Fairly short list:
Barn owl (Belgium / france / spain / canada)
Long eared owl (Belgium / netherlands)
short eared owl (Belgium / netherlands)
eagle owl (Belgium / spain)
little owl (Belgium / france / spain)
Tawny Owl (Belgium)
African Eagle Owl (Tanzania)
Great Horned Owl (Canada / Arizona)
Flamulated Owl (Canada)
Barred Owl (Canada)
Whiskered Screech Owl (Arizona)
Elf Owl (Arizona)
Burrowing Owl (Arizona)
13 species so far.
Barn owl (Belgium / france / spain / canada)
Long eared owl (Belgium / netherlands)
short eared owl (Belgium / netherlands)
eagle owl (Belgium / spain)
little owl (Belgium / france / spain)
Tawny Owl (Belgium)
African Eagle Owl (Tanzania)
Great Horned Owl (Canada / Arizona)
Flamulated Owl (Canada)
Barred Owl (Canada)
Whiskered Screech Owl (Arizona)
Elf Owl (Arizona)
Burrowing Owl (Arizona)
13 species so far.