Wing loading in 15 species of North American owls

Abstract

Information on wing morphology is important in understanding the mechanics and energetics of flight and in aspects related to reversed sexual size dimorphism in owls. I summarized wing span, wing area, wing loading, root box, and aspect ratio calculations from the available literature and from 113 owls examined in this study. Wing loading estimates for 15 species ranged from 0.211 to 0.545 g/cm². Measurements were available for both male and female owls in 12 species; males of all species had a lower wing loading. In five species with sufficient sample sizes, males had significantly lower wing loading (18 percent on average) than females of the same species. Root box area (the area between the wings) averaged 15.4 percent of the combined wing and root box areas. Aspect ratio, the ratio of the wing span to mean wing width, ranged from 4.84 to 8.90. Information is presented for the following species: Barn (Tyto alba), Short-ea ed (Asio flammeus), Long-eared (A. otus), Great Horned (Bubo virginianus), Barred (Strix varia), Great Gray (S. nebulosa), Northern Spotted (S. occidentalis caurina), Snowy (Nyctea scandiaca), Eastern Screech (Otus asio), Western Screech (O. kennicottii), Flammulated (O. flammeolus), Northern Pygmy (Glaucidium gnoma), Northern Saw-whet (Aegolius acadicus), Boreal (A. funereus), and Burrowing (Speotyto cunicularia) Owls.

Parent Publication

• Biology and conservation of owls of the Northern Hemisphere: 2nd International symposium

Citation

Johnson, David H. 1997. Wing loading in 15 species of North American owls. In: Duncan, James R.; Johnson, David H.; Nicholls, Thomas H., eds. Biology and conservation of owls of the Northern Hemisphere: 2nd International symposium. Gen. Tech. Rep. NC-190. St. Paul, MN: U.S. Dept. of Agriculture, Forest Service, North Central Forest Experiment Station. 553-561.