Type of phrase in a sentence

Question

Viral encephalitis is a disease transmitted by mosquitoes from infected small animals**, usually birds and rodents,** to humans.

In this sentence, what is the structure of ''usually birds and rodents''? Is it ''appositive structure'' or ''elips''?

Answer 1

While it is common to teach appositives as noun-phrases modifying a noun antecedent (e.g. John, a lazy student, slept through the lecture.), they actually come in more diverse forms:

1. Nominal, which modifies the antecedent noun with a noun phrase; e.g., John, a lazy student, slept through the lecture.
2. Adjectival, which modifies the antecedent noun with an adjective phrase; e.g. Helen, upset about John's snoring, gave him detention.
3. Prepositional, which modifies the noun with a prepositional phrase; e.g. John, in the detention room, had to miss the game.

Clearly, appositives are a more diverse and robust structure than one might think initially! In fact, beyond these three primary types, they can also include adverbs, as in your example.

I've left a source below that examines the exact function of adverb function in appositives; of interest for you might be the examples from part number 7. I've reproduced one such example for your convenience:

completely: The eastern arm is a golden building called the Café deParis, *completely rebuilt in 1988, which houses restaurants, sidewalk cafes and one-armed bandits. (New York Times online, ‘Churchill slept here’, 04/03/90)

http://www.academia.edu/1505474/An_analysis_of_adverbs_in_appositives