From Badger Run Wildlife Rehab
If you're an owl, the shape and size of your talons reflect what you mainly eat.
Different species of owls can have very different diets. There are Fish Specialists (FS), Insect Specialists (IS), Small Mammal Specialists (SMS), Generalists (G), and Seasonal Small Mammal Specialists (SSMS). So, it would make sense that owls would need different equipment (talons and feet) to capture, restrain, and kill a fish vs. a squirrel vs. a moth.
Researchers evaluated 15 different owl species for talon curvature, talon thickness and width, digit strength, and digit reach. And yes, they found that you are (or at least your feet are) what you eat if you're an owl.
Examples of generalists are Great Horned, Eurasian Eagle, and Barred owls. Small mammal specialists include Great Gray, Long-eared, and Barn owls. Some owls specializing in insects include Flammulated, Screech, and Scops owls. Fish eaters include Blakiston's and Buffy Fish owls.
Seasonal small mammal specialists usually stick to small mammals, but will make adjustment for time of year as needed. An example of this would be Snowy owls that will broaden their diet to include waterfowl and other birds if need be.
Source: C. Cameron et al., J of Zoology, 2023 doi:10.1111/jzo.13044.
I'm surprised with the difference between the small mammal and the seasonal small mammal. It is like that seasonal adaptability turned made them more generalists than the generalists.
I just found the whole paper, so I will try to get the opportunity to read it today and see if I can understand any further info. It's only about 8 pages, and there are more charts, graphs, and tables, so maybe we can get some more insight there.
If anyone beats me to it, don't be afraid to weigh in.