Northern Saw-whet Owl

Adults are 17–22 cm (6.7–8.7 in) long with a 42–56.3 cm (16.5–22.2 in) wingspan. They can weigh from 54 to 151 g (1.9 to 5.3 oz) with an average of around 80 g (2.8 oz), making them one of the smallest owls in North America. They are similar in size to the American robin (78.5 g). Northern saw-whet owls do not exhibit sexual dimorphism in their plumage, so are often sexed by size dimorphism—females are larger than males. Females on average weigh 100 g and males on average weigh 75 g. Northern saw-whet owls have porphyrin pigments in their flight feathers. Voice: The northern saw-whet owl makes a repeated tooting whistle sound. Some say they sound like a saw being sharpened on a whetstone. These calls are usually produced by males searching for mates, so they can be heard more often beginning in January and continuing through the end of the breeding season in early July. Despite being more common in spring, they do vocalize year round.