Aghtadī is from the root gh-d-w (غ د و), denoting setting out in the morning. It is a first-person singular imperfect: “I go out early.” The imperfect can present a characteristic, repeated practice rather than a single dated incident.
In wa-l-ṭayru fī wukunātihā, the wāw introduces a circumstantial clause. Al-ṭayru is its subject, and fī wukunātihā functions as its predicative prepositional phrase. Wukunāt denotes the birds' places of shelter or lodging.
Instead of stating the hour numerically, the poet uses the still-sheltered birds as a clock. The quiet background contrasts with the vigor of the rider preparing to move.