options and tend to be more nomadic after each breeding season. Reversed size dimorphism Lastly, size of males may play a role in mate choice in some species. The males in this genus provide direct benefit to females such as protection, territory, and resources. As a result, large male size (and smaller female size) would theoretically be more advantageous. However, in the boreal owl, this is not the case. Females tend to be larger and heavier than the male mates they choose, some suggesting this is the result of the starvation hypothesis (selection acts on females to increase ability to withstand long periods of time without food in polygamous lifestyles). Another theory suggests that females purposely choose short-winged, light males, as they would be able to hunt at lower energetic costs and compete for territory more efficiently than larger, long-winged individuals. This would provide the female with greater material benefits for her offspring. Reversed size dimorphism is also observed in northern saw-whet owls, but the differences are much more difficult to observe, as the species is smaller overall; the role of this in mate choice is unclear. Contests Relating to the observed size dimorphism in males, most species compete for territory in this genus, as it indirectly relates to better female mates. The intraspecific competition tends to be dependent on individual flight ability, individuals that can fly more efficiently and effectively tend to get better territory. However, interspecific competition also plays a role. Species in this genus are often smaller than other owls that have similar ranges; as a result, they often are outcompeted for territory by other species. This is especially true in boreal owls, as their range overlaps with the much larger Ural (Strix uralensis) and Eurasian eagle owls (Bubo bubo). As a result, when these species are present, the boreal owl often mates with less desirable subdominant females. Parental Care Parental care in the boreal and northern saw-whet owls is quite similar; females incubate and brood eggs, while males often provide protection, and resources such as food and nesting sites. This trend likely applies across the species in this genus, as some species may be conspecifics (i.e. northern saw-whet and unspotted saw-whet owls). In boreal owls, the level of investment