This species occurs in the Pribilofs on a nearly annual basis. Cuckoos typically appear during strong west winds during the second week of June, and are possibly anywhere on the island. Many sightings involve flyby birds which are not refound, but occasionally an individual will linger for a few days. Flyby sightings are best left as Cuckoo sp., as Oriental Cuckoo can also occur on our shores. The identification of Cuculus Cuckoos is quite difficult. On hepatic (red) morph birds look at the rump. If barred then you have an Oriental, if unbarred then it is a Common. For gray morph birds look at the width of the belly barring (broader in Oriental), length and curvature of the bill (longer and more curved in Common) , color of the vent (often yellowish on Oriental, white on Common) and relative color of the mantle as compared to the wing coverts (pale gray mantle for Common, slate gray in Oriental). It is believed that cuckoos seen in spring and early summer are more likely to be Common Cuckoos, while those seen in summer are more likely to be Orientals.