Which of the following is not a portion of a raptor's wing?

The cere is the correct choice because it is not a part of a raptor's wing but rather a fleshy, often colorful area located at the base of the beak, typically above the bird's nostrils. This structure can be important for various functions, including the display and identification of species, especially during mating season.

In contrast, coverts, alula, and secondaries are all integral components of a raptor's wing anatomy. Coverts are the feathers that cover the bases of the longer flight feathers, providing a smooth surface for air to flow over the wing. The alula is a small set of feathers on a retractable digit that aids in controlling flight, particularly during landing or slow flight. Secondaries are the feathers on the inner part of the wing that contribute significantly to lift and control while flying. Knowing the correct anatomy of a raptor's wing is crucial for falconers, as it impacts the bird's flight performance and overall health.