Although early nocturnal raptors were considered close to day raptors(eagles, hawks …), later studies have shown greater similarity with nightjars and other nocturnal birds (podargos, nictibios, egotelos, etc.).
Based on DNA studies, some authors have come to group these strange birds and nocturnal raptors in the order Strigiformes, although later studies advised to maintain the traditional separation between them.
The classification by the definitive moment, and therefore more commonly used is the following:
| N. Comonn | N. Scientific | Order | Family |
|---|---|---|---|
| Eagle owl | Bubo bubo | Strigidae | Strigiforme |
| Tawny owl | Strix aluco | Strigidae | Strigiforme |
| Long-eared owl | Asio otus | Strigidae | Strigiforme |
| Short-eared owl | Asio flammeus | Strigidae | Strigiforme |
| Llittle owl | Athene noctua | Strigidae | Strigiforme |
| Scops owl | Otus scops | Strigidae | Strigiforme |
| Boreal owl | Aegolius funereus | Strigidae | Strigiforme |
| Barn owl | Tyto alba | Tytonidae (lechuzas) | Strigiforme |
The differences between the two families are clear and are based on morphological characters, such as the following:
| Caracter | Strigidae | Tytonidae |
|---|---|---|
| Skull | Rounded | Elongated |
| Orbits | Big | Small |
| Beak | Short, curvy and width | Long, straight and stretch |
| Notches at the posterior border of sternum | Two pairs of recesses | Two recesses |
| Tarsus-metatarsus | Short | Long |
| Ears | Symmetrical in shape and size, but left higher than right. | Often asymmetrical in size / shape (right is larger) |
| Furcula | Pneumatic | Not Pneumatic |
| Sawing on the nail of the middle finger | Smooth | Sawed |
| 2nd and 3rd finger | 3rd larger 2nd | Same size |
| Eggs | Rounded | Elongated |
Taxonomic comparison of Owl Royal (left) and Barn Owl (right).
