In this food web, birds would be classified as

Omnivores

Explanation:

Omnivores refer to those organisms that are dependent on both the plants as well as animals. For example, Human beings, turtles and lizards.

Birds are also often considered to be omnivores. They are mostly dependent on the plants and their seeds, but their main source of protein is insects and worms, which most of the birds directly eat. For example, eagle, crows.

Thus, in a food web, birds are classified as omnivores.