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Owls

Lisa (Elisa) Fosco

Natural History

Owls make up the order Strigiformes and are divided into two distinct families based on natural
history as well as anatomical differences. Barn owl species make up the family Tytonidae, which
includes about 14 species. The family Strigidae, also known as the “typical” owls, includes about
167 species worldwide and is further divided into two subfamilies: Striginae (long‐eared and for-
est‐adapted owls) and Buboninae (small‐eared and visual hunting species.)
Owls are found on all continents except Antarctica. Most species are nocturnal and all are hunt-
ers that will scavenge only when necessary. They hunt by both sight and sound, and most species
have feathers adapted for silent or noiseless flight. In general, owls are relatively sedentary, and
typically only the smaller and more specialized species are migratory.
The reproductive period of owls tends to be prolonged compared to other raptor species. They
have a long incubation period, and the pre‐fledging period is also comparatively long. Cavity‐nest-
ing species usually remain securely hidden in their nest for most of their pre‐fledging time where
they are visually isolated from their surroundings. Unlike other owls, most of these species use no
visual cues in any of their food‐begging behaviors.
Tree‐nesting species tend to grow and develop at a faster rate. They are more physically active
and mobile, climbing up and around the nest as legs develop. This behavior often results in owlets
of these species leaving the nest before they are flighted. Unlike most other avian and raptorial
species, this is considered a natural or normal behavior and rarely impacts parental care. Also,
unlike other raptors, juvenile owls of most species tend to remain with the parents for (compara-
bly) longer periods of time after fledging while they are learning and refining their hunting skills.

­ Criteria­for Intervention

Whenever possible, healthy owlets should be returned to the nest site for familial recovery. Healthy
owlets are well‐fleshed, bright‐eyed, and responsive to all stimuli. Feathered nestlings are usually
accepted when placed safely off the ground in the vicinity of the nesting tree or structure. If the
owlet repeatedly grounds itself, is in a structurally questionable nest, or is in an urban or visible
location, protective measures may be helpful. Temporary barriers surrounding the tree base at a

Hand-Rearing Birds, Second Edition. Edited by Rebecca S. Duerr and Laurie J. Gage.
© 2020 John Wiley & Sons, Inc. Published 2020 by John Wiley & Sons, Inc.